基于中国地震台网1970—2021年地震目录，结合赤峰及通辽地区地质构造和地震活动分布，采用最大似然法，对研究区域进行b值时空扫描，结果显示，低b值主要分布在研究区西北侧NE向大兴安岭断块隆起带两侧和赤峰—开原断裂及一系列NE向断裂相交汇区域，符合研究区域应力分布特点。对研究区域内15次中强地震及1次小震群活动进行震例回溯，发现5次地震事件发生在低b值及周边区域，表明b值变化对区域中强地震的发生有一定指示作用，但效果不够理想。
Using the earthquake catalogue of the China Earthquake Networks Center from 1970 to 2021, combined with the geological structure and seismicity in the study area, this study carries out a temporal and spatial scanning of the b value in the study area using the maximum likelihood method. The results show that the low b value in Chifeng and Tongliao areas is mainly distributed on both sides of the NE trending Daxinganling fault block uplift belt in the northwest and the intersection area of the Chifeng-Kaiyuan fault and a series of NE trending faults, which conforms to the characteristics of stress distribution in the study area. By tracing back 15 moderate earthquakes and 1 small earthquake swarm in the study area, it is found that 5 moderate earthquakes occurred in the low b value and its surrounding areas, indicating that the b value has a certain indication significance on the occurrence of moderate earthquakes in the study area.
2022,43（5）: 9-15 收稿日期：2022-04-19
DOI：10.3969/j.issn.1003-3246.2022.05.002
基金项目：内蒙古自治区地震局局长基金（项目编号：2022JC09）
作者简介：范东海(1989-),男,助理工程师,主要从事地震监测和仪器运维工作。E-mail:631780094@qq.com
参考文献：
李全林,陈锦标,于渌,等. b值时空扫描——监视破坏性地震孕育过程的一种手段[J]. 地球物理学报,1978,21(2):101-125.
李正芳,周本刚. 利用断裂带上的低b值识别凹凸体方法的探讨——以龙门山断裂带和鲜水河断裂带为例[J]. 震灾防御技术,2014,9(2):213-225.
马鸿庆. 华北地区几次大震前的b值异常变化[J]. 地球物理学报,1978,21(2):126-141.
梅世蓉,冯德益,张国民,等. 中国地震预报概论[M]. 北京:地震出版社,1993:65-69.
王辉,曹建玲,荆燕,等. 川滇地区强震活动前b值的时空分布特征[J]. 地震地质,2012,34(3):531-543.
吴果,周庆,冉洪流. 震级-频度关系中b值的极大似然法估计及其影响因素分析[J]. 地震地质,2019,41(1):21-43.
谢卓娟,李山有,吕悦军. 滇西南地区主要活动断裂的b值空间分布特征[J].地球科学(中国地质大学学报),2015,40(10):1 755-1 766.
易桂喜,闻学泽,苏有锦. 川滇活动地块东边界强震危险性研究[J]. 地球物理学报,2008,51(6):1 719-1 725.
易桂喜,闻学泽,辛华,等. 龙门山断裂带南段应力状态与强震危险性研究[J]. 地球物理学报,2013,56(4):1 112-1 120.
张帆,韩晓明,陈立峰,等. 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[J]. 地震学报,2018,40(6):785-796.
Aki K. Maximum likelihood estimate of b in the formula logN=a-bM and its confidence limits[J]. Bulletin of the Earthquake Research Institute, University of Tokyo,1965, 43(2):237-239.
Sandri L, Marzocchi W. A technical note on the bias in the estimation of the b-value and its uncertainty through the Least Squares technique[J]. Annals of Geophysics, 2007, 50(3):329-339.
Scholz C H. The Frequency-magnitude relation of microfracturing in rock and its relation to Earthquakes[J]. Bull Seismol Soc Am, 1968, 58(1):399-415.
Mori J, Abercrombie R E. Depth Dependence of Earthquanke Frequency-magnitude Distributions in California:Implications for rupture Initiaition[J]. J Geophys Res:Solid Earth, 1997, 102 (B7):15 801-15 090.
Utsu T. A statistical significance test of the difference in b-value between two earthquake groups[J]. Journal of Physics of the Earth,1966, 14(2):37-40.
