Passive low-frequency seismic is an area of active research and development, and is rapidly being taken up as a new direct hydrocarbon indicator (DHI) technique for exploration. The interest in the method is high, in particular since Spectraseis AG, the leading provider of low-frequency geophysical solutions to the oil and gas industry won the World Oil Award for Best Exploration Technology in October 2007. However, despite the empirical evidence supporting the technique, the underlying physical mechanism has not yet been fully identified.
