This is a collaborative project to install a synchronously operating array of 25 magnetotelluric stations in the interior of Alaska beneath the footprint of the PFISR ionospheric incoherent scattering radar array. The MT data were obtained to provide the first systematic look at the 3-D electrical resistivity structure of the crust and uppermost mantle in the Alaska interior in the Yukon-Tanana Terrain north of the active deformation zone along the Denali fault system and across the Tintina fault system into the transition to cartonic North America. Simultaneously the PFISR data provides control on ionospheric source fields that was used to validate the plane wave assumption used in the MT imaging fo subcrustal/mantle structure.