基于烈度数据点的历史强震参数估计研究

The research on historical strong seismic parameters estimation based on intensity data points

摘要:

由于地震仪器记录的历史较短，不足以据短时间、小尺度范围内的地震资料搞清地震活动的规律，因而对历史地震的研究非常重要。尤其是6.5级以上的历史强震，其参数的不确定性，直接对地震活动性规律和地震安全性评价等问题产生重大影响。根据6.5级以上强震烈度分布特征，本文提出了基于烈度数据点的考虑断层破裂长度的烈度椭圆分布模型，在此基础上联立椭圆数学方程确定了强震参数估计方法，并采用蒙特卡洛方法定量分析了所得参数的不确定性，结果表明：本文计算得到的震级精度在1级以内，震中计算精度可达2类。进而对华北地区5个历史强震参数进行了估算。本文直接采用数学模型分析烈度数据点来估算历史地震震级与震中，故减少了历史地震参数确定上的主观性，提高了科学性。由于在建模过程中，8.0级以上特大地震的资料太少，因此本方法只适用于6.5～8.0级的历史强震。

Abstract:

Due to the short history of seismic instruments record，it is difficult to know well the law of seismic activity in a short time and within a scope of small-scale，and it's thus very important to study on the historical earthquakes. The uncertainty of the seismic parameters of the historical MS≥6.5 earthquakes would have direct significant impact on some important issues such as seismicity and seismic safety evaluation. Based on the intensity distribution characteristics of MS≥6.5 earthquakes，this paper proposed an elliptical intensity distribution model based on intensity data points and fault rupture lengths. Then，we set the oval mathematical equation and the model together to establish a strong seismic parameters estimation method. Afterward we used the Monte Carlo method to analyze quantitatively the uncertainty of the resulting parameters. The results show that the accuracy of calculated magnitude using this method is within 1 and the accuracy of calculated epicenter is of Class 2. Finally，we estimated parameters of 5 historical strong earthquakes in North China. We used the mathematical model to analyze intensity data points directly in order to estimate seismic parameters of historical strong earthquake，reduced the subjective uncertainty and improved the scientific. Since the information of MS≥8.0 earthquakes is insufficient，this method is only applicable to MS6.5 to MS8.0 historical earthquakes.