Tsunamis are rare and occur only about 6 times in every century.  Many people think that tsunamis are the result of earthquakes.  The earthquakes have to happen underwater and be of greater intensity then a 6.0 for them to cause a tsunami.   Most earthquakes that take place underwater, at the teutonic plates or earths crust, which slips, and causes the displacement of a vast amount of seawater; have the ability to cause a tsunami, but not every one does.  Researchers say that if a person suddenly sees the water recede from the beaches, chances are that a tsunami is coming and the person should immediately get to higher ground.  It is difficult to warn people about a tsunami because it occurs suddenly then rushes in all directions at a speed of over 600 miles an hour, but it is not over 2 to 3 feet high until it reaches shallow water near land.  At that point, it suddenly swells and rushes forward, destroying everything in its path.