Abstract Using the three-component teleseismic wave shape data recorded by 85 mobile seismic stations in northwest Yunnan(25.0°N to 26.9°N, 99.20°E to 100.74°E), we extract the P-wave receiving function, and obtain the Moho depth and Poisson’s ratio by H-k scanning method. Then, we apply the receiving function common transformation point(CCP) stacking method, plotting a total of 6 vertical sections NW and NE were plotted. The results show that the crust thickness in the study area varies from 38.5 to 52.4 km, with the crust thickness being thicker in the northwest and thinner in the southeast. Poisson’s ratio varied between 0.24 to 0.34, showing a four-quadrant distribution. The wave velocity ratio decreases with the increase of crustal thickness in the study area, showing a certain negative correlation. Yunlong M5.1, Eryuan M5.5 and Yangbi M6.4 earthquakes all occurred in the high gradient zone of Poisson’s ratio. According to the CCP profile, the Moho in the study area fluctuates significantly in the NW direction, becoming shallower from the north to the south. The uprise amplitude is about 5 to 10 km. The fluctuation of NE toward Moho is relatively smooth, with an average depth of about 42 km. The stratification in the Earth’s crust is complicated, and there are few continuous interfaces. There is a wide negative amplitude band in the middle and upper crust below the Yangbi earthquake, which may provide seismogenic environment for the occurrence of earthquakes. The average depth of the D410 discontinuity plane is about 420 km, the average depth of the D660 discontinuity plane is about 660 km, and the thickness of the mantle transition zone is 210 to 260 km.
CHA Wenjian,JIN Mingpei,WANG Weijun et al. Study on Crust-Mantle Structure and Seismogenic Environment in Northwest Yunnan Based on Dense Array[J]. jgg, 2024, 44(6): 611-617.
CHA Wenjian,JIN Mingpei,WANG Weijun et al. Study on Crust-Mantle Structure and Seismogenic Environment in Northwest Yunnan Based on Dense Array[J]. jgg, 2024, 44(6): 611-617.