Seismicity in Changning Sichuan, China

Li Sun

Published August 15, 2019, SCEC Contribution #9713, 2019 SCEC Annual Meeting Poster #072

A magnitude 6.2 earthquake occurred in Changning Sichuan, China on June 17, 2019. Before this event, there was no earthquake larger than 6.0 occurred Changning and surrounding area. The aftershocks of this event spread nearly 20 km in northwest of the mainshock. The aftershock area is much larger than the scale of a M 6.0 event and the magnitude and number of aftershocks did not follow the Bath Law. They are last much longer time with large magnitude and high density.

This area is famous for the shale gas production and the triggered events. Some researchers understand this event as a triggered one. We try to analyze the seismicity in detail. First, we relocated the aftershocks from June 17 to July 6 with a high-resolution method, hypoRelocate. The direct P and S phases of 10 stations within 100 km are utilized in the relocation. The relocated result indicates most aftershocks locate shallower than 5 km and there is gap in the middle of the aftershock belt. Then the seismicity between 2009 to 2019 is examined. From 2009, there are some small event swarms around the mainshock area. Previous study indicates the event swarms are trigged by water injection of salt well. After 2011, some new swarms appear on the northwest end of the aftershock sequence where located salt well. Our result is consistent with the field research after the mainshock. The clues show potential relationship between the salt well mining and the mainshock. We explain the gap of the aftershock that the mainshock ruptured 10 km and triggered the seismicity on the northwest end of the aftershock area.

Key Words
seismicity, Changning, aftershock, triggered

Citation
Sun, L. (2019, 08). Seismicity in Changning Sichuan, China. Poster Presentation at 2019 SCEC Annual Meeting.

Related Projects & Working Groups
Seismology