STUDY OF SAND LIQUEFACTION HAZARD FEATURES INDUCED BY YINGJIANG Ms 5.8 EARTHQUAKE ON MARCH 10, 2011

On March 10, 2011,a Ms5.8 earthquake,focal depth 10km,struck Yingjiang county locating on Dehong Autonomous Prefecture of Yunnan province closed to Sino-Burna border,induced 25 persons killed, 250 injured,about 130 thousand people affected,many institutions(building)damaged,extensive liquefaction developed,about 19km Yingjiang embankment cracked.Such greater secondary disasters trigged by a Ms 5.8 earthquake is rare in recent seismic events.By analyzing the geological background of the earthquake and investigating geological hazards,this paper obtained an initial understanding of geo-hazards: (1)This earthquake is the results of continue enhance of Yingjiang scale 4 earthquake swarm beginning in 2011; in recent years,seismic swarm in Yingjiang region present a gradual migration from north to south along Sudian Fault; this earthquake is a continuation of this trend; the main shock and aftershocks show that Yingjing co-seismic rupture is a conjugate rupture between Shudian Fault and Dayingjing Fault.(2)Sand liquefaction is one of main reasons that this earthquake induced so severe loss.Sand liquefaction products lots of secondary geo-hazard phenomenon,sand and water blasting to the surface,sliding along the lateral ramp,ground cracking and subsidence,et al., which results in greater damages to houses,river banks,roads,water facilities and electric poles and other agencies.(3)Sand liquefaction are mainly developed in Dayingjiang Holocene alluvial deposits of fine sand,serious liquefied area is the Dayingjiang old river channel,construction(building)damaged area and degree is better accord with the extent and degree of liquefaction.The late Pleistocene as the second terrace of Yingjiang is not only high altitude,better flood resistance capacity,but also strong engineering geological conditions for non-liquefaction,so where is the better place as the planning development area of the local towns.