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筆者：1) 下元

一輝，理学研究科，学生（博士前期課程）；2) 筧

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楽麿，理学研究科，助教

CASE STUDY OF SEISMIC WAVE

PROPAGATION FROM THE EARTHQUAKES

OCCURRING IN THE SEA AREA BASED ON

NUMERICAL SIMULATIONS

Kazuki Shimomoto

Yasumaro Kakehi

Abstract

In order to investigate the effects of source location and underground structure on seismic wavefield

in detail, we systematically study the changes of seismic wavefield for three different velocity structure

models in northeastern Japan by numerical simulations using finite difference method. For the source, upper

intraslab earthquake is assumed, and the station is put in the land area. In case of the close and deep source,

direct wave is dominant in the calculated wave and the waveform is simple, accompanied with later phases

of very small amplitudes. In case of far and shallow source, the later phases of S-wave and the Rayleigh

wave have larger amplitudes, waveforms becomes more complex, and the waveform duration becomes longer.

This result is comprehended based on whether the incident angle of the direct wave to the discontinuous

boundaries is high or low. For the evaluation of the source term of the shallow source far from the coastline,

the observed data at the land-area stations with large epicentral distances are not suitable, and the observation

at the sea-area stations close to the source is significant.

©2023 Research Center for Urban Safety and Security, Kobe University, All rights reserved.

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