(1. Key Laboratory of Neotectonic Movement and Geohazard of Ministry of Land and Resources，Institute of Geomechanics，Chinese Academy of Geological Sciences，Beijing 100081，China；2. Institute of Geomechanics，Chinese Academy of Geological Sciences，Beijing 100081，China；3. Institute of Crustal Dynamics，China Earthquake Administration，Beijing 100085，China)
Abstract：Results of geostress measured respectively in 2003，2008 and 2010 in four boreholes located in Baoxing County and Kangding district in Sichuan Province，together with seismic geological data，were used to study the geostress state and seismic risk in Southern segment of Longmenshan fracture belt after Wenchuan Ms 8.0 earthquake. The study results show that the present stress conditions do not appear to be totally relieved after the region tectonic stress field adjustment caused by Wenchuan earthquake，and the adjustment tendency of geostress is accumulated after Wenchuan earthquake in this region. Primary analysis reflects that the maximum horizontal principal stress values have reached the lower limit of fault activity in the Southwest segment of Longmenshan fracture belt. The fault has been in critical state and will probably slip in the way of reverse fault in the future. Based on the measured geostress state and earthquake migration data，there is a potential seismic risk in the Southwest segment of Longmenshan fracture belt. It is suggested that more attention should be paid to this region. The research results have great significance for mobility analysis of fracture，long-term monitoring of geostresses and disaster prevention and mitigation in the Southwest segment of Longmenshan fracture belt.
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2013, Vol. 32 
