Coast Effect in Magnetotelluric Data from Continental Southern Far East of Russia

Abstract—The manifestation of coast effect is studied based on magnetotelluric (MT) data from three profiles in the southern part of the Sikhote-Alin folded system (SAFS), which is bounded in the south and east by the Sea of Japan. It is shown that the coast effect barely distorts the MT apparent resistivity curves but is well pronounced in the behavior of the magnetovariational response functions. The analysis of the complex Wiese tipper and its real induction arrows in the northward and eastward directions has revealed the extent of the coast effect within the study area and the impact of the deep faults and conductive zones in the Earth’s crust and upper mantle on the manifestation of the effect. Three-dimensional (3D) numerical modeling is used to identify the key factors determining the behavior of the MT apparent resistivity curves subjected to coast effect for the conditions of the SAFS southern part and different geoelectric models.