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
Abstract
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.
Topics & Concepts
GeologySeismologyFocal mechanismGeothermal gradientFluid pressurePore water pressureFault (geology)GeophysicsGeotechnical engineeringMechanicsPhysicsearthquake and tectonic studiesHigh-pressure geophysics and materialsSeismology and Earthquake Studies