著者

高橋 浩晃 宮村 淳一

出版者

北海道大学大学院理学研究院自然史科学部門(地球物理学) = Department of Natural History Sciences (Geophysics), Graduate School of Science, Hokkaido University

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.72, pp.177-190, 2009-03-15

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We investigate the activity of deep low-frequency earthquakes (DLE) in Japanese Islands by JMA hypocenter catalogue during 1997 to 2008. It is confirmed that DLE cluster is distributed in every region. This implies that DLE phenomenon is common in Japanese subduction zone. Many active DLE clusters are identified in and around the quaternary volcanoes in whole area. There are also many non-volcanic clusters in Hokkaido and Tohoku regions, but very few in Kanto, Koushinetsu, Chubu, Hokuriku and Kyushu regions. High activity of non-volcanic clusters is observed in Kinki region. No clear correlation between DLE number and volcano activity index during 100 and 10,000 years is recognized. This fact implies the possibility that DLE activity is not precursor signal of shallow volcanic activities such as eruption at any time. Lower limit of DLE hypocenter depth generally coincides with depth of Moho discontinuity of each region. This may indicates that structure of upper mantle and lower crust and its boundary strongly control the occurrence of DLE's.