Seismo Lab Seminar

Theoretical models of earthquake ruptures were well-established by the 1980s, primarily through the concept of a sudden shear stress drop on a planar fault. These models successfully explain many first-order geophysical observations, including double-couple radiation patterns, the relationship between radiation energy and earthquake magnitude, earthquake source scaling, typical slip rates on the order of m/s, and rupture speeds on the order of km/s. Further insight into the stress drop mechanism can be gained by applying a constitutive law, often referred to as fault rheology or friction law, which describes how fault strength evolves with slip history, such as the rate-and-state friction law.

However, some recent observations challenge the ability of existing models to explain certain earthquake behaviors. In this seminar, I will present my recent efforts to reconcile seemingly "strange" observations of earthquake sources, including slow earthquakes, stochastic seismic radiation at high frequencies, and the apparent magnitude-dependent stress drop in megathrust earthquakes. I will also explore the physical implications of the empirical rate-and-state friction law and discuss the theoretical foundation for its application at the tectonic scale.