Abstract:This paper applies the finite difference travel time inversion and time-term method to model the upper crustal velocity structure and the crystalline basement structure beneath Yibin-Jinchuan profile. The tomographic and time-term method results show that: the basement depth of the Sichuan basin in the southeastern section is about 3~5 km, the unconsolidated sedimentation is very thick, and the shallow velocity is very low. In the northwest section the burial depth of the crystalline basement is gradually reduced by 0~3 km, partly exposed on the surface, and the shallow velocity increases obviously relative to other segments. The crystalline basement depth beneath the profile is obviously heterogeneous. The velocity structure gradual variations obviously correlate with the faults of Longquanshan mountain, Mingshan-Chengdu and the area of Longmenshan mountain. The velocity structure and the interfacial morphological characteristics of the crystalline basement provide seismic evidence for the studies of seismogenic mechanism and earthquake risk assessment in this area.
DENG Xiaoguo,WANG Fuyun,LIU Baofeng et al. Upper Crustal Velocity Structure of the Yibin-Jinchuan Profile and Its Implications[J]. jgg, 2018, 38(12): 1256-1261.