OCEAN BOTTOM REFLECTION LOSS FROM ELASTIC SOLID MATERIALS:REFLECTIONS ON REFLECTIVITY

摘要

In large regions of the Pacific Ocean the ocean bottom is characterized by a thin layer of sediment over an elastic solid crust. The presence of the solid basement close to the sea floor generates additional losses that affect long range acoustic propagation. This paper describes geoacoustic inversion of reflection loss versus angle data at very low frequencies (-16 Hz) to obtain estimates of the compressional (p) and shear (s) wave velocities in uppermost oceanic crust, Layer 2A. The data were obtained in experiments using small explosive charges and a horizontal line array. The measurements were made at thin sediment sites located at increasing distance from the spreading centre at the Endeavour segment of the Juan de Fuca Ridge of the west coast of British Columbia to determine the effect of crustal age of the basalt on the seismic velocities.