5:15 PM - 6:30 PM
[SSS11-P17] Strong motion simulation of an intraslab earthquake beneath Kanto region using MeSO-net observation data
Keywords:MeSO-net, Strong motion simulation, Empirical Green's function method, Strong motion generation area, Intraslab earthquake
MeSO-net (Metropolitan Seismic Observation network) conducted dense and real-time observation of seismic motion at approximately 300 stations in the metropolitan area. The network has contributed to researches of underground structure and seismic activity, and advancement of strong motion evaluation for the Kanto region. However, to authors’ knowledge, the observed waveform itself has not been used for the strong motion simulation as empirical Green’s function. We have noticed advantage of the observed MeSO-net data which contains the effects of the small heterogeneities of underground structure we cannot fully model. We, therefore, have performed strong motion simulation for an intraslab earthquake within the Philippine Sea plate beneath Tokyo by applying the empirical Green’s function method to the MeSO-net observed waveforms.
We used waveforms recorded during an MW5.0 intraslab earthquake that occurred at a depth of 57km on September 12, 2015 as empirical Green’s functions. This event has a normal-fault-type mechanism of N-S and E-W striking nodal planes with high-dipping angle. We extended these two nodal planes to M7-class fault models for the strong motion simulation. The fault models have one strong motion generation area whose parameters were assumed considering the strong motion evaluation of Cabinet Office. Empirical Green’s function simulation was conducted following the method proposed by Irikura (1986) and Irikura et al. (1997).
Simulated acceleration waveforms at MeSO-net E.TYPM station (Shinjuku, Tokyo) show the peak values of approximately 500gal and 250gal for horizontal and vertical components, respectively. The simulation results for N-S and E-W striking fault models are similar. Acceleration response spectra have the peak value at a period around 0.2 seconds and the spectral amplitude decreases as the period approaches to 1 second. It seems that the empirical Green’s function used here lacks enough power for long-period components to simulate M7-class earthquake. Further examination to model the long-period components using the theoretical approach is necessary to simulate the strong motions that can be used to promote the disaster resilience in the metropolitan area.
We used waveforms recorded during an MW5.0 intraslab earthquake that occurred at a depth of 57km on September 12, 2015 as empirical Green’s functions. This event has a normal-fault-type mechanism of N-S and E-W striking nodal planes with high-dipping angle. We extended these two nodal planes to M7-class fault models for the strong motion simulation. The fault models have one strong motion generation area whose parameters were assumed considering the strong motion evaluation of Cabinet Office. Empirical Green’s function simulation was conducted following the method proposed by Irikura (1986) and Irikura et al. (1997).
Simulated acceleration waveforms at MeSO-net E.TYPM station (Shinjuku, Tokyo) show the peak values of approximately 500gal and 250gal for horizontal and vertical components, respectively. The simulation results for N-S and E-W striking fault models are similar. Acceleration response spectra have the peak value at a period around 0.2 seconds and the spectral amplitude decreases as the period approaches to 1 second. It seems that the empirical Green’s function used here lacks enough power for long-period components to simulate M7-class earthquake. Further examination to model the long-period components using the theoretical approach is necessary to simulate the strong motions that can be used to promote the disaster resilience in the metropolitan area.