Crustal Stress State and Seismic Hazard along Southwest Segment of the Longmenshan Thrust Belt after Wenchuan Earthquake

The crustal stress and seismic hazard estimation along the southwest segment of the Longmenshan thrust belt after the Wenchuan Earthquake was conducted by hydraulic fracturing for in-situ stress measurements in four boreholes at the Ridi, Wasigou, Dahegou, and Baoxing sites in 2003, 2008, and 2010. The data reveals relatively high crustal stresses in the Kangding region （Ridi, Wasigou, and Dahegou sites） before and after the Wenchuan Earthquake, while the stresses were relatively low in the short time after the earthquake. The crustal stress in the southwest of the Longmenshan thrust belt, especially in the Kangding region, may not have been totally released during the earthquake, and has since increased. Furthermore, the Coulomb failure criterion and Byerlee＇s law are adopted to analyzed in-situ stress data and its implications for fault activity along the southwest segment. The magnitudes of in-situ stresses are still close to or exceed the expected lower bound for fault activity, revealing that the studied region is likely to be active in the future. From the conclusions drawn from our and other methods, the southwest segment of the Longmenshan thrust belt, especially the Baoxing region, may present a future seismic hazard.