The Alpine Fault is a long, straight, geologically fast moving fault that typically produces very large earthquakes rupturing along large segments of its total length.
At its northern end the Alpine Fault branches into a number of different faults that cross Marlborough and are known as the Marlborough Fault System. This means that here the Alpine Fault only takes up a proportion of the total displacements in this region and is likely to have a different earthquake history compared to the
central and southern parts of the fault.
Recently a GNS Science expedition to the northern part of the Alpine Fault near Springs Junction, involved digging two trenches across it to better understand its local earthquake history through some careful investigation. This location features as one of our GeoTrips that you can visit. www.geotrips.org.nz/trip.html?id=59 .
You can also see the effect of fault movements on the river sediments below the ground. The grey clay layer on the left has been cut off at the fault and the overlying gravel layer has been dragged out of shape by repeated fault movements.
Here is a 3 minute video of the project:
And this video explains radiocarbon dating:
Finally click here for the TVNZ news report on the trenching.