Earthquake in Southern China
Devastating Earthquake Hits Southern China
An earthquake of revised magnitude 6.9 (originally listed at M7.1) struck China’s Qinghai province. The earthquake struck on April 14th at 7:49am local time, April 13th at 23:49pm UTC (coordinated universal time, used by the US Geological Survey — USGS and other earthquake reporting agencies).
Hundreds, if not thousands, of people have been killed and at least 10,000 injured. Many of the survivors are homeless as thousands of homes and other buildings were destroyed by the earthquake. Rescue efforts are reportedly underway, although the extreme altitude (13,000 feet), cold temperatures (below freezing at night) and scattered settlements of the Tibetan plateau are not making things easy for help to get in or news to get out.
The Geology of the Qinghai 2010 Earthquake
As I wrote in the Haiti earthquake post, the Earth’s crust is not one solid mass, but is made up of several large pieces called tectonic plates. These plates float around on the Earth’s liquid mantle and interact with each other in areas known as fault zones. The plates are constantly moving, but occasionally a part of a plate sticks against another plate, creating tension. When this tension is finally released, the result is a sudden shift in the Earth’s crust. The energy released by the slip rolls through the crust surrounding the shift zone. We experience this as an earthquake. If the right type of slip happens in or near the ocean it can also create a tsunami or series of tsunamis. For example, the December 2004 Indian Ocean tsunami that devastated parts of Southeast Asia was caused by a massive magnitude 9.1 earthquake off the coast of Sumatra.
Wednesday’s earthquake occurred in a tectonically complicated region of Asia. According to the USGS, the Tibetan plateau is influenced by several tectonic forces, including the northward, upward movement of the Indian plate into the Eurasian plate (the force which is creating the Himalayas and the plateau itself) and the eastward, side to side shifting of the plateau region with respect to the India-Eurasian plate interaction. This shifting occurs along two major fault systems, the Altyn Tagh and the Kunlun. The April 14th earthquake occurred within the Tibetan plateau, on or near a branch of the Kunlun fault system.
The plateau area is geologically very active, and there have been a number of large earthquakes in the Southern China/Tibetan plateau region. On May 12, 2008 a devastating M7.9 earthquake hit China’s Sichuan province, at the edge of the plateau. The 2008 Sichuan/Wenchuan earthquake was one of the 10 most destructive earthquakes in history, killing approximately 70,000 people and leaving as many as 5 million people homeless.