鄂尔多斯地块北缘b值的时空特征及其地震预测效能分析  

Spatio-temporal characteristics of b value in the northern margin of Ordos block and its earthquake prediction efficiency

作　　者：张帆[1] 韩晓明[1] 陈立峰[1] 李娟[1] 李拴虎[1] 胡博[1] 

机构地区：[1]内蒙古自治区地震局,中国呼和浩特010051

出　　处：《地震学报》2018年第6期785-796,832,共13页Acta Seismologica Sinica

基　　金：内蒙古自治区地震局局长基金(2018ZD02);内蒙古自治区2016年度科技重大专项"重点地区地震预测预警技术研究开发与推广示范";中国地震局监测预报司2017年度震情跟踪定向跟踪任务面上课题(2017020102)共同资助

摘　　要：使用中国地震台网1970—2017年地震目录,在评估目录完整性和删除余震的基础上,使用最大似然法对鄂尔多斯地块北缘进行b值时空扫描.扫描结果显示,鄂尔多斯地块北缘的低b值区域主要分布于阿拉善和晋冀蒙地区,低b值区域的空间分布随时间呈现一定变化.低b值区域与中强地震存在一定的对应关系,对14次震例的回溯性检验显示,其中10次地震发生在低b值区域及其边缘.使用Molchan图表法和R值评分法对b值时空扫描结果进行预测效能检验,以低于阈值的区域为预测区域,计算不同阈值的漏报率、报准率和时空占有率。Molchan图表法检验结果显示,本文所使用的b值时空扫描方法的预测效果优于泊松分布,最优结果的概率增益达到2,显著性水平达到0.25. R值曲线显示,当阈值为0.8时,达到最高R值0.28,并达到97.5%置信水平.Using earthquake catalogue of China Earthquake Networks Center from 1970 to2017,the b values of the north edge of Ordos block were scanned by the maximum likelihood method after evaluating completeness and deleting aftershocks. The results show that the low b value region of the north margin of Ordos block is mainly distributed in the Alxa area and the Shanxi-Hebei-Inner Mongolia area,and the spatial distribution of low b value region changes with time to a certain extent. Meanwhile,there is a certain corresponding between the low b value region and the location of moderate-strong earthquakes. The retrospective test of 14 earthquake cases shows that ten earthquakes occurred in the low b value regions and their edges,and four earthquakes occurred beyond the low b value region. And then Molchan chart method and R value scoring method were used to test the prediction efficiency of b value spatio-temporal scanning. Taking the area below the threshold as the predicted area,the missing rate,the hit rate and the spatio-temporal occupation rate of different thresholds were calculated. The result of Molchan chart test shows that the prediction efficiency of spatio-temporal scanning is better than that of Poisson distribution,the probability gain of the optimal result reached 2,and the significance level reached 0.25. The R value curve shows that the highest R value is 0.28 at the threshold of 0.8 with 97.5% confidence level.

关 键 词：B值 时空扫描 预测效能 Molchan图表法 鄂尔多斯地块北缘 

分 类 号：P315.7[天文地球—地震学]