I study the mechanics and physics of earthquakes, volcanoes, and tsunamis. Our group has been developing numerical models of earthquake rupture propagation that incorporate sophisticated descriptions of the processes within and around the fault zone that are thought to control how fault strength evolves during rapid slip. The models include transport of heat and pore fluid within fault zones, microscopic weakening processes that have been observed in laboratory experiments, and inelastic deformation of the off-fault material. We are using these models to explore how earthquake ruptures excite seismic waves, with a particular focus on strong ground motion and seismic hazard. Recently, my group and I have been working to understand the origin of incoherent high frequency ground motion by directly modeling rupture propagation on fractally rough fault surfaces. We are also studying subduction zone megathrust earthquakes, like the March 2011 Tohoku-Oki event that was responsible for the devastating tsunami in Japan. In addition to the rupture process, we are studying the excitation of ocean acoustic waves and tsunamis in these events. These modeling efforts involve high-performance computing, using resources at the Stanford Center for Computational Earth and Environmental Science as well as the national XSEDE supercomputer centers. In addition to earthquakes, we study seismic waves from volcanic eruptions. We have developed a code that solves for the fully coupled flow of a compressible, viscous magma through cracks and conduits in deformable solids. We hope to learn about the dynamics of eruptions from seismic signals recorded at Earth's surface.
As part of our new geophysics undergraduate curriculum I teach a course (Geophysics 120: Ice, Water, Fire) in which we apply the principles of continuum mechanics to explain readily observed properties of tsunamis and ocean waves, volcanic eruptions, and ice sheets and glaciers. At the graduate level, I teach earthquake seismology (Geophysics 287: Earthquake Seismology) and have lead seminars on several topics including strong ground motion modeling for seismic hazard analysis, fluid dynamics of volcanic eruptions, and earthquake rupture dynamics. I am also an affiliated faculty member of Stanford's Institute for Computational and Mathematical Engineering (ICME) program. As part of that program, I teach an undergraduate scientific computing course (CME 108: Introduction to Scientific Computing).
NSF CAREER award, 2013; Alfred P. Sloan Fellow in Physics, 2012; Co-leader of Computational Science disciplinary group and member of Planning Committee, Southern California Earthquake Center (SCEC), 2011-present; Co-organizer for Seismological Society of America annual meeting special session on Seismicity in Volcanic Environments, 2012; Co-organizer for SIAM Geosciences Minisymposium on Computational Challenges in Earthquake Simulation, 2011; Delegate for U.S.-Japan Natural Resources (UJNR) Panel on Earthquake Research, 2010; Co-convener for International Workshop on Multiscale and Multiphysics Processes in Geomechanics, 2010; USGS-NEHRP (National Earthquake Hazards Reduction Program) External Program review panel, 2010; Co-organizer for Southern California Earthquake Center earthquake rupture code validation project, 2007-present; Co-convener for Southern California Earthquake Center Workshop on Dynamic Weakening Mechanisms, 2009; Associate Editor, Journal of Geophysical Research-Solid Earth, 2005-08; Certificate of Distinction in Teaching, Harvard University, 2008; Editors' Citation for Excellence in Refereeing for Geophysical Research Letters, 2007
Mechanics and physics of earthquakes, seismic waves from volcanic eruptions, computational geophysics