巴颜喀拉地块及其周边地震危险性分析

Earthquake Hazard Analysis of the Bayankala Block and Its Surroundings

巴颜喀拉地块及其周边因地震动活动频繁成为中国地震预测研究的重要目标区,我们利用广义极值(GEV)分布对该地区的最大震级进行了极值统计分析。本文首先对于分布参数进行估计,然后计算出重现水平、地震平均复发周期与发震概率和震级危险率等参数,并比较了GEV分布99%分位数和b值截距法最大震级、历史最大震级。最后基于Monte Carlo模拟方法验证了运用GEV分布对研究区域做极值统计分析的稳定性。经计算,该地区6.0级地震的平均复发周期为1.8年,8.0级以上巨震的复发周期仅为76.8年。百年的重现水平高达8.08级。另外,该地块未来发生5.0~7.0级地震的概率较大,说明该地块未来仍然会比较活跃。Monte Carlo模拟结果表明,利用GEV分布探讨该地块的地震危险性在一定程度上是稳定的。

Bayankala block and its surroundings have become the important target area because of the frequent earthquake activities.The largest earthquake magnitude is one of the basic parameters in regional seismicity descriptions.It is widely used in seismic risk analysis research.In this paper,we carry out the extreme statistical analysis on Bayankala block and its surroundings using the generalized extreme value distribution.We get the estimation of GEV distribution parameters.Then the recurrence level,the average recurrence period of the earthquakes,the probability of earthquake occurrence and the magnitude of the danger are calculated.We compare the quantile of a level 0.99 for extreme value distribution,the theoretic maximum magnitude from G-R relation and historical maximum magnitude.Finally,the Monte Carlo simulation method is used to verify the stability of the extreme value statistical analysis using the GEV distribution.According to calculation,the average recurrence period of magnitude 6.0 is 1.8 years,and the recurrence period of magnitude 8.0 is only 76.8 years.The 100-year reproduction level is as high as 8.08.In addition,the probability of occurrence of an earthquake of magnitude 5.0 to 7.0 in this block is relatively high,which indicate that the block will still active in the future.Monte Carlo simulation results show that the use of GEV distribution to explore the seismic hazard of this block is stable to a certain extent.