GEOLOGY

Detailed explanation-1: -The crests of tsunami waves may be more than a hundred kilometers or more away from each other. Therefore, passengers on boats at sea, far away from shore where the water is deep, will not feel nor see the tsunami waves as they pass by underneath at high speeds.

Detailed explanation-2: -Tsunamis are always largest at the coast. In the deep ocean, the height of a tsunami is usually too small to be noticed, even by small boats in the water.

Detailed explanation-3: -Because of their large wavelength and deep water (thus low amplitude), most tsunamis pass in the mid-ocean unnoticed. However, as the wave encounters shallower water, its velocity slows, wavelength decreases, and its amplitude increases (image from GlobalSecurity.org).

Detailed explanation-4: -Tsunami movement Once a tsunami forms, its speed depends on the depth of the ocean. In the deep ocean, a tsunami can move as fast as a jet plane, over 500 mph, and its wavelength, the distance from crest to crest, may be hundreds of miles.

Detailed explanation-5: -Even if a tsunami wave may have been 1 meter of less in the deep ocean, it may grow into a huge 30-35 meter wave when it sweeps over the shore. Thus, tsunami waves may smash into the shore like a wall of water or move in as a fast moving flood or tide-carrying everything on their path.