RELOCATION OF MAIN SHOCK AND AFTERSHOCKS OF THE 2014 YINGJIANG MS5.6 AND MS6.1 EARTHQUAKES IN YUNNAN

doi:10.3969/j.issn.0253-4967.2016.04.019

Abstract

Abstract:

Yingjiang area is located in the China-Burma border,the Sudian-Xima arc tectonic belt,which lies in the collision zone between the Indian and Eurasian plates.The Yingjiang earthquake occurring on May 30th,2014 is the only event above M_S6.0 in this region since seismicity can be recorded.In this study,we relocated the Yingjiang M_S5.6 and M_S6.1 earthquake sequences by using the double-difference method.The results show that two main shocks are located in the east of the Kachang-Dazhuzhai Fault,the northern segment of the Sudian-Xima Fault.Compared with the Yingjiang M_S5.6 earthquake,the Yingjiang M_S6.1 earthquake is nearer to the Kachang-Dazhuzhai Fault.The aftershocks of the two earthquakes are distributed along the strike direction of the Kachang-Dazhuzhai Fault (NNE).The rupture zone of the main shock of Yingjiang M_S6.1 earthquake extends northward approximately 5km.The aftershocks of two earthquakes are mainly located in the eastern side of the Kachang-Dazhuzhai Fault with a significant asymmetry along the fault,which differ from the characteristics of the aftershock distribution of the strike-slip earthquake.It may indicate that the Yingjiang earthquakes are conjugate rupture earthquakes.The non-double-couple components are relatively high in the moment tensor.We speculate that the Yingjiang earthquakes are related to the fractured zone caused by the long-term seismic activity and heat effect in the deep between Kachang-Dazhuzhai Fault and its neighboring secondary faults.Aftershock distribution of the Yingjiang M_S6.1 earthquake on the southern area crosses a secondary fault on the right of the Kachang-Dazhuzhai Fault,suggesting that the coseismic rupture of the secondary fault may be triggered by the dynamic stress of the main shock.

Key words: Yingjiang earthquake, Sudian-Xima arc tectonic zone, Kachang-Dazhuzhai Fault, aftershock sequences, double-difference relocation

摘要：

盈江地区位于中缅边境的苏典-昔马弧形构造带，地处欧亚板块与印度板块的碰撞带，2014年5月30日发生的盈江地震是该区有地震记录以来第1次M_S6.0的地震。使用双差定位方法对盈江M_S5.6和M_S6.1地震序列进行了重定位。结果表明，2次主震均位于苏典-昔马断裂带北段的卡场-大竹寨断裂的东侧。相比于M_S5.6主震，盈江M_S6.1主震震中位置更靠近卡场-大竹寨断裂。2次地震的余震主要沿卡场-大竹寨断裂走向（NNE向）展布，M_S6.1地震的主震破裂区向N扩展了约5km。2次地震的余震区主要分布在卡场-大竹寨断裂的东侧，呈现出沿断裂明显的不对称性，并具有较大的宽度，与走滑型地震典型的余震分布特征存在差异，可能表明此次盈江地震为共轭破裂地震。地震矩张量反演结果表明，盈江地震主震存在明显的非双力偶成分。推测盈江地震可能与卡场-大竹寨断裂和其邻近次级断裂之间的深部介质在长期地震活动中遭受破坏以及深部热作用有关。盈江M_S6.1地震分布在南段的余震跨越了卡场-大竹寨断裂右侧的次级断裂，认为主震的动态应力可能触发了其邻近次级断裂的同震破裂。

关键词: 盈江地震, 苏典-昔马构造带, 卡场-大竹寨断裂, 余震序列, 双差地震定位

CLC Number:

P315.2

YANG Ting, WU Jian-ping, FANG Li-hua, WANG Wei-lai. RELOCATION OF MAIN SHOCK AND AFTERSHOCKS OF THE 2014 YINGJIANG M_S5.6 AND M_S6.1 EARTHQUAKES IN YUNNAN[J]. SEISMOLOGY AND GEOLOGY, 2016, 38(4): 1047-1057.

杨婷, 吴建平, 房立华, 王未来. 2014年云南盈江M_S5.6和M_S6.1地震余震序列重定位[J]. 地震地质, 2016, 38(4): 1047-1057.

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