Seismic quiescence before the 2000 M = 7.3 Tottori earthquake

Abstract

We investigated the characteristics of the seismic quiescence associated with the 2000 M = 7.3 Tottori earthquake by applying the Region-Time-Length (RTL) algorithm to the earthquake catalog of the Japan Meteorological Agency (JMA). We calculated the RTL parameters at the epicenter after eliminating aftershocks from the catalog and estimating its completeness. The RTL parameters at the epicenter indicated that a seismic quiescence started in 1999 and reached its minimum in May, 2000. This quiescence is unlikely an artifact due to the changes of model parameters. The close investigation indicated that the quiescence, which appeared in a broad region around the epicenter during 1999-2000, is the only alarm group in study space and time and is therefore most probably a precursor of the Tottori earthquake. The seismicity changes revealed in this study may give better understanding of the seismo-tectonics in the region and the preparation process of the Tottori earthquake.