Three-Dimensional Pore Fluid Pressures in Source Region of 2017 Pohang Earthquake Inferred From Earthquake Focal Mechanisms

Toshiko Terakawa, Wooseok Seo, Kwang Hee Kim, Jin Han Ree

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)

Abstract

We analyzed 91 focal mechanism data with relocated hypocenters to estimate the 3-D pore fluid pressure field in the source region of the 2017 Pohang earthquake in South Korea using the method of focal mechanism tomography. The upper limit of pore fluid pressure was 8 ± 3 MPa in a location northwest of the enhanced geothermal system. The overpressurized fluids were localized in the footwall of the causative fault. It was directly connected to the open hole section of PX2, and fluid injection into this hole could have triggered the mainshock.

Original languageEnglish
Article numbere2019GL085964
JournalGeophysical Research Letters
Volume47
Issue number9
DOIs
Publication statusPublished - 2020 May 16

Bibliographical note

Funding Information:
We thank Toshihiko Shimamoto and the anonymous reviewer for useful suggestions and discussion. We would like to thank the Editor Jeroen Ritsema. The seismic data for this paper are listed in Kim et al. ( 2020 ). This work was supported by JSPS KAKENHI Grant 18 K03801, by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan, under its The Second Earthquake and Volcano Hazards Observation and Research Program, by the KMA Research Development Program Grant KMI2018‐02810, and by the Nuclear Safety Research Program through the Korea Foundation of Nuclear Safety using financial resources granted by the Nuclear Safety and Security Commission of the Republic of Korea (1705010).

Funding Information:
We thank Toshihiko Shimamoto and the anonymous reviewer for useful suggestions and discussion. We would like to thank the Editor Jeroen Ritsema. The seismic data for this paper are listed in Kim et al. (2020). This work was supported by JSPS KAKENHI Grant 18 K03801, by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan, under its The Second Earthquake and Volcano Hazards Observation and Research Program, by the KMA Research Development Program Grant KMI2018-02810, and by the Nuclear Safety Research Program through the Korea Foundation of Nuclear Safety using financial resources granted by the Nuclear Safety and Security Commission of the Republic of Korea (1705010).

Publisher Copyright:
©2020. The Authors.

Keywords

  • Pohang earthquake
  • earthquake focal mechanism
  • friction coefficient
  • inversion analysis
  • pore fluid pressure
  • stress

ASJC Scopus subject areas

  • Geophysics
  • General Earth and Planetary Sciences

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