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Abstract—The geoelectric structure of the junction region between three largest segments of the East European Craton (EEC)–Volga–Uralia, Sarmatia, and Fennoscandia—is studied. We analyze electrical conductivity anomalies within the Orsha depression revealed by synchronous array magnetotelluric (MT) and magnetovariational (MV) crustal soundings. The study is based on the data from deep MT/MV survey acquired in 2018–2020 under the SMOLENSK experiment in the vicinity of the Orsha depression and the results of similar studies carried out since 2007 in the previous KIROVOGRAD experiment east on the slope of the Voronezh crystalline massif (VCM). The data are interpreted in the class of two-dimensional (2D) geoelectrical models constructed on the long latitudinal geotraverses combining the soundings from the SMOLENSK array in the west and KIROVOGRAD array in the east. Interpretation of MT/MV data within the Orsha depression is substantially complicated by intricate interference of deep and shallow responses. The latter are determined by current systems within the conductive sedimentary cover, ~2 km thick at the center of the depression and having an integrated longitudinal conductance of ~1000 S. Shallow quasi 3D effects obscure responses of crustal conductive features in a wide range of periods, challenging their analysis in the scope of 2D interpretation of impedance data. Important role in overcoming these obstacles is played by MV tipper data which are immune to surface distortions. To develop the strategy of joint MT/MV interpretation, we carried out experiments on inverting synthetic data calculated in a series of 2D models simulating possible geoelectric structure of the study region. The numerical results demonstrated the effectiveness of using the REduced Basis OCCam's (REBOCC) algorithm in the two-stage successive 2D-inversion scheme which inverts at the first stage the electric (TE) mode MT/MV data alone, and at the second stage incorporates the magnetic (TM) mode impedance data. This technique reliably identifies deep conductive structures beneath thick sedimentary strata. The importance of using a priori information about the geoelectric structure of sedimentary cover when constructing the starting inversion model is demonstrated. The joint 2D inversion strategy worked out on the synthetic MT/MV data was used to interpret observations along three combined profiles of the SMOLENSK and KIROVOGRAD arrays. The interpretation refined the structure of the Kirov–Baryatino crustal anomaly on VCM western slope, revealed complex architecture of crustal anomalies beneath the Orsha depression, and allowed preliminary conclusions about the nature of conductivity anomalies and their connection with ancient and recent geodynamic processes. [ABSTRACT FROM AUTHOR]