Coast effect in magnetotelluric soundings on the continental south of the Russian Far East

Abstract

The manifestation of coast effect is studied based on the magnetotelluric (MT) soundings made on three profiles in the southern part of the Sikhote-Alin folded system (SAFS) surrounded by the Sea of Japan in the south and east. It is found that the coast effect is poorly expressed in the MT sounding amplitude curves while well pronounced in the behavior of the magnetovariation response functions. The analysis of the complex Wiese tipper and its real induction arrows in the north and east directions identified the intensity of the coast effect within the study area and the influence of the main deep faults and conductive zones in the Earth’s crust and upper mantle on the effect. Based on the three-dimensional (3D) numerical modeling, the main factors affecting the behavior of the amplitude MT sounding curves in the presence of coast effect are determined for the conditions of the southern part of SAFS and different geoelectric models.