Cause of Wenchuan earthquake

Generally speaking, Wenchuan is located in the North-South seismic belt, a major seismic belt in China.

The macro explanation is that "plates collide and the collision zone arches the Qinghai-Tibet Plateau." Professor Ni Sidao from the School of Earth and Space Sciences of HKUST told the Southern Weekend reporter, "The Qinghai-Tibet Plateau moved to the northeast while uplifting, squeezing the Sichuan Basin to slide to the northeast, and the Wenchuan earthquake occurred in the southeast of the Qinghai-Tibet Plateau."

Ni Sidao said that the specific mechanism of the earthquake is squeezing. "At the beginning, it was mainly squeezing, and there may be a slip of energy release at the end of the earthquake." Ni Sidao said that the Wenchuan earthquake occurred on the southeast edge of the Qinghai-Tibet Plateau, in the center of Longmen Mountain in western Sichuan, and was located on the Wenchuan-Mao Wen fault zone.

To Xiaoli, Wenchuan is in the Longmenshan earthquake zone in Sichuan. Longmenshan is the intersection of the new Qinghai-Tibet uplift plate and the old Yunnan and Sichuan plates. Seen from this angle, this place is an earthquake-prone area.

Erchie Wang, a researcher at the Institute of Geology and Geophysics of Chinese Academy of Sciences and an expert on the Qinghai-Tibet Plateau, is familiar with the geological structure of Wenchuan and has just been to Wenchuan in early May. He analyzed that the Wenchuan earthquake occurred on the southeast edge of the Qinghai-Tibet Plateau, in the center of Longmen Mountain in western Sichuan, and was located on the Wenchuan-Mao Wen fault zone. Plate compression caused the uplift of the Qinghai-Tibet Plateau. While the plateau is uplifting, it is also moving eastward, squeezing the Sichuan Basin. Sichuan basin is a relatively stable block. Although there seems to be weak tectonic activity in the main body of Longmen Mountain (according to historical records, although there was no major earthquake in the main body of Longmen Mountain, there was a strong earthquake in Songpan in the north of the last century), it may be in the process of stress accumulation, and when it accumulates to a certain extent, the crust will rupture and an earthquake will occur.

Li Yonggang, a professor at the Earthquake Research Center in Southern California, told Xinhua that the Longmenshan fault zone is an active fault in earthquake-prone areas. The eastward flow of materials from the deep Qinghai-Tibet Plateau to the Sichuan Basin is blocked and moves upward, and the boundary between them is the fault plane. If the fault moves a few centimeters every year, every 50 to 70 meters, the accumulated stress and energy can produce a major earthquake with a magnitude of more than 7 on the Richter scale. The news released by the Geological Survey also believes that the epicenter and focal mechanism of this earthquake are consistent with the movement of Longmenshan fault zone or a related structural fault, and the earthquake is the result of a thrust fault moving northeast.