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Anomalous depth dependency of the stress field in the 2007 Noto Hanto, Japan, earthquake: Potential involvement of a deep fluid reservoir
Author(s) -
Kato Aitaro,
Sakai Shinichi,
Iidaka Takashi,
Iwasaki Takaya,
Kurashimo Eiji,
Igarashi Toshihiro,
Hirata Naoshi,
Kanazawa Toshihiko,
Katsumata Kei,
Takahashi Hiroaki,
Honda Ryo,
Maeda Takahiro,
Ichiyanagi Masayoshi,
Yamaguchi Teruhiro,
Kosuga Masahiro,
Okada Tomomi,
Nakajima Junichi,
Hori Shuichiro,
Nakayama Takashi,
Hasegawa Akira,
Kono Toshio,
Suzuki Syuichi,
Tsumura Noriko,
Hiramatsu Yoshihiro,
Sugaya Katsunori,
Hayashi Aiko,
Hirose Tetsuya,
Sawada Akihiro,
Tanaka Keisuke,
Yamanaka Yoshiko,
Nakamichi Haruhisa,
Okuda Takashi,
Iio Yoshihisa,
Nishigami Kin'ya,
Miyazawa Masatoshi,
Wada Hiroo,
Hirano Norio,
Katao Hiroshi,
Ohmi Shiro,
Ito Kiyoshi,
Doi Issei,
Noda Shunta,
Matsumoto Satoshi,
Matsushima Takeshi,
Saiga Atsushi,
Miyamachi Hiroki,
Imanishi Kazutoshi,
Takeda Tetsuya,
Asano Youichi,
Yukutake Yohei,
Ueno Tomotake,
Maeda Takuto,
Matsuzawa Takanori,
Sekine Shutaro,
Matsubara Makoto,
Obara Kazushige
Publication year - 2011
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2010gl046413
Subject(s) - geology , seismology , dependency (uml) , stress (linguistics) , stress field , geophysics , philosophy , linguistics , physics , finite element method , thermodynamics , systems engineering , engineering
We have elucidated depth variations in the stress field associated with the 2007 Noto Hanto, Japan, earthquake by stress tensor inversion using high‐quality aftershock data obtained by a dense seismic network. Aftershocks that occurred above 4 km in depth indicated a strike‐slip stress regime. By contrast, aftershocks in deeper parts indicated a thrust faulting stress regime. This depth variation in the stress regime correlates well with that in the slip direction derived from a finite source model using geodetic data. Furthermore, the maximum principal stress ( σ 1 ) axis was stably oriented approximately W20°N down to the depth of the mainshock hypocenter, largely in agreement with the regional stress field, but, below that depth, the σ 1 axis had no definite orientation, indicating horizontally isotropic stress. One likely cause of these drastic changes in the stress regime with depth is the buoyant force of a fluid reservoir localized beneath the seismogenic zone.