Julian's Blog

Reptile Fossil Hunting Video

2012-01-24T17:17:00.000+13:00

Tyre Tubing the Mangahouanga Stream

2012-01-17T14:26:00.004+13:00

On our second day in the Maungataniwha Forest, some of us explored the lower Mangahouanga Stream using the well established kiwi river transport method of tyre tubes. This allowed us to visit parts of the river that would otherwise be very difficult to reach. Initial access to the river was via bush bashing through pine and then native forest, and down a steep climb to the water's edge.

In the second photo I am following Ben towards our next fossil hunting stop off.

James Crampton gets speedy on one of the faster sections of the stream.

Where possible we stopped to closely inspect each boulder for the tell tale signs of fossil bones, wood or shells.

Here is an example of fossil reptile bone (centre of photo). Because of the hard surrounding rock, these bones are not removable except using painstaking laboratory methods over many months. Although we found several interesting fossils, we were surprised that they did not seem to be as abundant as they were in 2009. This will have been due to the higher river levels, and the random redistribution of boulders during occasional flood events.

Pete Shaw, forestry conservation manager, about to launch down some rapids.

Finally we arrived at the Rockhounds Huts, - built by Joan Wiffen and her team in the seventies as a base for their summer explorations of the Mangahouanga Stream.

Reptile Fossils from an Unexplored Valley.

2012-01-16T17:08:00.002+13:00

The first barrier to accessing Mangahouanga Stream

Three years ago I visited Mangahouanga Stream in Hawkes Bay along with a group of GNS Scientists. This is the area where Joan Wiffen, New Zealand's famous "Dragon Lady" found the only known bones of dinosaurs from New Zealand, as well as various marine reptiles, prior to her retirement from fieldwork about ten years ago. I described this visit in my blog at the time.

What I didn't mention in my blog was the existence of a remote valley that we believe might have only been visited once by a geologist prior to 2009. The valley is a tributary of the Mangahouanga Stream.

Pete Shaw with marine reptile bones from Wiffen Valley

As well as being protected behind a large privately owned forestry block, this hidden valley is made particularly inaccessible by a high waterfall and densely forested ridge. Along with the forest manager Pete Shaw, I had managed to enter the valley via very steep and rugged bush in 2009. We spent several unforgettable hours travelling down the un-named stream (now called Wiffen Stream), finding several Cretaceous reptile bones in large concretions.

The photo shows Pete in 2009 with the prize find of the day moments after he pulled it out of the stream. It is a cluster of several reptile vertebrae, subsequently identified as belonging to an elasmosaur. Although heavy, Pete managed to carry it out, whereas most of the fossils we found that day had to be left in place.

Last week I returned to the area with a team of GNS palaeontologists along with Victoria University student Ben Hines. One of our aims was to explore the hidden Wiffen Valley to have a closer look at its geology and fossils,

This photo shows GNS palaeontologists James Crampton and John Simes in the upper section of Wiffen Stream.

There were log jams, tree trunks and waterfalls to negotiate as we travelled down the stream.

We took our time to throughly check out the boulders for fossils as we moved slowly along.

The reptile bones are typically found in very hard concretions like this one. We were unable to identify this particular bone, or remove it from the concretion, so it was left in situ along with several others that we saw.

In this photo Marianna Terezow of GNS Science can be seen tackling the dense bush that must be traversed to access and return from the hidden valley.

Moa Hunting

2012-01-06T15:14:00.003+13:00

Takaka limestone country

Whilst on holiday in the Nelson area last week, I went for a look around the limestone plateau of Takaka Hill, not far from the huge natural shaft of Harwood's Hole. I managed to persuade a couple of friends to come along for the adventure.

The area is very rugged, covered with rock outcrops and tangled vegetation. There are many caves (see my earlier blog post from January 2010) and my particular interest was to look for small vertical shafts that might have acted as lethal traps to the moa that once roamed the area.

The delights of moa hunting

With some careful searching, it did not take long to find some cave entrances. Some of the shafts are very deep and obviously care is needed in this environment to avoid the fate of becoming entombed and fossilised just like the moa that we were hoping to discover.

As you can see, some of these caves are very small. With a bit of wiggling and squirming, we were able to push down into them.

Moa bones lie scattered at the bottom of a cave

Sure enough, a couple of them contained parts of moa skeletons lying at the bottom. In this image you can see a variety of bones, including leg bones and a pelvis. The number of different bones that we saw in this cave indicated that at least three or four moa individuals had been caught there.

Moa pelvis

This is a close up of the pelvic bones of a moa

Moa bones in narrow fissure

At the very bottom of this cave, there were more bones visible, but the fissure was too tight to get close to.

We were very satisfied with our discoveries, and happy to leave the bones in place for future rediscovery and study.

Groundwater dating around Lake Rotorua

2011-09-29T14:20:00.005+13:00

"If you want to have an insight into a society, just look at the water in the streams and rivers"

Uwe Morgenstern, GNS Science's specialist in groundwater and ice dating, runs a laboratory that is the most accurate water dating facility in the world. His methods are so precise, that they are four times more accurate than the next best lab, out of a total of about 70 such laboratories worldwide.

In a nutshell, groundwater dating works like this: Cosmic rays from outer space interact with our atmosphere and form very small amounts of tritium, a radioactive hydrogen isotope with a half life of 12.3 years. This cosmogenic tritium eventually becomes part of the atmospheric water, with one normal hydrogen atom replaced by a tritium atom. As this water (or snow) precipitates and becomes incorporated into groundwater, it is no longer interacting with the atmospheric tritium, and its tritium concentration starts to deplete due to radioactive decay. Measurement of tritium concentrations in groundwater allows the time since it fell from the sky to be calculated, back to a maximum age of about 100 years.

Over the last few days I have been out in the field with Uwe and Mike Toews (a groundwater modeller at GNS Science) sampling the streams and springs around Lake Rotorua.

The water quality in Lake Rotorua, and the many other smaller lakes in the area, is very important to the local community, for drinking, agriculture, recreation and tourism, including world famous trout fishing.

Farming, especially dairy, beef and sheep farming, is also a very important activity around the region. Farm effluent and fertilisers cause nutrients, particularly nitrates, to enter the groundwater and eventually get transported into the lake. As a result the chemical balance changes, with potential negative impacts such as the growth of toxic algal blooms and other ecological changes such as impacts on fish.

To understand the effects of land use on the water quality in the ground, in streams, rivers, and lakes, you need to not only monitor the concentration of pollutants in the water, but also measure the age of the groundwater.

For this reason, Uwe has been studying the groundwater around Lake Rotorua for a number of years. With such large groundwater systems, it can take many years or decades for polluted water (for example nitrate from farms) to reappear back on the surface in streams and lakes. Because of this time lag, large groundwater systems can silently become
contaminated until the contaminated water reaches the spring discharge. Then it will also take the same long time to flush the contaminated water out of the groundwater system.

The data Uwe is coming up with shows a range of time spans for the input of lake water, from very quick (months) to over a hundred years in the case of Hamurana Spring. The map shows coloured dots representing the springs and streams that were on our list for resampling.

“Drop, cover and hold on” is the best advice…

2011-08-10T15:03:00.005+12:00

How to Respond to an Earthquake in New Zealand

This article has been compiled by Karen Hayes at GNS Science with the help of experts including Julia Becker and David Johnston from GNS Science, and Adrian Prowse from the Ministry of Civil Defence and Emergency Management.

Information about the ‘Triangle of Life’ has been disseminated via a chain e-mail that has been in circulation since the 1990’s. The claims regarding the “Triangle of Life” earthquake response are widely discounted.

The "Triangle of Life" is not an advocated approach to responding to earthquakes and has been internationally dispelled as being unsound practice. In modern countries such as New Zealand, most buildings are constructed well and you are more at risk of getting hurt from objects flying around rooms.

Therefore people should "drop, cover and hold on" in an earthquake. The New Zealand Ministry of Civil Defence and Emergency Management includes the recommended "drop, cover and hold on" advice on their webpage and has a fact sheet you can download: I recommend you print the two page fact sheet and stick it on your fridge to remind yourself and your family of how best to respond in an earthquake.

Let’s just take a quick moment to consider one of the claims in the “Triangle of Life” chain e-mail. It states that children have been killed in past earthquakes because they were under their school desks and these were flattened when the building collapsed. It states that they would have been safe had they been lying beside the desk, instead of under it, where a supposed ‘void space’ should be. Realistically speaking, if the desk was not substantial enough to protect the child under it and was flattened by the collapse of a building, then any void space wouldn’t have been large enough to protect the child lying on the floor next to it either. A child is better off getting under the desk to prevent them from being struck by falling items. In the Christchurch earthquake on 22 February 2011, when children did “drop, cover and hold on” under desks, there were no significant injuries reported from any school in the Christchurch area. Building codes designed to reduce earthquake risk will ensure that buildings are unlikely to collapse in the first place.

Why Rescuers and Experts Recommend Drop, Cover, and Hold On

(the following is taken directly from the earthquakecountry website)

Trying to move during shaking puts you at risk: Earthquakes occur without warning and may be so violent that you cannot run or crawl; you therefore will most likely be knocked to the ground where you happen to be. On that basis, it is best to drop before the earthquake drops you, and find nearby shelter or use your arms and hands to protect your head and neck. "Drop, cover, and hold on" gives you the best overall chance of quickly protecting yourself during an earthquake... even during quakes that cause furniture to move about rooms and even in buildings that might ultimately collapse.

The greatest danger is from falling and flying objects: Studies of injuries and deaths caused by earthquakes over the last several decades show that you are much more likely to be injured by falling or flying objects (TVs, lamps, glass, bookcases, falling masonry, etc) than to die in a collapsed building. "Drop, cover, and hold on" (as described above) will protect you from most of these injuries.

If there is no furniture nearby, you can still reduce the chance of injury from falling objects by getting down next to an interior wall and covering your head and neck with your arms (exterior walls are more likely to collapse and have windows that may break). If you are in bed, the best thing is to stay there and cover your head with a pillow. Studies of injuries in earthquakes show that people who moved from their beds would not have been injured had they remained in bed.

You can also reduce your chance of injury or damage to your belongings by securing them in the first place. Secure top heavy furniture to walls with flexible straps. Use earthquake putty or velcro fasteners for objects on tables, shelves, or other furniture. Install safety latches on cabinets to keep them closed.

Building collapse is less of a danger: While images of collapsed structures in earthquakes around the world are frightening and get the most media attention, most buildings do not collapse at all and few collapse completely. In earthquake-prone areas of New Zealand, as in many other countries, strict building codes have worked to greatly reduce the potential of structure collapse. However, there is the possibility of structural failure in certain building types, especially unreinforced masonry (brick buildings) and in certain structures constructed before the latest building codes. Rescue professionals are trained to understand how these structures collapse in order to identify potential locations of survivors within "survivable void spaces".

The main goal of "drop, cover, and hold on" is to protect you from falling and flying debris and other non-structural hazards, and to increase the chance of your ending up in a “survivable void space” if the building actually collapses. The space under a sturdy table or desk is likely to remain even if the building collapses – pictures from around the world show tables and desks standing with rubble all around them and even holding up floors that have collapsed. Experienced rescuers agree that successfully predicting other safe locations in advance is nearly impossible as where these voids will be depends on the direction of the shaking and many other factors.

If you receive the email in future...If you receive the “Triangle of Life” email, you should reply to the sender and let them know the advice is wrong, and point them in the direction of correct information about how and why to "drop cover and hold on"!

Summary:

Do:

• Identify safe places at home and at work such as tables, sturdy furniture and interior walls, and share this information with other family members and work colleagues

• Shelter under something as quickly as possible when the shaking starts and hold on to prevent it moving away (drop, cover and hold on)

• Secure large objects and cupboard doors to minimise their movement during an earthquake

• Store heavy items lower – especially in kitchens

• Consider reinforcing or removing chimneys

• Know where to turn off electricity and gas supplies if necessary as fire is the greatest hazard following an earthquake

Don’t:

• Run outside, especially in a city or built up area, as you greatly increase your risk of injury from falling glass and masonry. Instead, act quickly to “drop, cover and hold on”

• Remain near large glass panes such as office partitions

• Wait to see if the shaking gets worse. Act quickly when you first experience earthquake shaking

• Turn off gas unless you smell gas after the shaking stops

Further information

GNS Science has a number of video clips posted on YouTube. These will be of interest to a lot of you, but particularly for residents of the Canterbury area still being harassed by nature, there are a number explaining the science of earthquakes, research and the like. CERA are also posting videos of their media briefings.

www.civildefence.govt.nz/

www.geonet.org.nz/

www.earthquakecountry.info/dropcoverholdon/

http://www.daretoprepare.org/

www.earthquakesolutions.com/id44.html

http://en.wikipedia.org/wiki/Triangle_of_Life

http://science.howstuffworks.com/nature/natural-disasters/survive-earthquake5.htm

Te Mata Peak

2011-08-10T11:24:00.005+12:00

Last week, following my visit to Castlepoint I also headed further north to Hawkes Bay. State Highway 2 runs parallel to the central North Island mountain ranges, which had just received fresh snow from a recent southerly blast, to provide a classic New Zealand pastoral scene...

Te Mata Peak near Havelock North is a popular spot for runners, hikers and paragliders. On a clear day there are spectacular views across the landscape from the coast all the way to the volcanic peaks of Ruapehu in the centre of the North Island.

The buttresses of Te Mata Peak are made of Awapapa Limestone. This formation, which is about three and a half million years old, is also found to underly other nearby coastal hills in the Hawks Bay area. It was formed along a string of offshore shallow water shoals and tidal banks. At that time the coastline was about 40 kilometres to the west, along the present edge of the central mountain ranges. In between, the sediments of the same age are mudstones that represent much deeper water than the Awapapa limestone.

Armed with my Kiwi Fossil Hunter's Guide, I located a way to climb down on the eastern side of the peak to have a close up look at the cliff section just north of a radio mast, a few hundred metres down from the summit car park.

Although there isn't a wide variety of fossils in these rocks, there were some vary well preserved specimens such as these examples of a scallop called Phialopecten marwicki, as well as barnacles, oysters, brachiopods (lamp shells) and coral-like bryozoans.

In places, thinly bedded layers of shell fragments
show that water currents were strong, indicating shallow water conditions when the limestone was deposited.

Careful research by scientists has found that the alternating bands of hard, strongly cemented grey limestone and softer, orange sandy layers represent cycles of sea level change during the Pliocene Epoch.

The harder layers formed because at shallower depths there were more water currents, which allowed more calcium carbonate rich water to flow through the sediments. This would have been during the ice ages, when huge amounts of sea water were locked up in polar ice caps, thus lowering the sea level.

The warm period (interglacial) deposits have less carbonate cement to strengthen them and are therefore etched out more easily by erosion. These deeper water sediments are now underneath overhangs of the harder layers. The example here had clusters of large oyster shells scattered within it.

