Controlled source electromagnetic (CSEM) surveying

In the marine environment, a survey or method in which an electromagnetic field is generated in the substrate using a controlled source and measured at different offset locations using surface/seabed receivers

In principle, CSEM techniques cover all geophysical, electromagnetic surveys with an active source. The CSEM method when applied offshore may be known as marine CSEM, mCSEM or seabed logging (SBL).