Magnetotelluric method: uniqueness theorems
One-dimensional (1D) Earth: Bailey (1970): Unique radial conductivity distribution in a concentrically stratified Earth. Uses principle of causality. Need perfect data at all frequencies. Two-dimensional (2D) Earth: Gusarov (Weidelt, 2000, pers. comm.): Uniqueness theorems for 2D modes of induction (TE - transverse electric and TM - transverse magnetic) Three-dimensional (3D) Earth: Nothing yet exists