SEGJ Technical Conference

Effects of deep subsurface structures on long-period ground motion characteristics around the Tachikawa fault zone

Abstract Tachikawa fault is one of the most activity faults in the western part of the Tokyo metropolitan area. Strong motion estimation is necessary to know the possible damage due to rupture of the fault considering effects of geological structure. However, three-dimensional subsurface structural models have not been well tuned in the vicinity of the fault. In this study, we estimated a three-dimensional structure of deep sedimentary layers around the Tachikawa fault zone using Rayleigh wave phase velocity and horizontal-to-vertical spectrum obtained from microtremor explorations and receiver functions from the obtained records of the K-NET, KiK-net and SK-net. Furthermore we simulated seismic ground motions around the Tachikawa fault zone using the three-dimensional finite difference method considering three-dimensional velocity structure down to 50km to validate of our model of deep sedimentary layers. The results indicate that the maximum velocities in simulated waveforms are similar to the observed ones.