Seminar by Dr. Hiroe Miyake: Characterization of Extreme Ground Motions
Characterization of Extreme Ground Motions
Hiroe Miyake (University of Tokyo)
Ground motion time history is one of most important factors to judge whether ground motion prediction works well in the scenario-based seismic hazard assessment. To link between seismology and earthquake engineering, ground motion response spectra became the first priority to validate broadband ground motions. Although the duration and phase information are useful to separate near-fault ground motions with rupture directivity pulses and long-period ground motions for the similar ground motion response levels, ground motion response spectra is helpful to direct use for design basis ground motions. It is well known that ground motion pulses increase the response at the dominant periods that largely affects structures. Significant impact of ground motion pulse on response spectra is indicated for the 1992 Landers, 1995 Kobe, 1999 Kocaeli, 1999 Chi-Chi, 2015 Gorkha, 2016 Kumamoto and other earthquakes. In theory, both duration and amplitude of ground motion pulse increase as a function of earthquake magnitude, therefore the upper bounds of response spectra are increasing as a function of period. Due to the accumulation of extreme ground motions with dense strong motion observations, empirical upper bounds of peak ground accelerations and peak ground velocities are still increasing due to seismic source complexity and strong site amplification. However, this study found the empirical upper bounds of response spectra exist and can be shaped by a few extreme ground motions of crustal and collusion earthquakes. On the other hand, many simulated ground motions for subduction earthquakes exceed the current empirical upper bounds of response spectra.
Hiroe Miyake is an Associate Professor at the Interfaculty Initiative in Information Studies and Earthquake Research Institute of the University of Tokyo. She earned her doctoral degree at Kyoto University in 2003. After postdoctoral research at Stanford University and the University of Tokyo, she joined the faculty of the University of Tokyo in 2005. Her research interests cover earthquake source modeling and strong motion seismology.