OFFSHORE USE OF THE SELF‐POTENTIAL METHOD*

Abstract An offshore self‐potential array, towed behind a small boat, has recorded anomalies of up to −300 mV. These anomalies were related to conductive onshore deposits, and appear to be caused by offshore extensions of the deposits. Along with locating onshore deposits and their offshore extensions, the system may be useful for locating offshore deposits with no onshore extension. The background noise level of the system typically is a few tenths of a millivolt, allowing reliable recording of one millivolt gradient anomalies under average sea conditions.