Regional features of seismotectonic deformations in East Asia based on earthquake focal mechanisms and their use for geodynamic zoning

Seismotectonic deformations of crustal volumes related to geographical coordinates were calculated from data on earthquake focal mechanisms. The crust of the western part of Asia, including the Tien Shan, Tarim massif, Tibet, Pamir-Karakorum, and Kun Lun, undergoes predominantly longitudinal shortening and latitudinal extension. In the eastern part, longitudinal extension and latitudinal shortening are observed. The notional boundary separating these parts is determined over a fairly wide range between longitudes 95° and 103° E and is apparently related to the northward compression from the Indian plate in the south and the westward compression from the Okhotsk and Philippine plates in the east. At the same time, this boundary may indicate the maximum zone of influence of the Indian plate. The boundaries of the Amurian plate are inferred from changes in seismotectonic deformations in the eastern part of Asia. Differences in the seismotectonic deformation of the Earth’s crust are found within the northern part of the Okhotsk plate and the surrounding area.