Which is heterogeneous, stress or strength? An estimation from high-density seismic observations

• Iio, Yoshihisa

  Research Center for Earthquake Prediction, Disaster Prevention Research Institute, Kyoto University

• Yoneda, Itaru

  Research Center for Earthquake Prediction, Disaster Prevention Research Institute, Kyoto University

• Sawada, Masayo

  Research Center for Earthquake Prediction, Disaster Prevention Research Institute, Kyoto University

• Miura, Tsutomu

  Research Center for Earthquake Prediction, Disaster Prevention Research Institute, Kyoto University

• Katao, Hiroshi

  Research Center for Earthquake Prediction, Disaster Prevention Research Institute, Kyoto University

• Takada, Yoichiro

  Department of Earth and Planetary Sciences, Hokkaido University

• Omura, Kentaro

  National Research Institute for Earth Science and Disaster Prevention

• Horiuchi, Shigeki

  Home Seismometer, Fukushima

Abstract

Using data from high-density seismic observation networks installed in the western Nagano Prefecture region in Japan, we precisely determined focal mechanisms and estimated the high-resolution stress field at a scale of 1 km. Almost all differences between observed and calculated slip directions (misfit) were smaller than the errors in focal mechanisms at grid points away from the mainshock fault. This finding clearly indicates that the estimated uniform stress suitably explains focal mechanisms in each subregion apart from the mainshock fault. Misfits are relatively large at grid points near the mainshock fault, but many of these misfits are smaller than the errors in focal mechanisms, and stress is regarded as uniform for a greater portion within each subregion. However, we found that focal mechanisms and P-axes varied widely and differed from each other for a short focal distance of 100 m. These results clearly show that stress can be regarded as uniform, but that strength is heterogeneous.

The Correction to this article has been published in Earth, Planets and Space 2018 70:20.

Journal

• Earth, Planets and Space

  Earth, Planets and Space 69 144-, 2017-10-20

  Springer Nature

Keywords

• Stress
• Heterogeneity
• Fault strength
• Stress inversion
• Focal mechanism

Details

• CRID: 1050001338207702144
• NII Article ID: 120006523818
• ISSN: 18805981
• DOI: 10.1186/s40623-017-0730-3
• HANDLE: 2433/234588
• Web Site: http://link.springer.com/article/10.1186/s40623-017-0730-3/fulltext.html
• Web Site: http://link.springer.com/content/pdf/10.1186/s40623-017-0730-3.pdf
• Text Lang: en
• Article Type: journal article
• Data Source:
  • IRDB
  • Crossref
  • CiNii Articles
  • KAKEN