Sunday 24 June 2012

Earthquake in southwest China.

On Sunday 24 June 2012 slightly before 4.00 pm local time (slightly before 8.00 am, GMT) an Earthquake hit southwest China in the border region between Sichuan and Yunnan States, roughly 53 km west of Qiaowa in Sichuan. This was recorded by the United States Geological Survey as measuring 5.5 on the Richter Scale and occurring at a depth of 9.3 km, and by the World Data Center for Seismology in Beijing as 5.7 on the Richter Scale at a depth of 11 km. The area is remote and mountainous, so the extent of the damage and casualties is unclear, but at the time of writing three people are reported dead in Ninglang County in Yunnan and one in Yanyuan County in Sichuan. Over a hundred more are reported to have been injured, 20 seriously, but these figures are likely to rise.

Map showing the location of the 24 June quake. USGS.

The southwest of China is fairly prone to Earthquakes, being effected by the impact of the Indian Plate into the Eurasian Plate from the south. Most of the Earth's convergent plate boundaries are between continental and oceanic plates, with the oceanic plate being subducted beneath the continental, or between two oceanic plates, where one is subducted beneath the other. In South Asia two continental plates are colliding; neither of these readily subducts beneath the other, so a crumple zone has formed along the margin of the two plates, forming the Himalayas, the Tibetan Plateau and the mountain ranges of Central Asia. This is far from being a smooth process, and Earthquakes are common across the region.

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