HR: 15:25h
AN: S13F-08    [Abstracts]
TI: Bottom Interaction in Long-Range Ocean Acoustic Propagation
AU: * Stephen, R A
EM: rstephen@whoi.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, MA 02543- 1542, United States
AU: Mercer, J A
EM: mercer@apl.washington.edu
AF: University of Washington, 1013 NE 40th Street, Seattle, WA 98105-6698, United States
AU: Andrew, R
EM: rex@apl.washington.edu
AF: University of Washington, 1013 NE 40th Street, Seattle, WA 98105-6698, United States
AU: Howe, B A
EM: howe@apl.washington.edu
AF: University of Washington, 1013 NE 40th Street, Seattle, WA 98105-6698, United States
AU: Dzieciuch, M A
EM: mdzieciuch@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, CA 92093-0225, United States
AU: Worcester, P F
EM: pworcester@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, CA 92093-0225, United States
AU: Colosi, J A
EM: jacolosi@nps.edu
AF: Naval Postgraduate School, 1 University Circle, Monterey, CA 93943, United States
AB: Four Ocean Bottom Seismometers, consisting of one hydrophone and one vertical component geophone channel each, were deployed below the deep vertical line array (DVLA) on the North Pacific Acoustic Laboratory/ Long-range Ocean Acoustic Propagation Experiment (NPAL/LOAPEX). Data, sampled at 500sps, were recorded continuously from the deployment in September 2004 for over 100days. The OBS's were on the seafloor in about 5,000 m of water and would be in the shadow zone for long range, ducted propagation in the sound channel. The goals of the deployment were: 1) to quantify the amount of energy that leaks out of the sound channel into the shadow zone, 2) to measure the relative sensitivity (signal-to-noise) of seafloor hydrophones and vertical component geophones to long- range signals and 3) to study the physics of earthquake generated T-phases. Leakage was observed out to 3200km on the vertical component geophone and out to 1000km on the hydrophone. Propagation velocities to the furthest ranges correspond primarily to sound channel paths (not surface or bottom reflected paths). The ratio of the pressure to vertical velocity varies between arrivals on the same trace. Some arrivals are extremely robust (appear on each transmission over 30hours with an arrival time varying be less than +/- 7msec) and some arrivals are ephemeral (magnitude varies tremendously over 2-3 minutes ) (eg at 500km range). (The OBS deployments were funded by contributions from ONR, NSF and WHOI. Data analysis funded by ONR.)
DE: 0935 Seismic methods (3025, 7294)
DE: 3025 Marine seismics (0935, 7294)
DE: 3050 Ocean observatories and experiments
DE: 4259 Ocean acoustics
DE: 7294 Seismic instruments and networks (0935, 3025)
SC: Seismology [S]
MN: 2007 Fall Meeting