学会誌「自然災害科学」

鳥取県西部地震 －前駆的群発地震・本震・余震－

The 2000 Western Tottori Earthquake - Precursory Swarm Earthquake, Main Shock and Aftershock -

梅田 康弘*・松村 一男*・澁谷 拓郎*・大見 士朗*・片尾 浩*

Yasuhiro UMEDA*, Kazuo MATSUMURA*, Takuo SHIBUTANI*, Shiro OHMI* and Hiroshi KATAO*

Abstract

The earthquake with M7.3 occurred in the western part of Tottori prefecture. At epicentral area, the higher level of intensity 6 was recorded. No one was killed, but more than 100 people were injured. The seismicity has been high on the border area of Tottori-Shimane prefecture. In the epicentral area, the swarm earthquakes have occurred since 1989. Most of these swarm earthquakes are distributed on the low slip portion of the main shock. Four low frequency earthquakes which occurred at 30 km depth were observed after October 1997. About 12 hours before the main shock, small event of Ml.7 occurred at 3 km distance from the rupture start point of the main shock. Aftershock distribution was obtained from the routine network and the urgent temporary observations. On the south part, aftershocks are distributed within the narrow zone, but they disperse in the north part. The induced earthquakes occurred in two areas, south-east of Mt. Daisen and east of Shimane prefecture. Most of aftershocks related with the rupture of the main shock are distributed on the low slip portion of the main shock.

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