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A new radiomagnetotelluric (RMT) instrument has been developed that can record time series of electric and magnetic fields in the frequency range from 10 kHz to 1 MHz. Military and civilian radio stations broadcasting in this frequency range are used as transmitters. Transfer functions (e.g., apparent resistivities and phases as a function of frequency) are determined by spectral analysis using a newly developed processing software. The transfer functions presented here are the first ones ever at frequencies above 300 kHz and they can lead to a better resolution of the shallow structure. The new RMT instrument enables quick and efficient mapping of shallow structures and supports tensor measurements thereby allowing a 2D or 3D interpretation of field data. The new RMT system was tested in the laboratory and then applied successfully in the field to several environmental and engineering problems. Case studies from applications in St. Petersburg, Russia and in Uzin, Ukraine will be presented. The observed apparent resistivities and phases are reliable and they show smooth frequency dependence. The data were inverted for 2D conductivity models under the assumption that the strike direction was known beforehand.

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