Tsunami Detection System
Patent application, Filed 22 March 2010
DEPARTMENT OF THE NAVY WASHINGTON DC
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The present invention is directed to tsunami detection. In particular, the present invention is directed to a system that can reduce the amount of time it takes to detect a tsunami by an order of magnitude by using an underwater fiber optic cable as a pressure sensor. Although tsunami waves contain tremendous energy, their distributed nature e.g., very long periods and wavelengths make detection difficult. A satellite radar sensor spanning the length of an ocean. A tsunami is considered a shallow water wave, having a large wavelength compared to the ocean depth. A tsunami can have wavelengths ranging from 100 to 500 km, and amplitudes up to 60 cm i.e., a pressure signal of up to 1 psi. A telecommunications grade optical fiber cable fitted with repeaters, can measure pressure signals over spatial cells as small as 0.5 m using Rayleigh scattering effects and optical time delay reflectometry. The tsunami pressure signals are extracted from the pressure signals generated by wind-generated water waves through signal processing to distinguish between the substantial differences in wavelength, period and propagation speed.
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