1954年腾格里沙漠北7级地震断层面参数和滑动性质研究

Fault Parameters and Slip Properties of the 1954 Northern Tengger Desert M7.0 Earthquake

1954年腾格里沙漠北发生7级大震,由于此次地震发生在戈壁深处,风沙作用强烈,震后破坏现象不易保存,给通过地质踏勘研究地震增加了难度。到目前为止,涉及此次地震的发震构造研究内容较少。本研究根据成丛小震发生在大震断层面附近的原则及参考前人给出极震区长轴形态,采用1985—2012年发生在地震破裂区的精定位地震目录,选定了一个长条状研究区域,将模拟退火算法和高斯一牛顿算法结合,给出了利用小震密集程度求解的主震断层面走向、倾角,并确定地震发震断裂的长度、位置。在此基础上考虑区域构造应力参数,给出已求得断层面上的滑动角。最后将反演结果与已有结果做了对照,显示反演结果与已有的结果基本一致,反演到的震源断层位于前人给出的此次地震等震线的最高烈度圈内表明反演结果是真实可信的。

The northern Tengger Desert M 7.0 great earthquake that occurred in 1 954 resulted in varying degrees of damage in many areas of Neimenggu and its adjacent regions.Thus far,research results of the cause of this earthquake are few and inconsistent.Because it occurred in the Gobi Desert,the aeolian effect of was intense.These facts cause difficulties in studying the earthquake through geological prospecting methods.It is known that clustered small earthquakes often occur in the fault plane vicinities of large earthquakes.We used precisely relocated earthquakes that oc-curred near the earthquake rupture zone between 1 985 and 2012 and selected a strip-shaped zone according to clustered small earthquakes and long-axis morphology in the meizoseismal area.On the basis of simulated annealing and Gauss-Newtonian nonlinear inversion algorithms,we ob-tained fault plane parameters of earthquakes such as strike,dip,and location by using data of densely populated small events.On this condition,rake angles of the fault plane are further in-ferred from regional tectonic stress parameters.Finally,we determine that the inverted results and known results are similar and that the former are in the cycle of the highest seismic intensity. These findings indicate that the inverted results are reliable.