28th September (Thu), 2023
Physics of fast and slow earthquakes
The University of Tokyo, Japan
Earthquakes are fast shear slip along underground fault system and radiate strong shaking that may cause severe disaster. Since around 2000, we are observing different types of underground shear slip events that progress slowly without radiating strong shaking. These are “slow earthquakes”, recently studied intensively by researchers worldwide. Although the locations of two types of earthquakes have little overlap, their proximity suggests certain interactions, which might give important information for forecasting future seismic activity. Slow earthquakes are different from fast (ordinary) earthquakes in their quasi-regular repetition, migration pattern, and response to external forces such as tidal stress. This slow process can be understood as a diffusive propagation of a relatively small stress disturbance, which is fundamentally different from earthquakes, where rupture propagate as a scale-invariant process, coupled with the propagation of seismic waves. I will review observational evidence and theoretical models that support this idea.
I graduated from The University of Tokyo in 1992 and finished my PhD at The University of Tokyo in 1997. Since 1997, I worked as Assistant Professor at Earthquake Research Institute, The University of Tokyo for five years. In 2000-2001, I stayed at Stanford University for 1 year. Since 2002, I have been working at the Department of Earth and Planetary Science, The University of Tokyo, as Lecturer (2002-2008), Associate Professor (2008-2013), and Professor (2013-). I have received “Japan Society for the Promotion of Science Prize” and “Japan Academy Medal” in 2014 and elected as Fellow of American Geophysical Union in 2016. Currently, I am leading the Grant-in-Aid Transformative Research Areas (A) Project “Science of Slow-to-Fast Earthquakes”, and serving as Editor of Journal of Geophysical Research Solid Earth.