@article{6055e7ffc98c4e8ab2f4053049f0af5a,
title = "Stress Field in the 2016 Kumamoto Earthquake (M 7.3) Area",
abstract = "We used 1-D and 3-D velocity models to determine focal mechanism solutions (FMSs) of 349 crustal earthquakes (M 2.7–7.3) and stress tensors in the source area of the 2016 Kumamoto earthquake (M 7.3) that occurred on the Futagawa-Hinagu fault zone in Kyushu, Southwest Japan. There are some differences in the FMSs determined with the 1-D and 3-D velocity models. The use of the 3-D velocity model leads to better results of stress tensors, which are determined by inverting the FMSs. The orientation of the minimum stress (σ3) axis is more accurately determined, which trends NNW-SSE to N-S nearly horizontally. In contrast, the axes of the maximum and intermediate stresses (σ1 and σ2) trend WSW-ENE to E-W with wide ranges. Significant spatiotemporal variations of the stress field are revealed in the Kumamoto source zone, indicating a small magnitude of deviatoric stress. The friction coefficient of the faults is estimated to be relatively small (~0.4), indicating that the seismogenic faults in central Kyushu are weak. The fault weakening may be caused by fluids beneath the source area and arc magma under the nearby Aso active volcano.",
keywords = "2016 Kumamoto earthquake, 3-D velocity model, arc magma, fluids, focal mechanism solution, stress rotation, stress tensor",
author = "Zhiteng Yu and Dapeng Zhao and Jiabiao Li and Zhouchuan Huang and Yukihisa Nishizono and Hirohito Inakura",
note = "Funding Information: We thank the Hi‐net data center and the JMA unified earthquake catalog (http://www.hinet.bosai.go.jp) for providing the P wave polarity and arrival time data used in this study. Most of the figures are made using the free GMT software (Wessel & Smith, 1998). We appreciate the thoughtful discussions with Cunrui Han. This work was partially supported by the National Key R&D Program of China (2016YFC0600402), State Oceanic Administration (SOA) Global Change and Air‐Sea Interaction Special Project (GASI‐GEOGE‐01), Japan Society for the Promotion of Science (Kiban‐S 23224012), the Ministry of Education, Culture, Sports, Science and Technology (26106005), National Natural Science Foundation of China (91828214, 41860811, and 41706044), the Core Research Cluster of Disaster Science in Tohoku University (a Designated National University in Japan), and the Postdoctoral Innovation Talents Support Program of China (BX20180080). The data used in this work and details of the 349 focal mechanism solutions are available in the supporting information (Data Set S1). We are very grateful to M. Savage (the Editor), an Associate Editor, and two anonymous referees for their thoughtful review comments and sug gestions, which have improved this paper. Funding Information: We thank the Hi-net data center and the JMA unified earthquake catalog (http://www.hinet.bosai.go.jp) for providing the P wave polarity and arrival time data used in this study. Most of the figures are made using the free GMT software (Wessel & Smith,). We appreciate the thoughtful discussions with Cunrui Han. This work was partially supported by the National Key R&D Program of China (2016YFC0600402), State Oceanic Administration (SOA) Global Change and Air-Sea Interaction Special Project (GASI-GEOGE-01), Japan Society for the Promotion of Science (Kiban-S 23224012), the Ministry of Education, Culture, Sports, Science and Technology (26106005), National Natural Science Foundation of China (91828214, 41860811, and 41706044), the Core Research Cluster of Disaster Science in Tohoku University (a Designated National University in Japan), and the Postdoctoral Innovation Talents Support Program of China (BX20180080). The data used in this work and details of the 349 focal mechanism solutions are available in the supporting information (Data Set S1). We are very grateful to M. Savage (the Editor), an Associate Editor, and two anonymous referees for their thoughtful review comments and suggestions, which have improved this paper. Publisher Copyright: {\textcopyright}2019. American Geophysical Union. All Rights Reserved.",
year = "2019",
month = mar,
doi = "10.1029/2018JB017079",
language = "English",
volume = "124",
pages = "2638--2652",
journal = "Journal of Geophysical Research: Solid Earth",
issn = "2169-9313",
publisher = "American Geophysical Union",
number = "3",
}