Total field EM for highly conductive targets

Abstract

Total field magnetometer sensors, such as those of the optically-pumped cesium vapour variety, are not conventionally used in electrical geophysics. Exceptions to this are Sub-Audio Magnetics (SAM) surveys, carried out with such a sensor typically moving and measuring magnetic fields continuously at sample rates of 1 - 4 kHz. At the very low base frequencies (often below 1 Hz) used in EM surveys for highly conductive targets in very conductive terrain, cesium vapour magnetometers have an instrument noise level which is superior to almost all sensor types. This is an important issue for the detection and discrimination of highly conductive targets and can accelerate data acquisition.