1. n. [Geophysics]

A variation of the electromagnetic method in which electric and magnetic fields are induced by transient pulses of electric current in coils or antennas instead of by continuous (sinusoidal) current. These surveys have become a popular surface EM technique used in exploration for minerals and groundwater and for environmental mapping.

Synonyms: TDEM,  time-domain electromagnetic method

Alternate Form: transient electromagnetic method