County stops shale gas development after three quakes

Rongxian county in Sichuan province planned to stop local shale gas development on Monday, said county magistrate Zheng Xiaoqing.

He made the announcement in the wake of public outcry that three earthquakes measuring at more than magnitude 4.0, had occurred in the county within two days. There was speculation that local shale gas development might be related to the earthquakes.

Monday's magnitude 4.9 quake took place at 1:15 pm and killed two people. Its epicenter was monitored at 29.48 degrees north latitude and 104.49 degrees east longitude at a depth of 5 km, the China Earthquake Networks Center said.

At 8:40 am on Sunday, a magnitude 4.3 quake jolted Rongxian at a depth of 5 km. Three hours and two minutes earlier, a magnitude 4.7 quake had taken place in the county at a depth of 5 km.

All three quakes were at a depth of 5 km and human industrial use could not reach that depth, said Du Fang, chief of the Sichuan Provincial Earthquake Research Center.

The seismic waves from the quakes show that they are related to structural earthquakes, he said.

Human activities are concentrated in the earth's shallow crust while earthquakes often occur deep in the crust. Whether earthquakes are related to human industrial utilization needs further study.