Wednesday 24 July 2013

Series of Earthquakes in Gansu Province kills at least 95.

A series of Earthquakes in Gansu Province in northwest China has killed at least 95 people and injured over a thousand more, with an estimated 27 000 people being made homeless. The first quake had a Magnitude of 5.9 and stuck at 7.45 am on Monday 22 July 2013 local time (11.45 pm on Sunday 21 July GMT), at a depth of 9.8 km, 13 km east of the town of Chabu, according to the United States Geological Survey. This was followed by a Magnitude 4.7 quake at a depth of 9.4 km 14 km southwest of Xinsi Zhen slightly before 8.10 am local time (slightly before 0.10 am GMT) and a Magnitude 5.6 quake at a depth of 10.1 km 9 km north of Chabu slightly after 9.10 am local time (slightly after 1.10 am GMT). While none of these are exceptionally large quakes, they appear to have triggered a series of landslides across the mountainous region, as well as the collapse of a large number of buildings.

Rescue workers try to restrain a man who has seen his wife's shoes under a mudslide being cleared in Yongguang Village in Minxian County, Gansu Province. AFP/Getty Images.

Much of western China and neighbouring areas of Central Asia and the Himalayas, is 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 approximate location of the Gansu Earthquakes. Google Maps.

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