Using Surface Wave and Receiver Function to Jointly Inverse the Crust-Mantle Velocity Structure in the West Yunnan Area

Abstract

Considering the respective sensitivity superiority of surface wave dispersion to the S-wave velocity and receiver function to the interface depth, the data of surface wave and receiver function are combined to realize the joint inversion, and to obtain the crust-mantle velocity structure in the West Yunnan Area. In this paper, the technique of matched-filter frequency-time analysis is used to process the data of surface wave in the West Yunnan Area, the dispersion of group velocity of surface wave in the period range of 10.5~105.0s is acquired, and further, using the method of grid inversion the pure path dispersion is obtained within the grid of 1° × 1°. Based on the teleseismic broadband recordings of three components in the West Yunnan Area, the receiver function of teleseismic P-wave under the station is obtained after deconvolution. Jointing the dispersion information of pure path of surface wave with the data of receiver function, a systematical equation has been set up. Utilizing the differential damped least-squares scheme to realize the joint inversion, and the velocity structure of S-wave of the crust-mantle in the West Yunnan Area has been acquired. The results show that taking the Red River Fault as a boundary there exists an obvious difference of the crust-mantle structure on east and west sides. There exists a low velocity layer with thickness of ~10km at the depth of ~20km on the west side of the fault, but not obvious on the east. Wanding and Cangyuan located in the Yunnan-Myanmar-Thailand block belong to the low velocity area in the upper mantle, and another one is located in the Kongdian Palaeo-upheaval of the Mid-Yunnan block. Both low velocity areas have good corresponding relations with the geothermal distribution and strong earthquakes.