Abstract: A system for assessing underwater biomass that comprises a frame that can float and hold the system on a body of water; a transducer that emits and receives wave signals; a motor box, that positions the transducer below a water line; a control unit to allow a user to operate the system and view results obtained from the system; an electronics housing that receives a CPU board that communicates with and relays information to and from, the control unit; and a communication device to facilitate communication between the control unit and the CPU board.

Abstract: A method for detecting the seismic discontinuity in acoustic impedance caused by an acoustically hard, reflective object buried a few feet below poroelastic soil using seismic activity induced through acoustic coupling with a remote sound source. The abrupt change in the soil impedance caused by the buried object causes sound to reflect between the object and the surface and increase the amplitude of the seismic vibrations induced by the incident acoustic energy. The change in the seismic displacement of the soil is on the order of angstroms which can be detected using remote optical test equipment such as a laser-doppler vibrometer (LDV) commonly used in nondestructive testing. A sound source emits sound at frequencies that induce significant seismic coupling with the poroelastic soil. Part of a beam of laser light of an LDV is scanned over the ground. The laser light is shifted in frequency from its source frequency by an amount intended to approximate the frequency of the anticipated seismic vibrations.