Love wave tomography in Sichuan-Yunnan area from ambient noise

We collected seismic ambient noise data recorded at 98 permanent seismic stations in Sichuan-Yunnan area to image crustal structure. The Love wave cross-correlation functions are obtained by cross-correlation of ambient noise. The group velocity dispersion curves for Love wave are measured by automated time-frequency analysis. Love wave group velocity is mapped in the periods between 8 s and 30 s. The tomographies show seismic images at short periods exhibit apparent horizontal heterogeneities, which is largely consistent with geological features and geophysical studies. The Sichuan basin appears as low group velocity anomaly, and the Chengdu plain shows lower group velocity relative to the hilly area in Sichuan basin, with the line connecting Suining with Emeishan being the boundary between higher velocity and lower one. The variation of group velocity anomalies in Sichuan basin reflects variable sedimentary thicknesses. The Panzhihua area appears as high velocity anomaly, which is associated with an ancient mantle plume. The materials from mantle is remained at the different depth in crust in the form of intrusive rocks and magmatic underplating, resulting in the characteristics of high velocity anomaly. These seismic images provide necessary information for the research on crustal radial anisotropy and understanding of tectonic process.