基于总强度年变对张家口-渤海地震带震磁特征的分析  

Analysis of Seismomagnetic Characteristics of Zhangjiakou-Bohai Seismic Belt Based on Annual Variation of Total Intensity

作　　者：王朝景 李博[1] 苏树朋[1] WANG Zhaojing;LI Bo;SU Shupeng(Mobile Survey Team of Hebei Earthquake Agency,206 Mid-Tianwei Road,Baoding 071000,China)

机构地区：[1]河北省地震局流动测量队,河北保定071000

出　　处：《大地测量与地球动力学》2024年第10期1064-1070,共7页Journal of Geodesy and Geodynamics

基　　金：中国地震局“三结合”课题(3JH-202401066);河北省地震科技星火计划(DZ2024112200008,DZ2021121400007)。

摘　　要：利用2015-05~2021-05流动地磁矢量数据,结合M_(S)≥3.0地震资料对张家口-渤海地震带及邻区总强度年变演化特征和震磁特征进行研究。结果表明:1)73.3%震例的震中总强度变化量绝对值在0~4.0 nT之间,变化量值小;70.0%震例的震中强度变化梯度值在0~5.0 nT/°之间,梯度值相对较小。2)2015-05~2021-05张家口-渤海地震带总强度年变呈正异常-正异常-正异常-正异常-负异常-正负异常相间分布的演化趋势,其中2018-05~2019-05变化量值相对较小,2019-05~2020-05发生10次M_(S)≥3.0地震;2019-05~2020-05演化趋势发生变化,由2015-05~2019-05的正异常为主转变为负异常为主,2020-07-12发生唐山M_(S)5.1地震;2020-05~2021-05以正负异常相间分布为主,2021-05~2022-05发生8次M_(S)≥3.0地震。张家口-渤海地震带总强度年变演化趋势的转变可能与区域应力场背景下局部应力的变化和集中有关,同时可能与构造带的孕震过程关系密切。岩石圈磁场变化趋势的转变包含了重要的震磁异常信息,应重点关注。Using the mobile geomagnetic vector data from May 2015 to May 2021,combined with earthquakes(M_(S)≥3.0),we study the evolution characteristics and seismomagnetic characteristics of the annual variation of total intensity in Zhangjiakou-Bohai seismic belt and its adjacent areas.The results show that:1) The absolute value of the total intensity change in 73.3% of the earthquake cases ranges from 0 to 4.0 nT,and the epicentral variation is small;70.0% of the total intensity gradient values at the epicenter of earthquakes are 0 to 5.0 nT/°;and the gradient value of the epicenter is relatively small.2) From May 2015 to May 2021,the annual variation of the total intensity of the Zhangjiakou-Bohai Sea seismic belt shows an evolution trend of positive anomaly-positive anomaly-positive anomaly-positive anomaly-negative anomaly-positive and negative anomalies.Among them,the variation value from May 2018 to May 2019 is relatively small,and 10 earthquakes(M_(S)≥3.0) occurred from May 2019 to May 2020.The evolution trend of May 2019 to May 2020 changed from positive anomaly in May 2015 to May 2019 to negative anomaly,and Tangshan M_(S)5.1 earthquake occurred on July 12,2020.In May 2020 to May 2021 Zhangjiakou-Bohai seismic belt is characterized by alternating distribution of positive and negative anomalies,and 8 earthquakes(M_(S)≥3.0) occurred from May 2021 to May 2022.The change of annual variation evolution trend of total intensity in Zhangjiakou-Bohai seismic belt may be related to the change and concentration of local stress under the background of regional stress field and may be closely related to the seismogenic process of this seismic belt.The change of lithospheric magnetic field trend contains important seismomagnetic anomaly information,to which should be paid more attention.

关 键 词：流动地磁 总强度 演化趋势 震磁异常 

分 类 号：P315[天文地球—地震学]