青藏高原中强地震前的地电场变异及构成解析
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摘要
青藏高原及邻区的地电场常态波形存在场地的选择性现象,场地的岩石结构、裂隙及裂隙水、构造活动等因素影响地电场的常态波形,较大湖泊有助于附近出现TGF-A波形,在第四纪沉积层较厚、岩石含水度高和透水性强的地区多出现TGF-B波形,而构造活动剧烈的基岩山区易出现无日变形态的地电场.该地区中强地震前,地电场的短临异常存在时间上或同步或有十余天差的丛集现象,而在空间上可分布于该区多个断层附近,表现出离散现象,这种时间上丛集、空间上离散的现象是该区域地电场短临前兆特征.引入Σ-Δ求和方法从地电场观测数据中解析出自然电场通常的稳定性,说明了中强地震之前部分地电场的背景值跃变是一种自然电场变化现象;建立潮汐谐波振幅比TA值的概念及计算方法,从定量角度说明了青藏高原地区TGF-A、TGF-B和无日变波形的潮汐影响在逐次降低;使用一阶差分ΔE方法,解析出地电场分钟数量级的高频电磁成分,通常这种高频突跳表现出一定程度的随机性、有限性.三种不同的分析方法,从地电场的构成中解析出自然电场、大地电场和高频电磁成分的特征,为地电场的物理解析提供了理论和方法上的基础.
Site-selective phenomenon exists in the normal waveforms of the geoelectrical fields of Qinghai-Tibet Plateau and its adjacent areas: rock structure of the sites,cracks and fissure water,tectonic activity and other factors affect the normal waveforms of the geoelectrical field,a large lake will contribute to the occurrence of TGF-A waveforms nearby,TGF-B waveforms will mostly occur in the areas where there are thick Quaternary sediments,high water content,and good water permeability of rocks,while the geoelectrical fields with no diurnal variation are prone to appear in the bedrock mountains where there are intense tectonic activities.Before moderate or strong earthquakes in the region,short-term and impending anomaly of the geoelectrical field has a cluster phenomenon,in which there is a temporal synchronization or a few days′ difference,while spatially it can be distributed near several faults in the region,manifested as a discrete phenomenon.This phenomenon of temporal clustering and spatial scattering is the short-term and impending precursor characteristics of the geoelectrical field in the region.The Σ-Δ summation method is introduced to analyze the usual stability of spontaneous field through the observational data of the geoelectrical field,which indicate that before a moderate or strong earthquake,background value jumps of part of geoelectrical fields are a transformation phenomenon of spontaneous field;the concept and calculation method,in which the TA value is the sum of the first 10 order tidal harmonic amplitude divided by the sum of the first 100 order harmonic amplitude,are established to show from a quantitative point of view that the tidal effect of waveforms of TGF-A,TGF-B and non-diurnal variation are successively reduced;the first order difference method of ΔE is adopted to analyze the higher frequency electromagnetic components in the minute order geoelectrical field monitoring data,usually the high-frequency jumps show a certain degree of randomness and limitedness.By using three different methods of analysis,the features of spontaneous field,the telluric field and high-frequency electromagnetic components are analyzed from the composition of the geoelectrical field,which provides a theoretical and methodological basis for the physical analysis of the geoelectrical field.
Site-selective phenomenon exists in the normal waveforms of the geoelectrical fields of Qinghai-Tibet Plateau and its adjacent areas: rock structure of the sites,cracks and fissure water,tectonic activity and other factors affect the normal waveforms of the geoelectrical field,a large lake will contribute to the occurrence of TGF-A waveforms nearby,TGF-B waveforms will mostly occur in the areas where there are thick Quaternary sediments,high water content,and good water permeability of rocks,while the geoelectrical fields with no diurnal variation are prone to appear in the bedrock mountains where there are intense tectonic activities.Before moderate or strong earthquakes in the region,short-term and impending anomaly of the geoelectrical field has a cluster phenomenon,in which there is a temporal synchronization or a few days′ difference,while spatially it can be distributed near several faults in the region,manifested as a discrete phenomenon.This phenomenon of temporal clustering and spatial scattering is the short-term and impending precursor characteristics of the geoelectrical field in the region.The Σ-Δ summation method is introduced to analyze the usual stability of spontaneous field through the observational data of the geoelectrical field,which indicate that before a moderate or strong earthquake,background value jumps of part of geoelectrical fields are a transformation phenomenon of spontaneous field;the concept and calculation method,in which the TA value is the sum of the first 10 order tidal harmonic amplitude divided by the sum of the first 100 order harmonic amplitude,are established to show from a quantitative point of view that the tidal effect of waveforms of TGF-A,TGF-B and non-diurnal variation are successively reduced;the first order difference method of ΔE is adopted to analyze the higher frequency electromagnetic components in the minute order geoelectrical field monitoring data,usually the high-frequency jumps show a certain degree of randomness and limitedness.By using three different methods of analysis,the features of spontaneous field,the telluric field and high-frequency electromagnetic components are analyzed from the composition of the geoelectrical field,which provides a theoretical and methodological basis for the physical analysis of the geoelectrical field.
