Prestate of Stress and Fault Behavior During the 2016 Kumamoto Earthquake (M7.3)

Satoshi Matsumoto, Yusuke Yamashita, Manami Nakamoto, Masahiro Miyazaki, Shinichi Sakai, Yoshihisa Iio, Hiroshi Shimizu, Kazuhiko Goto, Tomomi Okada, Mako Ohzono, Toshiko Terakawa, Masahiro Kosuga, Masayuki Yoshimi, Youichi Asano

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5 Citations (Scopus)

Abstract

Fault behavior during an earthquake is controlled by the state of stress on the fault. Complex coseismic fault slip on large earthquake faults has recently been observed by dense seismic networks, which complicates strong motion evaluations for potential faults. Here we show the three-dimensional prestress field related to the 2016 Kumamoto earthquake. The estimated stress field reveals a spatially variable state of stress that forced the fault to slip in a direction predicted by the “Wallace and Bott Hypothesis.” The stress field also exposes the pre-condition of pore fluid pressure on the fault. Large coseismic slip occurred in the low-pressure part of the fault. However, areas with highly pressured fluid also showed large displacement, indicating that the seismic moment of the earthquake was magnified by fluid pressure. These prerupture data could contribute to improved seismic hazard evaluations.

Original languageEnglish
Pages (from-to)637-645
Number of pages9
JournalGeophysical Research Letters
Volume45
Issue number2
DOIs
Publication statusPublished - Jan 28 2018

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Earth and Planetary Sciences(all)

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    Matsumoto, S., Yamashita, Y., Nakamoto, M., Miyazaki, M., Sakai, S., Iio, Y., Shimizu, H., Goto, K., Okada, T., Ohzono, M., Terakawa, T., Kosuga, M., Yoshimi, M., & Asano, Y. (2018). Prestate of Stress and Fault Behavior During the 2016 Kumamoto Earthquake (M7.3). Geophysical Research Letters, 45(2), 637-645. https://doi.org/10.1002/2017GL075725