摘要
系统研究了1970年以来辽宁及邻区发生的25次震群活动,总结了辽宁地区震群活动的参数特征,探讨了该地区震群活动与未来中强震的关系。结果表明：1研究区的25次震群中,最大地震优势发生时段在震群出现后3天内的占68%,84%的震群中最大地震与次大地震的震级差≤0.5级,平均为0.35。80%的震群持续活动时间约2个月;2震群中最大地震的震级越大,相应地2、3级地震频次也越多,通常1个4级左右的震群,2级地震频次平均约为28,3级地震平均约为6;3当震群中3、4级地震频次分别≥10和4,同时序列的b值为0.6~0.9,此时可判定震群为前兆震群。未来中强震3要素的判定依据为：发震时间为震群开始后1年内,平均6个月;震中距离震群所在地约0~400km,平均为180km;最大强度为G-R预测的最大地震震级加2.0级。当b〈0.5时,震群有可能为前震序列,即震群开始后1~20天内原地有发生M≥5地震的危险;425次震群中的80%在震群出现1年后对应了M≥4.6地震,空间上辽宁内陆的震群对辽南和唐山地区的M≥4.6地震有较好的指示,长岛和黑山岛附近海域的震群对渤海海峡及其附近地区的M≥4.6地震有较好的指示。
In this paper,25 earthquake swarms occurring in Liaoning and its adjacent area since1970 were systematically studied. The parameter characteristics of the earthquake swarms were summarized, and the relationship between earthquake swarms and the moderately strong earthquake in the future was discussed. The results showed that：（ 1） 68% of the largest earthquake occurred within 3 days,84% of the magnitude difference between major earthquake and the maximum earthquake was less than or equal to 0. 5,with the average of 0. 35,and 80%of the earthquake swarms had a duration of 2 months;（ 2） the greater the magnitude of the maximum earthquake,the more frequent the corresponding earthquakes of M2. 0 and M3. 0. In general,there were about 28 earthquakes with M2. 0 and 6 earthquakes with M3. 0 in an M4. 0earthquake swarm;（ 3） when the frequency of earthquakes with M3. 0,M4. 0 in the earthquake swarms was greater than or equal to 10 and 4 times respectively with the b-value of the sequence being 0. 6 ~ 0. 9,it would be determined as a precursor earthquake swarms. The criterion of three factors of med-strong earthquake in the future was determined as follows： the seismogenic time should be within 1 year（ 6 months averaged） after the appearance of the earthquake swarms; the epicenter should be located ranging from 0km to 400km（ 180 km averaged） of the earthquake swarms; the maximum intensity should be added 2 to the G-R predicted maximum magnitude;when the b-value was less than 0. 5,the earthquake swarms would become foreshock sequence,which means M≥5. 0 earthquake would occur in situ area in 1 day to 20 days after the earthquake swarms;（ 4） 80% of 25 earthquake swarms were corresponding to M ≥4. 6 earthquake after 1year. The earthquake swarms in Liaoning Inland could provide a good prediction for M4. 6earthquake in the Liaonan and Tangshan region,while the same method could be used analyzing the earthquake swarms in the waters near Heishan island and Long island for M4. 6 earthquake in the Bohai Strait and its nearby region.
出处
《中国地震》
北大核心
2015年第1期45-55,共11页
Earthquake Research in China
基金
辽宁省科学技术计划项目"辽宁省重点地震构造地震危险性研究"(2014231003)
辽宁省地震局重点实验室项目"辽宁省地震活动性研究"(LZ-Z201501-2)
辽宁省地震局重点实验室项目"未来1~3年辽宁省6~7级地震高危区研究"(LNDZ2014003)共同资助
关键词
震群
强度
持续时间
B值
Earthquake swarms Intensity The duration b-value
