Multi-Scale Studies of the Physics of Earthquakes

Speaker(s): Candidate A

Earthquake faults are complex systems that span a huge range of length and time scales. These scale-rich systems are challenging to model, as each scale is itself a complex system that depends on the dynamics occurring at the other scales. Because the largest, damaging earthquakes are rare, estimates of risk based on historical event occurrence is highly uncertain, and physics-based models are needed to better evaluate hazard in earthquake-prone areas. In this seminar, I highlight ways that physical models can be used to understand earthquake processes at a variety of scales, ranging from microscopic frictional contacts through seismic event occurrence at the global scale. At the smallest scales of frictional interactions, I show how a spring block model combined with a physical model for frictional sliding provides insight into the physics of tiny earthquakes occurring deep in the crust. At the fault scale, I examine how complex, fractal fault geometries and dynamic models for earthquake slip can be used to understand earthquake interaction and aftershock production. At the global scale, I study the statistics of large magnitude event occurrence to examine if great earthquakes cluster in time. These studies show how a variety of quantitative, physics-based modeling approaches, combined with seismic observations and laboratory experiments, can improve our understanding of the basic physics of earthquakes and help bound uncertainties in estimates of earthquake hazard and risk.