Some ground-breaking research into a rock is unlocking the secrets of earthquake faults. From Aoraki Mt Cook to Waiheke Island, and even further North, greywacke is our nation's most common type of rock. But it's the rock no-one particularly loves. Greywacke is a variety of sandstone. It's hard, dark, and has nothing shiny, pretty or particularly valuable about it. But lecturer in geology at Victoria University of Wellington Dr Carolyn Boulton is very interested in it. Dr Boulton tells Kathryn Ryan she has been granted EQC-funding to look specifically at how greywacke rocks behave before, during and after earthquakes, and how faults can communicate with each other.