Practical Magnetotellurics

Abstract

Practical Magnetotellurics lives up to its title and nicely fills a big hole in the literature on the subject of the magnetotelluric (MT) method, a means by which the geological and physical properties of the crust and mantle may be studied using electrical conductivity images.In an MT sounding passive time series, measurements of the Earth's naturally occurring magnetic and electric fields are used to generate an electromagnetic impedance of the subsurface as a function of frequency, which may in turn be interpreted in terms of Earth electrical conductivity. Because short‐period (higher frequency) energy is absorbed more rapidly in conductive rocks than longer‐period MT fields, the method has an intrinsic depth resolution, which for appropriate frequencies can span the range from a few meters at the surface all the way to the lower mantle. Electrical conductivity is a strong function of porosity, mineralogy, and temperature, so applications of the MT method include petroleum and mineral exploration, groundwater and environmental studies, structural geology and understanding the geodynamical state of the planet.