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 | EARTHQUAKE - A shaking of part of the earth's crust due to natural subterranean causes. The vibrations are strongest near the origin of the shock, dying out gradually at increasing distances. Earthquakes result from stresses in the earth's crust. This stress can be relieved by the slipping of one rock surfaces over another. Earthquakes thus set up are tectonic, or due to fractures in the rock. |
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 | TSUNAMI - Tsunamis are large water waves typically generated by seismic activity. When these earthquakes occur beneath the sea, the water above the deformed area is displaced from its equilibrium position. Waves are formed as the displaced water mass, which acts under the influence of gravity, attempts to regain its equilibrium. |
