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.
That's very fast and it's all because of how deep the water is (thousands of feet) and how much energy the earthquake puts into the tidal wave. So now to directly answer your question, the amount of time it takes for a tsunami to come after an earthquake occurs can be as little as 5 minutes or as long as 24 hours. It just depends on how far away the earthquake was from the coast.