汶川、玉树大地震前的地电场异常
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摘要
"九五"以来,国内布设了地震地电场观测网,目前有100多个台正式投入观测,部分台站至今已积累了近十年的资料.期间发生了2008年5月12日汶川8.0级地震和2010年4月14日玉树7.1级等强烈地震,这对检验大地电场前兆方法的监测效果具有非常重要的意义.本文收集了汶川、玉树地震区附近的39个地电场观测台自投入运行以来的观测资料,并对全部资料的观测质量和映震情况进行了检查和分析,发现观测资料中存在不规则的与地磁场或固体潮汐变化相关的扰动变化,很难从中识别出地震前兆信息.为突出地震前兆信息,作者采用同台地电场观测的同一测向长、短极距测值的比值方法进行了分析处理.结果发现在地震前,多数台站的地电场观测资料存在不同形态的比值异常变化.研究结果表明,汶川、玉树地震前震源区附近的地电场观测资料中有较为丰富的地震前兆信息,只是由于这些信息混杂于正常大地电场变化的背景中,从原始观测数据中或使用常规的分析方法无法识别和提取.而使用本文的数据处理方法能有效地排除资料中来自大地电场的正常变化以及自然电场的远场变化,突出了近场的变化信息,使得地震前源自孕震区一定范围内的地电场异常信号容易识别.由图4可见,2002年的玉门5.9地震和2003年的山丹-民乐6.1地震前震源区的电场观测也出现了比值异常变化,而其他时段的比值曲线近似直线变化,因此表明本文地电场观测资料的分析处理方法是识别和提取观测资料中地震前兆信息的有效方法之一.分析结果还表明地电场前兆的不同形态可能与观测台的台址条件有关.
Geoelectric filed network has been established for inland seismic monitoring since the ninth five-year plan.More than 100 stations have been observing and some of them have accumulated data about ten years.On May 12,2008 an earthquake with MS 8.0 struck Wenchuan,Sichuan Province and on April 14,2010 an earthquake with MS 7.1 struck Yushu,Qinghai Province.The earthquakes verified the monitoring effect of geoelectric field network.In this paper,the data set from39 stations near Wenchuan and Yushu area,have been collected and analyzed for their observation quality and earthquake-reflecting ability.It is found that seismic precursor could not identify due to the anomalous disturbance in observation data set related with geomagnetic field and solid tide.In order to highlight the seismic precursor information,a ratio method is used between the long and short dipole distance observation data in the same direction of the same station.The result indicates most of the stations appear ratio anomaly with different shape before an earthquake. The research also indicates that the geoelectric data,accumulated from stations around Wenchuan and Yushu area near the epicenter,contain plenty of seismic precursor information.Such information is hardly distinguished and extracted from original observation data or using ordinary methods,hided by the normal geoelectric change background.The ratio method used in this paper can effectively eliminate the disturbance from the normal geoelectric change and the far-field change of the natural electric field and simultaneously highlight the near-field geoelectric information,finally make it easy to identify the geoelectric abnormal information before earthquake around epicenter area.As figure 4 shows,geoelectirc data ratios in epicenter area appear anomaly before Yumen earthquake with magnitude of 5.9 in 2009 and Shandan-Minle earthquake with magnitude of 6.1 in 2003.Besides,ratio curve in other period is nearly straight with no anomaly,which also proves that it is effective to distinguish and extract geoelectric precursor information using ratio method.At last,it is indicated that different forms of geoelectric precursor are likely related with the location of the earthquake stations.
Geoelectric filed network has been established for inland seismic monitoring since the ninth five-year plan.More than 100 stations have been observing and some of them have accumulated data about ten years.On May 12,2008 an earthquake with MS 8.0 struck Wenchuan,Sichuan Province and on April 14,2010 an earthquake with MS 7.1 struck Yushu,Qinghai Province.The earthquakes verified the monitoring effect of geoelectric field network.In this paper,the data set from39 stations near Wenchuan and Yushu area,have been collected and analyzed for their observation quality and earthquake-reflecting ability.It is found that seismic precursor could not identify due to the anomalous disturbance in observation data set related with geomagnetic field and solid tide.In order to highlight the seismic precursor information,a ratio method is used between the long and short dipole distance observation data in the same direction of the same station.The result indicates most of the stations appear ratio anomaly with different shape before an earthquake. The research also indicates that the geoelectric data,accumulated from stations around Wenchuan and Yushu area near the epicenter,contain plenty of seismic precursor information.Such information is hardly distinguished and extracted from original observation data or using ordinary methods,hided by the normal geoelectric change background.The ratio method used in this paper can effectively eliminate the disturbance from the normal geoelectric change and the far-field change of the natural electric field and simultaneously highlight the near-field geoelectric information,finally make it easy to identify the geoelectric abnormal information before earthquake around epicenter area.As figure 4 shows,geoelectirc data ratios in epicenter area appear anomaly before Yumen earthquake with magnitude of 5.9 in 2009 and Shandan-Minle earthquake with magnitude of 6.1 in 2003.Besides,ratio curve in other period is nearly straight with no anomaly,which also proves that it is effective to distinguish and extract geoelectric precursor information using ratio method.At last,it is indicated that different forms of geoelectric precursor are likely related with the location of the earthquake stations.
