Features of Seismicity in the Northeastern China Region and Their Relation to the Subduction of the Japan Sea Plate

Based on the analyses of grouped activity features of deep-focus (M ≥ 6.0) and shallow-focus(Ms ≥ 5.0) earthquakes in the Northeast China region, the time-space correlation betweendeep focus earthquake group and shallow focus earthquake group have beenstudied. The study was mainly on the characteristics of earthquake distribution on the collisionzone between the west Pacific plate and the Eurasian plate and on its relations to themorphological feature of the western Pacific subduction zone. Moreover, emphasis was laid onanalysis of the effect of the west Pacific plate on the seismicity of Eurasian plate. It is shownthat in the region where the west Pacific plate subducts at low angles, the seismicity on theplate collision zone is strong, the effect of plate subduction on Eurasian continent is strong too,and the subduction zone is under a state of high compressional stress. However, in the regionwhere the west Pacific plate subducts at high angles, the seismicity along the plate collision zoneis weak, the effect of plate subduction on Eurasian continent is weak too, and the tensile stressproduced by the subduction zone at depth is enhanced. We therefore propose that the seismicityin the northeast China region will enter an active period of shallow earthquake groupin the future 10 years. In the period, six earthquakes of Ms ≥5.0 may occur. Therefore, the work of earthquake monitoring and prediction in this region shall be strengthened.