The deep structure of the southern kamchatka volcanic zone from geophysical data

We discuss the interpretation method and results of magnetotelluric soundings in combination with other geological and geophysical data. The interpretation method was developed by studying possible distortions in MTS curves using 3D-numerical modeling of the magnetotelluric field. Deep conductivity was studied by using longitudinal MTS curves below a period of 400 s, which are nearly unaffected by the induction effect due to marine electrical currents. Transverse curves were used to obtain more detail for the geoelectric model. Inversion of average longitudinal MTS curves resulted in a geoelectric section of the lithosphere down to a depth of 60 km. Anomalies of high conductivity in the lithosphere were detected and were found to produce certain effects in gravity and seismic velocities. MTS and seismic tomography data were used to determine the possible origin of the high conductivity anomaly and to estimate rock porosity and the concentration of magma melts.