2016年青海门源MS6.4地震序列重定位*
黄 浩,王培玲,沙成宁

(青海省地震局,青海 西宁 810001)

门源MS6.4地震; 双差定位; 逆时成像; 余震序列; 震源参数

Double Difference Relocation of Qinghai Menyuan MS6.4 Earthquake Sequences in 2016
HUANG Hao,WANG Peiling,SHA Chengning

(Earthquake Administration of Qinghai Province,Xining 810001,Qinghai,China)

Menyuan MS6.4 earthquake on Jan.21,2016 and 878 aftershocks by double difference method,and obtained the source parameters of 701 earthquakes finally. The statistical location errors(two times of mean square deviation)was 0.4,0.5 and 0.9 km in EW,NS and vertical directions respectively,the mean time error is 0.2 s. The length of aftershocks in NW-SE and NE-SW is 16 km and 10 km respectively. The focal depth distributes in the range of 2～25 km,which can be divided into three layers,it mainly distributes in the range of 6～10 km. Based on the focal depths profile,we conjectured that the seismogenic fault is a reverse fault tilt towards NE and its depth is deep. The main shock located on the top of the seismogenic fault,and there is a V-shaped asperity under it. Combined with focal mechanism result,we consider that Menyuan earthquake occurred in the thrusting process of seismogenic fault which is blocked by the V-shaped asperity. Key words:Menyuan b>S6.4 earthquake; the double-difference relocation; Time-Reversal Imaging Technique; aftershock sequences; source parameter

备注

采用逆时成像技术,重新定位2016年1月21日青海门源MS6.4地震。使用双差定位方法对余震序列中878次余震进行重定位,获得了701次余震的重定位结果。统计定位误差(两倍标准偏差)在EW、NS和UD方向依次为0.4 、0.5和0.9 km,平均定位误差为0.2 s。余震在NW-SE向展布约16 km,在NE-SW向展布约10 km。震源深度分布在2～25 km,可以分为3层,优势分布在6～10 km。据震源深度剖面推测,发震断层为NE向倾斜的逆断层,深度较深。主震位于发震断层顶部,其下方存在V形凹凸体,结合震源机制结果认为,门源地震可能是发震断层在逆冲过程中受阻于V形凹凸体而产生的。

Based on TRIT(Time-Reversal Imaging Technique),we relocated the Qinghai Menyuan MS6.4 earthquake on Jan.21,2016 and 878 aftershocks by double difference method,and obtained the source parameters of 701 earthquakes finally. The statistical location errors(two times of mean square deviation)was 0.4,0.5 and 0.9 km in EW,NS and vertical directions respectively,the mean time error is 0.2 s. The length of aftershocks in NW-SE and NE-SW is 16 km and 10 km respectively. The focal depth distributes in the range of 2～25 km,which can be divided into three layers,it mainly distributes in the range of 6～10 km. Based on the focal depths profile,we conjectured that the seismogenic fault is a reverse fault tilt towards NE and its depth is deep. The main shock located on the top of the seismogenic fault,and there is a V-shaped asperity under it. Combined with focal mechanism result,we consider that Menyuan earthquake occurred in the thrusting process of seismogenic fault which is blocked by the V-shaped asperity. Key words:Menyuan MS6.4 earthquake on Jan.21,2016 and 878 aftershocks by double difference method,and obtained the source parameters of 701 earthquakes finally. The statistical location errors(two times of mean square deviation)was 0.4,0.5 and 0.9 km in EW,NS and vertical directions respectively,the mean time error is 0.2 s. The length of aftershocks in NW-SE and NE-SW is 16 km and 10 km respectively. The focal depth distributes in the range of 2～25 km,which can be divided into three layers,it mainly distributes in the range of 6～10 km. Based on the focal depths profile,we conjectured that the seismogenic fault is a reverse fault tilt towards NE and its depth is deep. The main shock located on the top of the seismogenic fault,and there is a V-shaped asperity under it. Combined with focal mechanism result,we consider that Menyuan earthquake occurred in the thrusting process of seismogenic fault which is blocked by the V-shaped asperity.