THE REGIONAL CHARACTERISTICS OF FOCAL MECHANISM SOLUTIONS IN CHINA AND ITS ADJACENT AREAS

Based on analysis of distribution of 2 660 earthquake focal mechanism solutions from “Database of Crustal Stress of China and Adjacent Area” (updated to December, 2003), the regional characteristics of focal mechanism solutions are studied. In the Northeast and North China stress regions, the orientations of maximum horizontal stress mostly are in the near EW direction and NEE-SWW direction. The strike-slip focal mechanism is predominant in Northeast and North China stress regions. In the South China stress region, the predominant orientation of maximum horizontal stress is in NE-SW direction. The focal mechanisms mainly include thrust faulting and strike-slip faulting. In the Xinjiang stress region, the predominant orientation of maximum horizontal stress is in near N-S direction. There is a significant number of thrust faulting events and strike-slip faulting events in Xinjiang stress region. In the south Tibetan stress region, the predominant orientation of maximum horizontal stress is in near N-S direction, and the focal mechanism solutions are of strike-slip and normal faulting. In the stress region of north Tibet plateau and in the northeastern edge, the predominant orientation of maximum horizontal stress is not concentrated, and the focal mechanisms mostly are of strike-slip faulting, with some normal faulting and thrust faulting.