Crustal deformation characteristics in the southwest segment of the Longmenshan structural belt before Lushan Mw6.6 earthquake and seismogenic structural model

Based on the calculation of precise leveling and GPS observation data, the crustal deformation characteristics of the southwest segment of Longmenshan structural belt before the Lushan Mw6.6 earthquake were analyzed. The results indicate: (1) Before the Lushan earthquake, the focus area and the SW section of the Longmenshan structure zone underwent weak crustal deformation and had large-scale crustal stress strengthening. The crustal deformation field was in a locking state, and the far-field area to the NW underwent obvious crustal deformation. This large-scale crustal deformation weakening or even locking phenomenon has a certain indicative significance for the occurrence of future moderately strong earthquakes in the same tectonic background area. (2) The Wenchuan earthquake caused the adjustment of the tectonic stress from the plateau and accelerated the accumulation of stress in the SW part of the Longmenshan structural belt, which contributed to the Lushan earthquake to a certain degree. (3) The seismogenic structure of the Lushan earthquake is not a simple thrust-type structure, but more likely to be an immature and complex blind thrust fault pattern that developed during the expansion and growth period of the multiple thrust nappe structural system. The seismogenic mechanism has reference value for the prediction of moderately strong earthquakes and scientific research in the periphery of the continental plateau.