[S-SS10] Strong Ground Motion and Earthquake Disaster

[SSS10-03] The origin of large, long-period near-fault ground velocities during surface-breaking strike-slip earthquakes

*Yoshihiro Kaneko¹, Hiroyuki Goto² (1.Kyoto University, 2.Disaster Prevention Research Institute, Kyoto University)

Keywords:Strong ground motion, Dynamic rupture simulations, Earthquake physics

Records of near-fault ground motions from recent surface-breaking earthquakes are characterized by large (> a few m/s), long-period (a few seconds) ground velocity pulses, which may pose significant hazard for tall buildings and large infrastructures. Yet, the generation mechanism is not well understood. Here, using spontaneous rupture simulations, we examine the origin of large velocity pulses recorded at near-fault stations during the 2016 Mw7.0 Kumamoto (Japan) earthquake. We show that near-fault, strong-motion waveform data as well as seismologically estimated moment and radiated energy can be well reproduced by a relatively simple model with uniform along-strike pre-stress and frictional properties. Our results suggest that large, long-period fault-parallel ground velocities in the near-fault regions are caused by the dynamic interaction of propagating rupture and the Earth's surface. Such a generic mechanism suggests that large, long-period ground motion is a common occurrence in near-fault regions during surface-breaking, strike-slip earthquakes.