Pn Travel-Time Tomography of the Paleo-Continental-Collision and Rifting Zone around Korea and Japan

Abstract

Abstract A recent dense deployment of seismic stations in South Korea and Japan allows regional seismic imaging of the far-east Asian region that experienced continental collisions and riftings. We perform seismic imaging based on a mantle-lid P -wave ( Pn ) travel-time tomography to exploit the tectonic imprints in the lithosphere. The average Pn velocity in the region is estimated to be 7.95±0.03 km/sec. The inverted Pn velocities illuminate the tectonic structures. High velocities of ∼8.15 km/sec are observed in the Precambrian massif regions, while low velocities of ∼7.8 km/sec are associated with the fold belt and sedimentary basin regions in the southern Korean Peninsula. The Pn velocity is estimated to be low in the backarc basins, including the Ulleung and the Yamato basins, while it is estimated to be higher on the continental fragments, including the South Korea plateau and the Oki bank. The high-velocity structures along the Japanese Islands support the separation of the Japanese province from the Eurasia plate. The high-velocity anomaly along the east coast of the Korean Peninsula around the Hupo bank suggests intrusion and solidification of high-density material in the lower crust and mantle lid.