Proceedings of a Workshop on the Physical Properties of Volcanic Seafloor, Held at Woods Hole, Massachusetts on April 24-26, 1990
WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
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The volcanic ocean floor, defined by the uppermost basaltic lavas of oceanic Layer 2, is the single largest and most consistent contrast in physical properties on the earths surface. More than 60 of our planet is coated by this boundary that constitutes a contrast in both compressional and shear wave velocity of several kms. Propagation through the ocean floor, and reflection and scattering from it, cannot be understood quantitatively without a knowledge of the properties of this boundary. The compressional wave velocity of the volcanic seafloor on the scale of tens to hundreds of meters is almost one third the velocity when measured in the laboratory at the scale of centimeters, and evidence exists to suggest that at the large scale of 10-100 meters this velocity doubles during the first 7-10 my after the formation of the crust or within a few hundred kilometers of the ridge axis. Both these phenomena are illustrated in the figure on the cover of this report. A knowledge and understanding of the spatial variability in structure of the uppermost oceanic crust is a key to the understanding of both the temporal and along-axis variability in accretion processes. This is currently one of the most important unknowns that blocks progress in the quantitative modeling of mid-ocean ridge systems.
- Physical and Dynamic Oceanography
- Geology, Geochemistry and Mineralogy
- Acoustic Detection and Detectors