汶川8级地震前电磁扰动与电磁立体监测体系

Electromagnetic perturbations before Wenchuan M8 earthquake and stereo electromagnetic observation system

研究分析了在2008年5月12日四川汶川8.0级地震前出现的地面电磁与电离层中观测到的中、短临电磁异常,其中距离震中最近的郫县台地电阻率显示了2年左右的趋势下降异常,下降幅度7.2%,同时多台电阻率观测在震前1个月左右显示短临突变异常;震前18天地磁垂直分量出现低点位移,分界线两侧的低点时间超过2h;震前3天即5月9日,地磁低点位移、利用GPS反演得到的电离层总电子含量(TEC)、电离层测高仪得到的foF2和电磁卫星监测的离子密度和温度等均观测到局部电磁扰动现象,多数异常幅度超过50%。汶川8.0级地震前各种电磁观测技术记录到的明显异常现象,揭示了电磁学科在地震预报研究领域巨大的潜力,加强天-地一体化的立体电磁监测对地震预报水平的提高是非常必要的。

Abstract Middle-term,imminent anomalies observed in geoetectrical and geomag- netic and ionospheric detecting before Wenchuan M8.0 earthquake in Sichuan Prov- ince, on May 12th 2008, are studied and analyzed. Earth resistivity at Pixian sta- tion nearest to the epicenter showed a decreasing trend of 2 years with the reducing amplitude of 7.2%. At the meantime, earth resistivity at some stations exhibited short-term abrupt anomalies a month prior to the earthquake. Low point displace- ment of geomagnetic vertical component occurred 18 days before the event, in which the tow point time at two sides of dividing boundary exceeded 2 hours. On May 9,3 days before the earthquake, many local electromagnetic perturbations were detected by geomagnetic tow point displacement, total electron concentration（TEC） inversed by GPS observation, foF2 obtained by ionospheric sounding and ion density and temperature detected by electromagnetic satellite,with most amplitude exceeding 50%. These apparent anomalies recorded by kinds of electromagnetic observation technology before Wenchuan M8 earthquake reveals great potentialities of electromagnetic subject in the field of earthquake prediction,and it is necessary to enhance stereo electromagnetie observation by space-ground integration for improving the level of earthquake prediction.