Marine Electromagnetics

The DASI deep-towed electromagnetic transmitter system being deployed at sea (courtesy of Tim Minshull)

The Vulcan electromagnetic receiver (courtesy of Tim Minshull)

More Information

About the Marine Electromagnetics

We carry out marine controlled source electromagnetic (CSEM) surveys - for both academic and applied research topics.

The combination of the DASI transmitter and Vulcan receivers allows sub-bottom electromagnetic profiling to depths of c. 100-200 m beneath the seafloor. This approach can be applied to map resistive gas accumulations or gas hydrate deposits, conductive mineral deposits, and other shallow geological features.

We commonly combine this equipment with ocean bottom electromagnetic receivers supplied by OBIC, allowing us also to survey deeper, crustal-scale targets.

Technical specification

Our equipment base includes:

The DASI-2 deep-towed electromagnetic transmitter system, capable of 100-200 Amperes of transmission along a 50-300 m dipole antenna at a frequency range of 0.25 Hz to 10 Hz and with a variety of waveforms. The DASI vehicle is also equipped with a conductivity-temperature-depth (CTD) sensor, an altimeter and an ultra-short baseline (USBL) beacon.
Two Vulcans (developed at Scripps Institution of Oceanography) receivers that can be towed in behind DASI at distances appropriate for the geological target. Vulcan records all three components of the electric field transmitted from DASI. Vulcan also contains a Parasci pressure gauge to give an accurate measure of its depth, a compass to give the instruments heading, pitch and roll, as well as a three axis accelerometer to measure its motion as it is towed about 50 m above the seafloor.