CAJ | 학술논문

基于法国DEMETER卫星记录的空间电场频谱资料,提取分析了汶川地震前可能存在的电场异常信息.首先利用轨道的重访特性分析了四川汶川8级地震前震中上空固定纬度点(31°N)的VLF电场信号2年多的正常频谱变化背景,结果显示1～6月各频点变化比较稳定,但在7～10月份各频点谱值扰动比较剧烈,存在整体幅度上升或者下降的现象,因此电场可能存在年周期变化.在背景分析的基础上,收集了2008年4月1日～5月12日震中区上空2000 km范围内所有夜间的降轨轨道在北纬31°记录的电场所有频点资料,计算结果显示震前1周内即5月6～10日相对4月份呈现明显的电场能量增强现象,增强幅度达到3σ,频率集中分布在2～6kHz范围内,异常区域的空间统计分布反映该电场增强现象位于震中以南较大范围内.这次异常发生在空间电磁活动平静时期,可能与汶川地震的孕育过程有关.最后讨论了空间地震电场异常的可能形成机理,对地震电离层耦合机理的深入认识还需要地基和空间的联合立体观测来支持.
기우법국DEMETER위성기록적공간전장빈보자료,제취분석료문천지진전가능존재적전장이상신식.수선이용궤도적중방특성분석료사천문천8급지진전진중상공고정위도점(31°N)적VLF전장신호2년다적정상빈보변화배경,결과현시1～6월각빈점변화비교은정,단재7～10월빈각빈점보치우동비교극렬,존재정체폭도상승혹자하강적현상,인차전장가능존재년주기변화.재배경분석적기출상,수집료2008년4월1일～5월12일진중구상공2000 km범위내소유야간적강궤궤도재북위31°기록적전장소유빈점자료,계산결과현시진전1주내즉5월6～10일상대4월빈정현명현적전장능량증강현상,증강폭도체도3σ,빈솔집중분포재2～6kHz범위내,이상구역적공간통계분포반영해전장증강현상위우진중이남교대범위내.저차이상발생재공간전자활동평정시기,가능여문천지진적잉육과정유관.최후토론료공간지진전장이상적가능형성궤리,대지진전리층우합궤리적심입인식환수요지기화공간적연합입체관측래지지.
Based on the information of spatial electric field spectrums recorded at DEMETER satellite.the possible electric field anomalies before Wenchuan earthquake were extracted and analyzed.Firstly using the revisited feature of satellite orbis,background spectrum of VLF electric field during more than 2 years at certain latitude(31°N)above the Wenchuan M8 earthquake in Sichuan were analyzed.It is found that,the spectrum curves are steady during January to J une,but during July to October,the spectrums are disturbed violently,uprising wholly or decreasing quickly,so electric field in this area may exist annual variation.On the basis of background information analysis,using electric filed spectrums at all frequency points recorded at 31°N on all up-orbits in local nighttime in a distance of 2000 km to Wenchuan epicentre during 1 April～12 May 2008,it was shown that during 1 week before the earthquake,that is 6～10 May,the amplitude of electric field spectrums increased apparently,reaching 3σ at the band of 2～6 kHz,while with the anomalous area distributing in a large area at the south of the epicenter.This anomalous phenomenon occurred in the quiet period of spatial electromagnetic activity,so it may be related to the preparation process of Wenchuan earthquake. Finailv the forming mechanism of spatial seismo electric field anomalies was discussed,and it is thought that further understanding on the coupling mechanism between earthquakes and ionosphere needs the support of united and stereoscopic observation at surface and space.