Several aftershocks rock quake-hit Southwest China's Sichuan

By Zhang Han Source:Global Times Published: 2019/6/23 21:58:40

Fracking not to blame as region is seismically active: experts


Residents sit on the street outside their homes, preferring to sleep in tents after a 5.4-magnitude earthquake struck Gongxian county of Yibin city, Southwest China's Sichuan Province on Saturday night. The earthquake was an aftershock of a deadly 6.0-magnitude quake in neighboring Changning county on June 17. Photo: IC



A deadly earthquake and its aftershocks in Southwest China's Sichuan Province have caused public concern about whether there is an increased risk of tremors in the area, but experts noted that the seismic activity is within normal parameters, so there is no cause for alarm.

A 5.4-magnitude earthquake and a series of aftershocks have rattled Gongxian county, Yibin in Sichuan Province since Saturday night, injuring at least 31 people, less than a week after a major quake in nearby Changning county claimed 13 lives.

After the Changning 6.0-magnitude earthquake, three aftershocks of 5.0-magnitude and above, as well as many smaller tremors have hit Gongxian and Changning, the epicenters of which range from 8 kilometers to 17 kilometers deep, according to the Sichuan Earthquake Administration. 

Observations suggested the earthquakes are part of two seismic events that are close to each other. But there is no clear understanding yet if the seismic events are connected or what the cause is, Sun Shihong, a researcher at the China Earthquake Networks Center, told the Global Times on Sunday. 

The public have expressed concern that the province seems to have experienced more earthquakes since 2008, when a massive 8.0-magnitude earthquake struck Wenchuan in western Sichuan, claiming more than 69,000 lives. 

The 2008 seismic event is one of the reasons why there have been more earthquakes during the past decade, as the ground readjusts. But this is within normal range and not unexpected, Guo Xun, a seismologist with the China Earthquake Administration, told the Global Times on Sunday.

Both Guo and Sun agreed that Sichuan has experienced a slight increase in the annual average number of earthquakes in the past decade, compared with data collected over the last 120 years, since there has been reliable monitoring of earthquake magnitudes. Guo said that the figure was 1.5-2 times of the average in the longer period, although he did not have exact figures to hand.  

Sun said the area around the epicenter of the 2008 tremor has been very seismically active in the past 11 years, with two 7.0-magnitude earthquakes in 2013 and 2017. 

"But the active period is about to end, so it is likely to see a decay in seismic activities for a while in the future," Sun said. 

Some residents in Yibin are concerned that there have been more earthquakes lately.  

In February, a 4.9-magnitude earthquake hit the neighboring city of Zigong, killing two and injuring 13. 

Sun said that the southeastern Sichuan earthquakes took place in an area different from the seismic belt of previous major quakes. "Seismic activities in this area require more observations and studies," he said. 

There are many shale gas mining operations in southeastern Sichuan, and there is widespread public concern that it could trigger earthquakes, given that the province is already seismically active.  

Guo said that although fracking can cause small earthquakes, they are usually of 2.0- to 3.0-magnitude with shallow epicenters less than one kilometer in depth.  Such earthquakes are unlikely to cause destruction to properties or threat to human lives.
Newspaper headline: Several aftershocks rock quake-hit Yibin


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