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Earth Surface & Interior

Erroneous estimation of tsunami amplitude recently resulted in enormous losses in life and property [e.g., December 26, 2004, Sumatra region]. Among the strength of early warning systems are its capability to provide an estimation of magnitude and location of earthquakes. It is, however, severely limited in estimating the extent of the danger a subsequent tsunami poses to the coastal region. The fault mechanism at the epicenter cannot exactly explain the tsunami source as it is only approximated by the seismic source. The fault slip is not transmitted linearly at the ocean bottom due to e.g., the effect of the bathymetry, the fault depth and the local lithospheric properties. Recently, observational and modeling results confirmed the existence and detectability of tsunamigenic signature in the ionosphere. Based on first principles, the small displacement produced by tsunamis at the sea surface and transmitted in the atmosphere is strongly amplified by the effects of the conservation of kinetic energy and the decrease of density during the upward propagation of the perturbation. The natural high frequency ocean surface variability however does not transfer detectable energy in the atmosphere (Earth's atmosphere behave as an "analog filter"). In about 15 minutes, the waves generated at the sea surface reach ionospheric altitudes (above 100 km) creating fluctuations in the ionospheric plasma. The resulting electron density perturbations can be detected by measurements using GPS satellites. Therefore, an indirect method of ocean monitoring and tsunami detection is possible using ocean-atmosphere-ionosphere coupling. Our objective is to better understand the process of tsunami-atmosphere-ionosphere coupling to estimate the feasibility of a confirmation step in the tsunami warning system based on ionospheric sounding. This technique would support the seismic early warning system and complement the more traditional methods of tsunami detection including tide gauges and ocean buoys. The strength of vast ground-based GPS TEC measurements supported by the numerical modeling of the coupling phenomena will provide us the necessary tools to estimate the amplitude of the sea surface displacement and consequently the strength of the tsunami. The expected significance of this work is that the ionospheric monitoring of TEC perturbations may become an integral part of tsunami warning system that could potentially save thousands of human lives and save tens of billions in property, environmental and other damages.

Project PI: Attila Komjathy/Jet Propulsion Laboratory

Jet Propulsion Laboratory California Institute of Technology M/S 238-600 4800 Oak Grove Drive Pasadena CA 91109

Phone: (818)393-6828

Fax: (818)393-5115

Email:  Attila.Komjathy@jpl.nasa.gov

http://www.gpsworld.com/gps-author/attila-komjathy-72

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Started: Aug 09, 2010

Last Activity: Dec 10, 2010

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