Spatial distribution of similar aftershocks of a large inland earthquake, the 2000Western Tottori earthquake, in Japan

摘要

We detected similar aftershocks of the 2000 Western Tottori earthquake and we have examined their spatial distribution on the source fault. Many similar aftershocks are distributed in the northern part of the source fault, but few in the southern part. Specifically, similar aftershocks on the source fault are located outside of the asperity. The cumulative slip estimated from the similar aftershocks is 0.4-2.4 cm. The largest one is found at the edge of the major asperity. We observe that shallower events show a larger cumulative slip than deeper events. Large cumulative slip in the shallow depth in the northern part is coincident with the geodetic observation of afterslip. These facts suggest that similar aftershocks can provide information related to afterslip. However, the slip velocity estimated from both the slip and the recurrence interval of the similar aftershocks shows no distinct distribution.