The Deep Structure of the Central Kamchatka Depression: Geoelectrics and Seismic Tomography

Abstract

Data from magnetotelluric sounding surveys (MTS) and seismic tomography were used to study the distribution of geoelectric and velocity inhomogeneities in the crust and upper mantle beneath the Central Kamchatka Depression. The geoelectric model for the depression was obtained using modern approaches and numerical modeling software for magnetotellurics. The main features of electrical conductivity have been identified for the sedimentary–volcanogenic cover and the lithosphere. We have detected crustal and mantle anomalies of higher conductivity in areas of recent volcanism. Anomalies of lower seismic velocities to depths around 200 km were detected in the crust and upper mantle. Transverse seismic tomography lines across the depression show crustal anomalies of lower seismic velocity existing in areas of active volcanoes. A technique has been proposed for an integrated interpretation of MTS and seismic tomography data. The technique was applied to unravel the origin of these anomalies of higher conductivity and lower seismic velocity and to estimate porosity in the rocks that contain magma melts and hydrothermal brine.