活动推覆构造区潜在震源的边界和震级上限——以1902年阿图什8(1/4)级地震构造区为例  

The Boundary and Upper Limit Magnitude of Potential Seismic Source Zone in Active Nappe Structure Region——An Example from M8(1/4) Atushi Seismic Structure Region

作　　者：杨晓平[1] 冉洪流[1] 

机构地区：[1]中国地震局地质研究所,北京100029

出　　处：《震灾防御技术》2010年第2期145-156,共12页Technology for Earthquake Disaster Prevention

基　　金：地震行业科研专项"天山北麓活动构造及地震危险性评价技术(200808013)";国家科技支撑计划"强震区活动褶皱-逆断裂带深浅构造关系研究和潜在震源区位置;边界划分原则与方法(2006BAC13B010102)"共同资助

摘　　要：1902年阿图什81/4级地震发生在西南天山山前推覆构造体中,逆冲推覆构造由推覆体的根部断裂、推覆体、滑脱断层和前缘逆断裂-褶皱等组成,大地震的发震断裂往往是推覆构造的根部断裂,而地震地表破裂和同震褶皱隆起则位于山前逆断层-褶皱带内。高震级的潜在震源区(MU>7.5)对应于低速的天山地块和高速的塔里木地块之间的根带断裂,其长度对应于推覆体根带断裂的长度,宽度对应于根带隐伏逆冲断裂在地表的投影宽度。推覆体前缘的每个活动逆断裂-背斜对应于一个潜在震源(MU≤7.5),其长度与活动逆断裂-背斜的长度相等,宽度应覆盖活动褶皱的两翼。潜在震源的矩震级上限由W-C统计关系式确定,其中发震断裂的面积为活动褶皱的长度与隐伏断坡宽度的乘积。The M81/4 Atushi great earthquake of 22th August 1902,take place in the nappe structure region at the front of southwest Tianshan.The thrust systems on the piedmont of southwest Tianshan are composed of foot thrust fault,nappe,detachment fault and front thrust fault-fold.Great earthquake is likely to occur at the foot thrust fault near Tianshan Mountains,while earthquake surface rupture and coseismic fold uplift usually appear in the frontier active reverse fault and fold zone.Potential seismic source zone（MU7.5）of large earthquake corresponds to the foot thrust fault which is also the transition-zone of low P-velocity in Tianshan block and high P-velocity in Tarim block,in which its length correspond to the long of the foot thrust fault and its width correspond to the projection width of foot thrust fault.Each active reverse fault-fold at the frontier of nappe structure correspond to a potential seismic source zone（MU≤7.5） whose length is equal to length of the active reverse fault-fold,whose width is equal to the width of active fold.Upper limit magnitude of moment magnitude for potential seismic source zone is calculated with the W-C statistical relationship.The seismogenic fault area is the product of the length of active reverse fault-fold and width of blind fault.

关 键 词：西南天山 推覆构造 活动褶皱 潜在震源 震级上限 

分 类 号：P315[天文地球—地震学]