包谷垴-小河断裂——2014年8月3日云南鲁甸M_S6.5地震发震构造  

Baogunao-Xiaohe Fault: the Seismogenic Fault of Ludian Ms6.5 Earthquake in Yunnan on Aug. 3^(rd),2014

作　　者：王腾文 李勇[1] 李敬波[1] 马超[2] 邵崇建 杨彦通[1] 周游[1] 

机构地区：[1]成都理工大学油气藏地质及开发工程国家重点实验室,四川成都610059 [2]四川省地震局工程地震研究院,四川成都610041

出　　处：《防灾科技学院学报》2015年第2期1-7,共7页Journal of Institute of Disaster Prevention

基　　金：国家自然科学基金(41172162)

摘　　要：2014年8月3日云南鲁甸发生MS6.5地震。通过对鲁甸地震震源机制解、余震分布、断裂组合样式及区域地质构造背景综合分析,得出以下结论:根据地震等震线长轴衰减方向、震源机制解、震后前期强余震分布样式及地表破裂,判定本次地震的发震构造为包谷垴-小河断裂;根据莲峰断裂、昭通断裂和包谷垴-小河断裂之间的构造组合样式、地表GPS水平运动速率及水平缩短速率的差异性判断包谷垴-小河断裂为同向差异逆冲型捩断层;根据莲峰、昭通断裂带上的地震震源深度分布规律,认为在断裂带下15~20km处地壳物质呈塑性流动状态,在来自大凉山次级块体南东向运动给予的应力挤压下,形成了包谷垴-小河捩断层,并且导致了鲁甸地震的发生。Ludian earthquake （Ms6. 5, August 3, 2014） occurred in Yunnan. On the basis of analysis of focal mechanism solutions, distribution of relocated early aftershocks, style of fault assemblage and regional geological tectonic setting, the authors draw the following conclusions： （1） According to earthquake isoseismal line long axis direction of attenuation, focal mechanism solution, prophase strong aftershock distribution pattern and the surface rupture after the quake, the authors preliminarily predicate that Baogunao--Xiaohe Fault is the causative structure in this earthquake; （2） Zhaotong Fault and Lianfeng Fault zones are located in the juncture of Sichuan and Yurman, and Zhaotong Fault is associated with a series of NE-trending and NW-trending secondary faults named Xiaohe Fault. Zhaotong Fault and Lianfeng Fault are thrust fault, parallel to each other, trend, to the northeast, and dip to the northwest. They are linked up by Xiaohe Fault which stricken in NW, almost perpendicular to them. Zhaotong Fault and Lianfeng Fault are divided into north section and south section by Xiaohe Fault. And north section of Zhaotong Fault is different from south section in terms of activity by analyzing geologic structure characteristic, GPS velocity field and stress field of north and south section of Zhaotong Fault. On the one hand the crust shorten average rate of north section of Zhaotong Fault is 4 -6mm/a and the south section is 2 - 3mm/a, on the other hand north section of Zhaotong Fault receives smaller resistance than south section. Xiaohe Fault has three characteristics. The first one, it is almost perpendicular to the trend and parallel to thrusting direction of Zhaotong Fault and Lianfeng Fault zone. The second, it is formed by different movement of Zhaotong Fault north section and south section. The third, Xiaohe Fault is a left strike-slip fault and high dip angle. In conclusion, Xiaohe Fault is a same direction, differential thrust type of tear fault; （3） According to the earthquake focal depth d

关 键 词：鲁甸地震 包谷垴-小河断裂 捩断层 断裂活动性 

分 类 号：P542[天文地球—构造地质学]