青藏高原东南缘丽江—剑川地区地应力测量与地震危险性

In-situ stress measurement in Lijiang-Jianchuan area and tentative discussion on the seismic hazards on the southeastern margin of the Tibetan Plateau

为获得川滇块体腹地现今的地应力场,分析边界断裂发生地震活动的危险性,进而探讨块体运动的动力学特征,2010—2011年,在青藏高原东南缘丽江—小金河断裂带西南段的丽江—剑川地区,开展2个300m钻孔水压致裂地应力测量。地应力测量结果揭示了研究区地壳浅表层现今主应力的分布规律。结合研究区部分中强震震源机制解及20世纪80年代地应力结果,分析了跨度近30a后该区构造应力场的变化特征,进而探讨了其动力学指示意义。依据断层滑动摩擦准则,讨论了丽江—剑川地区现今地震活动危险性。

In order to obtain the present in-situ stress field in the hinterland of Sichuan-Yunnan block, the authors analyzed the seis- mic hazards near the boundary faults and, on such a basis, explored the dynamics of the block. Hydraulic fracturing in-situ stress mea- surements were made in two 300m drill holes in Lijiang-Jianchuan area in the vicinity of southwest Lijiang-Xiaojinhe faulted zone on the southeastern margin of the Tibetan Plateau from 2010 to 20l 1. The results of stress measurement in the study area preliminarily re- veal the main distribution of the shallow crustal stress. In combination with the focal mechanism solutions and the in-situ stress resuks during the 1980s, Various characteristics of the tectonic stress field and its dynamic indication significance were analyzed in the time span of nearly 30 years. Based on the fault slip friction criteria, this paper discusses the current seismic hazards of Lijiang-Jianchan area.