Tsunami Travel

The average jetliner travels at 550 miles per hour.

As waves travel across they ocean they cause crests and troughs.  The crest is the peak of a wave, and the trough is the bottom of a wave.  These are known as swells, which rise and fall with a steady motion.  A Tsunami acts very similar to a traditional swell, sometimes rising mere inches above the usual swell height.  A ship passing over a Tsunami while in deep water would not notice the passage.  But Tsunamis are different in several regards in how they travel.

• Their length is often several hundred miles long.
• The speed of the wave can exceed 500 miles per hour.

As the Tsunami increase in height it decreases in speed.

As a Tsunami approaches a coastline it begins to lose its speed and gain in height.  This is because the water depth becomes less, pushing the volume of the water high into the air.  The average speed of a Tsunami making landfall is 50 miles per hour.

Usually, as the Tsunami reaches land it does not break like a nice surfing wave.  Instead it crashes together, creating a white froth that carries debris with it on the front of the wave.

If the portion of the wave to first reach land is the trough, instead of crest, the sea will draw back, sometimes as much as several hundred meters.  The sight of this can attract people down onto the exposed portions of the sea which are normally submerged.  This is a always a fatal mistake.

This is a video from 2010 showing the rise and fall of the ocean over a period of two hours, caused by a Tsunami traveling across the ocean and making landfall in areas.