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Three‐Dimensional Pore Fluid Pressures in Source Region of 2017 Pohang Earthquake Inferred From Earthquake Focal Mechanisms
Author(s) -
Terakawa Toshiko,
Seo Wooseok,
Kim KwangHee,
Ree JinHan
Publication year - 2020
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2019gl085964
Subject(s) - geology , seismology , focal mechanism , geothermal gradient , fluid pressure , pore water pressure , fault (geology) , geophysics , geotechnical engineering , mechanics , physics
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.