2013年德令哈郊区M_L4.5震群特征及发震背景研究  

Characteristics and Seismic Tectonic Background of the 2013 Delingha M_L4.5 Earthquake Swarm

作　　者：姚家骏[1] 马玉虎[1] 赵燕杰[1] 袁伏全 冯红武[2] 

机构地区：[1]青海省地震局,青海西宁810000 [2]中国地震局兰州地震研究所,甘肃兰州730000

出　　处：《地震》2014年第4期118-126,共9页Earthquake

基　　金：2014年地震科技星火计划青年项目(XH14050Y);2013年度震情跟踪青年课题(2013020105);"十二五"国家科技支撑计划"南北地震带强震综合预测与跟踪方法研究"(2012BAK19B01-07)

摘　　要：2013年3月底至4月初青海省德令哈郊区连续发生了数次ML4.5左右的地震,市区震感强烈。利用双差定位法对该震群进行重新定位,发现震群空间分布呈近NS向,深度集中于4~10km的地表浅层,纵向深度剖面呈＂斗状＂断层特征;利用CAP（Cut and Paste）方法反演了震群中ML≥3.3地震的震源机制解,结果为走滑类型,震群特征与附近的主构造宗务隆山断裂带性质不符。地质勘探发现凹陷或盆地边缘主构造附近通常存在横向伴生断裂,这些断裂规模不大,以走滑性质为主。本次震群位于柴达木盆地北边缘,通过相似构造的对比,认为该区附近同样满足横向断裂存在的条件。由于本次震群各项特征与横向断层的构造理论十分相符,推断出该震群应该是这种微小断裂活动的结果,横向断裂通常规模不大,因此可判断出震群震源区未来发生强震的可能性较小。were stro the doub the NS d ly funnel ML≥3. 3 slip. The Several earthquakes with ML4.0--4. 5 occurred in Delingha suburbs in 2013, and ngly feltin theurban area. We carried out relocation forthe earthquakeswarm by e-difference method. The results show that epicenter distribution is extended in rection nearly, the focal depth is concentrated at 4～1km and it is unsymmetrical- shaped in the vertical section. Using CAP method, focal mechanism solutions of earthquakes are also determined, which shows that these earthquakes are strike- characteristics of earthquakes warm are completely different from the Zongwu- long mountain fault that is the main structure in this region. It is discovered that there are many small transverse ruptures with strike slip propertiesin the vicinity of the main struc ture at the edge of depressions or basins. Delingha is located in the northern margin of Qaidam basin and some transverse ruptures may be inferred by the comparison of similar- tectonics. The characteristics of this earthquakes swarm correspond to transverse ruptures with strike slip properties, we infer that the earthquakes warm is not connected with the Zongwulong mountain fault directly, and may be a result of the activity of transverse rup- ture. The small scale of transverse ruptures restricts the strength of seismic activity, so it can be judged that the possibility of strong earthquake with larger magnitude is rather small in the region.

关 键 词：德令哈ML4.5震群 双差定位 CAP方法 横向断裂 

分 类 号：P315.7[天文地球—地震学]