摘要
在地震孕育发生过程中,不同频率地电场观测出现异常现象已有相关报道,但地电场不同频率成分与地震震级(能量)的相关性统计特征仍不清晰。文章基于小波变换对都兰台地电场观测资料进行分析处理,使用滑动相关性方法对地电场不同频率成分与台站周围400 km范围内地震事件进行分析研究,并以青海玛多M S7.4地震前后大地电场优势方位角计算结果进行回溯性检验。结果表明:(1)都兰地电场不同频率成分不仅在地震孕育发生过程中会出现异常现象,而且出现异常的频率与地震事件震级(能量)存在一定关联性:高频成分(3.4 h和8 h)与<5.0及≥5.0两个地震序列的地震事件均有关联性,其中与<5.0在震前约25(±5)天、10天和5天相关性异常显著,与≥5.0在震前约55天、35天、15天和5天相关性异常显著,而低频成分(24 h)则仅与≥5.0地震序列中的地震事件在约55、35、20及5天左右出现较强的相关性;(2)玛多M S7.4地震前,都兰地电场低频成分(24 h)的大地电场优势方位角在地震前约55(±5)、20(±5)天左右出现明显异常现象,其出现的时间与相关性统计特征具有较高的一致性,原因可能是孕震断层与日、月潮汐作用相互耦合。地电场低频成分与中强震之间的相关性特征对破坏性地震的分析研究具有一定借鉴作用,但要厘清地电场地震异常的统计特征,则需要积累更多观测资料和典型震例。
Earthquake preparation and occurrence is accompanied by geoelectric field anomalies at different frequencies.However,the statistical characteristics of the correlation of the different frequency components of the geoelectric field with earthquake magnitude(energy)remain unclear.In this study,the geoelectric field data of Dulan station was decomposed into different frequency components using the wavelet transform,and the shifting correlation method was used to analyze the correlation of the different frequency components of the geoelectric field with seismic events within 400 km of the station.We calculated the dominant azimuth of the telluric field before and after the Maduo M S7.4 earthquake in Qinghai Province to retrospectively verify the results.The following conclusions were drawn:(1)the different frequency components of the Dulan geoelectric field show anomalies during the earthquake preparation and occurrence and a certain correlation with the magnitude(energy)of seismic events.High-frequency components(3.4 and 8 h)are correlated with seismic events in the sequence of<5.0 and≥5.0 earthquakes.For<5.0 earthquakes,the correlation is evident about 25(±5),10,and 5 days before the earthquake.For≥5.0 earthquakes,the correlation is evident about 55,35,15,and 5 days before the earthquake.By contrast,the low-frequency component(24 h)demonstrates a significant correlation only with seismic events in≥5.0 earthquakes 55,35,20,and 5 days before the earthquake.(2)Anomalies are observed in the dominant azimuth of the telluric field of the low-frequency component(24 h)about 55(±5)and 20(±5)days before the Maduo M S7.4 earthquake.A high consistency is detected between the occurrence time and the statistical characteristics of correlation,possibly due to the interaction between seismogenic faults and solar and lunar tides.Data on the correlation of the low-frequency components of the geoelectric field with mid-strong earthquakes have some value for the analysis and investigation of destructive earthquakes.Additional observation data and typical earthquake cases are warranted to explain the statistical characteristics of seismic anomalies in the geoelectric field.
作者
付阿龙
安张辉
范莹莹
侯泽宇
吴优
FU Along;AN Zhanghui;FAN Yingying;HOU Zeyu;WU You(Lanzhou Institute of Seismology,CEA,Lanzhou 730000,Gansu,China;Gansu Lanzhou Geophysics National Observation and Research Station,Lanzhou 730000,Gansu,China;Sichuan Earthquake Agency,Chengdu 610000,Sichuan,China)
出处
《地震工程学报》
CSCD
北大核心
2023年第3期574-584,共11页
China Earthquake Engineering Journal
基金
甘肃省科技计划(20JR10RA498,21JR7RA791)
中国地震局地震预测研究所基本科研业务费专项(2021IESLZ07)。
关键词
地电场
相关性统计
小波变换
滑动相关性
大地电场优势方位角
geoelectric field
correlation statistics
wavelet transform
shifting correlation
dominant azimuth of telluric field
