摘要
地电场是重要的地球物理场,本文利用传统的时间序列统计分析方法和快速傅里叶变换信号处理方法,从时间域和频率域两个方面,对距离玛多M_(S)7.4地震震中约170 km的青海省大武地震台的秒采样地电场动态变化基本特征,进行了分析和讨论.研究结果显示,大武地震台在玛多M_(S)7.4地震前后:(1)记录到了比较典型的地电场震前异常变化和同震变化,该变化过程在不同的观测装置下,具有较强的同步性和相关性;(2)地电场异常变化主要表现为不定期交叠出现的单向阶跃变化和双向扰动变化,其中双向扰动变化延续更长时间段,并在不同阶段表现出突发性或持续性变化特征;(3)地电场同震变化的主要变化过程与Sg波基本同步,并且与地磁场的动态变化过程具有较强的时序相关性;(4)地电场秒采样观测数据的动态变化过程,在"时间域"和"频率域"具有较强一致性.综合分析认为,在排除电磁暴、雷电等空间电磁信号变化的情况下,在玛多M_(S)7.4地震前后,大武地震台的秒采样地电场动态变化过程,主要与较强地应力和地应变作用下,地下流体在断层、孔隙及裂隙中的运移过程以及渗流作用的突发性、振荡性或震颤性变化有关.
Geoelectric field is an important geophysical field.Using the traditional time series statistical analysis method and the FFT(Fast Fourier Transform)signal processing method,this paper analyzes and discusses the basic characteristics of the dynamic changes of geoelectric field from time domain and frequency domain,which recorded at Dawu seismic station,Qinghai Province,about 170 km away from the epicenter of Madoi M_(S)7.4 earthquake.The results show that before and after the Madoi M_(S)7.4 earthquake:(1)both typical pre-earthquake abnormal changes and co-seismic changes of geoelectric field are recorded,and the change process has strong synchronization and correlation under different observation devices;(2)the abnormal changes of geoelectric field are mainly manifested as one-way step change and two-way disturbance change that occur irregularly,and the two-way disturbance change lasts for a longer period of time,shows the characteristics of sudden or continuous change in different stages;(3)the main change process of the co-seismic change of the geoelectric field is basically synchronous with the Sg wave,and it has a strong time series correlation with the dynamic change process of the geomagnetic field;(4)the dynamic change process of second sampling geoelectric field observation data has a strong consistency in time domain and frequency domain.The comprehensive analysis shows that under the condition of excluding the changes of spatial electromagnetic signals such as electromagnetic storm and lightning,the dynamic change process of geoelectric field,which recorded at Dawu seismic station before and after Madoi M_(S)7.4 earthquake,is mainly related to the migration process of underground fluid in faults,pores and fractures,and the sudden change or vibration change of seepage flow,under the action of strong in-situ stress and strain.
作者
席继楼
赵家骝
高尚华
王晓蕾
李国佑
张兴
王涛
XI JiLou;ZHAO JiaLou;GAO ShangHua;WANG XiaoLei;LI GuoYou;ZHANG Xing;WANG Tao(Institute of Earthquake Forecasting,China Earthquake Administration,Beijing 100036,China;Key Laboratory of Earthquake Prediction,China Earthquake Administration,Beijing 100036,China;Qinghai Earthquake Agency,Xining 810001,China)
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2022年第2期580-593,共14页
Chinese Journal of Geophysics
基金
国家重点研发计划项目(2018YFC1503700)
中国地震局地震预测研究所基本科研业务费专项(2021IEF1207)资助。
关键词
玛多M_(S)7.4地震
大武地震台
地电场观测
秒采样
动态变化
Madoi M_(S)7.4 earthquake
Dawu seismic station
Geoelectric field observation
Second sampling
Dynamic change
