Absorption estimation in marine sub-bottom layers summary

Continued advances in signal processing has allowed the generation of a process to extract individual layer absorption parameters (decibels/meter) from marine sub-bottom acoustic profiling data. The absorption data can be used to classify the sediment type for unconsolidated clean marine sediments based on a historical database generated from more than 30 years of field data. Optimum results are obtained by using fully system-calibrated data with absolute source spectrum and wavelet information. However, useful estimates can be obtained with source spectrum and wavelet data extracted from the trace data. Even with this partially calibrated data, anomalous contaminated and gases sediments are easy to detect. These anomalous detections are important in contaminated and off-shore construction project mapping. Utilization of this technique with local core data in areas of complex geological conditions allows for sediment tracking and mapping in these complex areas to be improved. An overview of the historical database, and typical processed records are presented. This paper provides the step-by-step analysis and background to the processing results provided in the Opishinski, Caulfield, 2000 paper which covered acquisition and system installation. The detailed problems of file formatting, quality assurance, modeling and signal processing are discussed. The importance of this discussion is to insure that future data is gathered in formats so that quality data processing can be carried out.