混合地震模型的建立及其科学意义

ESTABLISHMENT OF THE MIXED SEISMIC MODEL ANDITS SCIENTIFIC SIGNIFICANCE

利用中国西部古地震和历史地震资料建立了特征地震模型并与分档泊松模型结合组成混合地震模型 .研究了青藏高原东南缘的重要地震带鲜水河 小江断裂地区的地震危险性 ,并与 1 990年出版的中国地震区划图结果进行了比较 ,表明在 1 786年曾经发生过 7 级地震的康定地区 (离逝时间为 2 1 3a ,地震复发周期为 32 0a)的发震概率大于后者 ,Ⅷ度区面积同样是前者大于后者 .这说明地震离逝时间与地震复发周期关系对地震危险性计算是有影响的 ,特征地震与混合地震模型的引入解决了泊松模型无记忆性的缺陷 ,使计算的结果更科学、合理 .

The characteristic earthquake model is set up by using paleoseismic and historical earthquake data of the West China.The seismic hazard of Xianshuihe Xiaojiang fault zone located on eastern margin of Qinghai Tibet Plateau was estimated based on the mixed seismic model composed by characteristic earthquake model and magnitude apart Poisson model.Having compared with the seismic zonation map of China published in 1990,it is shown that both seismogenic probability and area of the region with I=8 obtained from the mixed model are larger than those on the seismic zonation map.That is to say,the leaving time and recurrence period influence on seismic hazard assessment.Therefore,the nonrecalibility of Poissin model could be solved by using characteristic earthquake and the mixed model,and scientific and reasonable results could be obtained.