Interpretation of Wenchuan earthquake in Sichuan

Xinhua News Agency, Beijing, May 18 (Reporter Wang Libin) According to the preliminary monitoring and evaluation by the China Geological Survey, the Wenchuan earthquake was caused by the rapid uplift of the Qinghai-Tibet Plateau due to the subduction of the Indian plate to the Asian plate, with a focal depth of 10 km-20 km and a long duration, so it was extremely destructive.

The reporter learned from the Ministry of Land and Resources on June 5438+08 that since June 5438+05, the China Geological Survey held an analysis meeting on Wenchuan earthquake and its induced secondary geological disasters. Experts from China Land and Resources Aerogeophysical Remote Sensing Center, China Geological Environment Monitoring Institute, Chinese Academy of Geological Sciences, Institute of Geology of Chinese Academy of Geological Sciences, Institute of Geomechanics and other units initially formed three disaster conclusions based on the results of investigation, monitoring and evaluation.

First, the Indian plate subducted into the Asian plate, which led to the rapid uplift of the Qinghai-Tibet Plateau. The plateau material slowly flows eastward and squeezes eastward along the Longmenshan structural belt on the eastern edge of the plateau, encountering the tenacious resistance of the rigid block under the Sichuan basin, resulting in the long-term accumulation of tectonic stress energy, and finally suddenly released in Beichuan-Yingxiu area of Longmenshan.

Second, thrust, dextral and compressional fault earthquakes. The seismogenic structure is the central fault zone of Longmenshan structural belt, which thrusts from southwest to northeast under the action of compressive stress. The earthquake was a one-way rupture earthquake, which moved from southwest to northeast, causing aftershocks to expand to northeast. After the main earthquake, the process of stress propagation and release is slow, which may lead to strong aftershocks and long duration.

The third is shallow earthquakes. Wenchuan earthquake does not belong to the deep plate boundary effect, but occurred in the brittle-ductile transition zone of the crust with a focal depth of 10 km-20 km, which is extremely destructive.