利用DEMETER卫星数据分析强震前后的电离层异常  

Ionospheric disturbances before and after strong earthquakes based on DEMETER data

作　　者：颜蕊[1] 王兰炜[1] 胡哲[1] 刘大鹏[1] 张兴国[1] 张宇[1] 

机构地区：[1]中国地震局地壳应力研究所,中国北京100085

出　　处：《地震学报》2013年第4期498-511,1,共14页Acta Seismologica Sinica

基　　金：中国地震局地壳应力研究所基本科研业务专项(ZDJ2011-6)资助

摘　　要：基于法国DEMETER卫星观测的离子温度(Ti)、VLF电磁场单频点频谱数据探索了2008年5月12日汶川MS8.0、2010年1月12日海地MS7.3和2010年2月27日智利MS8.8等3次强震前后与地震有关的电离层异常现象.结果发现,汶川地震前3天(5月9日)震中北偏西方向离子温度明显升高,震前4天(5月8日)VLF磁场低于200Hz的频段范围频谱在震中2°以内有明显突升;智利地震前9天(2月18日)震中北东方向离子温度有剧烈扰动,震前4天(2月23日)VLF磁场100—160Hz频段范围内出现突升;海地地震震前没有观测到明显的异常现象,但地震发生当天(震后约4—5小时)的Ti,40—160Hz频段电场频谱,以及120—480Hz磁场频谱均有明显突升,应为地震发生后能量释放所引起.分析认为,不同地震由于发震机制等各种情况的不同,其地震前后的表现也各不相同.虽然目前没有直接的证据表明本文研究的异常变化是由地震的孕育和发生引起的,但在数据处理中已尽可能排除了太阳、地磁等因素的影响,并且研究结果与前人的研究经验吻合,因此本文发现的异常可能与地震发生的关系较大.Using ion temperature （Ti）, VLF electromagnetic field single-frequency spectrum data from DEMETER satellite, this paper studies variation of these parameters associated with the strong earthquakes： the Wenchuan MS8.0 earthquake of China on 12 May 2008, the Haiti MS 7.3 earthquake on 12 January 2010 and the Chile MS 8.8 earthquake on 27 February 2010. The result for Wenchuan MS8.0 earthquake shows that the ion temperature （Ti） northwest to the epicenter increased 3 days before the mainshock, and the data of VLF magnetic field spectrum below 200 Hz showed disturbance within 2° of the epicenter on May 8 before the mainshock. The result for the Chile MS 8.8 earthquake shows that the ion temperature （Ti） northwest to the epicenter showed fluctuation 9 days before the mainshock; on February 23 before the Chile earthquake the frequency range from 100 Hz to 160 Hz of VLF magnetic field spectrum showed sudden rise within the area of 5° around the epicenter. No obvious anomalies of the three parameters were observed before the Haiti earthquake, but after the mainshock some anomalies were found. Ti and the frequency band from 40-160 Hz of VLF electric field spectrum and the VLF magnetic field spectrum in the 120-480 Hz frequency band showed significant anomalies on the day of earthquake occurrence, which might be caused by energy release after the earthquake. Currently we have no evidence to conclude that these changes result from seismic activity, but in the data processing we have excluded the disturbances induced by solar activity and magnetic field to a certain degree, and the data selected are closely linked with the time and space of the earthquake. This result is consistent with previous research results, and we propose that the abnormities found in the paper may be related to the three strong earthquakes.

关 键 词：DEMETER卫星 离子温度(Ti) VLF频段频谱 电场磁场 

分 类 号：P318.63[天文地球—固体地球物理学]