Castlepoint and the Kiwi Fossil Hunter's Handbook

2011-08-09T15:32:00.005+12:00

James Crampton and Marianna Terezow's The Kiwi Fossil Hunter's Handbook won the LIANZA Elsie Locke Award in the non fiction category. With James away from town, Marianna attended the awards ceremony last night to accept the prize. Here you can see clearly that Marianna was one of the people behind the book!

Armed with the fossil hunter's guide, I recently went to visit a couple of the localities described within it. The first was Castlepoint, a popular spot on the Wairarapa coast of the North Island. It is a dramatic rocky promontary, enclosing a lagoon and extending out to sea. Just to the south is a steep track leading up to the top of high cliffs overlooking the bay. The spectacular coastline is a favourite spot for fishing and hiking as well as exploring for fossils.

The Castlepoint Reef is jam packed with fossil fragments, indicating that it was created under the sea and has since been uplifted. The fossils have been dated at about 2.4 million years old. Because of fault lines on either side of the reef, nearby older and softer strata have been uplifted even more, and then eroded away, leaving the hard limestone of the reef to stand proud of the surroundings. The seaward side of the reef is a dramatic cliff, that I looked over with care...

From studying structures such as slumped (buckled) beds and mixed rock fragments within the reef, geologists think that it represents the debris that accumulated in a steep sided canyon. Material occasionally avalanched down into the depths from above, mixing up fossil fragments and rocks into the sedimentary sequence. Here you can see an example of these disturbed beds, with a scattering of white fossil shells included.

In this photo you can see that much of the reef is made up of densely packed shell fragments ( in this case clams and barnacles) that are piled up on top of each other.

This univalve is similar to some that are found today on many New Zealand beaches.

Both cold water and warm water fossil shell species can be found in the Castlepoint reef . It is thought that at least two ice age cycles are represented in the rocks, each lasting about 40 000 years.

The fossils assemblages at Castlepoint show a mixture of deeper water species that would have lived several tens of metres below the surface in the bottom of the canyon, and shallower types that were washed down from the sea floor alongside.

This small scallop, called Mesopeplum convexum, was a filter feeder, sitting on the sand of the sea floor.

Where was that earthquake and how big was it?

2011-08-01T17:01:00.001+12:00

We have a new GNS Science video today that explains how scientists locate the source of an earthquake and then calculate the magnitude. John Ristau, from GNS Science's GeoNet programme talks through the steps of the process...

And in case you missed this earlier video, here is Matt Gerstenberger, describing how earthquake forecasts are made using statistics derived from global aftershock sequences:

Christchurch Quake Q&As

2011-07-01T16:41:00.003+12:00

Kelvin Berryman (Image: Stuff.co.nz)

The following questions were posted by a Christchurch resident on our GNS Science Facebook page. I think they are good questions which will be of interest to many people in the quake affected area. I have re- posted them here, along with answers provided by Kelvin Berryman, a leading earthquake scientist at GNS Science, and manager of the Natural Hazards Research Platform. Kelvin was awarded the Queen's Service Order in the 2011 Queen's Birthday Honours recently for his services to science.

Request on behalf of everyone who lives in Christchurch, we are all so afraid and re-thinking our futures - it would be good if some questions could be answered in plain English for us:

1. Are you aware of ALL the major fault lines in Canterbury -

Yes I think the research community knows where the MAJOR faults are. However, the current Canterbury earthquakes are being generated by some quite moderate-sized faults - they are buried beneath many 100's of metres of gravels or the several million year old volcanic rocks of Banks Pensinsula. We cannot see all of this size of fault.

Liquefaction volcanoes dot the beach, June 2011

2. Which faults are the biggest risk for large earthquakes?

The faults that are being strained the hardest have the highest chance of producing large earthquakes. In the South Island these are the Alpine, Hope (through Hanmer to Kaikoura), Porters Pass (look to the right the next time you drive over Porter's Pass toward the West Coast to see the fault line crossing the hillsides), and further north into Marlborough. Unfortunately all faults that are being strained have to break some time, and this is what is happening around Christchurch at present. These are very rare events for Canterbury, although I realise completely this scientific understanding provides no solace for the people who have lost so much.

Ready to topple... Port Hills boulder

3. What are the future implications, area by area e.g. which are the safest areas to live in?

In Canterbury the safest areas are probably those farthest from current earthquake activity, and to the west away from the liquefaction susceptible areas are better. In New Zealand areas north and west of New Plymouth and Hamilton have a lot fewer earthquakes than other parts of the country. But remember that other natural hazards like floods, and tsunami have different likelihoods in different parts of New Zealand.

4. What % risk is there of a tsunami - I do understand that there are many faults on our coast line, how sure are you that there is no tsunami risk, vertical or horizontal, and why?

Rockfall at Redcliffs RSA

Canterbury does have a risk of tsunami but the principal source is huge earthquakes occurring in South America, and it takes roughly 12 hours for the tsunami to arrive, so there is plenty of time to be safe. The fault lines offshore of Canterbury are small and not capable of producing a major tsunami, but if you are on the beach when you feel a big earthquake and the shaking goes on for 20 seconds or more then it is important to get several metres above the beach. Go quickly walking, perhaps drive if practical, but watch out for being stuck in a traffic jam at low elevation when simply walking or running for 50-100m is all you need to do. If you live near the coast join a local group, obtain readily available information on self evacuation planning, and make a community plan. The local civil defence officer will help you.

Extreme Shaking

5. Are you - (scientists/geologists in Christchurch) afraid when an aftershock hits, if you shared exactly your feelings thoughts on this issue it could give us all some peace on the subject.

To be honest I think the residents of Canterbury have now have more experience of earthquakes than most earthquake scientists. I think most people whether they are scientists or not are apprehensive when an earthquake starts and will often be afraid too. Perhaps we have the advantage of trying to remember our scientific training when in those few seconds we are thinking about how big will it be. I am sure now that with your experience you know that the really big and damaging earthquakes hit so hard that you are thrown down or find it difficult to move. Fortunately these ones are much less common than the smaller but nevertheless worrying ones.

~ ~ ~ ~

For more geoscientist's answers about the Christchurch Earthquakes, have a look at the 'Ask an Expert' page published earlier this week in the Christchurch Press.

The White Terraces Reappear after 125 years

2011-06-10T11:58:00.003+12:00

On 10th June 1886, exactly 125 years ago today, Mount Tarawera erupted briefly and violently, resulting in the disappearance of the Pink and White Terraces of Rotomahana, and devastation of the landscape. The former lake disappeared and was slowly replaced by the much larger and deeper lake which remains to this day.

This 1880 Charles Spencer image is courtesy of Te Papa Museum

Last January, in a GNS Science led international expedition, Cornel de Ronde and his team rediscovered the Pink Terraces at the bottom of the modern lake, which had been so drastically altered and deepened by the eruption. The Pink Terraces were first spotted in images from a side-scan sonar that was mounted in an autonomous underwater vehicle (AUV) used to survey the lake.

Today Cornel de Ronde announced that the White Terraces have also been found using data retrieved on the last day of the expedition, that had not been analysed until recently. When the Pink Terrace side-scans were first seen, they were nothing like anything that had been observed by the team before. An underwater camera was used to confirm that they did indeed represent the Pink Terraces. (For details of the Pink Terrace discovery watch this video).

Similar looking side scan images have now been found in the location where the White Terraces are expected to have once existed. A horizontal segment of the formations over 150 metres across may be the remains of the silica terraces along the former shoreline of the lake, now tens of metres below water level. It is not yet known whether more of the terraces lie hidden beneath volcanic mud, or whether the rest of them were forever destroyed in 1886. Future exploration may settle this question.

Ron Keam of Auckland University is an expert on the history of the Tarawera Eruption and the Rotomahana landscape. He compiled this map of the former Lake Rotomahana as accurately as possible by detailed study of pre 1886 photographs. The Pink Terraces can be seen on the left (west) side of the lake, with the White Terraces at the top (northern) end, about a kilometre northeast of the Pinks.

The image to the right is the compiled side scan of the part of the modern lake under which the remains of the terraces lie. The long straight lines show the path of the AUV as it progressed up and down the lake area. The red circles show the locations of the two sets of terraces, about 1 kilometre apart. Lower left are the Pinks and upper right are the newly refound parts of White Terraces.

This close up of the side scan image shows the curved overlapping terrace formation on the lower half below the blank, unscanned area. These features are very similar in general appearance to the photographically verified scans of the Pink Terraces found last summer.

(All sidescan images courtesy of our US project partners at the Woods Hole Oceanographic Institution)

For more details have a look at our media release, and watch the video of Cornel de Ronde describing how the discovery unfolded step by step, including the crucial hook shaped landform that first led to the location of the Pink Terraces, followed now by the Whites:

Christchurch Geophysical Surveys

2011-06-02T09:12:00.001+12:00

There has been a lot of ongoing scientific work recenlty to assess Christchurch's future geological risks. In our latest video Vaughan Stagpoole explains the esoteric arts of Geophysics and what the surveys can help us to find out.

Shooting the SAHKE Seismic Survey across the North Island

2011-05-14T13:27:00.003+12:00

The blasts from the seismic survey were detectable by GeoNet as very small local ground tremors along the seismic line last week:

PRELIMINARY EARTHQUAKE REPORT

GNS SCIENCE
GeoNet Data Centre
Lower Hutt, New Zealand
http://www.geonet.org.nz

The following earthquake has been recorded by GNS Science:

Reference number: 3511346/G
Universal Time: 12 May 2011 at 10:24
NZ Standard Time: Thursday, 12 May 2011 at 10:24 pm
Latitude, Longitude: 41.15°S, 175.38°E
Location: 10 km south-east of Featherston
Focal depth: 0 km
Richter magnitude: 2.3

Web page: http://www.geonet.org.nz/earthquake/quakes/3511346g.html

Man-made explosion as part of a science experiment in lower North Island
* * *

Here is a video in which Stuart Henrys explains the seismic survey :

SAHKE - Seismic Array Hikurangi Experiment

2011-05-11T10:10:00.003+12:00

About a dozen field teams have been out over the weekend deploying geophones along the 90 kilometre transect of the SAHKE seismic survey.

The first photo shows some of the Orica contractors loading and priming one of the transect shot holes. 500 kilogrammes of explosive emulsion is being pumped down a 50m bore hole. The pile of gravel in the foreground is used to back fill the hole on top of the explosives. The idea is that the shock wave is directed downwards into the earth rather than up into the air. (Photo by Stuart Henrys)

It is very important that every geophone is in perfect working order and set up in exactly the right way, as there will be no possibility of repeating the survey if anything goes wrong.

The second photo shows Stuart Henrys, project co-ordinator, with some of the equipment being prepared at GNS Science, Lower Hutt. Getting all the equipment set up and deployed is a huge organisational feat. Stuart is holding one of the many hundreds of geophones that will be embedded in the ground along the survey line.

Apart from the New Zealand participants (Victoia University and GNS Science), a large amount of equipment and expertise is being contributed by the Earthquake Research Institute at Tokyo University, Japan, and the University of Southern California

The map shows the actual location of the seismic survey line, with the positions of the shot holes indicated as stars. Depending on the time required for putting all the geophones in place, the detonations will be set off overnight during this week. The explosions are detontated at night to avoid too much interference from vibrations caused by traffic on the roads.

When the geophones are deployed they have to be pushed into the ground so that they are well embedded. This ensures a solid contact. In this photo by Margaret Low (Photo Librarian at GNS Science) Vaughan Stagpoole is burying one of the 900 geophones alongside a road in the Wairarapapa.

Check out our time-lapse of the busy science teams preparing the equipment for the SAHKE survey. Two days compressed into just over a minute to the music of Lykke Li!

Wellington's Stuck Plate Boundary

2011-05-06T15:26:00.004+12:00

Ever since 1855, when New Zealand's largest ever recorded earthquake (magnitude 8.1) shook the Wellington Region, a lot of effort has gone into understanding the earthquake risk in and around New Zealand's capital city. There are several large fault lines in the area, including the Wellington Fault. This is the most active fault of the system, and stands out clearly, passing along the Hutt Valley and right through Wellington City itself. For more background information check here or watch this video.

However, the largest fault of all, the interface between the Pacific and Australian Plates, underlies the whole region.

The two dimensional map shows the line of the boundary between the plates east of the North Island. In three dimensions, it is a sloping boundary (known as a subduction zone), with the Pacific Plate dipping under the Australian Plate. Plate collision is occurring at an oblique angle rather than head on, which is why there is such a large component of strike slip (sideways) motion in the North Island Fault System.

The hidden, subsurface plate boundary has been mapped over the years using evidence from thousands of small or medium sized earthquakes generated on or nearby to it. Seismometers are used to locate these earthquakes, and the seismic waves give information about the geological structures and rock types that make up the two interacting plates. Under Wellington the boundary dips gently down to the North-West at an angle of about 9 degrees, and is about 25 kilometers deep under the city.

Over New Zealand there is a widespread array of GPS stations continually monitoring their location with great precision. This station is set up in the Tararuas, not far north of Wellington and the Hutt Valley.

Scientists also carry out GPS campaigns to make repeated measurements at a large number of locations when they want more detailed coverage.

Over time these recordings show that the surface of the landscape is being deformed by tectonic movements. These measurements indicate that a large segment of the crust of the Australian Plate in the Lower North Island is stuck to the underlying slab of Pacific Plate, and is being dragged along to the west faster than the Hawkes Bay or East Cape areas. There have been different reasons for this proposed by scientists, but it is believed to be caused mainly by roughness on the interface between the two plates.

It is very important for us to develop our understanding of the nature of this plate interface and the earthquakes that it produces, as subduction zone ruptures potentially create the most destructive earthquakes and tsunamis worldwide. The recent earthquake in Japan is one such example.

In this coloured image, the red colour indicates a high "slip rate deficit" or high degree of coupling between the subducting and overriding plates in the Lower North Island. This segment of stuck plate boundary is about 70 km wide and 140 km long.

If it ruptured it would produce an earthquake of magnitude 8 or above. It is even possible for larger sections (eg the length of the North Island) to rupture occasionally in a single massive earthquake.

In order to improve our knowledge of the plate boundary, a major GNS Science co-ordinated project is being carried out next week. This involves a 90 km seismic survey crossing the lower North Island from one side to the other. Instead of listening out for natural earthquakes, the survey will use explosives, detonated down boreholes, to produce the seismic waves. Hundreds of geophones, spaced 100 metres apart, will pick up reflected sound waves to map the plate interface, faults and other features in the crust. Scientists from GNS Science, Victoria University, Tokyo and California are collaborating in this project.

For some more background to this project, have a look at our media release, or listen to Tim Stern of Victoria University in this radio interview.

