Ambient noise data reveal the 3-D S-wave velocity of the Qinling-Dabie orogenic belt

The 3-D S-wave velocity model under the real path is obtained by applying the continuous seismic wave signals, which are recorded by 168 broadband seismographs in Hubei Province and its seven neighboring provinces from January 2021 to December 2022, using the direct inversion of surface wave dispersion method. Apparently, the results indicate that the S-wave velocity in the study area is non-uniform. The distribution of high-velocity anomalies and low-velocity anomalies in the shallow upper crust is highly consistent with the distribution of geological structural units, which can clearly outline the basin boundary. Due to the thin sedimentary layers in the orogenic and folded orogenic belts, such as in the Dabie Mountain area, there are even outcrops of bedrock, resulting in the existence of high-velocity anomalies in the upper and middle crust of the East Qinling fold belts, Dabie Mountains and Yangtze Block, among others. High-velocity anomalies in the middle crust beneath the Nanyang Basin, Sichuan Basin, and Jianghan Basin indicate that the upper crust in the study area is decoupled from the middle and lower crust.