2010 Yushu earthquake facts for kids

The 2010 Yushu earthquake struck on April 14 and registered a magnitude of 6.9 M_w (USGS, EMSC) or 7.1 M_s (CEA, CENC). It originated in Yushu, Qinghai, China, at 7:49 am local time (23:49 April 13 UTC). According to the Xinhua News Agency, 2,698 people were confirmed dead, 270 missing and 12,135 injured, 1,434 of them severely. The epicenter was located in Rima village (日玛村/日麻村), Upper Laxiu township (上拉秀乡) of Yushu County, in remote and rugged terrain, near the border of Tibet Autonomous Region, about 30 km from Gyêgu town or Jyekundo, the seat of Yushu County, and about 240 km from Qamdo. The epicenter was in a sparsely populated area on the Tibetan plateau that is regularly hit by earthquakes.

The 12th century Thrangu Monastery and surrounding villages were severely damaged and many monks and villagers were killed.

Geology

Tectonic map of the Tibetan Plateau showing location of the Xianshuihe fault zone

Qinghai lies in the northeastern part of the Tibetan Plateau, which formed due to the ongoing collision of the Indian Plate with the Eurasian Plate. The main deformation in this area is crustal shortening, but there is also a component of left lateral strike-slip faulting on major west–east trending structures such as the Kunlun and Altyn Tagh fault systems that accommodate southeastward translation of the Tibetan area.

The earthquake occurred on the Yushu fault, about 300 kilometres (186 mi) south of the Kunlun fault. The Yushu fault forms part of the Yushu-Garzê-Xianshuihe fault zone (玉树-甘孜-鲜水河断裂带), one of the most active fault zones in eastern Tibet. In history, many earthquakes greater than magnitude 7 have occurred in the Xianshuihe fault zone, for example, the magnitude 7.25 earthquake in the Luhuo area on March 24, 1923, and the M_s 7.6 earthquake on February 6, 1973, in Luhuo. Almost all sections of the Xianshuihe fault zone have produced strong earthquakes in records, except the sections of Yushu and Shimian (石棉). However, a trace of a strong earthquake occurred about 16,000 or 17,000 years ago has been found in Shimian. Hence, the Shimian section of the Xianshuihe fault zone is speculated to be currently locked and have the possibility of producing a strong earthquake in the future.

Earthquake

The earthquake was preceded by a large number of foreshocks (the largest M4.9) starting two hours before the mainshock and located near its epicenter. The mainshock was followed less than two hours later by a M6.1 aftershock. A total rupture length of about 80 km has been derived from a study of ground rupture backed up by SAR interferometry. Three fault segments have been identified, the most northwesterly of which ruptured during the M6.1 aftershock.

Analysis of the records from a seismometer located close to the fault rupture and the teleseismic responses from two distant seismometers (in Australia and Germany) suggest that the rupture propagated to the southeast at a speed well in excess of the S-wave velocity, making this an example of a supershear earthquake.

Damage

Earthquake cleft in the grassland

In Qinghai, building damage was reported with no casualties in the counties of Zadoi, Nangqên, and Qumarlêb of Yushu Prefecture. At least 11 schools were destroyed in the earthquake. Over 85% of buildings in Gyegu, mostly of wood-earth construction, were destroyed, leaving hundreds trapped and thousands homeless. A vocational school collapsed and trapped many students. Power outage was also reported in Gyêgu. Jiegu Town in Yushu suffered the greatest destruction; over 94 percent of buildings were destroyed; the maximum China seismic intensity of IX.

In Sichuan, strong shaking could be felt in the counties of Sêrxü, Dêgê, and Baiyü, Garzê Tibetan Autonomous Prefecture. Road damage was reported in Sêrxü County.

Due to the rough terrain and the fact that landslides destroyed the local infrastructure, the initial rescue operations were undertaken by the People's Armed Police and People's Liberation Army soldiers of Lanzhou Military Region. The Qinghai provincial government said in a public statement that five thousand tents, 100,000 thick, cotton coats, and heavy blankets were being sent to help survivors cope with the strong winds and near-freezing temperatures of around 6 °C (43 °F).

The Yushu Batang Airport was re-opened at noon on Wednesday, April 14, and the first flight with personnel and supplies of the China International Earthquake Rescue Team landed there at 8 pm.

The Changu (禅古) Dam, located on the Batang River (巴塘河; a right tributary of the upper Yangtze River) some 15 km upstream from the Yushu County seat (apparently at 32°54′40″N 97°02′50″E / 32.91111°N 97.04722°E / 32.91111; 97.04722), was damaged by the earthquake. Chinese language news reports as translated in a press release from the International Rivers stated that it is "at the risk of collapse at any time."

List of aftershocks

The initial earthquake was preceded by a foreshock and followed by several aftershocks, four above magnitude 5, including a M5.8 aftershock at a 4 km (2.5 mi) depth on April 14.

Only shocks with magnitude 4.0 or higher are listed. Shocks with magnitude 5.5 or higher are highlighted in light blue. The main shock with moment magnitude 6.9 M_w is highlighted in dark blue.

See also

• List of earthquakes in 2010
• List of earthquakes in China