Videos of Christchurch Rockfall Research

2011-04-28T14:43:00.001+12:00

In this video Garth Archibald explains the use of a laser to monitor rockfall hazards in built up areas around Christchurch City:

In the second video, Chris Massey analyses rock fall trajectories in the Port Hills to calculate future risks to housing:

Canterbury Gravity Survey

2011-04-27T13:20:00.007+12:00

There are a number of urgent scientific studies being carried out around Christchurch to help inform decision makers involved in the repair and recovery process following the recent earthquakes. These projects are being co-ordinated under the Natural Hazards Research Platform which is a collaboration of many of New Zealand's research institutions (universities and Crown Research Institutes).

One of these thirty 'recovery projects' is aiming to gain a more detailed understanding of the subsurface geological structure of the area using geophysical methods such as seismic reflection, magnetism and gravity measurements.

Although we usually think of the gravitational force of attraction at the Earth's surface as being something uniform wherever our location, there are actually subtle variations in different places. These depend on our distance from the equator (latitude), our altitude above or below sea level, the nearby landscape topography, and also the density of underlying rock masses in the crust below us.

Last week I joined a small GNS Science team who have been making a gravity survey over a wide area around Christchurch City and Canterbury. In the second photo, Vaughan Stagpoole, Jiashun Yu and Dan Barker are setting up the GPS base station at a survey mark, to calibrate the GPS location measurements of the gravity survey.

Measurements are made using a gravity meter that contains a very precise spring scale and weight. Minute changes in the force of gravity on the weight result in changes in the extension of the spring and gives a measure of the gravity at a particular location. This is read off on an electronic gauge and verified on a tiny scale in the meter that is observed using a magnifying lens. When readings are taken over a wide area, and latitude, and altitude, as well as local topography are factored in, areas of anomalous gravity can be mapped and interpreted in terms of geological structure. For example, faults completely hidden beneath the sedimentary strata of the Canterbury plains, that have offset underlying high density rocks, will have a distinctive gravity characteristic that is different to areas where the underlying rocks are uniformly flat.

The mapped gravity is used in conjunction with other geophysical observations to get a 3D picture of the subsurface.

Data from different geophysical surveys or other sources (such as aftershock locations) are then overlaid on top of the gravity map to help distinguish significant features. We can look at some earlier surveys to illustrate this:.

This is the present geological map of the Christchurch area, with different colours denoting the different rock types that occur immediately below the surface soil. The pink colours show volcanic rocks such as old lava flows that make up the Banks Peninsula, whilst the yellow and buff colours are sediments such as gravels that have been eroded off the mountains and laid down by rivers across the Canterbury Plains. Red lines are surface rupture faults, including the Greendale Fault in centre left, that ruptured during the September 4th earthquake. (The fault under the Port Hills that moved on February 22nd is not shown here as it is a 'blind' fault that did not extend to the surface).

This diagram is a gravity map of the same area. It was compiled recently from data collected some years ago. The colours show gradients of gravity intensity. You can see that quite a number of features become visible that are not seen on the geological map. Several of the linear structures are caused by fault lines criss-crossing through the basement rocks underneath the superficial rock deposits. If you click on the image to enlarge it, you will see many little red dots. These are the measurement stations where the actual gravity readings were taken. You will notice that there are significant gaps in some places where data from adjacent stations is extrapolated to fill in the map, rather than actual readings.These are the places where the present gravity survey is being carried out in order to add to this pre-existing data and fill out the missing details.

The last image shows the distribution of aftershocks superimposed on the previous gravity map. (The aftershock data is derived from the GeoNet website Quake Search facility). This helps us to find relationships between basement rock types, their distribution and structure, and the fault ruptures that have been causing the recent earthquakes.

These diagrams were compiled by Bryan Davy who is a geophysicist at GNS Science, specialising in the use of gravity and magnetic data and the use of interactive mapping software.

When the present gravity survey is completed, along with the seismic and magnetic surveys, the added information will further our knowledge of the distribution, length and alignment of fault lines in Canterbury. This information will be included in models that will help evaluate the potential size and frequency of future earthquakes.

Rockfall impacts from the Christchurch 'Quake

2011-04-13T23:09:00.004+12:00

Today I have been in the Port Hills of Christchurch with Chris Massey, an engineering geologist in the GNS Science Active Landscapes team.

Chris is part of a team undertaking a detailed study of the rockfalls that have been triggered in and around Christchurch as a result of the recent earthquakes. The aim of his research is to gather data from the recent rockfalls to map out the potential danger zones and quantify rockfall risk around the city. His research will help planners decide which areas will require mitigation of rockfall risk before rebuilding can occur.

We visited a few key localities which had suffered damage from rockfall during the February 22nd 'quake.

This property in Heathcote suffered severe damage from a large boulder that travelled roughly 500 metres from the slopes above, bouncing tens of metres at a time, and clearing a 2 metre fence before entering the house through the garage roof. (Photo 1).

Later in the day we joined Marty and Mike of Solutions 2 Access who are removing unstable boulders from Castle Rock, a popular climbers venue in the Port Hills. This outcrop was shaken and destabilised by the recent earthquakes, sending many boulders flying down slope towards the Lyttelton Road Tunnel entrance. Many other boulders were left precariously perched on the rock face, posing a risk to motorists on the road below, hikers and climbers. Marty and Mike have been contracted by Opus Consultants to remove these rocks which they do by levering them off with a crowbar or by other mechanical methods.(This is known as 'rock popping'). In the second photo, Marty has just sent large boulder off the edge of the cliff.

Chris is interested in analysing the rock fall trajectories as part of the hazard mapping.work.

My job was to record video footage of the falling boulders as they were released from the cliff and hurtled down the slopes. This will improve our understanding of how the boulders travel, including their bounce heights, velocities and angular rotation, which is important when analysing their destructive potential. Here you can see the dent in the hillside caused by a flying boulder impacting on the surface.

At the end of the day we went further along Summit Road to the area below the Gondola cable car. The road was covered with rockfall debris that had been shaken off the cliffs just above. The rocks had broken through the metal safety barrier, and some of them had travelled all the way down as far as the lower cable car station about 1 kilometre away.

It was interesting to observe the impact craters in the road. The last photo shows a rock deeply embedded in the asphalt - a sobering impression of the power of a falling rock.

Check out this informative poster for some more information about rockfalls and landslides being invstigated in Christchurch.

Check out the video of Chris's rockfall research in Christchurch:

Rockfalls and slips in Christchurch

2011-04-08T11:28:00.002+12:00

This week I have been with Garth Archibald, surveying areas in Christchurch that have been affected by rockfalls and slips. These surveys provide data which is used to calculate the stability of cliffs and slopes, and this provides useful information to planners and geotechnical engineers.

At Redcliffs, Garth set up his laser scanner to make a 3D scan of the rock face. Houses in this area suffered catastrophic damage from rockfall during the February 22nd quake.

Click here to listen to Radio NZ's Morning Report interview with Garth at work at Redcliffs.

The laser scanner sends out about 11000 laser pulses per second. The time it takes for the light to be reflected back to the scanner, gives a very precise measurement of the distance to each point, allowing Garth to make high resolution scan images. He will compare the results with those of a previous survey to see if any areas of the cliff are bulging or tipping over, if cracks are opening up, or if there have been any further rock falls.

Another area we worked in was part of Hillsborough where a large area of hillside slipped during the earthquake. This time we used a GPS (Global Positioning System) unit to precisely locate several points. These are being re-surveyed regularly to better understand the nature of the slip. In this photo Garth is setting up the GPS base station at a survey point well clear of the slipped area.

In the final photo, Garth is taking a GPS reading at the lower end of the slip. Here the ground has been compressed, and you can see how it has ridged up along the driveway. The fence has also buckled by the compression.

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Kermadec Arc Videos

2011-03-21T13:15:00.004+13:00

Our expedtion to explore the hydrothermal activity and mineralisation of the Kermadec arc volcanoes is now over. We arrived back in Auckland yesterday, after a successful three week research cruise.

Amongst the discoveries that were made were areas of present day and ancient hydrothermal activity, relatively fresh lava flows from previously uninvestigated volcanic craters, and possibly some new species of deep sea life, yet to be verified. Hundreds of geological and biological samples were collected, along with thousands of images of the sea floor, and innumerable sonar, magnetic and gravity measurements.

The volcanoes surveyed included Clark, Rumble III, Rumble II West, Healy and Brothers.

Rob Stewart of NIWA took the image of a squid that was pulled up by one of the sled tows. It is only a few centimetres long.

These videos will give you some idea of the methods used and the findings of our Kermadec Expedition 2011:

As a final image, here is a photo of our last sunset of the voyage as we steamed towards Auckland. It had many of us captivated as we stood on the deck admiring the changing colours:

Adventures of the Sentry

2011-03-16T12:35:00.002+13:00

Sentry is the showpiece of our 2011 expedition to the Kermadec Arc Volcanoes. It is an autonomous underwater vehicle (AUV) that has been developed by the team at the Wood's Hole Oceanographic Institution who are world leaders in submarine technology.

Unlike the other devices that are put over the side of the ship and lowered towards the seafloor, Sentry travels independently and therefore has the capacity to make long journeys over the volcanoes covering a wide area.
It has enough battery power to last for up to about 20 hours per mission.

All its missions are pre-programmed according to the bathymetry map that has been created from the ships multibeam sonar scanner. It moves at a constant height above the slopes of the volcanic cones, recording a range of measurements. Here you can see the track lines of a mission over Brothers Volcano yesterday, overlaid on the red contour lines.

For the duration of each Sentry mission, a couple of transponders are sunk down to the sea floor nearby to provide extremely precise location reference points that greatly increase the spatial accuracy of the resulting maps and records. At the end of the mission, these float back up to the surface for collection.

Because it is able to travel so close to the sea floor and can move in any desired grid or spiral pattern, Sentry enables incredibly high resolution maps to be made with previously unachievable detail. With up to 10 different sensors including side scan sonar, temperature, pH and magnetics, Sentry is able to detect and measure widely distributed hydrothermal hot spots.

Whilst Sentry is operating far below, the ship can move away and perform its other operations such as magnetic surveys, CTDO (water chemistry and cloudiness), TOWCAM and sled sampling, which all help to add layers of useful information to the total picture of these volcanic seamounts.

The Sentry team monitor the progress of the AUV via short acoustic messages that are updated every few minutes. If necessary they can send commands back to it to redirect it or get it out of trouble. In this photo, Dana Yoerger, leader of the Sentry team, is at his workspace in the Sentry control centre.

At the end of its mission, Sentry floats up to the surface, and the ship pulls alongside so that it can be winched back on board. Because it has a broad flat profile, it catches the wind, and these deployment and retrievals with the winch can be exciting to watch!

During this voyage, the team were faced with some major technical challenges, requiring new parts to be sent from the US to New Zealand and then dispatched to the ship via helicopter and boat. Al Duester and Andy Billings spent many hours involved in complex problem solving to allow the show to go on.

Amazing Deep Sea Life

2011-03-13T19:38:00.002+13:00

Yesterday I was talking to the NIWA biologists about some of their discoveries from this expedition to the Kermadec undersea volcanoes.

In this first photo, Malcolm Clark is having a last look at the sled net to check that all sea creatures have been collected from it before it is sent down to the bottom again to take more samples.

Rob Stewart has created an impressive series of photographs of the animals found so far. He has a top quality studio set up in the biology lab on board and takes exquisite shots of the specimens.
(Thanks to Kareen Schnabel, NIWA for these first two photos.)

Here is a small gallery of some of Rob's pictures, chosen from his amazing collection. All of them courtesy of NIWA:

This little lobster like crustacean was unknown until about 20 years ago. It is about 8 cm long.

This is a crinoid or sea lily. Related forms are found in the fossil record from long ago. They are related to starfish and fan out their feather like branches to catch food floating by in the water. This one can actually move along the sea bed using its leg- like lower branches. Its length is about 20cm.

This bivalve mollusc from Rumble 2 West Volcano has never been seen before by the NIWA biologists. It may be new to science. It is about 4 cm across.

This fish is known as a rat tail. It scavenges about the sea floor in the murky depths seeking scraps to eat. This specimen is about 30 cm in length.

It belongs to a large family of related species that are found between 30 to over 3000 metres of water depth.

This sponge is a filter feeder. It is made of glass (silica), and those spines are sharp! Its overall length is 30 cm.

This is a branching gorgonian coral from Clark Volcano. Unlike corals that live near the surface of the sea, deep sea corals do not have photosynthesising algae associated with them. They have to take all their food from the water that flows over them, using their tiny polyps. Brittle stars are very often found entwined in the coral branches.

Here is a segmented worm or polychaete. It is carnivorous and also lives in the branching coral. Total length of this specimen is about 8 cm.

This brittle star uses its sucker like tube feet to move around in the branches of coral and also to catch food and carry it into its mouth in the central disc. This image is about 3 cm across.

Rock in the Boat

2011-03-11T15:51:00.003+13:00

Along with biological specimens, the sled brings a lot of rock off the sea floor. Christian Timm sorts through all the samples, cuts some of them up with a rock saw, and packs and labels them to be studied in detail back at GNS Science.

The different minerals present in the samples will be analysed to give detailed information about the processes occurring deep down in the collision zone where the Pacific and Australian plates meet, as well as about the hydrothermal alteration of the rocks at the sea floor.

Here is a selection of examples from off the cone of Rumble 2 West volcano that we have been checking out for the last few days:

First up is a piece of volcanic rock (basalt) that comes from the cone of Rumble 2 West. It would have cooled rapidly as it encountered the sea water, which has preserved the flow structure running through the centre of the specimen.

Hydrothermal fluid contains a lot of iron that it has dissolved from the basalt it has passed through down in the crust. As it reaches the sea floor and cools, it precipitates out the iron as an oxide called haematite, which has a deep red colour

Silicon is the most common element in the earth's crust, along with oxygen with which it combines as silica (quartz). There are many other siliceous minerals too, some of which are precipitated around hydrothermal vents in association with microbes.

These yellow and orange pieces contain several types of silica with different quantities of trace elements that give a wide colour range.

The whitish stripes in this piece of basalt are from small crystals of barium sulphate or barite. As sea water flows down into a seamount and heats up, it loses a lot of calcium sulphate which precipitates out. The hot, sulphate poor fluid then dissolves barium from the surrounding rocks, bringing it back up to the sea floor. The barium then combines with the sulphate in the fresh sea water to give rise to these barite crystals. They tell us that hydrothermal fluids have been cycled through the crust in this area, and can even be dated to give a timescale for the process.

This small piece is a jam packed mixture of rock fragments and minerals. It It is part of the debris from an old broken up black smoker chimney. It is loaded with valuable metal rich compounds that have crystallised as the hot hydrothermal fluid gushed out into the surrounding sea water.

Cornel de Ronde is checking out the finds and explaining some of their features to crew member Peter Morrison.

The Magnetic Charms of the Sea Floor

2011-03-10T09:08:00.002+13:00

Fabio Caratori Tontini is interested in measuring the magnetic properties of the rocks on the sea floor. Because most of them are volcanic lavas that contain a lot of iron, they have become magnetised as they cooled and solidified in the presence of the Earth's magnetic field.

