Audio-frequency magnetotellurics (AMT) is an electromagnetic method that measures naturally occurring currents flowing in the subsurface. A transmitter can be used to supplement the natural field, known as controlled-source AMT (CSAMT). A hybrid source transmitter can be used (HSAMT), which is a more portable, less powerful option than the transmitter used for CSAMT.

Geode EM3D

A distributed AMT/CSAMT/HSAMT system with 24 to 240-channels.