[S-SS09] Seismic wave propagation: Theory and Application

[SSS09-P09] Simulation of envelope seismograms of double-couple interplate events along a subduction zone

*Youichi Asano¹ (1.National Research Institute for Earth Science and Disaster Resilience)

Keywords:interplate earthquake, seismogram envelope, heterogeneity, coda

We simulated S-coda envelopes of interplate earthquakes along a subduction zone by using a Monte Carlo simulation technique based on the radiative transfer theory. In this simulation, we assumed a realistic velocity structure having a subduction plate and an overriding plate with sedimentary layers and a spatially uniform scattering coefficient. Asano (2024) showed that these deterministic heterogeneities such as sedimentary layers more strongly control S-coda envelopes than the spatially uniform stochastic heterogeneity. In this study, we newly introduced the double-couple source radiation and investigated the effect of the source radiation on the simulated envelope seismograms. As simulation results for an interplate event with a 50-km depth, envelope seismograms for a double-couple source and an isotropic source show a clear amplitude difference especially for earlier coda than the mean free time. On the other hand, results of both sources for a near trench interplate event with a 15-km depth are not so different even in the early coda. This suggests that revelation caused by sedimentary layers near the source can mask source radiation pattern.