FAULT SCARP IDENTIFICATION IN SIDE-SCAN SONAR AND BATHYMETRY IMAGES FROM THE MID-ATLANTIC RIDGE USING WAVELET-BASED DIGITAL-FILTERS

Digital filters designed using wavelet theory are applied to high reso lution deep-towed side-scan sonar data from the median valley walls, c restal mountains, and flanks of the Mid-Atlantic Ridge at 29 degrees 1 0' N. With proper tuning, the digital filters are able to identify the location, orientation, length, and width of highly reflective linear features in sonar images. These features are presumed to represent the acoustic backscatter from axis-facing normal faults. The fault locati ons obtained from the digital filters are well correlated with visual geologic interpretation of the images. The side-scan sonar images are also compared with swath bathymetry from the same area. The digitally filtered bathymetry images contain nine of the eleven faults identifie d by eye in the detailed geologic interpretation of the side-scan data . Faults with widths (measured perpendicular to their strike) of less than about 150 m are missed in the bathymetry analysis due to the coar ser resolution of these data. This digital image processing technique demonstrates the potential of wavelet-based analysis to reduce subject ivity and labor involved in mapping and analyzing topographic features in side-scan sonar and bathymetric image data.