关键词: 震源机制, 构造应力场, 区域特征, 伽师及其周围

Abstract: Jiashi and its surrounding areas are composed of many structural zones.Using the focal mechanism solutions of 59 mid-strong earthquakes in Jiashi and its surrounding areas,and combining with the calculation result of system cluster and stress field inversion,we analyzed the evolvement characteristics of the stress field for the different times and the different regions.The result shows as follows:The earthquakes in Jiashi are mainly of strike-slip.However,those of Kalpin block are mainly of reverse events,showing an obvious thrusting.The regional characteristics are different from other areas.The direction of the regional principal stress field is near NS.However,under the different tectonic background,the directions of stress fields are different.The direction of the principal compression stress is near NS in Kashi-Wuqia area.But before and after the 3 earthquakes with M 7,the dynamic evolution from NW to NS and then to NE with time process was observed.Kalpin block has been dominated by the consistent stress field of the NW direction for a long time.However,the direction of the stress field of Jiashi region is NE.From 1996,the direction of the regional stress field has changed obviously.The direction of the P axis was deflected towards NE,and the elevation angle increased.The result shows clearly the regional characteristic and variation of distribution pattern of stress field in different tectonic environments.

Key words: Jiashi and its surrounding areas, focal mechanism solution, tectonic stress field, regional characteristics