Anomalous depth dependency of the stress field in the 2007 Noto Hanto, Japan, earthquake: Potential involvement of a deep fluid reservoir

Autor: Masahiro Kosuga, Hiroshi Katao, Haruhisa Nakamichi, Kiyoshi Ito, Takuto Maeda, Satoshi Matsumoto, Naoshi Hirata, Teruhiro Yamaguchi, Yoshihiro Hiramatsu, Youichi Asano, Shuichiro Hori, Masayoshi Ichiyanagi, Ryo Honda, Tetsuya Takeda, Junichi Nakajima, Kazushige Obara, Aiko Hayashi, Aitaro Kato, Kei Katsumata, Atsushi Saiga, Toshio Kono, Shiro Ohmi, Takashi Okuda, Akihiro Sawada, Tomomi Okada, Takaya Iwasaki, Toshihiro Igarashi, Masatoshi Miyazawa, Takashi Iidaka, Kazutoshi Imanishi, Takeshi Matsushima, Tomotake Ueno, Issei Doi, Toshihiko Kanazawa, Kin'ya Nishigami, Hiroo Wada, Syuichi Suzuki, Tetsuya Hirose, Shutaro Sekine, Shunta Noda, Akira Hasegawa, Hiroki Miyamachi, Shin'ichi Sakai, Takashi Nakayama, Hiroaki Takahashi, Eiji Kurashimo, Norio Hirano, Takahiro Maeda, Yoshihisa Iio, Yohei Yukutake, Yoshiko Yamanaka, Keisuke Tanaka, Makoto Matsubara, Noriko Tsumura, Takanori Matsuzawa, Katsunori Sugaya
Rok vydání: 2011
Předmět:
Zdroj: Geophysical Research Letters. 38
ISSN: 0094-8276
DOI: 10.1029/2010gl046413
Popis: [1] 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 (σ1) 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 σ1 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.
Databáze: OpenAIRE
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