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This paper describes geoacoustic inversion of low frequency air gun data acquired during an experiment on the New Jersey shelf. Hybrid optimization and Bayesian inversion techniques based on matched field processing were applied to multiple shots from three air gun data sets recorded by a vertical line array in a long-range shallow water geometry. For the Bayesian inversions, full data error covariance matrix was estimated from a set of consecutive shots that had high temporal coherence and small spatial variation in source position. The effect of different data error information on the geoacoustic parameter uncertainty estimates was investigated by using the full data error covariance matrix, a diagonalized version of the full error covariance, and a diagonal matrix with identical variances. The comparison demonstrated that inversion using the full data error information provided the most reliable parameter uncertainty estimates. The inversions were highly sensitive to the near sea floor geoacoustic parameters, including sediment attenuation, of a simple single-layer geoacoustic model. The estimated parameter values of the model were consistent with depth averaged values (over wavelength scales) of a high resolution geoacoustic model developed from extensive ground truth information. The interpretation of the frequency dependence of the estimated attenuation is also discussed.

In situ porosity and permeability were measured on Great Bahama Bank sediments using electrical conductivity and permeability probes. Core samples were recovered at the probe measurement sites for laboratory determinations of porosity and permeability. Penetration depths of cores and probes were approximately 2.5 m subbottom.In situ porosities of the oölitic sands for depths of 0-2.5 m subbottom ranged between 36% and 50%, and at sites in the somewhat muddier oölitic sediments the porosities ranged from 42% to 61%. The in situ permeabilities ranged from 0.0032 cm/s (3.3 darcys) to 0.068 cm/s (71 darcys) at the sites where porosities were determined. Laboratory values of porosity are comparable to values obtained by in situ measurements; however, laboratory permeability values are approximately an order of magnitude lower than in situ values. The reduced permeability measured in the laboratory is attributed to disturbance of the microfabric during coring, Mohsen Badiey's present affiliation is the University of Delaware. 1 Downloaded by [University of Florida] at 09:19 01 June 2016 2 R. H. Bennett et al. . transport, and laboratory sampling. A detailed examination of the microfabric can be found in a companion articleThe high in situ porosities and permeabilities of these carbonate sediments are predominantly the result of the combined effects of both the sediment grain size distribution and the microfabric. The classification scheme of Dunham (1962) for carbonate rocks (wackestone, packstone, etc.) does not always provide a clear picture of some of the crucial properties of carbonate sediments (porosity, permeability, etc.), nor does this scheme provide a realistic functional description of the behavior of these sediments when subjected to static and dynamic stresses.