关键词: 宁夏, 主压应力, 地震活动带

Abstract: From the recorded 18099 first motion symbols by the seismic station network in Ningxia and nearby regions and using the average of single earthquake source mechanism solutions and the average of small earthquake synthetic solutions,the local tectonic stress fields in 7 small areas are determined. The average direction of maximum compressive stress in the entire region is approximately N 30°E with local variations as N 60°E in Xi-Hai-Gu area; N 42°E in Yinchuan plain and Shizhuishan area; N 26°E in the north or west to the Shizhuishan as well as NE 17° in Wei-Ning area. The stress source of the areas are mainly from the southwest compression. It is also concluded that if the strike of weak seismic belts intersect in 25°—30° with the maximum compressive stress,the probability of moderate or large earthquake occurrence along these belts is relatively high.

Key words: Ningxia, Average direction of maximum compressive stress, Seismic active belt