@article{oai:kanazawa-u.repo.nii.ac.jp:00010427, author = {平松, 良浩 and 林, 伸彦 and 古本, 宗充 and 片尾, 浩 and Hiramatsu, Yoshihiro and Hayashi, Nobuhiko and Furumoto, Muneyoshi and Katao, Hiroshi}, issue = {3}, journal = {Journal of Geophysical Research B: Solid Earth}, month = {Mar}, note = {The seismicity in the Tamba region, northeast of the Hyogo-ken Nanbu earthquake in Japan (January 17, 1995; M(JMA) 7.2), increased significantly following this earthquake. This increase suggests that the static stress change due to a large earthquake causes a change in the crustal condition of dynamics. In order to reveal the changes quantitatively, we investigate the temporal variation in coda Q-1 and b value in the Tamba region. We analyze the waveform data of many shallow microearthquakes (M 1.5-3.0) in the region recorded in a period from 1987 to 1996. Coda Q-1 is estimated in 10 frequency bands in a range of 1.5-24 Hz based on the single isotropic scattering model. At frequencies between 1.5 and 4.0 Hz the temporal variation in coda Q-1 shows significant correlation with the occurrence of the Hyogo-ken Nanbu earthquake; coda Q-1 increases after the event. A variation in b value whose sign is opposite to that of coda Q-1 is recognized. The fracture dimensions of microearthquakes that contribute to the variation in b value are estimated to be 400 m. This scale length is consistent with the characteristic scale length of scatter, 300-600 m, which contributes effectively to a temporal variation in coda Q-1. The crustal activity in the Tamba region is possibly controlled by the heterogeneity with dominant scale of 102 m. The stress sensitivity of the coda Q-1 change is estimated to be 10 (MPa)-1. This value is an order of magnitude larger than the stress sensitivity of seismic velocity reported before.}, pages = {6141--6151}, title = {Temporal changes in coda Q-1 and b value due to the static stress change associated with the 1995 Hyogo-ken Nanbu earthquake}, volume = {105}, year = {2000} }