When the hot geothermal liquids pass through them, the rocks become progressively demagnetised because the hot fluid dissolves and carries away the metal (iron) ions. This is of course why the hydrothermal fluids become enriched in these ions, and bring them up to be precipitated when they contact cold sea water. In the second photo you can see that there is a lot of red iron in this rock.

Rocks that have been affected by hydrothermal activity will remain demagnetised even after the activity stops. By mapping the magnetic intensity across a volcano, it is possible to locate areas of present or past hydrothermal activity (low magnetism). This adds a time dimension to the other surveys that focus on present day hydrothermal activity only, and potentially reveals other areas rich in hydrothermal deposits.

Fabio uses a magnetometer that is towed behind the ship in a grid pattern above the volcanoes. This measures the variations in magnetism which are then plotted on a map. His results can be compared to maps of present day hydrothermal activity, to tell us something about how the activity has changed over time.

There is also a magnetometer on board our yellow submarine SENTRY that is run much closer to the sea floor, and picks up a lot more close-up detail. Here is a high resolution image of the magnetic anomalies on Clark volcano that were recorded by SENTRY a few days ago, and shown graphically by Fabio.

The blue lowly magnetised areas are the ' burn holes' that will generally be centres of rich hydrothermal mineralization because the minerals that have been leached from the deeper rocks are now spread out in deposits at or near the surface. The orange and red areas retain their more of their original magnetism and will not have been strongly altered by hydrothermal fluids.

In the second graphic, Fabio has added to the picture by overlaying the magnetic data onto a 3D image of the cone of Clark Volcano.

On a previous expedition, Fabio got some strange readings on his magnetometer, and noticed that there was extra tension on the cable. After pulling the device back on board, he found that it had been severely mauled by a shark, with nasty bite marks on two sides. In the photo you can see that there is even a small piece of white shark's tooth left behind in one of the gashes. I guess that the magnetometer now has a lower level of attraction for the shark who will think twice before attacking a large fast moving goldfish again...

Hot Water Plumes

2011-03-09T13:20:00.009+13:00

Hydrothermal activity in undersea volcanoes is largely the result of sea water descending into the crust, being heated up and then chemically breaking down the surrounding rocks as it rises back up to the sea bed. These mineral rich fluids then re-enter the water column either diffusely over a wide area, or out of one of many vents in a hydrothermal field.

As the emerging hydrothermal fluids mix with the sea water and quickly cool down, the dissolved minerals within them precipitate out. Some (such as metal sulphides) will accumulate immediately around the vent to create vertical chimney like structure, whilst others (such as iron and manganese oxides) will form particles that get carried up in the hot water plume to form a sheet like cloud that is pulled sideways by water currents. The particles within the cloud will slowly rain out back to the sea floor over a wide area.

Sharon Walker from NOAA (the National Ocean and Atmosphere Administration in the US) specialises in analysing the physical and chemical properties of sea water to locate hydrothermal plumes and the vents that have created them. She uses several tools mounted onto a CTDO (conductivity, temperature, depth and optical) recording device. In the photo you can see Cornel de Ronde and Matt Leybourne preparing the CTDO. It will be towed below the ship and lifted up and down to sample at different depths.

On it there is a light scattering sensor which detects reflected light to give a measure of the water's particle content.

It will also take samples of water from different levels in the water column for chemical analysis. Yesterday Sharon and Matt collated some results to create this diagram of the hydrothermal plume above Rumble 2 West volcano. The green and yellow lines represent light scattering. You can see that near the bottom there is a large spike indicating a hydrothermal plume about 30 metres thick. Faint red lines across the graph show the depths at which water samples were taken.

Finally here is a photo I took from the bridge during quite windy and choppy conditions the day before yesterday, just to show that it is not always flat as a mirror out here. For some of us landlubbers it meant spending a bit of time outside looking over the rail… just admiring the view of course.

Communal Living on a Kermadec Volcano

2011-03-06T16:16:00.002+13:00

The first image shows the depth profile created by the ship's sonar as it passed over the summit of Clark Volcano. It has the classic cone shaped profile of a typical land volcano such as Taranaki. They stick up above the deeper plains of the ocean floor and provide quite different habitats for deep sea creatures. The plains are mainly very soft muddy sediments which contain an abundance of worms and other burrowing animals. The seamounts on the other hand are covered by harder volcanic rocks that provide a solid surface for a different living community.

In order to gather actual samples of the rocks and animals that occur on the surface of these seamounts, a simple method is to use a sled. This is a crude metal cage with a net at the back. It is pulled along the sea floor for a short distance and then hauled up by winch. The second photo shows a fully laden sled just arriving back at the surface.

Once the sled has been emptied onto the deck, the biologists quickly pick off the largest and most obvious specimens and put them into a bucket of sea water. Then the rocks are scooped up into the yellow bins and checked more carefully for smaller creatures. Once all the different finds have been sorted and given an initial identification, they are put into carefully labelled bottles and preserved for later more detailed research.

These small lobster-like crustaceans probably all belong to the same species.
They are often found tucked away into a rock crevice with just their claws showing, ready to catch some food.

Rob Stewart, one of the team of NIWA biologists, showed me this large piece of coral that has come up with the sled. This branching coral often grows on seamounts and provides a living space for many other animals to hide in.
This one had several residents, including the large worm that you can see, as well as a hydroid coral, a couple of large flower like solitary corals, and a brittle star or two.

Rob has a camera set up in his lab to take a photographic record of such prize finds. The last photo shows another view of this sample in all its glory.

Because the different seamounts along the Kermadec Arc are separated from each other by the deeper ocean plains, the biologists are interested to compare the living communities on them. This will help improve our knowledge of how these animals have spread and diversified through time along a line of active volcanoes.

Help from above

2011-03-05T09:40:00.005+13:00

We have now been traversing above Clark Volcano for several days, and a variety of surveys have been operating, including dredging for mineral and biological specimens, photography of the sea floor, magnetic surveys and water chemistry sampling.

The technological centrepiece of our expedition to the Kermadec Arc is a strange object known as 'Sentry'.

Sentry is a bright yellow un-manned submarine that can be programmed to dive to the sea floor on journeys of up to 19 hours long, manoeuvre up and down over obstacles, and take a whole variety of close up readings with its many sensors.

On Sentry's initial dive a few days ago, its multibeam scanner stopped working. This feature is a very important part of the Sentry's armoury of equipment. It is used to make very high resolution maps of the sea floor, which are extremely detailed because Sentry is travelling so close by.

So while the other scientists have been very active with their own projects, the Sentry team have beam have been working on solving this key problem, finally organising to get a replacement scanner. This was flown to New Zealand from the US, cleared through customs, and immediately flown to us yesterday by helicopter out of Auckland.

The delivery was lowered down from the helicopter in a large container, whilst a crowd of us enjoyed the spectacle from the front of the ship.

Shortly afterwards, these beautiful fish called mahimahi, each about one and a half to two metres long, paid us a visit from below. Gently cruising around the ship for about half an hour, their offering to us was just the simple appreciation of their presence. And as from last night, Sentry is on duty, now deep below us.

Images from the Unknown

2011-03-04T09:27:00.006+13:00

TOWCAM is an underwater camera that is lowered down to the sea floor and pulled along just above the bottom on a long winch line. It has an altimeter on it that allows the scientists to pull it up or lower it to keep it just above the bed as the ship drags it along sideways.

Here you can see TOWCAM being lowered into the water and down into the deep blue depths to over 1100 metres depth.

Every ten seconds it takes a photo timed with a strobe flash to give a stream of images along the designated path. The red line on the map shows yesterdays mission across the summit of the southern cone of Clark Volcano, where hydrothermal activity was expected to be occurring. The total length of the path shown is about 3 kilometres. Up on the ship's bridge, the TOWCAM team from Woods Hole Oceanographic Institution in the US, manually adjusts the winch to keep the camera as close as possible to 4 metres above the sea bed. I watched Marshall Swartz as he continuously monitored the computer screen and adjusted the winch up and down in response to TOWCAMs signals of changing water depth.

When TOWCAM has completed its mission after several hours, it is pulled up to the surface again. Tim Shank, the biologist in the WHOI team, was delighted to find that by chance TOWCAM had hauled up some specimens off the sea floor including a beautiful coral, some brittle stars, and a crinoid.

Here are three of the three thousand photos that were taken on TOWCAMs first mission on Clark. They were downloaded after the camera had resurfaced, and Tim checked each one of them for signs of hydrothermal activity, variations in the geology, and evidence of interesting biological species. The first of the undersea pictures shown here includes a hard coral and some sea anemones living on hard volcanic basalt that was erupted from Clark Volcano.

In the next photo, you can see the yellowish colour of softer sediments that have been altered by hydrothermal activity.

Lastly here is an image of a steep face of volcanic lava that has also been stained by ongoing hydrothermal activity.

Mapping Volcanoes

2011-03-03T08:31:00.005+13:00

One of the amazing tools that is on the Tangaroa is a multibeam sonar scanner that maps the contours of the sea bed as the ship travels along. It sends high pitch sound waves downwards in a fan shape and calculates the shape of the sea floor from the complex acoustic reflections.

(Pic 2) Over the last hours the ship has been pulling a magnetometer (a device for measuring magnetism in the Earth's crust) back and forth over Clark Volcano, so at the same time the multi-beam sonar was at work to make a new map. This will enlarge the map made 7 years ago on a previous expedition, and also be used as a comparison to see if there have been any major changes to the volcano caused by eruptions or landslides. The top photo is the early version, and the next one is the latest one, produced for the first time today. (pic 3) The new map represents roughly 8 kilometres square.

You can see that Clark Volcano has two cones. The one to the north - east (top left) is relatively simple and is most likely much younger than the south - eastern one (bottom right of image).

There are several interesting surface features such as fault lines where the south – eastern cone has rifted apart, possible lava flows and a large rockslide. The next operation is to send a camera down to have a close up look for any hydrothermal activity.

(Pic 4 ) This is a 3D version of the new scan of Clark Volcano, which makes its landforms stand out more clearly. These digital terrain models can easily be manipulated to show the sea floor geological features from any angle.

Message in a bottle

2011-03-02T16:25:00.005+13:00

(pic 1) Here is a map of the ocean floor north of New Zealand. The different colours represent water depth, red and yellow are shallower than the blue and purple areas. The deep Kermadec Trench that marks the plate tectonic boundary is an obvious feature, with the Kermadec Ridge running parallel to the West (left) of the trench.

(pic 2) The line of arc volcanoes look like pimples very close to the Kermadec Ridge. All of the named volcanoes shown in the second image except for Lillie, are booked for a visit from us on this expedition.

For the last couple of days we have been traversing over the top of the first of these objectives, Clark volcano. Whilst the various science teams have been organising themselves and starting their first operations, I have been adjusting slowly to this new environment and the way things seem to work.

(pic 3) This is my first cruise and, like anyone in a new place for the first time, I find myself amazed by 'everyday' aspects of life at sea, and my perceptions sharpened by things that must be insignificant for regular sea-goers. Things like: the endless changes in the rhythms of the waves, the effortlessness ease of an albatross skimming over the wavetops, flying fish skittering away from the bow of the ship, and the endless, flat, 360 degree horizon.

On board the mysteries are more technical. It seems fantastic that the ship can navigate its way across this featureless ocean and then position itself so that it stays motionless above an invisible volcano deep below. Scientists stare at computer screens and announce that a piece of equipment they have lowered into the water precisely is three and a half metres above the bottom, or devise a solution when the un-manned submarine far below gets 'confused' and stuck beneath a rock overhang. These are things I hope to understand better over the next three weeks.

One of the crew, Russel Jones, has been working on the Tangaroa for the past 10 years. One of his hobbies is to periodically drop a wine a bottle with a message inside, over the side of the ship. Over the years, several of his bottles have been discovered washed up on beaches around the Southern Ocean.

One of them made TV news in NZ and Australia, having been found by Rod Davies on a beach in Western Australia after a five year circumnavigation of Antarctica! Russel showed me a bunch of letters from people in several different countries who had found his messages and subsequently become personal acquaintances.

Yesterday he launched another of his messages as you can see. Keep a look out for this one when you are down on the beach some years from now. Russel will be delighted to hear from you…

Off to the Kermadec Volcanoes

2011-02-28T14:40:00.009+13:00

For the next three weeks I will be at sea to the North of New Zealand, far away from the aftermath and unfolding ramifications of the events in Christchurch.

I am on board the NIWA research vessel Tangaroa with a group of geologists and biologists, many of whom were involved with the recent discovery of the Pink Terraces under lake Rotomahana .

We left Auckland Port yesterday, as the sun was setting beyond the city skyline, and have been travelling North East into the Pacific Ocean along the Kermadec Volcanic Arc.Our mission is to make detailed geological and biological surveys of several of the undersea volcanoes that lie parallel to the plate boundary as it runs north east of the North Island. This boundary is a geographically distinct line of several parallel features. Have a look at our video of a computer simulated flyby of New Zealand under the ocean .

To the east is the deep Kermadec Trench where the Pacific Plate dips below the Australian Plate. Just to the west of this is the Kermadec Ridge, uplifted by compression along the boundary. Near to the ridge are the Arc volcanoes that we will be investigating. West of the volcanoes is a "back arc basin" of deeper water which is a zone of extension. Further west again is the now inactive Colville Ridge.

Right now we are approaching Clark Volcano, the first of our objectives, the top of which is 850 metres below the surface. The various teams are sorting out the specialist tools for their particular research. I will be writing in more detail about how our explorations unfold over the next days.

Earthquake shock waves explained

2011-02-25T10:40:00.001+13:00

I asked Kevin Fenaughty, the GeoNet data centre manager at GNS Science, to explain something about the different types of seismic waves affecting Christchurch during the present aftershocks:

Bill Fry talks about aftershocks in Christchurch

2011-02-23T19:42:00.001+13:00

Christchurch Earthquake Feb 22

2011-02-23T11:14:00.002+13:00

If you are in Christchurch and need basic information and updates about the emergency response go to the Environment Canterbury Earthquake Website.

Whilst many scientists are busy at GNS Science with seismic data and interpretation of the physical and social impacts of the earthquake in Christchurch, everyone here is feeling sympathy for those still struggling to cope with the aftermath and continued aftershocks.

The image shows the ground shaking intensity across New Zealand
as measured by the GeoNet network of seismometers during the magnistude 6.3 quake yesterday. (Click on the image to enlarge.)

For an updated time lapse map of the aftershocks have a look here.

Posters of Lake Rotomahana

2011-02-22T10:51:00.001+13:00

Here is a last look at the posters of Lake Rotomahana created by Rotorua Primary and Intermediate school children.The first image is the winning poster created by Kaya Henderson-Corporaal, Georgia Perham and Breannah Wakefield of Galatea School. We were particularly impressed by the careful detail and realism of features on the lake floor in this poster.

The second prize was shared by two students from Rerewhakaaitu School: Mark Sincalir and Paige Skipper. They each created a very colourful and artistic poster. These portray the whole atmosphere of the lake as well as a variety of hydrothermal features and rocks on the lake floor.