引文
[1]李金铭.地电场与电法勘探.北京:地质出版社,2005:36-59.Li J M.Geoelectric Field and Electrical Prospecting(inChinese).Beijing:Geology Press,2005:36-59.
[2]程志平.电法勘探教程.北京:冶金工业出版社,2007:72-75.Cheng Z P.Electrical Prospecting Tutorial(in Chinese).Beijing:China Metallurgical Industry Press,2007,72-75.
[3]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):519-528.Mao T E,Xi J L,Wang Y Q,Yin S Z.The variationcharacteristics of the telluric field in the process of earthquake.Chinese J.Geophys.(in Chinese),1999,42(4):519-528.
[4]Varotsos P,Sarlis N,Skordas E,et al.Additional evidenceon some relationship between seismic electric signals andearthquake source parameters.Acta Geophysica Polonica,2005,53(3):293-298.
[5]Dologhiu E.A three year continuous sample of officiallydocumented predictiots issued in Greece using the VANmethod:l987-1989.Tectonophysics,1993,224(1-3):l89-202.
[6]Telesca1L,Colangelo1G,Hattori K,et al.Principalcomponent analysis of geoelectrical signals measured in theseismically active area of Basilicata Region(southern Italy).Natural Hazards and Earth System Sciences,2004,4(5-6):663-667.
[7]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.
[8]赵玉林,卢军,张洪魁等.电测量在中国地震预报中的应用.地震地质,2001,23(2):277-284.Zhao Y L,Lu J,Zhang H K,et al.The application ofelectrical measurements to earthquake prediction in China.Seismology and Geology(in Chinese),2001,23(2):277-284.
[9]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.
[10]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 geoelectirc filed method forshort-term and impending earthquake prediction.Earthquake(in Chinese),2005,25(2):33-40.
[11]杜学彬,陈有发,阮爱国等.祁连大地电场变化与地震关系的研究.西北地震学报,1994,16(3):84-87,92.Du X B,Chen Y F,Ruan A G,et al.Relation betweenvariation of electrotelluric field in Qilian region of Qinghai andearthquake.Northwestern Seismological Journal(inChinese),1994,16(3):84-87,92.
[12]沈红会,冯志生,燕明芝等.地电场震前变化的探讨.,西北地震学报,2006,28(1):74-77.Shen H H,Feng Z S,Yan M Z,et al.Approach on variationof geoelectric field before earthquakes.NorthwesternSeismological Journal(in Chinese),2006,28(1):74-77.
[13]解用明,韩和平,高登平等.大地电场日变化特征.山西地震,2006,127(3):1-4.Xie Y M,Han H P,Gao D P,et al.Daily variationcharacteristic of geoelectric field.Earthquake Research inShanxi(in Chinese),2006,127(3):1-4.
[14]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.
[15]叶青,杜学彬,周克昌等.大地电场变化的频谱特征.地震学报,2007,29(4):382-390.Ye Q,Du X B,Zhou K C,et al.Spectrum characteristics ofgeoelectric field variation.Acta Seismologica Sinina(inChinese),2007,29(4):382-390.
[16]杜学彬,叶青,赵杰等.地电场日变化研究.地震,2007,27(增刊):121-130.Du X B,Ye Q,Zhao J,et al.Study on geoelectric field dailyvariation.Earthquake(in Chinese),2007,27(Suppl):121-130.
[17]马钦忠.地电场多极距观测装置系统与文安MS5.1地震前首都圈地电场异常研究.地震学报,2008,30(6):615-625.Ma Q Z.Multi-dipole observation system and study on theabnormal variation of the geoelectric field observed at CapitalNetwork before the 2006Wen’an,Hebei of China,MS5.1earthquake.Acta Seismologica Sinica(in Chinese),2008,30(6):615-625.
[18]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.
[19]马钦忠,赵卫国,张文平等.文县地电场震前异常变化及其在2001年昆仑山口西MS8.1地震预测研究中的应用.地震学报,2009,31(6):660-670.Ma Q Z,Zhao W G,Zhang W P,et al.Abnormal variationsof geoelectric field recorded at Wenxian station precedingearthquakes and their application to the prediction of the 2001MS8.1Kunlun earthquake.Acta Seismologica Sinica(inChinese),2009,31(6):660-670.
