【摘要】 1996年 11月 19日新疆和田地区发生了ML=7.1地震 .在这次地震发生前 ,观测到了地震的超低频(ULF)电磁辐射前兆 .电磁辐射前兆的特点是电位漂移、极化椭圆主轴的垂直方向指向震中和大幅度的电磁辐射 .本文根据电磁辐射特征建立了地震电磁辐射前兆垂直电偶极子模型 ,并且给出了观测结果的物理解释 .偶极子产生一个不稳定的静电场使水平分量的电位日均值发生明显漂移 ,震前电偶极子中电荷复合放电产生的随机弱电磁噪声造成在ULF频段上水平分量偏振主轴方向偏转 .喀什台站和安西台站观测到的电势比值与模型估计值相近 ,从水平分量判断出偶极子间电流方向向下 ,与垂直电偶极子模型一致 .更多还原

【Abstract】 The earthquake M L7.1 took place at Hotan of Xinjiang province on Oct.19, 1996. Three types of Ultralow frequency(ULF) electromagnetic precursors were observed before the earthquake: (1) drift of dynamic zeros, (2) the vertical direction of the major axis of the polarization ellipse orientated to the epicenter, and (3) large amplitude of ULF electromagnetic radiation. A simple model for the generation mechanism of these precursors is proposed. Based on this model, we explain the effect of static electric field inducted by dipole on the variation of voltage and direction of axis on polarization ellipse for horizontal components.更多还原