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Gravity changes observed between 2004 and 2009 near the Tokai slow-slip area and prospects for detecting fluid flow during future slow-slip events

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Title: Gravity changes observed between 2004 and 2009 near the Tokai slow-slip area and prospects for detecting fluid flow during future slow-slip events
Authors: Tanaka, Yoshiyuki Browse this author
Kato, Aitaro Browse this author
Sugano, Takayuki Browse this author
Fu, Guangyu Browse this author
Zhang, Xinlin Browse this author
Furuya, Masato Browse this author
Sun, Wenke Browse this author
Okubo, Shuhei Browse this author
Matsumoto, Shigeo Browse this author
Honda, Masaki Browse this author
Sugawara, Yasuhiro Browse this author
Ueda, Isao Browse this author
Kusaka, Masaaki Browse this author
Ishihara, Misao Browse this author
Keywords: Slow earthquake
slow slip
gravity
fluid
poroelasticity
permeability
subduction zone
crustal deformation
Issue Date: 3-Feb-2010
Publisher: TERRAPUB
Journal Title: Earth, Planets and Space
Volume: 62
Issue: 12
Start Page: 905
End Page: 913
Publisher DOI: 10.5047/eps.2010.11.003
Abstract: Slow-slip events (SSEs) have been observed in many plate-boundary zones along the circum-Pacific seismic belt. Previous studies have revealed that high-pressure fluids supplied from the subducted oceanic plate can generate SSEs. However, the behavior of these fluids during an SSE has not been fully elucidated. This paper discusses possible fluid migration along the plate boundary on the basis of spatiotemporal gravity changes observed by absolute and relative gravimeters during a long-term SSE in the Tokai district, Japan. Relative-gravity data are sometimes unreliable because of limited observation accuracies and possible noise produced by groundwater. Nevertheless, the observed gravity changes show a systematic pattern of spatial changes over the slow-slip area. This pattern can be explained by a poroelastic model assuming fluid migration along the plate interface, for which an inversion indicates a permeability of about 10-15 m2. This lies within the range of permeability values inferred by other studies in slow-slip areas. Long-term SSEs have occurred repeatedly in the Tokai district. If the permeability remains greater than 10-15 m2 during a future SSE, it will be possible to detect fluid migration by improving the observation accuracy to the 1-μGal level and accurately evaluating groundwater-related noise.
Type: article
URI: http://hdl.handle.net/2115/52817
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: 古屋 正人

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