摘要
本文应用2013年芦山MS7.0与岷县漳县MS6.6地震震中周围的平凉等3个地电场台站观测数据,研究地震发生前后地电场在时间域、频率域内的变化。结果表明:1在芦山地震、岷县漳县地震前,位于青藏高原东北缘的平凉台记录到显著的地电场异常变化。2利用最大熵谱估计方法计算平凉、松山、古丰台在芦山地震以及岷县漳县地震发生前后地电场观测数据,得到在上述两次地震前均发生地电场功率谱密度(特别是低于4×10-3 Hz频段的成分)增大的现象,岷县漳县地震发生后,部分测向谱密度增大现象消失。3距离震源区越近,地震发生前后功率谱密度异常变化越明显,长短极距相关性越差,初步分析认为此现象的发生,可能是由于在震源孕育、发生过程中,台站所在位置地下介质形变激发宏观电磁辐射造成的。
We studied changes of geo-electric fields before and after the 2013 Lushan Ms7.0 earthquake in Sichuan Province and Minxiang-Zhangxian Ms6.6 earthquake in Gansu Province observed by the Pingliang and other stations around the epicenter.The results show that：① Before Lushan Ms7.0 earthquake and Minxiang-Zhangxian Ms6.6 earthquake,significant anomalies of geo-electric fields were recorded by Pingliang station.② Maximum entropy method was used to calculate geo-electric data observed by Pingliang,Songshan and Gufeng stations before and after the Lushan earthquake and Minxian-zhangxian earthquake,and the calculation reaults reveal that the phenomenon of increased power spectrum density （especially,anomalies of low frequency components under 4 ×10-3 Hz） occurred before the earthquake,and the phenomenon observed by some stations disappeared after the Minxian-Zhangxian earthquake.③ The nearer the location is to the epicenter,the more obvious change the power spectrum density anomalies and the weaker the correlation between long polar distance and short polar distance becomes.In the primary analysis for this phenomenon,we propose that the deformation of underground medium under stations in the process of earthquake preparation may stimulate macroscopic electromagnetic radiation.
出处
《地震》
CSCD
北大核心
2015年第1期100-111,共12页
Earthquake
基金
中国地震局地震预测研究所基本科研业务费专项(2012IESLZ06)
国家自然科学基金(41374080)联合资助
