A bottom gravity survey of the shallow water regions of southern Monterey Bay and its geological interpretation

Abstract

Eighty-two ocean bottom gravity stations in southern Monterey Bay were occupied in the summer and fall of 1972 from the R/V ACANIA. A land gravity survey of ten stations about the perimeter of the Bay was conducted in the spring of 19 72. Gravimeters employed were LaCoste and Romberg Models H6G and G-17B, respectively. Conventional steps in data reduction are discussed, and a terrain correction theory unique to ocean bottom gravimetry is presented. The complete Bouguer anomaly (CBA) field for bottom and shoreline surveys is included. The geological interpretation of the gravity data is discussed briefly. Sub-bottom structure of southern Monterey Bay as determined by seismic reflection is verified by the CBA field, and a calculated density contrast between the basement granodiorite and overlying sedimentary strata is found to be realistic. The data supports the existence of a fault oriented beneath the Monterey Submarine Canyon.