3D Seismic Velocity and Attenuation Structures of the eastern Sino-Korean Craton

This study investigates the three-dimensional seismic velocity and attenuation structures of the eastern Sino-Korean Craton through the analysis of an extensive dataset from China and South Korea. The dataset comprises 87,260 earthquakes recorded by 680 Chinese seismic stations since 2008 and 5,400 earthquakes recorded by 483 South Korean stations since 2017. The methodological framework includes 1D velocity model inversion, event relocation, and manual picking of Pg, Pn, Sg, and Sn arrivals, assisted by a machine-learning-based picking approach. A modified ray-tracing technique, optimized for tracking later Pg and Sg arrivals, is employed in double-difference velocity tomography to construct the velocity model. Attenuation factors (t*) for P-waves and S-waves are estimated via source spectral analysis. These factors, combined with the velocity model and arrival time data obtained in velocity tomography, are integrated into attenuation tomography. The dense coverage of seismic ray paths across the Yellow Sea and Bohai Sea enhances resolution, particularly in the boundary regions between mainland China and the Korean Peninsula.

The results identify a high-velocity zone extending from the Sulu Orogenic Belt northeastward through the northern and central Yellow Sea to the western Korean Peninsula, corresponding to the collision zone between the Yangtze and Sino-Korean blocks. Additionally, a low-velocity zone is observed from the crust of the South Yellow Sea to the mantle beneath Halla Volcano, suggesting post-collision extensional processes in the southern Yellow Sea Basin and a potential connection to volcanic activity. Preliminary seismic attenuation results exhibit features generally consistent with the velocity structure, providing insights into the region’s geodynamic evolution and comprehensive understanding of its tectonic and geological history.