Robert P. Comer, Department of Earth and Planetary Sciences, Massachusetts Institute of Technology and the Flat Earth Model

Robert P. Comer, Department of Earth and Planetary Sciences, Massachusetts Institute of Technology, Geophys. J. R. astr. Soc. (1984) 77, 1-21, “The tsunami mode of a flat earth and its excitation by earthquake sources”,

“Several other investigators have attacked the problem of tsunami generation with the ocean and solid earth fully coupled. Podyapolsky (1970) and Alexeev & Gusiakov (1976) considered a point earthquake source in the solid earth, which was represented by an elastic half-space; however, the accounts of their methods are rather incomplete and only a few results are illustrated. Yamashita & Sato (1974) extended a similar model to a finite, moving source, but the explanation of how they perform the key step of evaluating the residue at the ‘tsunami pole’ is omitted. And although the works just cited are all based on flat earth models, none make reference to the tsunami normal mode of a flat ocean-earth system… Ward’s results are useful and important, yet it is nonetheless also rewarding to explore tsunami normal mode excitation using a flat earth model. At the very least, two independent solutions of very similar problems can be used to check one another. Also, no significant increase in accuracy can be obtained simply by going from a flat earth model to a spherical one, since the tsunami mode eigenfunctions (unlike those of long-period seismic surface waves) do not penetrate the solid earth very deeply, and a correction for geometric spreading on a spherical, rather than flat, surface is easily applied. Of course, the geometric spreading of real tsunamis is different from either idealized case, due to the bathymetric variations (resulting in variations in wave speed) in the real oceans.” (pg. 2)



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