The massive security operation surrounding Barack Obama's inauguration showed that he will be the most protected president in the history of the United States. Photo: REUTERS.
The physics of a tsunami. Tsunamis can have wavelengths ranging from 10 to 500 km and wave periods of up to an hour. As a result of their long wavelengths, tsunamis act as shallow-water waves. A wave becomes a shallow-water wave when the wavelength is very large compared to the water depth. where g is the acceleration due to gravity (= 9.8 m/s2) and H is the depth of water.
All of the water above it also rises or falls, forming a high point (called a wave crest) or low point (a wave trough) in the water. In this way, each shudder or jolt of the earthquake sends out another tsunami front. In the very deep water of the open ocean, tsunamis travel quickly and spread out from one another. The spacing within a series of seismic waves can be as much as 100 miles (160 kilometers). A newborn tsunami traveling in open water is virtually invisible.