ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

4pUW3. Preliminary comparisons between bistatic reverberation from an ocean ridge and wavelength-scale geomorphology.

Nicholas C. Makris

Lilimar Avelino

Richard Menis

Naval Res. Lab., Washington, DC 20375

Bistatic reverberation measured from a highly lineated ridge in the mid-Atlantic during the ARSRP Main Acoustics Experiment of 1993 was compared with bottom slope orientation determined from 200-m resolution Hydrosweep bathymetry in a previous abstract [Makris et al., 3329(A) (1994)]. It was found that prominent returns register with extended scarps facing the source and receiving array. These scarps typically extend for lengths greater than 1 km and have widths that are less than 1 km. However, the hydrosweep bathymetry is not of sufficient resolution to determine the fine-scale geomorphology of the scarps, and leads to slope estimates (20(degrees) to 30(degrees)) that are a severe underestimate. Fine-scale bathymetry of 5-m resolution recently obtained for the same ridge shows that the scarps returning prominent reverberation generally contain cliff faces with slopes between 60(degrees) to 90(degrees). However, the separation between these cliff faces is typically less than the roughly 500-m cross-range resolution of the towed-array imaging system. An attempt is made to resolve individual cliff faces with remote returns measured at 1/2 CZ by exploiting the much higher range resolution of the towed-array imaging system (which approaches roughly 10 m) and examining differently oriented bistatic measurements of the same sites.