2001年10月27日永胜6.0级地震的成因探讨  

Study on the Cause of the Yongsheng Earthquake with M6.0 on Oct.27,2001

作　　者：周光全[1] 苏有锦[1] 王绍晋[1] 

机构地区：[1]云南省地震局,昆明650041

出　　处：《中国地震》2003年第2期166-174,共9页Earthquake Research in China

基　　金："十五"国家科技攻关项目 2 0 0 1BA6 0 1B0 1- 0 2- 0 2

摘　　要：20 0 1年 10月 2 7日云南永胜发生 6 0级地震 ,笔者先后参加了地震现场灾害损失评估和震后野外科学考察。考察表明 ,这次地震发生在程海断裂金沙江段上 ,断裂以左旋走滑活动为主。程海断裂分为 8段 ,各段的垂直差异运动不均匀 ,金沙江段中更新世以来的垂直位错速率为 0 4mm a ,远远低于程海断裂的垂直位错平均速率 (2 0mm a) ,从而使金沙江段成为断裂左旋走滑活动的构造障碍段。永胜 6 0级地震之前 ,金沙江段处于程海断裂带上强震活动的“空段”内。程海断裂控制下的次级块体———滇西北块体与滇中块体的边界沿程海断裂作相向运动。在此运动过程中 ,程海断裂有全线贯通无阻的趋势 ,构造障碍段和强震活动的围空段有利于构造应力集中、积累 ,从而孕育和发生了永胜 6 0级地震。苏家庄 -山岗辅段垂直位错速率仅为 0 3mm a ,同时也处于强震活动的围空段内 ,在程海断裂的贯通过程中成为新的构造障碍段 ,极有可能成为未来M≥ 6 0地震的危险地段。On October 27,2001,a large earthquake with M 6 0,named as the Yongsheng earthquake,occurred on the Jinshajiang segment of the Chenghai fault,Yongsheng county,Yunnan Province.It is the largest event occurred on the Chenghai fault for the last 200 years.The field seismogeological survey shows that the seismogenic fault,which is the Jinshajiang segment of the Chenghai fault,takes left lateral strike slip as dominant.According to the differences of vertical motion,motion time,landforms and scales,the Chenhai fault can be divided into eight segments.The Jinshajiang segment has a vertical dislocation rate of 0 4 mm/a,far lower than the mean rate of the Chenghai fault,about 2 0 mm/a.It's deduced that the two sides of the Jinshajiang segment sticked tightly and hindered the strike slip of the Chenghai fault.The strong earthquake distribution before this event showed that the Jinshajiang segment was in the seismic gap.The Chenghai fault,as a boundary of tectonic sub blocks,makes the Northwestern Yunnan block and Middle Yunnan block move clockwise,and their margins move oppositely along the Chenghai fault.In the motion process of the Chenghai fault,structure hindrance and the seismic gap of strong earthquake are propitious to the concentration and accumulation of structure stress.As a result,the Yongsheng M 6 0 earthquake occurred. The Sujiazhuang Shangangfu segment along the Chenghai fault is similar to the Jinshajiang segment with low vertical motion rate of 0 3 mm/a and in the seismic gap.So,it's postulated that the segment may become a new structure hindrance,and the Yongsheng M 6 0 earthquake may trigger the occurrence of future large earthquake along this segment.

关 键 词：永胜 地震 成因 构造块体 运动特征 垂直位错速率 

分 类 号：P315.1[天文地球—地震学] P315.2[天文地球—固体地球物理学]