Illuminating the seismogenic zones of large, hazardous faults with seismic arrays

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Earth's tectonic plates move past each other at cracks in Earth's crust called faults. Faults move in diverse ways - some faults slowly creep, while others are locked until they suddenly move in catastrophic earthquakes. We now understand that faults are not discrete planes but are zones of deformation, metres to kilometres wide. Laboratory and numerical models tell us that the structure and properties of fault zones control how a fault moves, including governing the size, speed, depth and direction of earthquakes - all factors that determine how much damage results from fault motion. To understand where and how earthquakes occur, and what their rupture styles are likely to be, we therefore have to better discern fault zone structure and controls on seismogenic behaviour.The best way to 'see' inside faults is by deploying seismic arrays above them. Advances in seismic technology and computing power now make deploying dense seismic arrays in remote areas feasible. I will use seismic arrays to investigate rarely studied but globally significant faults that offer answers to pressing questions in earthquake science. Why do some faults continuously creep whereas others slip in sudden earthquakes? Why do only a small proportion of recorded earthquakes rupture at supershear speeds, with a corresponding increase in ground shaking? How do large spatial (and temporal) temperature variations influence the rupture of faults that are co-located with active volcanoes? Addressing these questions is critical to our ability to mitigate seismic hazard and better understand the physics of faulting and earthquakes.