HIGH-RESOLUTION BATHYMETRY OF THE EAST PACIFIC RISE AXIAL SUMMIT TROUGH 9-DEGREES 49-51N - A COMPILATION OF ALVIN SCANNING SONAR AND ALTIMETRY DATA FROM 1991-1995

Bathymetric data acquired during six cruises to the East Pacific Rise crest 9 degrees 49'-51'N an compiled into a single bathymetric databas e and used to create high-resolution bathymetry maps of two geological ly and biologically active areas. Scanning sonar and Alvin altimetry w ere collected during 23 Alvin dives to the P-vent/Bio9 and Biomarker-1 41 areas during 1991-95. Bathymetry data were filtered, edited, and pr ocessed as individual dives then combined into a single database for e ach cruise and statistically evaluated. Cruise data sets were numerica lly and visually compared and cross-correlated to known bottom feature s and fixed seafloor reference markers, then horizontally shifted to e stablish a consistent database with 3 m vertical and 5 m horizontal re solutions. The compiled and corrected bathymetry was used to produce b athymetric maps of two areas within the axial summit collapse trough; a 2 x 10(4) m(2) area around P and Bio9 vents, and a 1.1 x 10(3) m(2) area around Biomarker 141. The resulting detailed bathymetry maps reve al topography dominated by low-relief volcanic constructional features and post-eruptive collapse of lobate and sheet lava surfaces.