Journal of Natural Disaster Science

TSUNAMI GENERATION OF THE 1995 HYOGO-KEN NANBU EARTHQUAKE

Kuniaki ABE
Niigata Junior College, Nippon Dental University, Niigata,Japan
and
Masami OKADA
Meteorological Research Institute, Tsukuba, Japan

(Received 22 May, 1996 and in revised form 5 September, 1996)

Abstract

A small tsunami generated by the Hyogo-ken Nanbu (Kobe) Earthquake (Ms:7.2) on 17 January l995 was recorded at tide stations along the coasts of Osaka Bay and the Harimanada Basin of Japan. Spectral analysis, numerical simulation of tsunami generation and propagation have been made for several fault models of the earthquake. The findings show that a tsunami source model consisting of two separate faults parallel to the coast line explains the observed tsunami waveform fairly well. They are right lateral strike-slip faults with small dip-slip components, and subsidence of the sea bottom was the main source of the tsunami. Travel times and amplitudes of the initial down motions, and the directivity of the spectra are explained by the numerical model which does not conflict with the strike-slip mechanism of the earthquake, the aftershock area and the geodetic data observed on land. The vertical displacement field estimated from the fault model shows good correspondence to the present distribution of land and sea in this district.

Key words

tsunami, Hyogo-ken Nanbu earthquake, numerical simulation