Was the 1952 Tokachi-oki earthquake (Mw=8.1) a typical underthrust earthquake?: Plate interface reflectivity measurement by an air gun-ocean bottom seismometer experiment in the Kuril Trench

Azuma, Ryosuke; Murai, Yoshio; Katsumata, Kei; Nishimura, Yuichi; Yamada, Takuji; Mochizuki, Kimihiro; Shinohara, Masanao

Was the 1952 Tokachi-oki earthquake (Mw=8.1) a typical underthrust earthquake?: Plate interface reflectivity measurement by an air gun-ocean bottom seismometer experiment in the Kuril Trench

Azuma, Ryosuke; Murai, Yoshio; Katsumata, Kei et al.

Geochemistry, Geophysics, Geosystems, 2012, 13(8), Q08015

Permalink : https://hdl.handle.net/2115/52028

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アクセス権	open access
URI	https://hdl.handle.net/2115/52028
タイトル	Was the 1952 Tokachi-oki earthquake (Mw=8.1) a typical underthrust earthquake?: Plate interface reflectivity measurement by an air gun-ocean bottom seismometer experiment in the Kuril Trench
著者	Azuma, Ryosuke ; Murai, Yoshio ; Katsumata, Kei ; Nishimura, Yuichi ; Yamada, Takuji ; Mochizuki, Kimihiro ; Shinohara, Masanao
著者名 Azuma, Ryosuke
e-Rad_Researcher 40301931 著者名 Murai, Yoshio
e-Rad_Researcher 10261281 著者名 Katsumata, Kei
e-Rad_Researcher 20208226 著者名 Nishimura, Yuichi
著者名 Yamada, Takuji
著者名 Mochizuki, Kimihiro
著者名 Shinohara, Masanao
言語	英語
キーワード	Kuril Trench
	crustal structure
	interplate reflectivity
	seismic gap
	tsunami earthquake
	underthrust earthquakes
発行日	2012-08-25
出版者	American Geophysical Union
収録物名	Geochemistry, Geophysics, Geosystems
巻(号)	13(8)
ページ	Q08015
抄録	The Kuril Trench subduction zone is one of the most seismogenic regions, where underthrust earthquakes with M > 8 recur along the trench. The seismic gap between the source areas of the 1973 Nemuro-oki and 2003 Tokachi-oki earthquakes, which are typical underthrust earthquakes faulting with rupture velocities of ～3 km/s, has been ruptured by the 1952 Tokachi-oki earthquake. The seismic gap has also slipped incidental to neighboring asperities. The difference in slip pattern on the plate interface generally appears as a spatial difference in seismic structure on the plate interface, such as a reflectivity of the plate interface. We estimated the crustal velocity structure and analyzed the reflectivity of the plate interface to investigate the physical properties of the plate interface by performing an air gun-ocean bottom seismometer experiment on the along-trench profile across the seismic gap. Strong reflections from the plate interface were observed in the 1952 Tokachi-oki source area including the seismic gap, rather than in the 1973 Nemuro-oki source area. The strong reflectivity of the plate interface in such the seismic gap with an incidental slip suggests that a slip pattern in the corresponding seismic gap would be conditionally stable. The coupling condition in the source areas of the eastern part of the source area of the 1952 earthquake is different from that in source areas of typical underthrust earthquakes, such as the 2003 Tokachi-oki and 1973 Nemuro-oki earthquakes. Our results suggest that the 1952 Tokachi-oki earthquake was a complex earthquake with the characteristic of a tsunami earthquake.
資源タイプ	学術雑誌論文
出版タイプ	Version of Record
権利情報	©2012 American Geophysical Union
PISSN	1525-2027
関連情報 (isIdenticalTo)	出版社版DOI https://doi.org/10.1029/2012GC004135