【摘要】 2014年2月12日在新疆于田县境内西昆仑山东段地区发生了Ms7.3级强烈地震,震后野外考察表明,这次地震在海拔4600~5100m的地区形成了由一系列张裂隙、张剪裂隙、剪切裂隙以及挤压鼓包和裂陷等雁行状组合而成的地表破裂带,破裂带沿阿尔金断裂带西南段的两条近平行的分支断裂阿什库勒-硝尔库勒断裂和南硝尔库勒断裂分布,整体呈NEE走向,全长约28km,其中,沿阿什库勒-硝尔库勒断裂展布的地表破裂带长约10km,主要呈N63°~65°E走向,以左旋走滑伴随伸展性质的破裂为主,最大左旋位移约0.7m,最大垂直位移约0.4m;沿南硝尔库勒断裂展布的地表破裂带长约15km,呈N54°~60°E走向,以左旋走滑伴随逆冲性质的破裂为主,最大左旋位移约1m,最大垂直位移约0.75m;上述两破裂带之间沿N15°E方向由零星的张裂隙和右阶雁行状分布的张裂隙或张剪裂隙组成的不连续破裂带长约5km,显示为伸展具有左旋走滑的性质;另外,在南硝尔库勒断裂北侧沿N100°~110°E方向展布一系列具有挤压、右旋走滑性质的地表破裂带长约4km,宽约2km,与NEE走向的左旋走滑破裂带构成同震共轭破裂带。这种特殊的地表破裂样式是近期发生的强地震中结构最复杂的走滑断层型地表破裂。发震断裂属于阿尔金断裂带西南段尾端分支断裂,它与郭扎错断裂和龙木错断裂构成"阿尔金断裂"向SW方向的延伸部分,它们是青藏高原西部晚新生代强烈活动断裂,其大地震活动是由于印度和欧亚板块间碰撞而产生大陆变形的应变能释放过程。更多还原

【Abstract】 On February 12,2014,aMs7.3earthquake struck the eastern region of the West Kunlun Mountains in Yutian County,Xinjiang,China.Immediate(Feb 20)field investigation following the earthquake shows that it produced surface ruptures at an altitude of 4600~5100 m.The surface rupture zone consists of a series of enechelon tensional,shear-tensional to shear cracks,mole tracks,and sag ponds.Striking NEE—SWW,with a total length of about 29 km,the surface rupture zone is distributde along two subparallel faults,the Ashikule– Xor Kol fault and the south Xor Kol fault,which both split from the southwestern Altyn Tagh fault.Surface ruptures along the Ashikule–Xor Kol fault strike N63°~65°E for about 10 km,and are characterized by left-lateral strikeslip motion with normal component.Maximum sinistral and vertical displacements observed along this fault are~0.7mand~0.4m,respectively.Striking N54°~60°E for about 15 km,surface ruptures along the south Xor Kol fault are characterized by left-lateral strike-slip motion with thrust component,with maximum horizontal and vertical displacements of 1mand 0.75 m,respectively.The N15°E-striking,right-stepping en-echelon tensional and shear-tensional cracks between the former two faults constitute a 5km-long discontinuous rupture zone,with a sinistral transtensional behavior.North of the south Xor Kol fault,series of dextral transpressional surface ruptures striking N100°~110°E,constitute a 4km-long,2km-wide secondary rupture zone.Compared with other strong earthquakes,especially strike-slip events recently,the surface rupture zone produced by the 2014 Yutian earthquake is the most complex one.The seismogenic faults of this earthquake are two splays at the southwestern end of the Altyn Tagh fault.These splays combined with the Gozha Co and the Longmu Co faults constitute the propagation of the Altyn Tagh fault in the SW direction.Considering about the location of the 2008 Yutian earthquake(Ms7.3),we suggest that the area along Guozhacuo fault is prone to great earthquake in the future.The SW extension of Altyn Tagh fault is the intense active fault in the western Tibet,so the great earthquakes on these faults is the result of the present tectonic stress field associated with the ongoing penetration of the Indian Plate into the Eurasian Plate.更多还原