2014年8月3日云南鲁甸M 6.5级地震概况  

Overview of the M 6.5 Yunnan Ludian earthquake in August 3,2014

作　　者：金明培[1] 杨军[1] 陈佳[1] 李孝宾[1] 

机构地区：[1]中国地震局滇西地震预报实验场办公室,大理671000

出　　处：《地球物理学进展》2014年第4期1980-1984,共5页Progress in Geophysics

摘　　要：2014年8月3日云南省鲁甸县龙头山镇发生了M 6.5级地震.此次地震为云南省14年来最大地震,已造成重大人员伤亡.地震位于北北西向包谷垴-小河断裂带与北东向西鱼河-昭通断裂带的交汇部位.综合余震空间展布的长轴方向和震源机制两个节面解,判定北北西向包谷垴-小河断裂为其发震构造,断层走向165°,倾角65°,滑动角12°,以左旋走滑为主.此次地震序列余震较为丰富,已发生1450多次,其中最大余震为M 4.2级地震.余震区呈不规则T字形,长轴约37 km,短轴约20 km.根据余震空间分布、序列随时间衰减h值和M≥3.0级余震震源机制解变化情况,初步判定该地震序列属主余型.此次地震发生在我国多年来持续圈定的川滇交界地震重点危险区,也是2014年度全国重点监视防御区.但地震并没有发生在全新世以来的活动断裂带上,而发生在一条规模较小、出露并不连续的晚更新世以前活动的次级断裂带上,很大程度上突破了强震与活动断裂的关系理论.文章最后还讨论了云南地区今后的震情形势.An M 6.5 earthquake occurred on 3 August 2014 in Longtoushan town,Ludian county of Yunnan province.This earthquake was the largest event in last 14 years in Yunnan area,has caused major casualties.The epicenter of this earthquake located in the intersection zone of the NNW Baogunao-Xiaohe fault and the NE Xiyuhe-Zhaotong fault.According to comprehensive analysis of the long axis direction of aftershock spatial distribution and two nodal-plane solutions of focal mechanism of the main shock,we regard the NNW Baogunao-Xiaohe fault as the seismogenic structure,with strike=165°,dip=65°,slip=12°.So Ludian M 6.5 earthquake is mainly a left-lateral strike-slip event.The aftershock sequence is rich,has occurred 1450 times,of which the largest aftershock earthquake M 4.2.The aftershock area was irregular T shaped,the long axis is about 37 km,the short axis is about 20 km.Combining the conjugate aftershock spatial distribution,sequence attenuation h value,and the different focal mechanism solution of the earthquake sequence,we conclude preliminarily that this sequence belong to main-aftershock type.The Ludian M 6.5 earthquake occurred in national long-term earthquakerisk-area covers the junction of Sichuan and Yunnan province,as well as the 2014 annually national key monitoring-prevention area.However,this earthquake did not happen in the Holocene active fault,but a smaller scale,discontinuous,secondary fault,the fault times even older than the late Pleistocene,which greatly exceeded the theory about the relationship between strong earthquakes and active faults.This paper also discusses the big earthquake trend in future in Yunnan.

关 键 词：鲁甸M 6.5级地震 震源机制 包谷垴-小河断裂 发震构造 

分 类 号：P315[天文地球—地震学]