[J08-1] Imaging and interpreting lithospheric structures using seismic and geodetic approaches I

[J08-1-01] 3-D S-wave velocity structure under the Changbaishan volcanic area in Northeast China inverted with dense NECsaids array

^○Qi-Fu Chen, Xing-Li Fan, Wu Wang (Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China)

Previous studies show the prevalence of low velocities beneath the Changbaishan volcano, but debate continues about the details of the structure. We use data predominantly from our dense temporary NECsaids array (NorthEast China Seismic Array to Investigate Deep Subduction), but also incorporating data from surrounding permanent broadband seismic stations, to map Rayleigh-wave phase speeds in the crust and lithospheric mantle under the Changbaishan volcanic area in Northeast China. Then the Rayleigh wave phase velocity dispersions are inverted to determine 1-D shear wave velocity and assembled into 3-D model. The results show the S wave velocity structure of the crust has lateral and vertical heterogeneity, the velocity structure of shallow crust is well related with the tectonic units on the surface, and the deep structure reveals the volcanism and regional deep thermal erosion effect. The low velocity anomaly bodies are found in the crust and upper mantle beneath the Changbaishan volcano and have a tendency to extend to deeper, which may be the magma chamber in crust of the Changbaishan volcano. There is also a weak low velocity anomaly body in the middle-lower crust and upper mantle beneath the Longgang volcano, which may be related to the remains after its eruption.

This study is supported by the National Science Foundation of China (41130316 and 41474041).