2014年新疆于田M_S7.3地震序列和震源特征初步分析

Study the characteristics of the Yutian,Xinjiang M_S7. 3 earthquake,February 12,2014

2014年2月12日新疆于田发生MS7.3地震,震中位置36.1°N、82.5°E,震源深度约17km,于田地震发生在西昆仑断裂与阿尔金断裂交汇区内,基于远震波形记录反演的震源机制为走滑型,此次地震破裂比较集中,滑动主要分布在深部,破裂未出露地表。截至2014年2月23日12时00分,于田MS7.3地震序列中2、3级地震较为丰富,衰减较为正常,b值约为0.7,h值为1.29,等待时间法显示4.5级以上余震遵从线性关系,符合以往主-余型地震的特征。基于由断层面上滑动位移反演结果和震源参数计算得到的经验关系认为,于田地震的动态破裂过程为应力下调模式,即地震能量的释放可能并不十分完全,这与该地震b值小于2008年于田MS7.3、2012年于田MS6.2地震b值的特征相符。

The Yutian MS7.3 earthquake,occurred on February 12,2014 in Xinjiang Uygur Autonomous Region,China,as a result of shallow strike-slip faulting in the tectonically complex region of the northern Qinghai-Tibetan Plateau,with depth of 17km.This earthquake occurred several hundred kilometers north of the convergent India-Eurasia plate boundary.The location of Yutian earthquake,36.1 °N,82.5°E,is 110km north of Yutian city,Hotan district.The number of rich ML2.0～3.0 aftershocks till February 23,2014,12：00,and the largest aftershock,MS 5.7,occurred at 17：24,February 12,2014.The b-and h-value of Yutian sequence is 0.7 and 1.29,respectively.The method of waiting time shows that these strong aftershocks above ML4.5 is linear,which is consistent with the characteristics of mainshock-aftershock sequence.Furthermore,we calculate the source parameters and analyze the rupture process based on the empirical relationships for the Yutian earthquake.The results indicate that the frictional undershoot behavior in the dynamic source process of the Yutian earthquake,which is also in agreement with the lower and similar b values comparing with the 2008,MS 7.3,Yutian earthquake and the 2012,MS6.2,Yutian earthquake.