利用改进型图像信息方法研究汶川8.0级地震震前电离层扰动异常特征

Study on MPI Method to Extract Ionospheric Disturbance Anomaly Related to Three Large Earthquakes

利用改进型图像信息方法(Modified Pattern Informatics Method,简称“MPI”)基于DEMETER卫星观测的电子浓度(Ne)、电子温度(Te)数据探索了2008年5月12日汶川Ms8.0震前出现的地震电离层电子参量异常现象,特别详细分析了汶川Ms8.0震前3个月的电子参量时空演化过程。在前人的基础上,对电离层电子浓度(Ne)、电子温度(Te)的观测数据进行了消除年变及由太阳活动等引起的长趋势变化,以期能够提取到由地震孕育与发生所引起的电离层扰动异常。结果发现,在震前一个月左右电子浓度(Ne)、电子温度(Te)等参量均出现了不同程度的扰动异常,震前10天左右异常减弱并趋于平静,即平静—异常出现—持续显著—异常减弱—震前平静的特点,显示了地震前存在清晰稳定的电离层扰动图像,从而对地震的发生时刻具有一定的短临指示意义。

Based on electron density and temperature data from DEMETER Satellite,using MPI method,ionospheric anomalies of electronic parameters before the large earthquake were studied.We especially analyzed the MPI tempo-spatial image of electronic parameters 3 month before Ms8.0 Wenchuan earthquake occured.To obtain anomalous ionospheric perturbations prior to big earthquakes,annual variations and long-time trend changes caused by sun activity are eliminated from the data.The results show that electronic anomalies appeared one month ago,then weakened and dispeared nearly 10 days before those three big earthquakes.The phenomena indicate that those anomalies may have some indicative significance for short-imminet earthquake prediction.