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Volcanic strain change prior to an earthquake swarm observed by groundwater level sensors in Meakan-dake, Hokkaido, Japan

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Title: Volcanic strain change prior to an earthquake swarm observed by groundwater level sensors in Meakan-dake, Hokkaido, Japan
Authors: Takahashi, Hiroaki Browse this author →KAKEN DB
Shibata, Tomo Browse this author
Yamaguchi, Teruhiro Browse this author
Ikeda, Ryuji Browse this author
Okazaki, Noritoshi Browse this author
Akita, Fujio Browse this author
Keywords: Deflation
Earthquake swarm
Groundwater level
Volumetric strain
Deep low frequency earthquakes
Issue Date: 15-Feb-2012
Publisher: Elsevier B.V.
Journal Title: Journal of Volcanology and Geothermal Research
Volume: 215-216
Start Page: 1
End Page: 7
Publisher DOI: 10.1016/j.jvolgeores.2011.11.006
Abstract: We installed and operated a low-cost groundwater level observation system at intermittent hot spring wells in order to monitor volcanic strain signals from the active Meakan-dake volcano in eastern Hokkaido, Japan. Data are sampled at 1 Hz and are transmitted to the data center in real time. Evaluation of the water level time series with theoretical predictive tidal strain and coseismic static strain changes has suggested that the wells penetrate to the artesian aquifer and act as a volumetric strain sensor. An active earthquake swarm with more than 400 events occurred at the shallower part of the volcano from January 9 to 11, 2008. Three independent wells recorded pre- to co-swarm groundwater drops simultaneously, which represented a decrease in volumetric strain. The total volumetric strain change during the three active days was estimated to be from 6 to 7 x 10^[-7]. The observed data, including changes in volumetric strain, absence of deformation in the GPS coordinates, and activation of deep low-frequency earthquakes, might imply possible deflation of a source deeper than 10 km, and these preceding deeper activities might induce an earthquake swarm in a shallower part of the Meakan-dake volcano.
Type: article (author version)
URI: http://hdl.handle.net/2115/49345
Appears in Collections:理学院・理学研究院 (Graduate School of Science / Faculty of Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 高橋 浩晃

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