HR: 1330h
AN: S52D-0163    [PDF]
TI: Designing a Deep-Towed/Seafloor Repetitive Sound Source
AU: * Sauter, A W
EM: asauter@ucsd.edu
AF: Marine Physical Lab, Scripps Institution of Oceanography, 0205, La Jolla, CA 92093-0205 United States
AU: Dorman, L M
EM: ldorman@ucsd.edu
AF: Marine Physical Lab, Scripps Institution of Oceanography, 0205, La Jolla, CA 92093-0205 United States
AB: A seafloor (or deeply towed) sound source has the fundamental advantage over a surface source of releasing its energy much closer to its sub-sea target, resulting in improved resolution. If used on the seafloor, it produces abundant shear-wave energy, useful for differentiating between solid and gas-producing areas. Since marine mammals spend most of their time near the surface, a seafloor source reduces their exposure to damaging acoustical signals. With funding from the NSF, we designed and built an implosive source for deep/seafloor use. Our existing device is designed to operate down to a depth of 2000 meters. It uses a two-stage valve that allows rapid flooding of a 20-liter cylinder. This volume is equivalent to 1/4 kg of explosive fired at 800 meters depth. It is, however, a single-shot implosive device and must be returned to the surface between firings, and is thus unattractive for track-line surveying. Through insight gained using this imploder, we have come up with a novel approach to seafloor signal generation that has the potential to open a new chapter in seismic prospecting, moving in the direction of higher spatial resolution and better measurements of shear velocities. We are designing a new model, powered by compressed air, which need not be returned to the sea surface between firings. It will possess an improved source spectrum for deep-water exploration. Modeling the hydrodynamic flow is an important step in the design process for finding optimal initial bubble volumes, valve closing rates, and chamber geometries that produce strong seismic signals largely confined to the 0 to 200 Hz bandwidth.
DE: 0935 Seismic methods (3025)
DE: 0994 Instruments and techniques
DE: 3025 Marine seismics (0935)
DE: 3094 Instruments and techniques
DE: 7294 Instruments and techniques
SC: Seismology [S]
MN: 2003 Fall Meeting