In August a large earthquake hit China's Yunnan Province, killing more than 600 people and injuring nearly 2,000 as tens of thousands of buildings collapsed and the shaking, along with heavy rains, caused the land to slide. Now, an engineer has laid out preliminary evidence suggesting that the earthquake was induced, that human activity pushed the fault to slip, says Nature.
Southwestern China is no stranger to earthquakes—the region has seen dozens of earthquakes stronger than magnitude 6 in the past 100 years. But Fan Xiao, an engineer with the Bureau of Geology and Mineral Resources in neighboring Sichuan province, says Nature, is arguing that the magnitude 6.2 earthquake was part of the increasingly common crop of human-assisted earthquakes. Seismologists call these “induced" earthquakes.
According to Xiao, the pressure put on the Earth's crust by filling a nearby reservoir with water may have caused an existing fault to slip. Nature:
Criss-crossed by active faults, the upper Yangtze region is seeing a boom in dam-building for the generation of hydropower. But when water flows quickly into the resulting reservoirs, it can change the stress on faults deep underground, either from the sheer weight of the water, or when water infiltrates the rocks through cracks and pores. These events might accelerate a fault’s natural ‘seismic clock’, hastening an earthquake that is already building, or increase the chance of one occurring at all.
Although it may seem like science fiction, man-made earthquakes have been a reality for decades. It has long been understood that earthquakes can be induced by impoundment of water in reservoirs, surface and underground mining, withdrawal of fluids and gas from the subsurface, and injection of fluids into underground formations.
As Smart News has written before, there is a long history of induced earthquakes in the scientific record. According to Nature, confirmation of Xiao's hypothesis will likely need to wait until other scientists can look at the more detailed seismic measurements captured of the earthquake, records which are, conveniently, “tightly controlled by hydropower companies.”