Seismic Properties of Shallow-Water Sediments: A Component of the STRATAFORM Program
CALIFORNIA UNIV REGENTS LA JOLLA CA SCRIPPS INST OF OCEANOGRAPHY
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My long-term goal is to understand and quantify the effects of seafloor structure on problems of interest to the Navy. The specific objective of this grant is to measure the shear velocity structure of the top few meters of the seafloor in the STRATAFORM study area off Eureka, California. The seafloor shear velocity is determined by the inversion of Scholte waves interface waves traveling at the water-sediment boundary. These waves were excited by small explosions and observed using Ocean-Bottom Seismometers OBSs originally constructed using ONR funding. The preliminary velocity model for this site at 200 meters water depth shows shear velocities about twice as high as those occurring on the deep sea floor, but significantly lower than the velocities occurring in shallower water. The velocity gradient with depth is strong, producing pronounced dispersion in the Scholte waves, in contrast with the shallow-water site nearby, which produced little dispersion in the Scholte waves. Strong dispersion increases the effectiveness of waveform matching types of signal processing and allows single-sensor determinations of range to impulsive sources.
- Physical and Dynamic Oceanography
- Fluid Mechanics