The proximity effect of earth conductivity change on geomagnetically induced current

During geomagnetic storms, the geoelectric field drives currents in transmission grids, railway system and pipelines. These geomagnetically induced currents (GIC) threaten the safe operation of equipment. The GIC recordings show that geological structure has significant implications for GIC in power gird (Liu Chunming et al. 2009). In the region with complex geological structure, the horizontal change of earth conductivity will change the distribution of geoelectric field (Albertson & Balelen 1970). In particular, the“proximity effect” will influence the electric field in the perpendicular direction of conductivity change. If the transmission line is parallel with the interface of conductivity change, the “proximity effect” has a significant impact on GIC of power grids. Therefore, the “proximity effect” is an important case of the earth conductivity in connection with studies of geomagnetically induced currents.