This is Westbrook School student Cassandra Kiff's picture of what she thought may be found by the Rotomahana scientists. "Maybe the Pink and White Terraces?" She has also shown colourful bubbles and vents in the lake.

Traci Benson of Owhata School created this small poster. She clearly related the present lake floor to the history of the Tarawera Eruption. A very colourful and eyecatching picture.

There were many other posters that impressed us. Here is another look at some of the display in Rotorua Central Library. The posters have now been moved to the GNS Science building in Avalon, Lower Hutt where they are on display in the foyer.

A big thank you to all the teachers, students and others involved in bringing this poster exhibition about, including Sue Heke and other staff at Rotorua Library, Jessie McKenzie of the Royal Society of New Zealand and Harvey James of Waimangu Volcanic Valley.

Poster Prizewinners

2011-02-21T12:18:00.002+13:00

Last week I toured a number of Rotorua Schools to show slides and to describe the rediscovery of the Pink Terraces as well as other results of the Rotomahana Project. Over three days I talked to over 1100 children.

I also took the opportunity to present prizes to the winners of the Rotomahana Project Poster Competition.

The Prizes were awarded to those students who had produced the most eye catching posters, that also most accurately predicted what the scientists would discover in the lake.

It was very difficult to choose the winners because of the high standard of the posters that had been entered. A lot of effort had gone into the children's creations. This photo shows the engagement and interest of the children in learning about the Rotomahana Project.

The youngest prizewinning scientists each won a Rotomahana Project baseball cap, a certificate and a family pass to a guided tour of the Waimangu Volcanic Valley as well as a boat cruise on Lake Rotomahana. In this picture, Traci Benson, age six, of Owhata School is getting her prize.

Cassandra Kiff of Westbrook School was also commended for her poster and won an award.

Second Overall Prize went to Rerewhakaaitu School students Paige Skipper and Mark Sinclair who produced visually outstanding posters. They won a guided tour of the Waimangu Volcanic Valley for 30 students and teachers, as well as hats and certificates for themselves. There were many very high quality posters from this school.

First Prize for best poster went to a trio of Galatea School students Kaya, Georgia and Breannah. Their teacher Marylou has been very enthusiastic about this project and was delighted at the success of her students.

Part of the first prize is a guided tour of Waimangu Volcanic Valley and also a boat cruise on Lake Rotomahana for 30 students and adults. This class produced a number of outstanding posters and it is fitting that they will all share in the prize. Well done!

Pink Terraces presentations for Rotorua Schools

2011-02-10T11:49:00.002+13:00

From Wednesday 16th February to Friday 18th, I will be touring Rotorua schools with a presentation about the Rotomahana Project. (If you haven't caught up about this yet you can read an earlier blog post about it or watch this video). Contact me soon if you would like your school included - there are a couple of time slots still available as I write this.

This is an opportunity for local school children to learn something of how scientists go about their work as well as the inside story of the Pink Terraces rediscovery.

I will also be announcing the winners of the Poster Competition. - If you haven't seen the posters yet, the exhibition in Rotorua Central Library is still open until Friday the 18th February.

The variety and detail of the posters makes for a colourful collection. Some of them have also proved to be very accurate predictions of what the scientists actually found on the lake bed of Rotomahana!

Picking winners has not been easy. Here is a photo of the project leader Cornel de Ronde having a careful look at the entries.

Watch this space after next week to see which ones were selected and earned the fantastic prizes offered by Waimangu Volcanic Valley

Cornel de Ronde on the Pink Terraces discovery

2011-02-04T23:10:00.001+13:00

Pink Terraces found!

2011-02-02T12:08:00.009+13:00

The Pink Terraces of Rotomahana before the Tarawera Eruption of 1886

(Permission of the Alexander Turnbull Library, Wellington, New Zealand, must be obtained before any re-use of this image).

Devastation after the Tarawera eruption

Yes - the unbelievable news is, that inspite of being located at the centre of New Zealand's most violent eruption of historic times, shaken by volcanic earthquakes, covered by many metres of mud and ash and then flooded underneath a large lake, a large area of New Zealand's iconic Pink Terraces of Rotomahana has been re-discovered!

Dan Fornari of WHOI

Scientists involved in the Rotomahana Project announced their findings last night at a special meeting in the marae at Whakarewarewa, 125 years after the Tarawera Eruption. Thanks to the underwater vehicle and imaging technology and skills developed by the Wood's Hole Oceanographic Institution (WHOI), and the expertise of marine scientists from Lamont-Doherty Earth Observatory (LDEO) and NOAA-PMEL in the USA, this discovery has been made possible. A key component of the expedition's field approach was the use of the Remus100 autonomous underwater vehicles (AUVs) developed at WHOI.

Dr. Vicki Ferrini of LDEO observed the terrace formations as she was processing images from the sidescan sonar on one of the AUVs on Saturday. After checking details like water depth, location, orientation, shape and size of the features, Cornel de Ronde and the rest of the science team reached the conclusion that these can only be a part of the original Pink Terraces last seen on June the 9th 1886.

The features show up as curved step like surfaces that are visible in the sonar images as bright reflectors due to their strong reflectivity, This means that they comprise a hard material, unlike the softer, therefore acoustically darker sediment that surrounds them. It is the steeply sloping or vertical sections that show up most brightly, probably because they are free from any overlying sediment.

This early, pre-eruption photo of the lake shows the Pink Terraces on the left. In the middle distance you can see a hooked spit of land extending into the lake as a very distinct feature. This gives the lake shore a very identifiable contour just northeast of the Pink Terraces.

In the compiled bathymetric map produced by Vicki from the AUV survey data, the same hooked-shaped peninsular can be seen in the lake bed, now several tens of metres under water. This is in the northern section of Lake Rotomahana, in the area that has been indentified as the probable location of the Pink Terraces by previous researchers.

The close-up of the lake floor bathymetry shows this feature clearly (depths in the map at right are color coded- pink is deep and red is shallow). The main cascade of the Pink Terraces would fit in the green embayment in the top centre of the image, and the wide lower part of the terraces should extend down roughly in the centre along the green or pale blue band.When overlaid on top of the bathymetric map, Vicki's step like rock features lie exactly on top of this location.

This means that the lower portion of the Pink Terraces still remain. It is possible that they were covered in debris by the eruption, and that subsequent water erosion has exposed their edges again. The question still remains as to whether the upper section of the terraces is still intact underneath a layer of sediment. The sonar sensors used in this survey are unable to reveal adequate subsurface detail to answer this. However, a future expedition could settle this question using seismic reflection techniques.

A further investigation was made by lowering an underwater camera, developed by Dr. Dan Fornari at WHOI, down to the bed of the lake to take a closer look. The following images are a selection from those taken.

The first shows a small crater with a hazy cloud of bubbles and coming out of it. This depression is roughly a metre across. Because of disturbance caused by the high level of hydrothermal activity, the ranges of the camera images are only a few metres. *

In the next photo you can see some vertical relief. On the right, the dark shadow is one of the terrace steps, whilst further to the left, across the sloping muddy lake floor there are some smaller exposed vertical sections of rock. These shapes are typical of hydrothermal silica deposits seen in other parts of the Rotorua geothermal area.*

The last of the underwater photos, taken near the region identified by Vicki as being where the strong reflectors of the Pink Terraces are located, show the vertical edge of a terrace head on. The scaling is not exact but in the region of one or one and a half metres in height and could be an exposure of the lower part of the Pink Terraces. *

These initial findings leave many questions that can be followed up in the future. But for now, to know that at least a part of the Pink Terraces of Lake Rotomahana are still there, hidden in the depths of the water, is a fantastic outcome of the Lake Rotomahana Project. Quite apart from this discovery, the analysis of the overall expedition findings will give the scientists plenty to do towards the goal of understanding the whole hydrothermal system of Rotomahana. Dr. Cornel de Ronde, of GNS and leader of the expedition has something to smile about.

* "Digital underwater photographs taken by Dr. Dan Fornari - Woods Hole Oceanographic Institution (WHOI), Cape Cod, MA, USA, using equipment developed with funding from the US National Science Foundation and WHOI. Digital underwater camera developed by Mr. Mark Olsson of DeepSea Power & Light, San Diego, CA, USA. Copyright D. Fornari - Woods Hole Oceanographic Institution."

The background story of the Rotomahana Project - video

2011-02-01T11:46:00.001+13:00

Scanning Details of Rotomahana Lake Bed

2011-01-31T15:04:00.001+13:00

Vicki Ferrini from Columbia University in the US, is a specialist at processing data from the side scanning sonar. In the photo taken from the shelter on the lake shore, she is showing her american colleagues some of the images that she has produced shortly after downloading data from the last AUV mission. Sharon Walker (left), Dan Fornari (just behind Vicki) and Amy Kukulya (right).

The image that Vicki has produced is an oblique side view of the lake floor, with a vertical scale of about 50 metres (the water depth). The amazing detail of the scan is visible in this image. You can see lots of little pock mark craters on the lake floor with streams of bubbles rising vertically above them. Obviously this area is hydrothermically very active. A lot of the emitted gas gets dissolved in the lake water before it reaches the surface, especially when it originates from vents at relatively deep levels in the water.

As the project reaches its final stages, the results of all the different surveys are being combined to fill out a fascinating picture of the Rotomahana hydrothermal system and present day bathymetry (lake floor topography). As project leader Cornel de Ronde keeps an overview and guides the activity of the different teams. (This photo Sharon Walker)

Rotomahana lake floor comes into focus

2011-01-29T14:13:00.002+13:00

There are three more days left before the scientists have to end the survey, and all systems are operatiing well.

A boat from the Univesity of Waikato has been used for several different purposes, including a magnetometer survey and also CTD (Conductivity Temperature and Depth) measurements.

Data from the different surveys are processed each day and combined to give an overview map of the lake floor and the distribution of its features.The imagery is starting to show the big picture, as well as some interesting details.

In this second image, Cornel de Ronde is discussing the magnetic anomalies map that Fabio has devised from a grid survey of the lake. The boat tows the magnetometer behind it as it travels up and down in a grid pattern. This was aligned mostly at right angles to the volcanic rift, with a few lines along it to 'tie' the readings together across the gaps. You can see the grid pattern as dark lines in the third picture. They more or less cover the lake area, and are about 100 metres apart.

The colours on the map represent the intensity of the magnetic field as measured from the surface. They cover an area wider that the lake itself as readings were taken from the surrounding land as well. Blue and green show a low level, whilst red and pink indicate more intense magnetism. Volcanic rocks like basalt are typically very magnetic, but hydrothermal activity can alter the rocks and reduce the magnetism. This means that the measurements tell us something about the underlying geology below the lake as well as the distibution of hydrothermal activity.

The positions of hydrothermal vents have also been roughly plotted (photo4), but at this stage the locations are approximate.

Sharon Walker processes the data from the CTD device that is lowered from the boat as it travels up and down. Different measurements can be combined to clarify the information about hydrothermal activity that affects the water above the lake floor.

The screen shows some readings from yesterday. On the left hand side, the blue line represents temperature, which is about 22 degrees C at the surface, but falls to roughly 14 degrees at 20 metres depth, and gets slowly cooler further down.

The green line is a measure of the amount of light scattering caused by particles in the water. Near the surface the reading is high, due to the presence of mud washed in by rain, as well as algae growing in the sunlight. Down near the bed of the lake there are some spikes that are caused by hydrothermal activity stirring up particles and introducing gas bubbles.

Underwater with an AUV

2011-01-28T01:44:00.004+13:00

Follow the AUVs into Rotomahana's depths:

Sensing Remote Rotomahana

2011-01-28T01:29:00.000+13:00

The submersibles, like two faithful and intelligent mechanised mammals, conitnued their diving and tracking progress today, closely monitored by their attentive minders. Seeking them at the end of a mission when they automatically float to the surface, is very reminiscent of looking for whales or dolphins, with only their 'dorsal fins' visible above water.

Most of today I spent with Vaughen Stagpoole and Fabio Caratori-Tontini from GNS Science, who were continuing their gravity and magnetic surveys. The instruments used allow extremely subtle variations of these forces to be measured. In contrast to the lake water and lake bed bathymetric measurements that are made by the AUVs, gravity and magnetism are influenced by the layout and distirbution of rocks deep in the crust.

The second photo shows Vaughan taking notes whilst Fabio is taking magnetic readings

We were ferried to the different locations by Brad Scott, a volcanologist also from GNS Science, who is very knowledgable about New Zealand's volcanoes.

As we progressed along the shore, we passed some underwater hydrothermal vents where streams of bubbles welled up from below the water surface.Brad reminded us that recent measurments of the CO2 gas released from the bed of Rotomahana showed that the total flow is twice as great as that from Ruapehu Crater.

As we travelled around the edges of the lake, we climbed ashore at places that would be totally inaccessible other than by boat.

Because Rotomahana has restricted access, on a calm windless day like this it is a very peaceful place. As we moved in stages towards the looming presence of Tarawera the atmosphere of the place seemd very powerful. At one point we landed at a small jetty, from where a 2 km long track through the bush led us to Lake Tarawera.

On the way we passed a memorial to the victims of the 1886 eruption.

Lake Rotomahana starts to show her hidden side

2011-01-25T23:59:00.003+13:00

Today was a very active day for our research below and around Lake Rotomahana

The different teams were working on or around the lake included:

A gravity survey of the back country to the East of the Lake
Magnetic survey of the lake floor
Rock sampling survey of volcanic deposits from points around the lake shore
The Automatous Underwater Vehicle survey

I was with the gravity survey yesterday. This involves taking a very precise gravity meter to different locations and making measurements through a small lens in the meter. The force of gravity varies very slightly over the surface of the Earth, depending on the density of rocks in the crust as well as the presence of mountains and valleys which cause a slight sideways pull. By measuring these variations and taking precise readings of the measurement locations using a GPS, a lot of information can be found out about the make up of the crust.

In the photo, Vaughan Stagpoole of GNS Science is taking a gravity reading.

Although I spent most of today with the AUV team, I did get to see a fascinating cliff section that the rock samplers had had a look at. The pale grey upper section of the cliff is a sequence of fragments of pumice known as Rotomahana Mud, that was erupted on June 10th 1886. The black line in the photo is the soil horizon that was the ground surface on June 9th. The incredible power of the Tarawera eruption is captured in this single location - it shows how much the landscape was buried by the volcanic debris in the space of perhaps four or five hours.

The AUVs operated over the north eastern section of the lake, including over the area of the old Lake Rotomahana, and Pink and White Terraces. I went out with the boat to deploy and retrieve the AUVs as they were tested some more and launched on their missions.

They are set to travel at a specific altitude above the lake floor - one at 10 metres, the other at 15, and so they rise and sink lower as they travel. However, at one point one of them collided with an underwater pinnacle which must have reared up vertically infront of it - allowing no warning to the sub. Although we had to check it over, the AUV was undamaged and was set back to work again.

