Accession Number : ADA231321


Title :   A Joint Sea Beam/SeaMARC II Survey of the East Pacific Rise and Its Flanks 7 deg 50 min-10 deg 30 min N, to Establish a Geologic Acoustic Natural Laboratory


Descriptive Note : Annual progress rept.


Corporate Author : CALIFORNIA UNIV SANTA BARBARA MARINE SCIENCE INST


Personal Author(s) : MacDonald, Ken C


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a231321.pdf


Report Date : 15 Jan 1991


Pagination or Media Count : 4


Abstract : The primary project objective is to establish a long-term Geologic/ Acoustic Natural Laboratory (GANL) near 8 deg - 10 deg N on the East Pacific Rise. Our Nov-Dec 1990 cruise has established the GANL boundaries for a fast- spreading environment and provides total coverage at a large scale within the area using combined Sea Beam and SeaMARC II bathymetry and side scan sonar. Incorporating earlier SeaMARC II and Sea Beam surveys, the are of the GANL in which total coverage exists is approximately 140,000 sq km. The principal study area extends form 7 deg 50 min - 10 deg 30 min N and 102 deg and 106 deg W. Twenty km wide surveys extend coverage along the EPR to 4 deg 50 min N and along the Siqueiros fracture zone to 100 deg 30 min W. The completed GANL survey includes these key terrain elements: (1) a remarkably uniform plate fabric of abyssal hills and normal faults; (2) two major fracture zones (first-order discontinuities); (3) numerous seamounts, seamount chains and one very prominent volcanic ridge; (4) a rapidly evolving series f intra-transform spreading centers along the Siqueiros fracture zone for at least the last 4 Ma.


Descriptors :   *TERRAIN , FRACTURE(MECHANICS) , BATHYMETRY , CHAINS , ACOUSTICS , LABORATORIES , DISCONTINUITIES , EAST PACIFIC RISE , VOLCANOES , FAULTS , SIDE LOOKING SONAR , RIDGES , SCANNING SONAR , SEAMOUNTS , GEOLOGY


Subject Categories : Physical and Dynamic Oceanography
      Acoustic Detection and Detectors


Distribution Statement : APPROVED FOR PUBLIC RELEASE