Wednesday 9 August 2017

Nineteen dead after 7.0 Earthquake in southern Gansu Province, China.

The China Earthquake Networks Center recorded a Magnitude 6.3 Earthquake at a depth of about 20 km in southern Gansu Province, slightly before 9.20 pm local time (slightly before 1.20 pm GMT) on Tuesday 8 August 2017. nineteen people are reported to have died as a result of the quake, with 247 more injured, mostly in northern Sichuan Province. The quake was felt across much of northwest China.

A rescue team in Jiuzhaigou County in Sichuan Province, China, following the 8 August 2017 Earthquake. Zheng Lei/AP.

Much of western China and neighbouring areas of Central Asia and the Himalayas, are prone to Earthquakes caused by the impact of the Indian Plate into Eurasia from the south. The Indian Plate is moving northwards at a rate of 5 cm per year, causing it to impact into Eurasia, which is also moving northward, but only at a rate of 2 cm per year. When two tectonic plates collide in this way and one or both are oceanic then one will be subducted beneath the other (if one of the plates is continental then the other will be subducted), but if both plates are continental then subduction will not fully occur, but instead the plates will crumple, leading to folding and uplift (and quite a lot of Earthquakes). The collision of the Indian and Eurasian plates has lead to the formation of the Himalayan Mountains, the Tibetan Plateau, and the mountains of southwest China, Central Asia and the Hindu Kush.

 The movement of India into Eurasia over the last 71 million years. USGS.

Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. The international non-profit organisation Earthquake Report is interested in hearing from people who may have felt this event; if you felt this quake then you can report it to Earthquake Report here.
The approximate location of the 8 August 2017 Gansu Earthquake. USGS.
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