In the photo, Amy is letting an AUV off on its next mission.

It is amazing to watch these robotic machines set off from the side of the boat, steer towards a prescribed direction and then suddenly vanish from the surface into the depths. They are then tracked on the land based computers which are informed of every aspect of progress, including position, speed, direction, depth, battery power etc.

Once they are finished with a mission, or if there is a malfunction, they float to the surface and are easily located by GPS to be hauled onto the boat and back to the shore. They are then hooked up to the computer to download all the data, which can be immediately processed to produce 3D images, plots and maps.

Of interest today was the discovery of numerous pock mark holes on the floor of the lake, with streams of gas bubbles above them. Down there also was even a terrace like formation, about 30 metres across - but don't be too excited, it was well away from the location of the former Pink and White Terraces. It is not possible so soon to know exactly what this feature is, or if it is one of the many other features known around the lake before the 1886 eruption.

Yellow Submarines

2011-01-23T22:23:00.005+13:00

Over the last two days quite some time was spent testing the Automated Underwater Vehicles. They are transported in the back of a van - in the photo you can see Rob Littlefield from the Woods Hole Oceanographic Institution preparing one of them for a trial run. The two AUVs each carry a different type of scanner that measures characteristics of the lake floor:

A multibeam scanner - this creates a detailed 3D topographical (bathymetric) map of the lake bed.

A sidescanner - this technology uses acoustic (sound) signals to gather information about the hardness or softness of the lake floor sediments. Lava, mud or coarse boulders will give different signals, and so some idea of the geology of the lake floor can be gleaned.

The second photo shows Amy Kukulya, from WHOI making adjustments to one of the AUVs on Rotomahana lake shore.

Different sensors on the AUVs take other readings. If you think about it you will soon see how they all combine help to detect mineral rich, hot, hydrothermal vents:

Temperature
pH (acidity or alkalinity)
Eh - this is the oxygen reduction potential of the water, where a high reading means that it has been introduced into the lake recently.
Turbidity - this uses a strobe light and measures the amount of reflection, indicating the density of particles in the water.
Conductivity - this depends on the amount of dissolved salt, which is also a feature of hydrothermal fluids.

Other sensors on the AUVs are there to help with navigation. This is a highly technical subject in itself, and makes it possible for the controller to have real-time information and remote control of the speed, direction and depth of the AUV. Amy deals with all this remotely from her computer in the back of the van. All the information she needs is at her fingertips...

The photos show that the weather has been pretty wet over the last two days, but some testing was done on the lake yesterday... and also in the hotel today:

Some of the guests were a bit surprised to see a torpedo like vessel in the swimming pool. One of the scanners wasn't quite behaving, until some of the settings were checked. This adds up to a very expensive way of finding out that the water depth was about 2 metres.

Everything is now set for work to begin.

Marae welcome and Rotomahana blessing

2011-01-23T12:58:00.011+13:00

The Rotomahana Project is of great interest to the Te Arawa people who regard the whole area around Mount Tarawera to be a sacred site. It is 125 years since that eruption of Mount Tarawera which took over 100 lives, destroyed several villages along with the Pink and White Terraces, and devasted the surviving Maori community who had been living in the area.

This history is still very much alive in the minds of locals around Rotorua, some of whom are direct descendants of those who died. There is therefore a strong personal interest in many people to learn more about the details of the eruption aftermath that may be revealed by the Rotomahana project.

At Hinemihi Marae, Ngapuna, all members of the project team were invited yesterday to a formal welcome ceremony, officiated by several senior elders of Te Arawa. The first photo shows the team assembling outside the Marae, awaiting the invitation to enter. It was a great privelege to be hosted with this welcome, and to be offered words of greeting, waiata (songs) recounting the history of the eruption and prayers for the success of the project. To round of the event there was a feast shared by all participants.

This morning we awoke to a widespread downpour of rain. This created a sombre atmosphere for a blessing ceremony held on the shores of Lake Rotomahana. It was again a beautiful and powerful event that expressed the deep feelings and respect associated with the history of this lake.

Rotorua kids show their inspiration about Lake Rotomahana

2011-01-21T21:45:00.001+13:00

The Rotorua Public Library has a display of about 70 posters created by Rotorua school children who have taken up the challenge of the GNS Science Poster Competition. Their challenge was to represent their prediction of what the Rotomahana Project scientists will discover in the next few days in their survey of the lake.

There is a wonderful range of images and ideas of what may lie beneath the surface of Lake Rotomahana. I'm sure you will agree that it is a colourful and diverse display

If you live somewhere near Rotorua or are passing through in the next two or three weeks, drop in for a look at the entries. The overall standard and impact of the posters is very high and shows that the children have really thought about what the scientists may find with the AUV survey being undertaken over the next week.It is going to be a tough job to choose some prizewinners! Scientists will make their choice based on visual impact and scientific accuracy in comparison with their survey results, and the verdict will be announced in mid February

Meanwhile, the team is gathering in Rotorua, including scientists from GNS Science, Columbia, NOAA and Woods Hole Oceanographic Institution in the US, the University of Waikato, Auckland University and Bayreuth University in Germany. There is also a film crew and a couple of TV news teams coming along for some or all of the time.Tomorrow our first engagement will be a formal welcome of scientists and visitors on the local Marae.

The Deep Fault Drilling Project

2011-01-19T17:03:00.001+13:00

The Deep Fault Drilling Project begins its first phase of drilling in the next few days. In this video Rupert Sutherland tells why scientists want to drill into New Zealand's huge Alpine Fault.

New Zealand's Alpine Fault

2011-01-14T11:25:00.004+13:00

For the latest on the Alpine fault drilling visit Rupert's Blog

This NASA photo of the South Island of New Zealand shows the green of lowland vegetation contrasting clearly with snow in the mountains of the Southern Alps. The straight edge of the mountains is the line of the famous Alpine Fault. This fault is the boundary between the Pacific and Australian tectonic plates which are sliding past each other in this region at an average rate of about 40 mm per year. The Alpine Fault is a globally significant feature and similar in character to the San Andreas Fault in America or the North Anatolian Fault in Turkey.

Every 200 - 400 years the plate movement is accomodated by a violent earthquake of about magnitude 8, and dislocation along a segment of the fault of roughly 8 metres. The last big earthquake rupture occurred in 1717 AD.

Most of the fault movement is sideways, but a portion of it is vertical, and has uplifted the mountains on the eastern side to reveal exposures of the rocks along the fault that have been buried and altered over millions of years. The second image shows a slice of this metamorphic rock with white streaks of quartz, black mica and a red garnet crystal that is about 5mm across.

Rupert Sutherland at GNS Science is one of the leaders of the Deep Fault Drilling Project (DFDP) which is about to drill into the Alpine Fault. Many other research organisations are involved in this very large, multi year project. To listen to a short radio interview of Rupert talking about the project go here.

From next week, the DFDP project will start by drilling two shallow (150m) boreholes through the fault near Whataroa on the West Coast. Rocks will be sampled and analysed and instruments will be left in the ground as part of a long term monitoring programme. In future years this reasearch will be extended by drilling down several kilometres.

In the photo of Rupert he is holding a specimen of fault breccia - a bit of rock that has been fragmented by rupturing of the Alpine Fault. In the close up image you can see how the rock is broken up. The dark patches are where some of the rock was melted and then solidified again in the spaces between the fragments.

Tsunami Video

2010-12-17T12:14:00.003+13:00

New Zealanders know by first hand experience that living on top of a plate boundary makes life unpredictable. The recent earthquake in Christchurch was just the latest example of that.

I recently had the privilege of interviewing several Kiwis who had experienced first hand the power of a tsunami. Luckily for them they all escaped with no more than cuts and bruises, but many around them were not so fortunate. These tsunami events were overseas - in Thailand 2004 and Samoa 2009. However, it is worth remembering that New Zealand is one of the most 'at risk' countries in the world when it comes to tsunami hazard.

In case you haven't seen it on our GNS Science Youtube Channel here is a video of the vivid tsunami accounts, hosted by Hamish Campbell:

NZ Volcano Fact Sheets

2010-12-09T12:32:00.001+13:00

The GNS Science website now has 10 one page Fact Sheets on the main New Zealand volcanoes. They give details of the landforms, rock types and eruption histories, with colourful images and diagrams.These are great for a school project, or to print off and take with you when you go for a tramp up one of our volcanoes.

Don't forget that there is lots of detailed volcano information on our website as well as webcams and updates of volcano activity levels on our GeoNet site.

Watch a video of scientists monitoring White Island Volcano, or follow some students whilst they check out the amazing Volcanic Landforms of Tongariro.

Rotomahana Fact Sheet

2010-12-03T12:13:00.004+13:00

To have some more background information on the Rotomahana project that you can print off and have at your fingertips, go here. It answers basic questions about the purpose of the project, the technology being used, and some of the scientific questions that will be answered by the investigation.

The photo shows the offical party at the Prime MInister's Science Prize ceremony in Auckland last weekend. Cornel is second from the right. He was awarded the prestigious prize for being the top science communicator of the year 2010.

Rotorua Schools' Tour

2010-12-02T12:44:00.008+13:00

I am in Rotorua this week visiting a number of the schools to tell the children about the Rotomahana Project.

It is wonderful to witness the excitement and engagement of the kids, and the enthusiasm of the teachers helping them to learn about the unique history and geology of the local area.

I have been describing some background of New Zealand's volcanic landscapes, the reasons why scientists want to understand the geothermal activity, the history of the Tarawera Eruption of 1886 and also the way we will be investigating the lake with the Autonomous Underwater Vehicles.

The photos show GNS Scientists at work studying our volcanoes and geothermal activity in New Zealand

Cornel's Science Communication Prize

2010-11-26T14:14:00.006+13:00

Cornel de Ronde, has today been awarded the Prime Minister's Science Media Communication Prize for 2010.

Cornel is the leader of the Lake Rotomahana project, the latest amongst a host of expeditions to look for underwater hydrothermal systems. Much of his research has focussed on the submarine volcanoes of the Kermadec Arc, to the north of New Zealand.

To read more about the background to this prize and Cornel's passion for communicating the adventure of science, check out the media release.

Chris Laidlaw interviewed Cornel about his work as a submarine geologist, and the Rotomahana Project in this National Radio Broadcast following the announcement of the prizewinners..

Poster Competition Update - Prizes and Exhibition details

2010-11-26T10:57:00.002+13:00

The Waimangu Volcanic Valley has sponsored some impressive prizes for our Rotomahana Poster Competition
for Primary and Intermediate Schools in the Rotorua.Area.

First prize is for free entry to Waimangu Volcanic Valley, a guided tour and a boat trip on Lake Rotomahana for a group of thirty school children and adults. (individually this would cost $77 per adult and $22 per child!)

Second prize is free entry and guided tour for thirty students and adults.

We also have runner up prizes of three family entry tickets.(two adults, two children) for a self guided walk and a boat cruise on the lake.

The poster competition is open to all Primary and Intermediate students. There are full guidelines on the GNS Science website and all completed posters are to be delivered to Rotorua Library by December 22nd..

We are hoping that as many as possible students will be encouraged to enter, and have the opportunity to think about their local Tarawera history and volcanic geology. The poster competition relates to the "Nature of Science" strand of the National Curriculum.

Rotomahana Poster Competition for Schools

2010-11-19T13:48:00.001+13:00

If you are a teacher of year levels 1 - 8 in the Rotorua area, you may be interested in our end of year Poster Competition for schools.

Our science team does not yet know what will be discovered at the bottom of Lake Rotomahana, although they have a few ideas!

Why not see what your students think and then compare their predictions with the actual scientific results that will be known in February?

We are offering a competition for primary and intermediate aged kids to draw a poster of the bed of Lake Rotomahana, with details of what could be down there - volcanic debris, mud, hot water (hydrothermal) vents, explosion craters etc.

You can read some background information about the history of Lake Rotomahana and the aims of this science project here.

The posters will be judged for 'best fit' with the science results at the end of the expedition, and results will be shared with the schools and public in mid February.

The Waimangu Volcanic Valley is kindly sponsoring our competition with some cool prizes!

I will post further details about the competition here soon.

Lake Rotomahana Project in the News

2010-11-16T15:31:00.004+13:00

The media have shown a lot of interest in the research we will be doing in Lake Rotomahana. Check out the article on the Stuff website, or the one from the Daily Post, or have a look at the TVNZ news item from yesterday Monday 15th.

Cornel is 'immersed in this project', says Radio New Zealand's Jim Mora today in his Afternoons radio interview.

If you are a Primary or Intermediate teacher in the Rotorua area, we will have some information out for you soon on how your students can be involved with the science of the 'Secrets of Lake Rotomahana'

Lake Rotomahana's Secret Underworld

2010-11-15T17:19:00.002+13:00

Cornel de Ronde is the world renowned GNS Science specialist in researching undersea volcanoes and hydrothermal activity. He has made numerous discoveries and had many adventures diving to the ocean floor in submarines of all shapes and sizes.
Visitors to Wellington's Te Papa Museum may recognise him from the "Deep Ride" submarine experience.

In 1886 Mount Tarawera near Rotorua erupted with extreme violence for a few hours over one night in June. By morning, several settlements had been buried in hot ash and mud with the loss of over 100 lives, the world famous pink and white silica terraces had disappeared and a crater several kilometres long had opened up in a reshaped and devasted landscape.

Lake Rotomahana, on whose shores the famous terraces had been located, had become part of the long, deep volcanic rift. Over time the lake refilled with water again to become a larger version of its former self.
In January, Cornel will be leading a team of researchers from New Zealand and the US, to plumb the depths of Lake Rotomahana with two very high tech, automated underwater vehicles (AUVs). They will map the lake floor, identify the hydrothermal vents, and make numerous measurements of the chemical and physical properties of the lake water and hydrothermal fluids.

(Permission of the Alexander Turnbull Library, Wellington, New Zealand, must be obtained before any re-use of this image of the Tarawera Eruption.)

The detailed survey will enable the scientists to find out the fate of the Pink and White Terraces after the Tarawera eruption in 1886. These terraces were world famous in the nineteenth century for being the largest silica terraces on the planet, and for their outstanding beauty and grandeur. Visitors used to wander over the terraces and bathe in the bath tub shaped depressions

Tineke Berthelsen is one of the science team. She will be managing some of the practical aspects of the project and operating equipment when the research team is on site in late January.

We will be posting more information on this blog over the coming weeks. For a more in depth introduction to the project you can read the press release that has been publicised today.

Bookmark this blog or link up to our facebook page if you want updates about the background and science of this unique research project.

