S?Wave Velocity Structure of the Sichuan?Yunnan Region, China: Implications for Extrusion of Tibet Plateau and Seismic Activities

The Sichuan-Yunnan region is located at the intersection between South China Block, Indian plate, and Tibet Plateau crisscrossed with deep large faults characterized by strong seismic activities extrusion of Tibetan Plateau. Here we employ 1-year continuous waveforms vertical component 89 broadband stations using noise tomography in this to evaluate velocity structure its implications. Through single station data preprocessing, cross-correlation calculation, stacking, group dispersion measurement, quality evaluation, curves Rayleigh waves for different periods were extracted area. We then use surface wave method obtain distribution 9–40s. Finally, S-wave depth range 0–60 km calculated pure path inversion. results show that a large-scale low-velocity anomaly lower crust runs through rhombus block (SYRB) Yangtze Block from west east, which might correspond or channel flow. On other hand, are mainly concentrated western part region, earthquakes distributed boundary low- high-velocity structures, as well adjacent correlate