TY - JOUR
T1 - Non-Double-Couple Microearthquakes in the Focal Area of the 2000 Western Tottori Earthquake (M 7.3) via Hyperdense Seismic Observations
AU - Hayashida, Yuto
AU - Matsumoto, Satoshi
AU - Iio, Yoshihisa
AU - Sakai, Shin'ich
AU - Kato, Aitaro
N1 - Funding Information:
We thank Dr. Šílený, the anonymous reviewer, and the editor for insightful comments that significantly improved the manuscript. We are grateful to the residents and local governments of the Tottori, Shimane, and Okayama Prefectures for their strong support and understanding of the hyperdense seismic observations. The “0.1-manten” hyperdense seismic observations data analyzed in this study are available via the website (http://www.sevo.kyushu-u.ac.jp/manten/manten_data.tar). The Hi-net waveform data are available at the NIED website (http://www.bosai.go.jp/e/). This work was supported by the Grant-in-Aid for Scientific Research on Innovative Areas (KAKENHI No. 26109004) from the Ministry of Education, Culture, Sports, Science, and Technology (MEXT) of Japan.
Publisher Copyright:
©2020. American Geophysical Union. All Rights Reserved.
PY - 2020/2/28
Y1 - 2020/2/28
N2 - Earthquakes with non-double-couple (NDC) components are indicators of geometric fault complexity, anisotropy, tensile failure, and fluid flow effects. NDC earthquakes have been observed in volcanic zones and interpreted as faulting related to fluid effects in the hypocentral region. In this study, we provide evidence of the occurrence of microearthquakes with NDC components in a tectonic zone. Aftershocks of the 2000 Western Tottori earthquake revealed definite NDC components based on a polarity analysis of the first P wave motion data from a hyperdense seismic observation. We modeled these events using both shear faulting with tensile failure and multiple shear ruptures. Six of the eight NDC events were well modeled by shear faults accompanied with an opening tensile crack. These results suggest that pressurized fluid or a weak tensile crack may exist along the rupture zone of the Tottori earthquake.
AB - Earthquakes with non-double-couple (NDC) components are indicators of geometric fault complexity, anisotropy, tensile failure, and fluid flow effects. NDC earthquakes have been observed in volcanic zones and interpreted as faulting related to fluid effects in the hypocentral region. In this study, we provide evidence of the occurrence of microearthquakes with NDC components in a tectonic zone. Aftershocks of the 2000 Western Tottori earthquake revealed definite NDC components based on a polarity analysis of the first P wave motion data from a hyperdense seismic observation. We modeled these events using both shear faulting with tensile failure and multiple shear ruptures. Six of the eight NDC events were well modeled by shear faults accompanied with an opening tensile crack. These results suggest that pressurized fluid or a weak tensile crack may exist along the rupture zone of the Tottori earthquake.
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U2 - 10.1029/2019GL084841
DO - 10.1029/2019GL084841
M3 - Article
AN - SCOPUS:85081072345
SN - 0094-8276
VL - 47
JO - Geophysical Research Letters
JF - Geophysical Research Letters
IS - 4
M1 - e2019GL084841
ER -