Temporal variations in seismic and volcanic activity and relationship with stress fields in East Asia

Abstract

The temporal characteristics in seismic and volcanic activity and relationship with seismogenic stress in East Asia were analyzed mainly based on the qualitative and statistical analysis of historical and instrumental earthquake data. A long-term synchronous variation in seismicity since 1400 A.D. exists in the intraplate region from northeastern China to the Inner Zone of Southwest Japan through the Korean Peninsula. Short-term synchronous variation in seismicity since 1900 is also found in the region from northeastern China and the Korean Peninsula to the western part of the Inner Zone of Southwest Japan. Historical volcanic activity in and around the Korean Peninsula is closely correlated with active seismicity. The seismogenic stress field in this intraplate region may be formed under the common tectonic conditions due to the regional tectonic forces originating from the collision between the Indo-Australian and the Eurasian plates in the west and the combined effects of subduction of the Pacific and the Philippine Sea plates around the Izu and Tokai area in the east, and the regional vertical force by uplifting of upper mantle. The direction of the regional forces is almost parallel to the great circle connecting the eastern part of the Himalayas to Japan. The intraplate regions from northeastern China and the Korean Peninsula to the western part of the Inner Zone of Southwest Japan may be responding as a unitary block to the regional tectonic force and comprising a province with a common seismogenic stress field in the eastern part of the Eurasian plate.