智利8.8级地震的震前电子浓度扰动

Electron density perturbation before Chile M8.8 earthquake

基于法国DEMETER卫星数据,在识别2级图像的基础上,通过对1级数据进行滑动中值处理、纬度变化分析以及空间差值研究,发现2010年2月27日智利8.8级地震的震前震中区上空附近有异常变化:20日距离震中1500 km处电子浓度升高,24日电子浓度降低;25、26日电场、磁场及部分等离子体参量呈现同步扰动;26日2条轨道的电子浓度值出现高于背景值的异常;27日震前4小时在磁赤道附近出现电场频谱下降,等离子体参量强烈扰动的现象.

Based on the data of France DEMETER （Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions） satellite, some abnormities in the ionosphere above the epicenter of February 27th, 2010, Chile M8.8 earthquake were found through distinguishing level 2 picture and analyzing level 1 data with moving median, latitude study, and spatial difference methods. In the area 1500 km apart from the epicenter, electron density rose on Feb 20th. Electron density declined on 24th. Electric, magnetic fields and some plasma parameters disturbed at the same time on 25th and 26th. Besides that, on 26th , electron density of 2 orbits exceeded the background values. Electric field spectrum around magnetic equator on 27th began to drop 4 hours before the earthquake, and there were simultaneous strong perturbations of some plasma parameters.