引文
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[9]钱家栋,陈有发,金安忠.地电阻率法在地震预报中的应用.北京:地震出版社,1985:5-8.Qian J D,Chen Y F,Jin A Z.The Application of the EarthResistivity Method to Earthquake Prediction(in Chinese).Beijing:Seismological Press,1985:5-8.
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[11]Tan D C,Wang L W,Zhao J L,et al.Influence factors ofharmonic waves and directional waveforms of tidalgeoelectrical field.Chinese Journal of Geophysics,2011,54(7):1842-1853.
[12]黄清华,林玉峰.地震电信号选择性数值模拟及可能影响因素.地球物理学报,2010,53(3):535-543.Huang Q H,Lin Y F.Numerical simulation of selectivity ofseismic electric signal and its possible influences.Chinese J.Geophys.(in Chinese),2010,53(3):535-543.
[13]Huang Q H,Lin Y F.Selectivity of seismic electric signal(SES)of the 2000 Izu earthquake swarm:a 3D FEMnumerical simulation model.Proc.Jpn.Acad.Ser.B,2010,86(3):257-264.
[14]马钦忠,冯志生,宋治平等.崇明与南京台震前地电场变化异常分析.地震学报,2004,26(3):304-312.Ma Q Z,Feng Z S,Song Z P,et al.study on the variationcharacteristics of the geoelectric field preceding earthquakes.Acta Seismologica Sinica(in Chinese),2004,26(3):304-312.
[15]马钦忠,钱家栋.地下电性非均匀结构对地电场信号的影响.地震,2003,23(1):1-7.Ma Q Z,Qian J D.The influence of inhomogeneousgeoelectric structure on the signals of geoelectric field.Earthquake(in Chinese),2003,23(1):1-7.
[16]赵国泽,陈小斌,肖骑彬等.汶川Ms8.0级地震成因三“层次”分析—基于深部电性结构.地球物理学报,2009,52(2):553-563Zhao G Z,Chen X B,Xiao Q B,et al.Generation mechanismof Wenchuan strong earthquake of Ms8.0inferred from EMmeasurements in three levers.Chinese J.Geophys.(in Chinese),2009,52(2):553-563.
[17]张永谦,王谦身,腾吉文.川西藏东地区的地壳均衡异常及其与地震分布的关系.地球物理学报,2010,53(11):2631-2638.Zhang Y Q,Wang Q S,Teng J W.The crustal isostaticanomaly beneath eastern Tibet and Western Sichuan and itsrelationship with the distribution of earthquakes.Chinese J.Geophys.(in Chinese),2010,53(11):2631-2638.
[18]秦四清,薛雷,徐锡伟等.川滇地区未来强震预测与汶川Mw7.9级地震孕震过程分析.地球物理学报,2010,53(11):2639-2650.Qin S Q,Xue L,Xu X W,et al.A prediction of strongearthquakes in the Sichuan and Yunnan regions and analysisof the seismogenic process of the Wenchuan Mw7.9earthquake.Chinese J.Geophys.(in Chinese),2010,53(11):2639-2650.
[19]张培震,王琪,马宗晋.中国大陆现今构造运动的GPS速度场与活动地块.地学前缘,2002,9(2):430-441.Zhang P Z,Wang Q,Ma Z J.GPS velocity field and activecrustal blocks of contemporary tectonic deformation incontinental China.Earth Science Frontiers(in Chinese),2002,9(2):430-441.
[20]黄清华.地震电磁观测研究简述.国际地震动态,2005,323(11):2-5.Huang Q H.The state-of-the-art in seismic electromagneticobservation.Recent Developments in World Seismolog(inChinese),2005,323(11):2-5.
[21]高曙德,汤吉,杜学彬等.汶川8.0级地震前后电磁场的变化特征.地球物理学报,2010,53(3):512-525.Gao S D,Tang J,Du X B,et al.The change characteristicsof electromagnetic field before to after Wenchuan Ms8.0earthquake.Chinese J.Geophys.(in Chinese),2010,53(3):512-525.