[20]马钦忠,唐宇雄,张永仙等.2008年西藏4次MS6.0以上地震前拉萨地电场异常信号特征.地震,2011,31(1):86-97.Ma Q Z,Tang Y X,Zhang Y X,et al.Abnormalcharacteristics of geoelectric field at Lhasa station before 4MS6.0earthquakes of 2008in Tibet.Earthquake(inChinese),2011,31(1):86-97.
[21]范莹莹,杜学彬,Jacques Zlotnicki等.汶川MS8.0大震前的电磁现象.地球物理学报,2010,53(12):2887-2898.Fan Y Y,Du X B,Jacques Zlotnicki,et al.Theelectromagnetic phenomena before the MS8.0 Wenchuanearthquake.Chinese J.Geophys.(in Chinese),2010,53(12):2887-2898.
[22]李艳,高振强,荆红亮等.青海海西6.4级地震前临汾台石英摆及大地电场短临异常分析.山西地震,2010,1:30-32,45.Li Y,Gao Z Q,Jing H L,et al.Analysis on short-impending anomalies of Linfen quartz tiltmeter and geoelecticfield before the Haixi,Qinghai M6.4 earthquake.Earthquake Research in Shanxi(in Chinese),2010,1:30-32,45.
[23]张小涛,马新欣,刘晓灿等.地电场方法在川滇地区地震观测中的应用.地震地磁观测与研究,2010,31(6):93-98.Zhang X T,Ma X X,Liu X C,et al.Application of telluricelectric field on seismic observation in the Sichuan-Yunanregion.Seismological and Geomagnetic Observation andResearch(in Chinese),2010,31(6):93-98.
[24]张小涛,陈化然,马新欣等.玉树MS7.1地震前地电场异常变化特征分析.大地测量与地球动力学,2011,31(B6):38-42.Zhang X T,Chen H R,Ma X X,et al.Preliminary analysisof characteristics of anomalous variation of geoelectric fieldbefore Yushu MS7.1earthquake.Journal of Geodesy andGeodynamics(in Chinese),2011,31(B6):38-42.
[25]田山,王建国,徐学恭等.大地电场观测地震前兆异常提取技术研究.地震学报,2009,31(4):424-431.Tian S,Wang J G,Xu X G,et al.Research on the techniqueof extracting seismic precursory anomaly from telluric electricfield observation.Acat Seismologica Sinica(in Chinese),2009,31(4):424-431.
[26]刘君,杜学彬,Zlotnicki J等.几次大震前的地面和空间电磁场变化.地球物理学报,2011,54(11):2885-2897.Liu J,Du X B,Zlotnicki J,et al.The changes of the groundand ionosphere electric/magnetic fields before several greatearthquakes.Chinese J.Geophys.(in Chinese),2011,54(11):2885-2897.
[2]程志平.电法勘探教程.北京:冶金工业出版社,2007:72-75.Cheng Z P.Electrical Prospecting Tutorial(in Chinese).Beijing:China Metallurgical Industry Press,2007,72-75.
[3]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):519-528.Mao T E,Xi J L,Wang Y Q,Yin S Z.The variationcharacteristics of the telluric field in the process of earthquake.Chinese J.Geophys.(in Chinese),1999,42(4):519-528.
[4]Varotsos P,Sarlis N,Skordas E,et al.Additional evidenceon some relationship between seismic electric signals andearthquake source parameters.Acta Geophysica Polonica,2005,53(3):293-298.
[5]Dologhiu E.A three year continuous sample of officiallydocumented predictiots issued in Greece using the VANmethod:l987-1989.Tectonophysics,1993,224(1-3):l89-202.
[6]Telesca1L,Colangelo1G,Hattori K,et al.Principalcomponent analysis of geoelectrical signals measured in theseismically active area of Basilicata Region(southern Italy).Natural Hazards and Earth System Sciences,2004,4(5-6):663-667.
[7]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.
[8]赵玉林,卢军,张洪魁等.电测量在中国地震预报中的应用.地震地质,2001,23(2):277-284.Zhao Y L,Lu J,Zhang H K,et al.The application ofelectrical measurements to earthquake prediction in China.Seismology and Geology(in Chinese),2001,23(2):277-284.
[9]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.
[10]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 geoelectirc filed method forshort-term and impending earthquake prediction.Earthquake(in Chinese),2005,25(2):33-40.
[11]杜学彬,陈有发,阮爱国等.祁连大地电场变化与地震关系的研究.西北地震学报,1994,16(3):84-87,92.Du X B,Chen Y F,Ruan A G,et al.Relation betweenvariation of electrotelluric field in Qilian region of Qinghai andearthquake.Northwestern Seismological Journal(inChinese),1994,16(3):84-87,92.
