Professor Dave Prior
The Alpine Fault is particularly special because it’s a type of plate boundary where one side is sliding past the other. It’s what we call a strike slip fault. But there’s also a component of movement in the other sense that, if this is the Earth’s surface, one side is moving up, so the combined movement is like this, and the reason why that is so cool is that it means that rocks which form say at 10 or 20 kilometres depth get carried up to the Earth’s surface. And we can look using microscopy and all sorts of other tools at rocks that were created at say 10 kilometres depth, 15 kilometres depth, 20 kilometres depth. So there’s nowhere else in the world where you can do this. One of the things we’ve moved a little further forward with is a programme to sample parts of the Alpine Fault by drilling. And one of the big reasons for doing is that if we drill to 1 and a half kilometres, then we can sample materials that in a few hundreds and thousands of years time will be at the surface, and similarly, stuff which is at the surface now would have been at those depths a few hundred thousand years ago. So we can get a full picture including what happens at depth on this particular fault.
Professor David Prior and Dr Virginia Toy, Department of Geology, University of Otago.
Strike slip fault animation, courtesy of US Geological Survey.
Stills of drilling rig and the Deep Fault Drilling Project site, courtesy of The Deep Fault Drilling Project – a multinational collaboration lead by GNS Science, the University of Otago and Victoria University of Wellington with researchers from the University of Auckland, the University of Canterbury, Liverpool University and the University of Bremen in Germany. Scientists from the United States and Canada are also participating.