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.
* A tsunami is a series of waves with a long wavelength and period (time between crests) generated by a large, impulsive displacement of sea water. * Time between crests of the wave can vary from a few minutes to over an hour, but generally are in the range of 15 to 30 minutes. The most common cause of a tsunami is sea floor uplift associated with an earthquake. * Tsunamis are also triggered by landslides into or under the water surface, and can be generated by volcanic activity and meteorite impacts.