辽宁海城及其邻区地震b值空间分布特征  

Spatial Distribution of b-Value in Haicheng Region,Liaoning Province

作　　者：郑确[1] 刘财[1] 田有[1] Zheng Que;Liu Cai;Tian You(College of GeoExploration Science and Technology, Jilin University, Changchun 130026, China)

机构地区：[1]吉林大学地球探测科学与技术学院,长春130026

出　　处：《吉林大学学报（地球科学版）》2018年第3期922-933,共12页Journal of Jilin University：Earth Science Edition

基　　金：国家自然科学基金项目(41430322;41474030);国家重点基础研究发展计划("973"计划)项目(2016YFC0600301)~~

摘　　要：震级-频度分布(FMD)是地震学研究中最重要的经验公式之一,相关系数b是构造学和地震危险性评估的重要因子,具有表征前震和余震的特性。辽宁省地震多发生在金州断裂附近,自1975年海城7.3级地震发生后,与金州断裂交汇的海城河—大洋河断裂开启活跃模式,其东南端岫岩附近在1999年又发生5.6级地震。近年来盖州附近地震活动也在增强。因此,本文利用b值空间分布特征对海城及其邻区的应力分布特点进行研究。震源定位准确与否直接影响b值计算,双差定位后的数据与常规目录相比具有更高的精度,但是完整性有一定下降。本文收集了中国地震台网1981—2005年的辽宁省地震目录,并进行双差定位,比较分析了常规目录数据和双差数据的b值分布差异,认为在地震密集区,双差定位后的数据可以被用来获得更准确的b值。对主要研究区进行网格划分,使用双差数据,得到b值的水平和垂直分布特征。结果表明:b值为0.6~1.8,随深度增加而降低;岫岩和盖州震区具有较低的b值,意味着具有较高的地震危险性;浑河震区与海城河—大洋河断裂东南方向具有较高的b值,说明该区域未来发生大地震的概率很低;与金州断裂交汇区域的b值在1.0附近,说明该地区应力暂时处于稳定状态,未来具有较低的地震危险性。The frequency-magnitude distribution（FMD）is one of the most important empirical equations.The parameter b,presenting the characteristics of foreshocks and aftershocks,is often used in the tectonics and seismic hazard assessment.Earthquakes frequently occurred in Jinzhou fault zone before.Since the Haicheng M_s 7.3 earthquake occurred in 1975,the Haichenghe-Dayanghe faultinterlaced with the Jinzhou fault has been active.An earthquake with M_s5.6 occurred in Xiuyan in the year of 1999,and Gaizhou has high seismic activities recently as well.In this study,the spatial distribution of b-values were used to detect current stress state of Haicheng region.Relocated earthquake data by double-difference（DD）algorithm can significantly improve the location precision,although suffer from the degeneration of data completeness.We collected arrival-time data recorded by the seismic network,and used the DD method from 1981 to 2005.The spatial distribution of b-values from routine catalogue and data after using DD method were compared and analyzed,which revealed that DD data can be used for b-value calculation and has higher accuracy when the earthquakes clustered.We got the vertical and horizontal variation of b-values using gridding techniques with DD data in Haicheng and Xiuyan area.Our results revealed that the b-values were varied spatial significantly,ranging from 0.6 to 1.8,and decreased with depth.The Xiuyan and Gaizhou area with lowb-values may indicate the area most likely seismogenic for future large earthquakes.The Hunhe area and the southeast part of Haichenghe-dayanghe fault have high b-values,indicating a low opportunity for seismic hazard.Near the intersection of Jinzhou and Haichenghe-Dayanghe faults,the b-value is closed to 1.0,such a stable stress suggests a low probability of future large earthquakes.

关 键 词：辽宁海城 B值 双差定位方法 地震危险性 

分 类 号：P631.4[天文地球—地质矿产勘探]