Julia Becker's Observations following the Darfield Earthquake

2010-09-14T11:17:00.002+12:00

Julia Becker is one of the Social Scientists at GNS Science. Her role is to understand the human response to natural hazards, and she works with other scientists and organisations to help plan for future disasters. I asked her to write a diary of her experiences of working in Christchurch in the week following the Darfield 'Quake:

06/09/2010
We arrive in Christchurch, two days after the earthquake. Driving into the city from the airport, much of the city looks quite normal. There are a few chimneys down and damaged brick fences. As we approach the city you start to see more damage, mostly to older brick buildings. Some are just a bit damaged with a few bricks fallen off while others’ facades have completely collapsed. There is quite a wide area around the city that is cordoned off and the cordons are blocked by police officers and military personnel. We have to take a big detour all the way around the city to reach our hotel. Many shops and supermarkets we pass seem to be operating. We drive past a clock tower and it has a big crack in it. At our hotel we drop our gear and then head to visit the city and regional emergency operation centres. They are very busy with many people coming and going, working away hard to respond to the earthquake. After having a few meetings with people to let them know we are here and providing offers of science and research support, we head back to our hotel for dinner and bed.

07/09/2010
Small aftershocks in the night occasionally wake me from sleep. I wake at about 6.00 am. While the water is working there is uncertainty over potential contamination so I have to remember to brush my teeth with boiled water. All drinking water needs to be boiled as well. In the morning we reconnect with the regional emergency operations centre and begin to set up an office there from which the scientific research response can be coordinated. I speak briefly to Red Cross volunteers at the regional emergency centre and they say the welfare centres are being well used, with more people turning up after the aftershocks in the night. A little later two of us from GNS obtain official passes to enter the cordoned-off city centre and inspect the buildings from the outside. Many new buildings look like they have stood up well to the earthquake. The Christchurch Cathedral seems pretty sturdy too. There are a number of buildings scattered throughout the centre that have red placards indicating that they cannot be entered due to structural damage. In the afternoon we head out to the suburbs and see the impacts of liquefaction. A few suburbs have experienced significant liquefaction, and sand volcanoes have popped up out of cracks in ground. Residents have already begun to clear away the sand by shovelling it up and placing on the grass verge in front of their houses, and the council is driving by and collecting it in trucks. Port-a-loo toilets have been set up for residents who don’t have working sewerage systems.

08/09/2010
Sleep is again disrupted by aftershocks throughout the night. This morning before breakfast we are also rattled by a large 5.1 aftershock (scary!), followed by several smaller ones. After breakfast we visit the town centre to observe more of the building damage. We see a whole row of shops made of bricks where the front of the building has simply fallen away on to the pavement in front. Luckily the earthquake happened at approximately 4.30 am so there were few people on the streets at that time and people were not hit by the falling masonry. A restaurant is housed in one of these buildings, and as you look through the gaping hole left by the fallen bricks you can still see the tables set up and ready for customers. In the afternoon we visit the newly ruptured fault near Darfield. You can see where the fault has torn through several roads and fields. The rupture has offset the roads sideways and vertically. Initial repairs to the roads have been made to make them drivable again. You can also see where the fault has offset power pylons, trees and fences. At the very western end of the fault, an electricity substation is perched directly over the rupture and the surrounding fences and gates are twisted, but because the fault is quite distributed at this location the substation appears to still be intact and in working order. At the eastern end of the fault a house-owner is not quite so lucky, with the fault causing building damage to a resident’s home.

09/09/2010

Today we visit a couple of land use planners in Christchurch and discuss issues related to recovery. We discuss having a strategic vision for Christchurch when going into the rebuilding and recovery phase. Following our meeting we take a drive out to Pegasus township, a new subdivision located approximately 30 minutes drive north of Christchurch. Previous studies have shown the site has liquefaction potential. There are a number of houses built there already, and also some empty lots. Pegasus seems to have survived remarkably well and our untrained eyes could not see any significant cracking or liquefaction. It

is suggested by the planners we speak to that geotechnical engineering works were undertaken when the subdivision was set up to try and avoid such problems. In the evening I attend a com

munity meeting in Darfield. The meeting was set up with the aim of to giving residents information about the earthquake, providing discussion on how they might feel after the earthquake, and providing advice on practical issues that might need addressing (e.g. water pumps, insurance, finance, government support). At the end of the meeting two guest speakers tell a couple of funny tales to provide some light humour to the meeting. The meeting is well attended with nearly 400 people coming along. On our way ho

me, driving down Riccarton Road we can see that the demolition of buildings has started, with several previously standing (but damaged) brick buildings now looking like piles of rubble.

10/09/2010
Attended several meetings related to recovery.

11/09/2010-12/09/2010
Back in Wellington.

13/09/2010
It has been 10 days since the earthquake and the clean-up of Christchurch City is well underway. Bricks have been moved from the pavements, and some buildings have already been demolished. Most of the city centre is now open to the public, with only a few areas still cordoned off. Most businesses that are able to access their premises are now operating. Out in the suburbs much of the liquefaction material has been swept up and carted away by the city council. However there are still many streets in the areas worst affected by liquefaction that are badly damaged, with large cracks in roads and properties, water issues and sewage issues. Signage placed by the Avon River reminds people not to enter the river due to potential contamination. A number of residents have moved out of their properties because of the damage they have incurred, or have gone to friends and family for reassurance. Some people are still residing in the welfare centres; however numbers have dropped since the earthquake occurred.

Scientists' response to the Canterbury Earthquake

2010-09-07T12:34:00.003+12:00

Whilst those of us in Wellington may have felt a short jolt and a bit of a wobble, the 7.1 magnitude earthquake hitting Christchurch on Saturday morning was an altogether different experience for the locals. People I have talked to referred to the noise of the quake as being one of the most powerful aspects of the experience.

Different specialist teams from GNS Science immediately leapt into action to capture vital information about the origin and effects of the quake, and to keep authorities, public and news media updated. Web traffic has been very high with the GeoNet website receiving 15 to 20 million hits per day.
chchseismic 4 sep 2010

This image is the seismic drum for McQueen's Valley, near Christchurch on the Saturday afternoon. You can see how the aftershocks are very frequent. Some of them are up to magnitude 5.4, though scientists think a larger one of up to magnitude 6 is possible sometime in the next few days.
waipu seismic 4 sep 2010

This seismic drum is from the same time, but recorded in the far north up at Waipu. You can see how the weaker ground shaking has not reached that far, but many of the aftershocks are still recorded there. It is interesting to look at the way the waveforms change when they are recorded a lot further away from the epicentre.
web_useful IMG_0564

An initial flyover of the surface rupture revealed a fault trace about 22kms long in the Rolleston area to the west of Christchurch, with a maximum of 4 metres of horizontal and 1.5 metres vertical displacement. The surface rupture passed close by a few farm buildings and beneath two farm houses. The fault dislocated some hitherto undisturbed glacial river terraces, showing that it has not moved for a minimum of 16 – 18 000 years

Here is a video of the fault trace from the air:

The Geonet seismologists started the analysis of the large number of aftershocks detected by the NZ network of seismometers, finding their locations and magnitudes, and using the information to interpret crustal stress and strain dynamics in the region. The data collection systems were thoroughly tested and have performed very well through this event.

A team flew down to Canterbury and installed an array of extra seismometers which add further data as the aftershocks continue.
web_useful Highfield Road IMG_0636

Other GNS Science teams are now in the Christchurch area assessing and monitoring such things as: infrastructure damage, including water and sewage, fault and landscape mapping, risk engineering, high resolution GPS measurements, and further measurements and mapping of ground moti

Romanian Salt

2010-08-25T12:57:00.003+12:00

Another place that I visited in Transylvania was the town of Torda, where there is a huge (1200 metre thick) salt deposit that formed about 18 million years ago. The salt can be found forming the sides of a nearby valley where it has been eroded by rainwater into pinnacles.

The salt is 99% pure and the crystals form cauliflower like surfaces covering large areas.

It has been mined since Roman times, and some of the undergound workings have become huge chambers up to 80 metres long, 50 metres wide and 40 metres high.

The high relative humidity, constant temperatures, absence of dust and high concentration of sodium chloride particles in the chambers are regarded as beneficial for sufferers of breathing disorders (eg asthma, allergies etc). Large areas are equipped with playgrounds, a restaurant, internet access and even a church so that visitors can spend days at a time underground.

Romanian Ice Cave

2010-08-20T11:56:00.005+12:00

On a recent trip to Europe, I spent time in Romania, France and Italy. Here are some of the geological highlights I visited:

This photo is an underground glacier in the Apuseni Park. This is an area of the Carpathian Mountains with over 200 limestone caves. The Focul Viu ice cave that we visited is one of several in Romania. There is about 25 000 cubic metres of ice which has accumulated as snowfall from a large hole in the ceiling of the cave ( along with branches and leaves from the surrounding forest). Due to the poor circulation, cold air sinks into the cave and maintains very low temperatures even in the hot summer months.

An 8 metre ice core has been retrieved from this cave. A piece of wood from 7 metres down was dated at about 1700 years old.

The Wellington Fault with LEARNZ

2010-05-11T09:02:00.016+12:00

LEARNZ is a unique kiwi organisation that runs 'virtual' field trips for primary and secondary schools in New Zealand.

Using videos, audioconferences and internet based information, school kids are able to interact with scientists and other expert professionals in different parts of New Zealand. LEARNZ even runs virtual field trips to Scott Base in Antarctica.

Last week, Shelley Hersey and Andrew Penny from LEARNZ were investigating the Wellington Fault. Russ van Dissen, Julia Becker and Hamish Campbell from GNS Science joined me to assist them. We looked at the way scientists work with planners and emergency services to understand the earthquake risk and prepare for the possibility of a 'Big One' striking Wellington. There is nothing like a detailed description of the potential impact of a natural disaster to remind you to re- check your personal Civil Defence emergency preparedness!

In addition to the many other active fault lines in the region that could cause an earthquake, there is a small but real possibility of a Wellington Fault earthquake occurring. This would cause a rupture along the fault line with perhaps 5 metres of sideways movement and one or two metres of vertical dislocation. Houses built across the fault would be ripped apart, and the whole city shaken violently, resulting in severe building damage, streets full of glass and other debris, broken water, gas and electricity supplies, roads, railways and the ferry terminal out of action and communications largely cut off. Did you click on that emergency preparedness link yet?

Over three days we visited a number of city viewpoints and structures, the emergency operations centre of the Wellington Regional Council, the fault line itself, and the water supply lakes at Te Marua. It was reassuring to see how much thought and effort has been put into planning for the earthquake risk by the authorities. In this photo of the place where the fault runs right below the Thorndon overbridge and the Wellington Railway, you can see the steel re-inforcement casings around the motorway support pillars and the large concrete slabs that are designed to prevent the motorway segments from collapsing.

The take home message is very much that local government and other organisations are doing their bit, and it is up to us individuals to make sure that we have our personal survival plans in place as well.

Over one hundred school classes participated in the event.

The GNS Science website has a lot of information about the Wellington Fault, including a tour guide, a fault line field trip, a photo gallery , a Google Earth flyby video

as well as our Wellington Fault short doco movie:

Under a cloud in the UK

2010-04-20T08:35:00.006+12:00

Having arrived at Heathrow a few hours before the shutdown of all flights over Britain due to the volcanic eruption in Iceland, it has been fascinating to watch the unfolding impact as the flight ban has been extended through the last few days. As with an earthquake or tsunami, a geological process is suddenly thrown into the public consciousness, even though it originates from far away. In this case the process is relatively prolonged and there is no-one who has any idea of how long the eruption might last or how the winds might be moving the ash cloud a week from now.

As well as having stressful consequences, there have also been benefits resulting from the ash cloud. I am staying in the south east of England, not far from Gatwick and Heathrow airports. For many people this is the first time ever that they are able to sit in their back yards and have a conversation without being drowned out by the roar of aircraft overhead. The weather has been sunny with clear skies, with no visible sign of the ash cloud that is causing so much disruption.

News bulletins are filled with the scientific background, economic predictions, traveler's personal stories and political commentaries. I have been increasingly grateful for my good fortune in having got here just in time, whilst wondering if my return journey at the end of April will be equally unaffected. There are direct lessons to be learnt for NZ too as Gill Jolly and Graham Leonard, both volcanologists at GNS Science, describe in this media release

Tararua Range

2010-04-13T14:10:00.015+12:00

With Uwe Morgenstern, also from GNS Science I hiked the length of the Tararuas just north of Wellington over 4 days. The Tararua mountains are a section of the 'backbone' of New Zealand. They are made of greywacke rock, pushed up by the tectonic forces of plate collision. Like most of New Zealand's mountains, they form an obstruction at right angles to the prevailing westerly winds and are renowned for high winds and high rainfall - often making for tough tramping. Luckily for our trip we had very stable and clear conditions, a rare treat!

We set out from the Putara road end near to Ekatahuna, at about 9am. After following a stream and hiking upwards in the forest, we came out into the open tussock after a couple of hours. It was quite cloudy through the day. This made for an amazing sunset as we continued along the ridge to Arete Hut which we reached after dark. For the final hour and a half we had to navigate by map and compass, with a bit of searching to finally reach our refuge for the night.

Day 2 saw us following the ridge for hour after hour. the distant point on the horizon was our objective for the night and again we reached Jumbo Hut after dark.

We passed by this possum that seemed to have lost its way and was hiding under a rock well above the tree line.

Day 3 was our longest day. Leaving Jumbo hut at about 7am, we traversed to Mount Holdworth, then dropped down through the forest to the Mid Waohine Hut which we reached at about 11am. After a very brief dip in the river, a long and exhausting climb saw us back on the tops further to the West. From Aokaporangi Peak we headed to Maungahuka Hut which we reached about 5pm. After a short break we decided to keep going in order to be able to complete our traverse in time for work on Monday.

As fast as possible we dashed over the Tararua Peaks - very steep ground which we didn't fancy attempting in the dark. Soon we were beyond them and darkness was upon us. Four hours of arduous tramping by headtorch we arrived at Kime Hut and the end of a fifteen hour day.

All that was left was to complete the Southern Crossing of the Tararuas, over Mount Hector and down the less travelled Quoine Ridge. The views in all directions were spectacular, including Taranaki and Ruapehu volcanoes, our own route through the Tararuas, the Wairarapa Plains, Palliser Bay, the Rimutaka Ranges, Wellington Harbour and the Kaikoura Ranges of the South Island.

Just above the tree line we came to this GNS Science continuous GPS station cemented into the bedrock. This device is part of a nationwide network that continuously monitors the horizontal and vertical displacement of New Zealand on its plate boundary.

As we descended, we entered the Goblin Forest - a wierd world of beech trees covered with mosses and lichens. Finally by 5pm we arrived at our awaiting vehicle and the prospect of a very satisfying rest.

Marlborough and Kaikoura from the air

2010-03-19T10:12:00.013+13:00

Yesterday I was offered a flight from Paraparaumu Airport to Kaikoura by Felix Morgenstern. His father Uwe is the water and ice dating specialist here at GNS Science. This was a great chance to admire some fantastic landforms created by the uplift of the leading edge of the Australian Tcctonic Plate right up close to the collision boundary, just east of the north end of the South Island.

