Allan Rubin joined the faculty in 1992. He is a geophysicist who combines seismic and geodetic observations with numerical models, with the goal of improving our understanding of brittle deformation of the crust. Applications are primarily to regions of active volcanism and faulting.
With past post-doc Jean-Paul Ampuero he developed numerical and analytical models of earthquake nucleation that have led to new, intuitive ways of understanding the complex equations of friction that seismologists have been using for over 2 decades. By identifying those aspects of the friction law that are most relevant to nucleation, this work has led to a collaboration with Chris Marone and former graduate student Pathikrit Bhattacharya to better constrain those frictional properties through laboratory experiments. With former graduate students Jessica Hawthorne and Yajun Peng, Rubin is extending these concepts to understand the mechanics of episodic slow slip and tremor events that have recently been detected in subduction zones worldwide, using borehole strainmeter data, seismic recordings of tremor, and numerical models. The tremor detection/location method he is building has produced tremor catalogs that are currently the most accurate in the world.
Other ongoing projects stem from the use of precise earthquake relocation techniques that enable one to image fault zone structures and earthquake interaction with unprecedented detail. These relocated earthquake catalogs, with relative location accuracies as good as a few meters, have spawned several projects concerning the origin of “streaks” of microearthquakes, the asymmetric distribution of aftershocks of microearthquakes on the San Andreas fault, and elastodynamic models of earthquakes on faults separating rocks with differing elastic properties.