资源环境科技发展态势分析平台

Shallow crustal velocity and Poisson’s ratio structures are of key importance to understand rock properties and near-surface tectonic deformation and evolution. We propose a novel imaging method to acquire such information at individual stations by joint inversion of amplitude ratios between the horizontal and vertical components of both teleseismic P- and S-waves. Our synthetic experiments demonstrate the validity of the method in recovering subsurface structure up to ∼8-10 km depth. We apply the method to construct the velocity and Poisson’s ratio images along a NW-SE-trending seismic array within the Sichuan Basin, southwestern China. The results reveal well developed stratification and localized high Poisson’s ratio anomalies, which reflect a long-term stable sedimentary environment and fault-related deformation in response to the Cenozoic Tibet-basin collision, consistent with geological observations. Our new method is building a bridge between fine-scale near-surface seismic exploration and large-scale deep passive-source imaging, especially for areas of weak seismicity.