--> Abstract: Estimating Geoacoustic Properties of Marine Sediments by Matched Field Inversion Using Ship Noise, by Michael G. Morley, N. Ross Chapman, Tom McGee, and Bob Woolsey; #90039 (2005)
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Estimating Geoacoustic Properties of Marine Sediments by Matched Field Inversion Using Ship Noise

Michael G. Morley1, N. Ross Chapman1, Tom McGee2, and Bob Woolsey3
1 University of Previous HitVictoriaNext Hit, Previous HitVictoriaTop, BC
2 University of Mississippi, University, MS
3 University of Mississippi, Oxford, MS

Geoacoustic inversion for seabed properties using ambient noise sources in the ocean has received a great deal of interest recently. A project is currently underway to establish a remote gas hydrate monitoring station in the Gulf of Mexico. A major goal of the project is to detect changes that occur in the acoustic properties of gas hydrate bearing sediments due to the formation and dissocation of hydrates. It is hoped that temporal monitoring of these properties can be achieved by Matched Field Inversion (MFI) using noise from passing ships of opportunity as a sound source. In MFI, an optimization scheme is used to determine the geoacoustic model that produces the best match between the observed acoustic data, and replica acoustic data calculated by a propagation model. Once a best-fit model is obtained, a Bayesian inversion approach is applied to estimate the Posterior Probability Distributions (PPD) of the geoacoustic model parameters. The moments of the PPD yield estimates of uncertainties, correlations and sensitivity of the model parameters in the inversion. In this study, the method is investigated using both synthetic data, and real ship noise data collected with a prototype vertical line array deployed in Mississippi Canyon region of the Gulf of Mexico.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005