[12]沈红会,冯志生,燕明芝等.地电场震前变化的探讨.,西北地震学报,2006,28(1):74-77.Shen H H,Feng Z S,Yan M Z,et al.Approach on variationof geoelectric field before earthquakes.NorthwesternSeismological Journal(in Chinese),2006,28(1):74-77.
[13]解用明,韩和平,高登平等.大地电场日变化特征.山西地震,2006,127(3):1-4.Xie Y M,Han H P,Gao D P,et al.Daily variationcharacteristic of geoelectric field.Earthquake Research inShanxi(in Chinese),2006,127(3):1-4.
[14]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.
[15]叶青,杜学彬,周克昌等.大地电场变化的频谱特征.地震学报,2007,29(4):382-390.Ye Q,Du X B,Zhou K C,et al.Spectrum characteristics ofgeoelectric field variation.Acta Seismologica Sinina(inChinese),2007,29(4):382-390.
[16]杜学彬,叶青,赵杰等.地电场日变化研究.地震,2007,27(增刊):121-130.Du X B,Ye Q,Zhao J,et al.Study on geoelectric field dailyvariation.Earthquake(in Chinese),2007,27(Suppl):121-130.
[17]马钦忠.地电场多极距观测装置系统与文安MS5.1地震前首都圈地电场异常研究.地震学报,2008,30(6):615-625.Ma Q Z.Multi-dipole observation system and study on theabnormal variation of the geoelectric field observed at CapitalNetwork before the 2006Wen’an,Hebei of China,MS5.1earthquake.Acta Seismologica Sinica(in Chinese),2008,30(6):615-625.
[18]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.
[19]马钦忠,赵卫国,张文平等.文县地电场震前异常变化及其在2001年昆仑山口西MS8.1地震预测研究中的应用.地震学报,2009,31(6):660-670.Ma Q Z,Zhao W G,Zhang W P,et al.Abnormal variationsof geoelectric field recorded at Wenxian station precedingearthquakes and their application to the prediction of the 2001MS8.1Kunlun earthquake.Acta Seismologica Sinica(inChinese),2009,31(6):660-670.
[20]马钦忠,唐宇雄,张永仙等.2008年西藏4次MS6.0以上地震前拉萨地电场异常信号特征.地震,2011,31(1):86-97.Ma Q Z,Tang Y X,Zhang Y X,et al.Abnormalcharacteristics of geoelectric field at Lhasa station before 4MS6.0earthquakes of 2008in Tibet.Earthquake(inChinese),2011,31(1):86-97.
[21]范莹莹,杜学彬,Jacques Zlotnicki等.汶川MS8.0大震前的电磁现象.地球物理学报,2010,53(12):2887-2898.Fan Y Y,Du X B,Jacques Zlotnicki,et al.Theelectromagnetic phenomena before the MS8.0 Wenchuanearthquake.Chinese J.Geophys.(in Chinese),2010,53(12):2887-2898.
[22]李艳,高振强,荆红亮等.青海海西6.4级地震前临汾台石英摆及大地电场短临异常分析.山西地震,2010,1:30-32,45.Li Y,Gao Z Q,Jing H L,et al.Analysis on short-impending anomalies of Linfen quartz tiltmeter and geoelecticfield before the Haixi,Qinghai M6.4 earthquake.Earthquake Research in Shanxi(in Chinese),2010,1:30-32,45.
[23]张小涛,马新欣,刘晓灿等.地电场方法在川滇地区地震观测中的应用.地震地磁观测与研究,2010,31(6):93-98.Zhang X T,Ma X X,Liu X C,et al.Application of telluricelectric field on seismic observation in the Sichuan-Yunanregion.Seismological and Geomagnetic Observation andResearch(in Chinese),2010,31(6):93-98.
[24]张小涛,陈化然,马新欣等.玉树MS7.1地震前地电场异常变化特征分析.大地测量与地球动力学,2011,31(B6):38-42.Zhang X T,Chen H R,Ma X X,et al.Preliminary analysisof characteristics of anomalous variation of geoelectric fieldbefore Yushu MS7.1earthquake.Journal of Geodesy andGeodynamics(in Chinese),2011,31(B6):38-42.
[25]田山,王建国,徐学恭等.大地电场观测地震前兆异常提取技术研究.地震学报,2009,31(4):424-431.Tian S,Wang J G,Xu X G,et al.Research on the techniqueof extracting seismic precursory anomaly from telluric electricfield observation.Acat Seismologica Sinica(in Chinese),2009,31(4):424-431.
[26]刘君,杜学彬,Zlotnicki J等.几次大震前的地面和空间电磁场变化.地球物理学报,2011,54(11):2885-2897.Liu J,Du X B,Zlotnicki J,et al.The changes of the groundand ionosphere electric/magnetic fields before several greatearthquakes.Chinese J.Geophys.(in Chinese),2011,54(11):2885-2897.
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