Research Technical Report

Multibeam Bathymetry and Acoustic Backscatter Imagery of the Southern Monterey Bay Shelf

Eittreim, S.L., A.J. Stevenson, L.A. Mayer, J. Oakden, C. Malzone, and R. Kvitek (1997)

In: S.L. Eittreim (editor), Southern Monterey Bay Continental Shelf Investigations: Former Fort Ord Restricted Zone. U.S. Department of the Interior, U.S. Geological Survey, Open File Report 97-450. p. 1-21.

ABSTRACT

The seafloor of the former Fort Ord Restricted Zone (FORZ) and surrounding area is a generally flat, featureless plain with the exception of a) the subtle sculpting of coarse sand troughs due to active sand transport, and b) the outcrop of older consolidated bedrock over limited areas. Outcropping bedrock surrounds the Monterey Peninsula and occurs in the Monterey Bay Fault zone, a moderately active fault zone north of Monterey that has locally tilted and disrupted the shelf stratigraphy. Within the realizable limits of detection of the EM-1000 multibeam system, no surficial debris could be identified that might be interpreted as leftover from the Army's use of this area over the last 70 years. The EM-1000 system in this water depth range has a horizontal pixel resolution of 5 m in bathymetry and 2.5 m in backscatter, and a vertical resolution better than 1 m. Higher resolution surveys using 500-kHz side-scan systems with 10-cm pixel resolution were carried out in a 1x1 km2 core area of the FORZ. Only ephemeral features, interpreted to be biologic targets, could be found.