Abstract: Teleseismic waveform data from 38 temporary stations along the main fault zone (Anninghe, Zemuhe, Xiaojiang fault zone) of the eastern boundary of the Sichuan—Yunnan block and 14 permanent stations in Sichuan regional seismic network were used to compute crustal thickness and velocity ratio (Vp/Vs) of 30 stations by time domain iterative deconvolution extracting receiver function and the H inversion method. The results show that crustal thickness becomes thinner gradually from 60 km from west to east to that 35 km in South China block. In the west of Anninghe—Daliangshan fault zone, the average crust thickness is about 54 km, while in the east, as the front junction between South China block and Sichuan—Yunnan block, the average crust thickness is 42～48 km. Crust lithology and component obviously differ between Xiaojiang fault and that to its nouthern region. The poisson′s ratio between 0.20 and 0.27 at the northern segment of Xiaojiang fault zone indicates that its crust is mainly composed of basic rock. Nevertheless, the poisson′s ratio that is mostly lies between 0.27 and 0.32 at the Anninghe, Zemuhe and Mabian—Yanjin fault zones. Below most of the stations on Anninghe—Zemuhe fault zone, there is an ultra high Poisson′s ratio that greater than 0.30, which is inferred as evidence of local partial melt.

Key words: Crustal thickness, Poisson′s ratio, Receiver function, Sichuan—Yunnan block