2010年4月14日青海玉树发生7.1级地震,这是该区历史上发生的最为强烈的地震。该地震属走滑型,地处青藏高原巴颜喀拉地块南边界,发震断裂为甘孜—玉树—风火山左旋走滑断裂,地震破裂主要向震中东南方向。该地震是巴颜喀拉地块与羌塘地块以不同速率向东运动,地块间的差异运动使其边界应力积累到一定程度引发破裂的结果。根据地震定标律估算的主震断层破裂参数和应力参数为:地震矩M0=1.78×1019 N·m,矩震级MW=6.8,断层破裂面积S=468 km2,断层错距D=1.4 m,断层破裂长度L=37 km,断层破裂宽度W=12.6 km,剪应力τ0=16.8 MPa,应力降Δσ=7.03 MPa。历史地震分析表明,玉树7.1级地震是在世界8级以上地震、中国西部大三角7.8级以上地震、南北地震带7级以上地震和巴颜喀拉块体7级以上地震处于强烈活动背景下发生的。玉树地震后,青藏高原巴颜喀拉地块、羌塘地块及川滇菱形块体未来发生7级以上地震的危险性较大。
On April 14,2010,an earthquake of magnitude 7.1 occurred in Yushu,Qinghai Province,it is the strongest earthquake that have ever taken place in this region.The earthquake is a strike-slip earthquake in the plateau,the Bayankala block south boundary.Seismogenic fault is Ganzi-Yushu-Fenghuoshan left-lateral and strike-slip fault,the earthquake major rupture to the southeast of the epicenter.The earthquake results from the Bayankala block and Qiangtang block east at different rates of movement,differential movement between the block boundary to accumulate stress to a certain extent to trigger fault rupture.Based on scaling law,fault rupture and stress parameters of the MS7.1 Yushu earthquake are estimated,resulting the seismic moment M0=1.78×1019 N·m,moment magnitue MW=6.8,area S=468 km2,maximum offset D=1.4 m,fault length L=37 km,the width W=12.6 km,shear stress τ0=16.8 MPa,stress drop Δσ=7.03 MPa.Analysis on historical earthquakes shows that Yushu magnitude 7.1 earthquake occurred in the world for more than magnitude 8 earthquake,in West China Triangle over magnitude 7.8 earthquake,north-south seismic zone earthquakes above magnitude 7 and the Bayankala block more than magnitude 7 earthquake in the context of intense activity.After the earthquake Yushu,Bayankala block and Qiangtang block and the Sichuan-Yunnan Rhombic block of Qinghai-Tibet Plateau future occurrence of more than magnitude 7 earthquake in more dangerous.
