云南地区地震烈度评估模型研究

Study of the evaluation model of the earthquake influence in Yunnan

摘要:

本文对1900~2014年发生在云南地区的146次5.0级以上地震的烈度数据进行了统计回归分析，并按照前人划分的云南地区的3个构造分区进行分类，将各分区内的烈度等震线作为样本，拟合出各分区的烈度衰减模型。由于样本所覆盖的时间段在百年左右，所涵盖的7级以上强震较少，故强震烈度衰减关系中隐含着随机性或不确定性，我们尝试引入破裂尺度来对强震烈度等震线的生成进行限定。通过分析对比已有研究成果，并选用李忠华和秦嘉政的震级-破裂尺度经验关系式组合作为破裂尺度的经验公式，对强震烈度衰减模型评估的影响场大小进行了修正。通过对本文拟合出的烈度衰减模型与已有研究结果进行比较发现，在某个分区内，本文给出的模型评估结果与实际烈度等震线平均偏差最小，故此采用更精细的分区比大分区在评估具体区域的地震烈度时更具有合理性。

Abstract:

In this paper,we conducted a regression analysis of the data of the intensity distribution of 146 earthquakes(M≥5.0)which occurred in the period from 1900 to 2014. According to the previous research results,Yunnan is divided into 3 tectonic regions. Then,we use the data of the isoseismic lines in these 3 regions to fit the intensity-attenuation model of each region. Since there are a few earthquakes with M≥7.0 in this defined 114-year period,the fitted intensity-attenuation model of the strong earthquakes would be random or uncertain. To solve this problem,we introduce the Rupture scale relation to limiting our fitted intensity-attenuation model of the strong earthquakes. We choose the empirical relation of magnitude and rupture-scale,which was proposed by Li Zhonghua and Qin Jiazheng,to correct the size of the influence field estimated through our intensity-attenuation model. Comparing our intensity-attenuation models with the previous ones,we found that,in a certain tectonic region,the intensity isoseismal estimated through our model averagely have minimum error with the real intensity isoseismal decided through the field investigation. Therefore,it is more advisable to choose the small-scale zone for the intensity-attenuation evaluation.