Seismic activity associated with the 2014 Shiraoi earthquake (MJMA 5.6) in middle east Iburi region, Hokkaido
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
26 , 2018-03-19 , 北海道大学大学院理学研究院
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.