幔羽现象与地震电磁流体效应的可能联系——电磁流体效应和平面电流模型

综合分析了 2 0世纪 70年代以来发生在中国的 14个强震前地磁和地下流体参量动态图像的时空演化特征 ,发现强震前这些参量均呈现十分明显的异常图形。这些图像十分复杂 ,且随时间不断变化 ,并与孕震过程有某种时空规律性联系。 90年代地学家通过地震资料分析发现了幔羽现象。笔者设想核幔边界的幔羽磁流体物质上涌是地震电磁流体效应的一种可能成因。幔羽中的流体物质螺旋上涌至地壳的底部 ,并形成“蘑菇云”。流体在地壳中扩展或挤压 ,形成异常电流 ,可将其看作在孕震区地下 10 2 0km深处有一等效平面电流。再考虑到近地表的电磁环境———电离层电流体系的局部异常 ,计算了一个地下和电离层组成的等效平面电流模型在地面产生的磁场分布 ,结果与强震前地球磁场的零等变型异常动态图像较吻合。

THE POSSIBLE CONNECTION OF THE MANTLE PLUME PHENOMENON WITH THE SEISMO-HYDROMAGNETIC EFFECT PRIOR TO EARTHQUAKES ——Seismo-hydromagnetic effect and a planar current model

From synthesizing the spatial and temporal pattern of anomalous dynamic images for the parameters of geomagnetic field and underground fluid for 14 strong earthquake cases occurred in China since 1970,the authors found that those parameters reveal obvious anomalous images which are very complex and changeable,and bear a regular relation with seismogenic process.In the 1990’s geo-scientists, through the processing of seismic data, discovered the phenomenon of mantle plumes at the core-mantle boundary. The authors ,from the above results and the mantle plume phenomenon, put forward that the surging-up of hydromagnetic mass at the core-mantle boundary leads to seismo-hydromagnetic effect possibly.It is imagined that the fluid mass in the conductive mantle plumes gush up spirally to the lower part of the crust and from the mushroom cloud. Then, the fluid expanded or compressed in the crust. So, there is an equivalent planar current at a depth of between 10 and 20 km in the seismogenic region.Taking into consideration of the local anomaly of the ionospheric current system—the nearest electromagnetic environment—to the earth surface, the distribution of magnetic field by a planar current model in the seismogenic region has been calculated which coincided to a certain degree with the dynamic image of zero isoporic geomagnetic field prior to strong earthquakes.