[22]毛桐恩,席继楼,王燕琼等.地震过程中的大地电场变化特征.地球物理学报,1999,42(4):520-528Mao T E,Xi J L,Wang Y Q,et al.The variationcharacteristics of the telluric field in the process of earthquake.Chinese J.Geophys.(in Chinese),1999,42(4):520-528.
[23]谭大诚.地电观测中工频干扰的分析.见:石特临,陈有发,李清河编.地震地电学发展与展望.兰州:兰州大学出版社,1998:176-183.Tan D C.A analyse of the 50 Hz interference duringmeasuring the apparent resistivity.In:Shi T L,Chen Y F,Li Q H.The Deveiopment and Prospect of the SeismicGeoelectric(in Chinese).Lanzhou:Lanzhou Univerity Press,1998:176-183.
[24]Huang Q H.One possible generation mechanism of co-seismic electric signals.Proc.Jpn.Acad.Ser.B,2002,78(7):173-178.
[25]朱守彪,张培震.2008年汶川Ms8.0地震发生过程的动力学机制研究.地球物理学报,2009,52(2):418-427.Zhu S B,Zhang P Z.A study on the dynamical mechanismsof the Wenchuan Ms8.0 earthquake,2008.Chinese J.Geophys.(in Chinese),2009,52(2):418-427.
[2]黄清华,刘涛.新岛台地电场的潮汐响应与地震.地球物理学报,2006,49(6):1745-1754.Huang Q H,Liu T.Earthquakes and tide response ofgeoelectric potential field at the Niijima station.Chinese J.Geophys.(in Chinese),2006,49(6):1745-1754.
[3]张学民,翟彦忠,郭学增等.远震前的地电场潮汐波异常.地震学报,2007,29(1):48-58.Zhang X M,Zhai Y Z,Guo X Z,et al.Tidal wave anomaliesof geoelectrical field before remote earthquakes.ActaSeismologica Sinica(in Chinese),2007,29(1):48-58.
[4]徐文耀.Sq发电机电流的逐日变化和Sq指数.地球物理学报,1992,35(6):676-683.Xu W Y.Day-to-day variability of the Sq dynamo currentsand Sq index.Chinese J.Geophys.(in Chinese),1992,35(6):676-683.
[5]赵旭东,杜爱民,徐文耀等.Sq电流系午前午后不对称性现象的来源.地球物理学报,2008,51(3):643-649.Zhao X D,Du A M,Xu W Y,et al.The origin of theprenoon-postnoon asymmetry for Sq current system.ChineseJ.Geophys.(in Chinese),2008,51(3):643-649.
[6]钱复业,赵玉林.地电场短临预报方法研究.地震,2005,25(2):33-40.Qian F Y,Zhao Y L.Study on geoelectric field method forshort-term and impending earthquake prediction.Earthquake(in Chinese),2005,25(2):33-40.
[7]谭大诚,赵家骝,席继楼等.潮汐地电场特征及机理研究.地球物理学报,2010,53(3):544-555.Tan D C,Zhao J L,Xi J L,et al.A study on feature andmechanism of the tidal geoelectrical field.Chinese J.Geophys.(in Chinese),2010,53(3):544-555.
[8]孙正江,王华俊.地电概论.北京:地震出版社,1984:23-28.Sun Z J,Wang H J.Geoelctrical Introduction(in Chinese).Beijing:Seismological Press,1984:23-28.
[9]钱家栋,陈有发,金安忠.地电阻率法在地震预报中的应用.北京:地震出版社,1985:5-8.Qian J D,Chen Y F,Jin A Z.The Application of the EarthResistivity Method to Earthquake Prediction(in Chinese).Beijing:Seismological Press,1985:5-8.
[10]谭大诚,王兰炜,赵家骝等.潮汐地电场谐波和各向波形的影响要素.地球物理学报,2011,54(7):1842-1853.Tan D C,Wang L W,Zhao J L,et al.Influence factors ofharmonic waves and directional waveforms of tidalgeoelectrical field.Chinese J.Geophys.(in Chinese),2011,54(7):1842-1853.
[11]Tan D C,Wang L W,Zhao J L,et al.Influence factors ofharmonic waves and directional waveforms of tidalgeoelectrical field.Chinese Journal of Geophysics,2011,54(7):1842-1853.
[12]黄清华,林玉峰.地震电信号选择性数值模拟及可能影响因素.地球物理学报,2010,53(3):535-543.Huang Q H,Lin Y F.Numerical simulation of selectivity ofseismic electric signal and its possible influences.Chinese J.Geophys.(in Chinese),2010,53(3):535-543.
