Introduction to NSAMT

The NSAMT (Natural Source Audio-frequency Magnetotellurics) method involves the measurement of electromagnetic fields that are generated by natural electromagnetic activity above the earth's surface.

Natural source signals are generated in the atmosphere and magnetosphere. MT signals (low frequencies < 1 Hz) are generated by the interaction between the earth's magnetosphere and the solar wind, sunspot activity and auroras. High frequency sources (> 1 Hz) in the Audio range (AMT) are generated by worldwide thunderstorms and lightning. These time-varying electric and magnetic fields induce currents into the earth and oceans.

Electric currents within the earth produce magnetotelluric signals that are measured by the Zonge AMT / MT System. The fields are measured over a range of frequencies using grounded dipoles and magnetic field antennas. The system calculates ground resistivity values by measuring the magnitude of the electric and magnetic fields.