著者

一柳 昌義 シェスタコフ ニコライ 奥山 哲 大園 真子 笠原 稔 高橋 浩晃

出版者

北海道大学大学院理学研究院

雑誌

北海道大学地球物理学研究報告 (ISSN:04393503)

巻号頁・発行日

vol.81, pp.17-26, 2018-03-19

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A M5.6 shallow earthquake occurred on 8 July 2014 in middle east Iburi region, southwestern Hokkaido. Maximum seismic intensity of 5- was observed at Shiraoi town. Three temporal seismic stations had been installed in the focal region from 9 July 2014 to 30 April 2015. We determined 384 aftershock hypocenters by the double-difference tomographic hypocenter determination with proper seismic velocity structure. Relocated aftershocks were clearly distributed on a southeastern ward dipping plane with 5~10 km depth. This configuration agreed with a nodal plane of mainshock focal mechanism. Aftershocks occurred in surrounding part of a low seismicity patch. Mainshock was located deepest part of aftershock zone. These facts suggested that mainshock rupture propagated from deep to shallow, and a low seismicity patch was mainshock slip area. No clear correlation between this earthquake sequence and nearest active Tarumae volcano activity were identified.