Introduction to CSAMT

Controlled source audio-frequency magnetotellurics (CSAMT) is a high-resolution electromagnetic sounding technique that uses a fixed grounded dipole or horizontal loop as an artificial signal source. CSAMT is similar to the natural source magnetotellurics (MT) and audio- frequency magnetotellurics (AMT) techniques, with the main difference being the use of an artificial signal source for CSAMT. The source provides a stable signal, resulting in higher-precision and faster measurements than are usually obtainable with natural-source measurements in the same spectral band. However, the controlled source can also complicate interpretation by adding source effects, and by placing certain logistical restrictions on the survey. In most practical field situations these drawbacks are not serious, and the method has proven particularly effective in mapping the earth's crust in the range of 20 to 2000 meters.