Growing seismicity in the Sichuan Basin and its association with industrial activities
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owing seismicity in the Sichuan Basin and its association with industrial activities 1*
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Xinglin LEI , Jinrong SU & Zhiwei WANG 1
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Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1,
Tsukuba, Ibaraki 305-8567, Japan; Earthquake Monitoring Centre, Sichuan Earthquake Administration, Chengdu 610041, China; State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China 2
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Received February 19, 2020; revised May 28, 2020; accepted June 22, 2020; published online September 22, 2020
Abstract In the Sichuan Basin, seismic activity has been low historically, but in the past few decades, a series of moderate to strong earthquakes have occurred. Especially since 2015, earthquake activity has seen an unprecedented continuous growth trend, and the magnitude of events is increasing. Following the M5.7 Xingwen earthquake on 18 Dec. 2018, which was suggested to be induced by shale gas hydraulic fracturing, a swarm of earthquakes with a maximum magnitude up to M6.0 struck Changning and the surrounding counties. Questions arose about the possible involvement of industrial actions in these destructive events. In fact, underground fluid injection in salt mine fields has been occurring in the Sichuan Basin for more than 70 years. Disposal of wastewater in natural gas fields has also continued for about 40 years. Since 2008, injection for shale gas development in the southern Sichuan Basin has increased rapidly. The possible link between the increasing seismicity and increasing injection activity is an important issue. Although surrounded by seismically active zones to the southwest and northwest, the Sichuan Basin is a rather stable region with a wide range of geological settings. First, we present a brief review of earthquakes of magnitude 5 or higher since 1600 to obtain the long-term event rate and explore the possible link between the rapidly increasing trend of seismic activity and industrial injection activities in recent decades. Second, based on a review of previous research results, combined with the latest data, we describe a comprehensive analysis of the characteristics and occurrence conditions of natural and injection-induced major seismic clusters in the Sichuan Basin since 1700. Finally, we list some conclusions and insights, which provide a better understanding of why damaging events occur so that they can either be avoided or mitigated, point out scientific questions that need urgent research, and propose a general framework based on geomechanics for assessment and management of earthquake-related risks. Keywords Citation:
Induced seismicity, Fluid injection, Sichuan Basin, Shale gas, Wastewater disposal, Salt mine
Lei X, Su J, Wang Z. 2020. Growing seismicity in the Sichuan Basin and its association with industrial activities. Science China Earth Sciences, 63, https://doi.org/10.1007/s11430-020-9646-x
1. Introduction Enhanced geothermal systems (EGSs), shale gas hydraulic fracturing (H
