Numerical modeling of spatial profiles of geomagnetically induced electric field intensity in and around Japan
Shigeru FUJITA, Ikuko FUJII, Arata ENDO & Hiroki TOMINAGA
Abstract
The nationwide intensity map of geomagnetically induced electric fields (GIEs) in Japan is presented by using a numerical modeling method. We estimate near-surface resistivity distributions from bathymetry and sediment thickness data. GIE intensity distributions are computed for external geomagnetic variations at periods of 200, 800 and 3,600 sec. The GIE intensity is normalized with respect to the magnetic variation of 100 nT at Kakioka Magnetic Observatory. The GIE appears significantly enhanced mainly in coastal areas. In addition, the enhancement penetrates a few tens of kilometers inland. From the present calculations, we identify the areas where the GIEs can be largely enhanced, these are (1) the northeast coast along the Sea of Ohotsuku, in Hokkaido; (2) the west coast along the Sea of Japan, in southern Hokkaido and Aomori Prefecture (Matsumae-Tsugaru area); (3) the northwest coast along the Sea of Japan, in Niigata Prefecture and Toyama Bay; (4) the southwest coast of the Pacific Ocean; and (5) the east coast of the Korean Peninsula. Further we need to know the geomagnetically induced currents (GICs) in Japan. However, we cannot calculate the GICs in Japan because the power line parameters are not disclosed by policy of Japanese power line companies.
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