What the cores can tell us

Transcript

Professor Dave Prior

What we hope to learn by our work on the Alpine Fault is what are the physics by which rocks deform. The process of deformation includes things like earthquakes but it also includes the longer-term kind of squidgy deformation of the rocks where they’re changing shape without actually breaking. Those two are closely related because, at depth in the Alpine Fault, say, 10 kilometres or deeper, the rocks don’t generate earthquakes, the deformation all occurs by the rocks simply squidging. So if you imagine if you have a chocolate bar on a summer’s day and you try and pull a bite off it, it tends to stretch in your mouth like this, whereas if you do it on a winter’s day, it snaps. At depth, things are hotter, so the rocks squidge. At a shallow level, they’re colder, so they tend to break. And the deformation at depth, this squidgy deformation, is ultimately what drives the deformation at a shallower level, so the Alpine Fault is in a sense a natural experiment.

Acknowledgements Professor David Prior, Department of Geology, University of Otago.