An Interpretation of Magnetovariational Data in the Northern Tohoku District, Japan, Using Multi Sheet Modelling.

Abstract

Magnetovariational data from thirty-seven sites in the northern Tohoku district of Japan are modeled quantitatively using a multi thin-sheet modelling program. The primary objective was to determine if current channeling of electromagnetic fields through the Tsugaru strait, to the north of the survey region, can account for the behavior of the observed large real induction vectors. The major conclusions that we draw are: (1) northward-directed induction vectors at 256 s period cannot be fully explained only by the channeling effect through the Tsugaru strait especially in the area to the east of the Quaternary volcanic front, and (2) a conductive anomaly is necessary at a depth of 10 km in the forearc region in order to account for the induction vectors at 16 s period.