[13]Huang Q H,Lin Y F.Selectivity of seismic electric signal(SES)of the 2000 Izu earthquake swarm:a 3D FEMnumerical simulation model.Proc.Jpn.Acad.Ser.B,2010,86(3):257-264.
[14]马钦忠,冯志生,宋治平等.崇明与南京台震前地电场变化异常分析.地震学报,2004,26(3):304-312.Ma Q Z,Feng Z S,Song Z P,et al.study on the variationcharacteristics of the geoelectric field preceding earthquakes.Acta Seismologica Sinica(in Chinese),2004,26(3):304-312.
[15]马钦忠,钱家栋.地下电性非均匀结构对地电场信号的影响.地震,2003,23(1):1-7.Ma Q Z,Qian J D.The influence of inhomogeneousgeoelectric structure on the signals of geoelectric field.Earthquake(in Chinese),2003,23(1):1-7.
[16]赵国泽,陈小斌,肖骑彬等.汶川Ms8.0级地震成因三“层次”分析—基于深部电性结构.地球物理学报,2009,52(2):553-563Zhao G Z,Chen X B,Xiao Q B,et al.Generation mechanismof Wenchuan strong earthquake of Ms8.0inferred from EMmeasurements in three levers.Chinese J.Geophys.(in Chinese),2009,52(2):553-563.
[17]张永谦,王谦身,腾吉文.川西藏东地区的地壳均衡异常及其与地震分布的关系.地球物理学报,2010,53(11):2631-2638.Zhang Y Q,Wang Q S,Teng J W.The crustal isostaticanomaly beneath eastern Tibet and Western Sichuan and itsrelationship with the distribution of earthquakes.Chinese J.Geophys.(in Chinese),2010,53(11):2631-2638.
[18]秦四清,薛雷,徐锡伟等.川滇地区未来强震预测与汶川Mw7.9级地震孕震过程分析.地球物理学报,2010,53(11):2639-2650.Qin S Q,Xue L,Xu X W,et al.A prediction of strongearthquakes in the Sichuan and Yunnan regions and analysisof the seismogenic process of the Wenchuan Mw7.9earthquake.Chinese J.Geophys.(in Chinese),2010,53(11):2639-2650.
[19]张培震,王琪,马宗晋.中国大陆现今构造运动的GPS速度场与活动地块.地学前缘,2002,9(2):430-441.Zhang P Z,Wang Q,Ma Z J.GPS velocity field and activecrustal blocks of contemporary tectonic deformation incontinental China.Earth Science Frontiers(in Chinese),2002,9(2):430-441.
[20]黄清华.地震电磁观测研究简述.国际地震动态,2005,323(11):2-5.Huang Q H.The state-of-the-art in seismic electromagneticobservation.Recent Developments in World Seismolog(inChinese),2005,323(11):2-5.
[21]高曙德,汤吉,杜学彬等.汶川8.0级地震前后电磁场的变化特征.地球物理学报,2010,53(3):512-525.Gao S D,Tang J,Du X B,et al.The change characteristicsof electromagnetic field before to after Wenchuan Ms8.0earthquake.Chinese J.Geophys.(in Chinese),2010,53(3):512-525.
[22]毛桐恩,席继楼,王燕琼等.地震过程中的大地电场变化特征.地球物理学报,1999,42(4):520-528Mao T E,Xi J L,Wang Y Q,et al.The variationcharacteristics of the telluric field in the process of earthquake.Chinese J.Geophys.(in Chinese),1999,42(4):520-528.
[23]谭大诚.地电观测中工频干扰的分析.见:石特临,陈有发,李清河编.地震地电学发展与展望.兰州:兰州大学出版社,1998:176-183.Tan D C.A analyse of the 50 Hz interference duringmeasuring the apparent resistivity.In:Shi T L,Chen Y F,Li Q H.The Deveiopment and Prospect of the SeismicGeoelectric(in Chinese).Lanzhou:Lanzhou Univerity Press,1998:176-183.
[24]Huang Q H.One possible generation mechanism of co-seismic electric signals.Proc.Jpn.Acad.Ser.B,2002,78(7):173-178.
[25]朱守彪,张培震.2008年汶川Ms8.0地震发生过程的动力学机制研究.地球物理学报,2009,52(2):418-427.Zhu S B,Zhang P Z.A study on the dynamical mechanismsof the Wenchuan Ms8.0 earthquake,2008.Chinese J.Geophys.(in Chinese),2009,52(2):418-427.
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