The low seismic activity of the Korean Peninsula surrounded by high earthquake countries.

Abstract

Although the Korean Peninsula is located near several great earthquake regions such as NE China and SW Japan, it has never suffered from catastrophic earthquakes for the last 2000 years according to historical and instrumental records. We investigated the low seismicity of Korea based on the hypothesis of the Baikal-Korea Plate (BKP) or Amurian Plate movement which is initiated by the Baikal Rift Zone spreading in a southeastward motion with a counter-clockwise rotation due to the collision of the Indian Plate against the Eurasian Plate. Many disastrous earthquakes of NE China, SW Japan and Sakhalin release large amounts of seismic energy along the boundary of the Baikal-Korea Plate. It is necessary to compute the released seismic energy along the presumed boundary of the Baikal-Korea Plate compared to the Korean Peninsula in order to estimate the micro-plate boundary. The total energy releases (1900–1999) from the major disastrous earthquakes (M≥6.0) along the Baikal-Korea plate are about 103–104 times as much as the Korean Peninsula (M≥3.0). The focal mechanisms for the intra-continental earthquakes near and/or along the Baikal-Korea Plate boundary of NE China, SW Japan, Sakhalin and Mongolia mostly represent the horizontal motions of the right-lateral strike slip type, indicating that the Baikal-Korea Plate is a counter-clockwise and transcurrent motion. The relative displacement vectors of GPS (global positioning system) also indicated that the Baikal-Korea Plate moves counter-clockwise around the Korean Peninsula. These factors may indicate that the Korean Peninsula is not located at the Plate boundary, but just within a margin of the Baikal-Korea Plate which moves southeastward with a counter-clockwise rotation from the Baikal Rift Zone in NE Asia. Therefore there is no enough accumulated strain to generate large earthquakes in the Korean Peninsula and it makes the Korean Peninsula free from seismic hazard of large catastrophic earthquakes.