川滇地区成组强震活动判别指标研究

Research on seismicity of group earthquakes and judging indexes in Chuan-Dian Area

在成组地震孕育模型的指导下,分析研究了川滇地区M≥6.5地震成组孕育的地震学和前兆异常特征。结果表明,川滇地区的M≥6.5成组地震都发生在云南强震活跃期内,这个时期云南地区多点水汞测值出现了比正常值高出几十倍甚至上百倍的变化,比强震平静期的"异常"测值也要高得多;成组地震前1-2年的中期阶段地震活动会出现大面积增强;成组地震的首发地震发生时有30％以上的前兆异常持续发展,不出现转折变化,而单一强震和成组地震的最后1个地震,震前有异常震后不出现转折继续发展的数量≤15％;成组地震的首发地震前兆异常数量比结束地震多。

Under the instruction of seismogenic model of group earthquakes, characteristics of seismological and precursory anomalies of group earthquakes with M≥6. 5 in Chuan-Di-an area are analyzed. It shows that group earthquakes with M≥6. 5 in Chuan-Dian area always occur in the active period of strong earthquakes, in this period the measured values of several Hg content in groundwater changed dozens even hundred times higher than normal value. The anomalies were much higher than those in the quite period of strong earthquakes. The seismicity increased 1 - 2 years before the occurrence of the group earthquakes over an extensive area. More than 30% of precursory anomalies changed consistently and there was no turning variation when the first earthquake occurred. As far as the single earthquake and the last earthquake of group earthquakes concerned, the number of anomalies appeared before the occurrence and changed consistently while no turning after the occurrence were less than and equals to 15%. The anomalies of the first earthquake were more than those of the last earthquake of group earthquakes.