Fault “corrosion” by fluid injection: potential cause of the November 2017 MW 5.5 Korean earthquake

Westaway, R. and Burnside, N. M. (2019) Fault “corrosion” by fluid injection: potential cause of the November 2017 MW 5.5 Korean earthquake. Geofluids, 2019, 1280721. (doi: 10.1155/2019/1280721)

[img]
Preview
Text
188589.pdf - Published Version
Available under License Creative Commons Attribution.

6MB
[img] Other (spreadsheet)
188589Supp.xlsx - Supplemental Material

27kB

Abstract

The November 2017 5.5 Pohang earthquake is one of the largest and most damaging seismic events to have occurred in the Korean peninsula over the last century. Its close proximity to an Enhanced Geothermal System (EGS) site, where hydraulic injection into granite had taken place over the previous two years, has raised the possibility that it was anthropogenic; if so, it was by far the largest earthquake caused by any EGS project worldwide. However, a potential argument that this earthquake was independent of anthropogenic activity considers the delay of two or three months before its occurrence, following the most recent injection into each of the wells. A better understanding of the physical and chemical processes that occur following fluid injection into granite is thus warranted. We show that hydrochemical changes occurring while surface water, injected into granite, reequilibrates chemically with its subsurface environment, can account for time delays for earthquake occurrence of such duration, provided the seismogenic fault was already critically stressed, or very close to the condition for slip. This candidate causal mechanism counters the potential argument that the time delay militates against an anthropogenic cause of the Pohang earthquake and can account for its relatively large magnitude as a consequence of a relatively small-volume injection. The resulting analysis places bounds on combinations of physical and chemical properties of rocks, injected volume, and potential postinjection time delays for significant anthropogenic seismicity during future EGS projects in granite.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Burnside, Dr Neil and Westaway, Dr Robert
Authors: Westaway, R., and Burnside, N. M.
College/School:College of Science and Engineering > School of Engineering > Systems Power and Energy
Journal Name:Geofluids
Publisher:Hindawi
ISSN:1468-8115
ISSN (Online):1468-8123
Copyright Holders:Copyright © 2019 Rob Westaway and Neil M. Burnside
First Published:First published in Geofluids 2019:1280721
Publisher Policy:Reproduced under a Creative Commons License

University Staff: Request a correction | Enlighten Editors: Update this record

Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
704811DESTRESSNeil BurnsideEuropean Commission (EC)691728ENG - ENGINEERING SYSTEMS POWER & ENERGY