A 6.0-magnitude earthquake struck Sichuan province in southwest China late Monday night, followed by a series of aftershocks measuring over magnitude 5.0 reports China’s official Xinhua news agency. Historical data indicates the event is an unprecedented one for the area.
According to the China Earthquake Networks Center, the earthquake struck at a depth of 16 kilometres. Its epicentre was located in Changning County, Yibin City, located in the confluence of the Yangtze and Jinsha rivers.
Local government officials confirmed on Tuesday that the death toll from the quake had risen to 13, with 199 injured and 92 houses destroyed or severely damaged. A population of 142,832 people were affected by the event.
Fan Xiao, former chief engineer of the Regional Geology Investigation Team of the Sichuan Geology and Mineral Bureau, told Probe International, Changning is a seismically prone region with several faults crisscrossing the area. However, historical data indicates that no seismic activity greater than magnitude 6.0 has been recorded in the area, making this quake an unprecedented one for the region.
Responding to the rumour that the Changning earthquake might be the result of shale gas development in the area, Mr. Fan said he believed that this was not the case. He said that because this was a major earthquake, accompanied by two 5.0-magnitude aftershocks, with a focal depth of 16 to 17 kilometres, this greatly exceeded the existing mining depth of local shale gas.
However, Mr. Fan warned, since the occurrence and development of seismic activity is a complex and gradual evolutionary process, the role of shale gas development cannot be taken lightly.
Mr. Fan has been monitoring the development of big dams, either already built or under construction on the middle and lower Jinsha River. It is worth noting, he says, that the Xiangjiaba Dam on the Jinsha River, is located just 50 kilometres west of the Changning earthquake’s epicentre.
Upstream of the Xiangjiaba Dam, at least three big dams have been completed or are underway, including the Xiluodu, Baihetan and Wudongde hydro power projects, built by the Three Gorges Group.
There is no evidence to prove the earthquake that occurred in Changning on Monday was related to the cascade of dams on the Jinsha River, said Mr. Fan. However, after the filling of the Xiangjiaba and Xiluodu reservoirs, several moderate to strong earthquakes of magnitude 4.0 and 5.0 occurred in the reservoir area.
The most recent case was on May 16, 2019, just a month before the Changning quake, when a 4.7-magnitude earthquake struck in Yongshan County in the Xiluodu reservoir area.
Mr. Fan said authorities should be on alert for more seismic activity in the high seismic-risk area along the Jinsha River west of Changning County.