Mass physical properties and slope stability of sediments of the Northern Middle America Trench

Abstract

The mass physical properties (shear strength, porosity, and density) of 32 cores from the northern part of the Middle America Trench have been determined. A stability analysis using the shear strength data (determinations made with a vane shear device) indicate that the sediments are generally stable except on the landward flank of the trench where slumping is possible under the slope conditions observed. Comparisons of gravity-piston core pairs indicate differences in porosity and shear strength that are the result of the coring procedure. The corer used in this study was designed to minimize sample disturbance, but clearly better coring devices are needed before in situ conditions are approached. Porosity and the log of shear strength are inversely related, and porosity has a positive relationship to per cent clay. The specific gravity of the sediments is 2.66 gm/cm3 (at zero porosity), a value similar to that of other areas with a high rate of terrigenous deposition.