| Abstrakt: |
1) The 17 november mw 5.4 Pohang, South Korea, main shock could have been either triggered or natural. 2) The pohang main shock was not induced by the nearby EGS project. 3) The dominant source of seismic hazard in and around the city of pohang is natural crustal strain accumulation. Understanding the cause of the November 2017 Pohang main shock is of considerable importance to the future of the geothermal industry because of its large magnitude compared to prior expectations based on case histories of other projects involving underground fluid injection. Of the three possibilities – induced, triggered or natural, "induced" can be ruled out based on the disproportionately large seismic moment of the main shock. Whether natural or triggered, the source of seismic hazard at Pohang was tectonic strain accumulation, not fluid injection. Arguably, the most timely indicator of seismic hazard and risk in the environs of Pohang was the September 2016 Mw 5.4 Gyeongju earthquake, which was natural and located about 40 km south of Pohang along the same active fault system. [ABSTRACT FROM AUTHOR] |
Full Text from ScienceDirect