We flew directly south across Cook Strait, away from Wellington's cloudy skies to a clear day over the South Island. This picture shows the coast of the Wellington Peninsula fringed by marine terraces that have been uplifted and tilted by successive earthquakes. Cook Strait is in the foreground and the white wind generator towers are making use of windy Wellington's prime natural resource!

On the other side of the Strait, the skies were clear. This is a view across the coastline to the south-east of Blenheim. The rocks that underly this landscape include several locations where the famous K-T boundary layer (Cretaceous - Tertiary or Cretaceous Paleocene boundary) is exposed. This thin dark layer of clay is found at different places worldwide. It marks the point in time when a massive asteroid impact in Mexico caused the extinction of the dinosaurs and many other life forms. One such place is the rocky hillside near to the true left of the river in the foreground.

Soon we were passing alongside the inland Kaikoura Range, whose highest peak is Tapuae o Uenuku at 2,885 metres. It is made up of a complex of resistant igneous rocks, thought to be of Cretaceous age. Faults active for the last 20 million years are lined up along each side of the range, parallel to the plate boundary just off the coast. These are mainly strike slip (sideways moving) faults but there is also significant vertical movement pushing the mountains up by up to 10 mm a year.

I took this picture as we were approaching the Kaikoura Peninsula. Suspended sediment in the sea from river outwash has developed into a nice spiral shaped eddy. Beyond the narrow peninsula is the area where the Hikurangi Trough meets the coast of the South Island. The Kaikoura Canyon - a deep slice in the ocean floor just off the coast, has created a haven for wildlife there including whales and other marine mammals.

After landing for a short while at the Kaikoura airstrip we took a short detour out to sea. We didn't see any whales but there was a crowd of dolphins surrounding a boat. A nice way to leave Kaikoura behind.

Palliser Bay

2010-03-04T09:53:00.008+13:00

Palliser Bay is an isolated sweep of coastline about 2 hours drive from Wellington. It is separated from New Zealand's busy capital city by the Rimutaka Range. Yesterday I visited the area with a group of Lower Hutt school children as part of their Year Seven geology camp.

Fully armed with the "Kiwi Fossils Hunter's Guide" as well as another excellent book by Lloyd Homer and Phil Moore that describes the geological features of the Wairarapa Coast called "Reading the Rocks", we visited several great geology hotspots along the coastline.

A striking feature that we noticed straight away was the flat topped escarpment that runs along much of the coast. This is a raised marine terrace that was at sea level about 80 000 years ago. It indicates that the whole area has been undergoing an enormous amount of uplift which continues to this day.

First stop was Hurupi Stream. (This is described in detail in the "Kiwi Fossils Hunter's Guide"). The soft mudstones at the sides of the stream were deposited under the sea in the Miocene Epoch (sometime between 11 and 7 million years ago) , when the Aorangi Range just to the North was an island, separated from other parts of the North Island by a shallow sea. We found quite a few marine molluscs that are very well preserved and easily spotted.

Not far along the coast road are the Putangirua Pinnacles. These spectacular features have been eroded out of a thick sequence of conglomerate. Hard layers or large individual boulders within the conglomerate form a protective cap at the tip of each pinnacle. The ground is strewn with loose rubble - testament to the fact that the erosion here is still very active. This might not be the best place to visit in a rainstorm!

A few kilometers along the coast road, there is a dramatic example of coastal erosion where a whole section of the original road itself has disappeared!

We followed the coast past the small settlement of Ngawi, and a huge tilted slab of fossiliferous sandsone called Kupe's Sail, to the Cape Palliser lighthouse. This is built on a cliff of volcanic rock that was erupted under the sea as pillow lavas about 100 million years ago. The long staircase up to the lighthouse leads up to a great viewpoint.

This is the Southeastern tip of the North Island of New Zealand, with nothing but ocean between here and Antarctica or South America. Just a few kilometres out to sea is the Hikurangi Trench, the collision boundary between the Pacific and Australian tectonic plates. The connection between uplifted terraces, fossils, erosion, earthquakes and volcanoes gave us all something to think about to round off our geological excursion.

Turning over an old leaf with the Fossil Hunter's Handbook

2010-02-25T08:57:00.009+13:00

If you are reading this blog, you presumably like the idea of getting outside and appreciating the landscape and its underlying geological features. James Crampton and Marianna Terezow are paleontologists here at GNS Science. They have just published a great book for fossil enthusiasts called the Kiwi Fossil Hunter's Handbook. It is full of interesting information and highlights a number of prime localities around the country for unearthing nice fossil specimens.

After a conversation with James,, and armed with information from one of the chapters in the book, I recently visited a fossil locality near Murchison in the South Island. About 6.5 kms north of Longford on the main State Highway 6, there is a sign indicating Nuggety Creek Road.

A few hundred metres along the track there are some crumbling cliffs by the roadside. This is a fantastic place to collect fossil leaves from the Miocene (about 16 - 13 million years old). They were deposited in a river valley that was surrounded by a rainforest.

Boulders at the foot of the cliff are absolutely packed with leaves of different plants. There were large trees here as well as smaller plants such as ferns living beneath them. The rock is quite crumbly, so it can take a while to find a lump that is solid enough to stay in one piece.

These fossils are evidence that the climate in New Zealand in Miocene times was very humid and warmer than at present.

As you can see from the last photo, some of the fossil leaves are superficially very similar in appearence to modern leaves found at the same locality today.

Cretaceous Reptiles in Hawkes Bay

2010-02-12T14:17:00.010+13:00

Over the last few days I have been with a GNS Science team exploring the remote Mangahouanga Stream in inland Hawkes Bay. This is the area that is famous for the discoveries of dinosaur and other reptile remains by Joan Wiffen (who died in June last year) and her team. It is on private land, deep in the forest and therefore rarely visited. Bones of marine reptiles seem to be relatively common in the hard concretions in the stream bed, but land dwelling dinosaur remains are very rare as they were washed some distance into the sea and separated before being buried in the sediments . An example of a therapod dinosaur toe bone, discovered by Joan Wiffen can be seen as a 3D image here

On the way to explore the river we passed the two expedition huts used by Joan's team . In the picture are Mike Wylde and Tunis Keenan, two Royal Society Primary Teacher Fellows being hosted by GNS Science this year.

After following a rough track through the bush, we reached the Mangahouanga Stream. In several of the large boulders we could see bone remnants. In this picture there is a large vertebra (backbone segment) of an unknown species of reptile. If you look carefully at the top of the rock in the right foreground you might see an oval shaped brown lump which is another similar vertebra.

Here John Simes (GNS Science palaeontology collections manager) and Pete Shaw (forestry manager) check out a rock slab containing shells, sharks teeth and fish bones.

Have a look at our video of fossil hunting in Mangahouanga Stream:

Oparara Limestone Arches

2010-02-01T15:14:00.009+13:00

On a recent trip up to Karamea on the west coast of the South Island, I went to visit the Oparara Caves. These are a few kilometers inland, and not far from the end of the Heaphy Track. They are an amazing example of limestone erosion...

Huge archways have been cut through the limestone by the Oparara River. The limestone was laid down in the ocean during the Oligocene Epoch, about 34 million years ago.

The third photo shows the largest of the arches (the Oparara Arch). You can see the clear boundary between the limestone and the underlying Karamea Granite. This is about 350 million years old, much older than the limestone. The arch is an impressive 200 metres long and 50 metres across.

There are several accessible caves in the area. The unique geology and ecology is a 'must see' if you ever make the trip to Karamea.

2010-01-15T09:15:00.001+13:00

Our "Discover Ancient Worlds" holiday programme finished this week, with a presentation from the participants of some of their activities and discoveries. Feedback from each of them has been very positive - particularly about the many hands on challenges they were involved with. Here are some examples:

In this picture you can see how to make a vessel float even though it has a hole in the bottom (like the drill ship). The task also required the 'ship' to carry a rock and still float.

We also investigated possible causes of sea level change. Here the participants are heating water whilst measuring the resulting thermal expansion.

This test was to find out the effect on sea level of melting ice caps compared to melting sea ice or ice shelves.

On one of our days we went to drill our own sediment core from Petone Wharf.

Alison Ballance from Radio New Zealand and Michael Kopp from Central Community Newspapers came along to see what we were up to.

Back in the laboratory we split open the core and identified some layering as well as a variety of shells. Each of the participants took samples.

The samples were then studied to look for microfossils and other features.

All in all it has been a great week for the GNS scientists to have some involvement with young enthusiasts. Listen out for the audio account on Our Changing World on New Zealand National Radio soon!

Ocean Drilling science holiday programme

2010-01-06T13:38:00.001+13:00

The JOIDES Resolution drill ship is back in Wellington after spending the last two months recovering sediment cores from off the east coast of the South Island. The photo shows the ship being loaded with fresh supplies in the Port of Wellington.

The expedition was very successful, with several holes being drilled, one of which was over 1900 metres deep. This is the deepest individual core drilled so far by the JOIDES Resolution. All of the rock retrieved has generated thousands of samples for analysis. In a few days the ship will depart for another trip, this time close to the coast of Antarctica.

Check out the TV3 news video here.

Also have a look at our own GNS video about the drilling programme:

GNS Science is running a 7 day holiday programme for school students that is investigating the science of ocean floor geology.

The students were amongst a priveleged few New Zealanders allowed to visit the ship today. They were able to ask all sorts of questions of a number of scientists and technicians.

Young scientist Thomas Seaton is admiring the
drill teeth that cut through the solid rock of the ocean floor.

Imaging specialist Bill Crawford explains the process for making high resolution digital images of the rock cores.

Richard Levy of GNS Science and Christian Ohneiser of Otago University explain how the cores are analysed in the on board laboratory.

Thanks to Victoria University, Capital E and the Museum of City and Sea for their collaboration with the Holiday Programme.

Caves and Moa Bones

2010-01-04T16:41:00.005+13:00

Takaka limestone landscape

On a recent trip up Takaka Hill near Nelson, I went exploring over the limestone landscape with my daughter Sophie (with permission from the landowner). The area is riddled with sink holes and caves. The most well known is Harwood's Hole - a huge vertical shaft about 50 metres across and over 180 metres deep. However most of them are much smaller - many only a few metres deep and blocked with debris.

Moa Trap - the cave entrance

In this second picture you can see a typical example. A small cave entrance half concealed by vegetation. Inside it, a few metres from the surface and half buried in the clay floor Sophie discovered a moa bone . With a bit of digging we eventually uncovered a variety of bones from several individual skeletons. They were jumbled up with blocks of rockfall debris and many of them were covered in a thick layer of white cave deposit (calcite). This showed that they were likely to be pre - ice age (at least 70 thousand years old) as it takes a long time for the bones to become coated in this way.

Finding a moa bone

There were once atleast 9 species of moa in New Zealand, although only two of them were common on Takaka Hill. The limestone pot holes were a death trap for many that fell in and were unable to escape.

The bone that Sophie is holding in the picture is a lower leg bone (metatarsus).

If you would like to see the bones, they are now resident in Ngarua Cave. This is a very worthwhile show cave that has beautiful formations as well as other Moa remains found previously. I can definately recommend a visit if you are passing over the hill some time!

Ocean Drilling in New Zealand waters

2009-12-04T14:44:00.001+13:00

Recently the ocean drilling ship JOIDES Resolution visited Wellington Harbour for a brief one day stop-over before heading out to attempt several drillings in the sea floor off the Canterbury Coast.

I had the opportunity to visit the ship and be shown around by GNS Science's very own Greg Browne. He is one of the science team on board for the drillling expedition. The main purpose will be to study the interrelationship between climate, sea levels and the uplift of the New Zealand landmass over the last 30 million years.

The ship is specially designed to remain in a stationary position on the sea surface whilst the drill operates. It achieves this by having a series of computer operated thrusters (propellers) which are positioned to push the ship in any direction to counter the effects of wind, waves and currents.

Once sections of sea floor sediment are pulled up from the drill hole, they are analysed in detail using a large variety of sophisticated methods. This is very similar to the way the ANDRILL programme has gained sediment cores from underneath the Ross Ice Shelf in Antarctica (- See my ANDRILL blog from 2006 here )

Greg led us on a tour of the labs, cafe, sleeping quarters and the bridge. If you would like a look around, check out this video from the visit:

The JOIDES Resolution will be returning to Wellington in early January.

At GNS Science we are organising a holiday programme "Discover Ancient Worlds Hidden Beneath the Ocean Floor". It is an opportunity for 12 - 15 year old budding scientists to be involved with lots of interesting hands on activities. It will be based in Wellington and runs from 5th - 13th January.

Participants will have special permission to tour the ship whilst it is re-provisioning for the January - February expedition to Antarctic waters. For more information and details of how to join the programme have a look here.

Dinosaur tracking in north west Nelson

2009-11-09T10:31:00.001+13:00

Last week, along with several other GNS scientists, I accompanied sedimentologist Greg Browne to the coast near Nelson, to check out his new dinosaur footprint discovery. His findings are being published this month in the New Zealand Journal of Geology and Geophysics. (photo courtesy of Marianna Terezow, GNS Science)

Kim Hill from Radio New Zealand joined our group as well. Here she is in conversation about the discovery with well known GNS geologist Hamish Cambell who was part of the team. To hear Kim's interview with Greg go to: http://www.radionz.co.nz/national/programmes/saturday/20091107

Greg works in the hydrocarbons section at GNS Science, and has been studying the rocks of north west Nelson for many years. These sediments are of interest to a hydrocarbon specialist because they are the onshore equivalent of the oil and gas producing sediments under the sea in the Taranaki Basin. By studying them, geologists can get a clearer picture of the inaccessible sea floor sediments just to the North.

Over years of detailed observations and mapping of the Upper Cretaceous (70 million year old) rocks, he came across several places where there were unusual structures visible in the rock layers. Pondering about these for a long time he finally decided to work out for certain what had created them. He scrutinised the rocks more closely and reviewed international scientific literature, finally concluding that the shapes can only be footprints of dinosaurs.

One of the reasons that the shapes are hard to interpret is that they appear on different surfaces and have been eroded out by different amounts. This means that it is hard to tell whether the differences in shape are due to erosion, to the way the creatures were walking through the mud, or because they were made by different animals. Some are rounded forms (like an elephant footprint might look) whilst others are more elongated - as if the imprint was caused by the animal dragging through the sediment with less of a stomp!

It was a fantastic opportunity to study these unique finds at first hand. John Simes and Marianna Terezow, helped by my 11 year old daughter Sophie, spent their time carefully making silicon casts of some of the best examples. It is important to get the best possible record of the prints as it is inevitable that they will be further eroded away with time.

Here are also a couple of links to the TV 1 news interviews about the discovery:

http://tvnz.co.nz/national-news/dino-footprints-found-near-nelson-3117525/video

http://tvnz.co.nz/national-news/dinosaurs-leave-their-mark-near-nelson-3117525/video

and here is a link to the TV 3 news item:

http://www.3news.co.nz/Nelsons-dinosaur-footprints-excite-scientists/tabid/309/articleID/128665/cat/772/Default.aspx