【摘要】 鲁甸6.5级地震造成了大量人员伤亡及房屋损毁,是云南近年来典型的"小震"致大灾现象。鲁甸地震后,针对重灾区龙头山镇开展了大量野外调查工作。调查涉及地震滑坡、地裂缝、断层剖面以及建(构)筑物震害等。调查发现,房屋损毁严重的龙头山镇政府所在地处在NW、NE向断裂交会部位;地震造成大量地质滑坡具有NE向优势分布特征,且与NE向展布的昭通-鲁甸断裂带关系密切;重灾区龙头山镇政府所在地地裂缝以NE向为主,龙头山镇南约6.5km的光明村大量地裂缝以NW向为主;同时,在光明村发现一系列NE、NW向断裂露头,疑似断层陡坎及槽谷,沿这些构造,在此次地震中均产生了裂缝或小位错。在野外调查基础上,结合余震序列分布及烈度等震线分布特征,认为此次地震由NW向包谷垴-小河断裂发震,同时大量NE向构造裂缝及滑坡等地质灾害显示不能完全排除NE向构造的作用。重要的是,地震地表裂缝和小位错与断裂的展布密切相关,有可能是地震同震地表破裂的表现。更多还原

【Abstract】 The 3rdAug 2014 Ludian MS6. 5 earthquake caused heavy casualties and damages to houses,which is one of the typical phenomena that a small earthquake causing heavy disasters in recent years in Yunnan Province. After the earthquake,a team( including the author) carried out a number of field investigations to the hardest-hit Longtoushan Township. The surveys involved various earthquake disasters,including landslides,ground fissures,fault profiles,building( construction) disasters,and so on. It is found that Longtoushan Township is the most seriously hit area,which locates on the intersection of the NW- and NE-trending faults. The earthquake caused a number of landslides with a predominant distribution in NE direction. The landslides distribution has a good relationship with the NE-trending Zhaotong-Ludian Fault. The ground fissures in the hardest-hit Longtoushan township showed a predominant distribution of NE direction,while the ground fissures in Guangming Village,which locates on the south of Longtoushan township about 6. 5km away( Fig. 2), showed a predominant distribution of NW direction.Meanwhile,a series of NE-,NW-trending fault outcrops,suspected fault scarps and troughs were found,and fissures and small dislocations were generated along these structures. On the basis of the field investigations,and considering the distribution characteristics of aftershock sequences and earthquake isoseismic lines,we infer that the seismogenic structure is the NW-trending BaogunaoXiaohe Fault. Meanwhile,we could not exclude the tectonic effect of the NE-trending fault,for a large number of geological disasters such as tectonic fissures and landslides were observed along the NE-trending fault. The ground fissures and small dislocations are closely related to the distribution of the faults,which are likely to be a reflection of coseismic surface rupture of this earthquake.更多还原