汶川8.0级特大地震前的地磁垂直分量日变“双低点”异常
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摘要
2008年5月9日,我国有13个地磁台(纳入国家地磁台网中心的台站)地磁垂直分量日变形态出现"双低点"异常.这些台站在空间上大致呈交汇的3个条带分布,其交汇处位于四川西部.异常出现3天后的5月12日,正好在四川西部的汶川发生了8.0级特大地震.地磁垂直分量日变"双低点"是客观存在的一种区域地磁异常现象.其成因可能是产生地磁静日变化Sq的外空涡旋电流体系发生变化,或可能是产生地磁静日变化的内源感应涡旋电流体系与外源涡旋电流体系产生数小时的滞后所引起.地磁垂直分量日变"双低点"异常与地震的关系,可能是前者反映了地球深部地震孕育状态的加速变化.
The "double low-points" anomaly of daily variation of the vertical geomagnetic component was observed in 13 geomagnetic observatories belonging to Geomagnetic Observatory Network Centre,China Earthquake Administration, on May 9th in 2008. These observatories distribute roughly in 3 intersected spatial belts, with the intersection located in western Sichuan. On May 12th, three days after the anomaly appearance, the great M8.0 Wenchuan earthquake occurred. The "double low-points" anomaly of daily variation of the vertical geomagnetic component is an anomalous phenomenon of regional geomagnetism, which does exist. The possible cause is the change of the extrinsic eddy current system resulting in geomagnetic daily quiet variation (Sq), or the delay between internal and extrinsic eddy current system. The relationship between "double low-points" anomaly of daily geomagnetic variation and earthquake may be that the former reflects the accelerative alteration of earthquake gestation in deep earth.
The "double low-points" anomaly of daily variation of the vertical geomagnetic component was observed in 13 geomagnetic observatories belonging to Geomagnetic Observatory Network Centre,China Earthquake Administration, on May 9th in 2008. These observatories distribute roughly in 3 intersected spatial belts, with the intersection located in western Sichuan. On May 12th, three days after the anomaly appearance, the great M8.0 Wenchuan earthquake occurred. The "double low-points" anomaly of daily variation of the vertical geomagnetic component is an anomalous phenomenon of regional geomagnetism, which does exist. The possible cause is the change of the extrinsic eddy current system resulting in geomagnetic daily quiet variation (Sq), or the delay between internal and extrinsic eddy current system. The relationship between "double low-points" anomaly of daily geomagnetic variation and earthquake may be that the former reflects the accelerative alteration of earthquake gestation in deep earth.
引文
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陈绍明,谢美娟.1989.地磁垂直分量日变低点位移预报方法研究[C]∥地震预报方法实用化研究文集:地磁地电学专辑.北京:学术书刊出版社:127--134.
陈化然,杜爱民,王亚丽,杨冬梅,张素琴,李琪,赵旭东,刘晓灿,朱荣,何宇飞,马君钊,王建国.2009.地磁低点位移与地磁场等效电流体系关系的初步研究[J].地震学报,31(1):59--67.
丁鉴海,黄雪香,周胜奎,李承生,张淑兰,印路.1989.地磁垂直分量日变“低点位移”预报地震方法实用化研究[C]∥地震预报方法实用化研究文集:地磁地电学专辑.北京:学术书刊出版社:96--126.
胡久常.1994.琼中地磁台以磁报震方法探索[J].华南地震,14(3):61--65.
李明光,梁秀兰.1989.利用地磁Z分量日变低点预报地震新探索[C]∥地震预报方法实用化研究文集:地磁地电学专辑.北京:学术书刊出版社:135--146.
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