What Causes a Tsunami?
Earthquake Causes TsunamiEnergy accumulates in the overriding plate until it exceeds the frictional forces between the two stuck plates. When this happens, the overriding plate snaps back into an unrestrained position. This sudden motion is the cause of the tsunami — because it gives an enormous shove to the overlying water. At the same time, inland areas of the overriding plate are suddenly lowered.Tsunami Races Away From the EpicenterThe moving wave begins travelling out from where the earthquake has occurred. Some of the water travels out and across the ocean basin, and at the same time, water rushes landward to flood the recently lowered shoreline.Tsunami «Wave Train»Many people have the mistaken belief that tsunamis are single waves. They are not. Instead tsunamis are «wave trains» consisting of multiple waves. The chart on this page is a tidal gauge record from Onagawa, Japan beginning at the time of the 1960 Chile earthquake. Time is plotted along the horizontal axis and water level is plotted on the vertical axis. Note the normal rise and fall of the ocean surface, caused by tides, during the early part of this record. Then recorded are a few waves a little larger than normal followed by several much larger waves. In many tsunami events, the shoreline is pounded by repeated large waves.For more details:Product Installation video Examples
Автор: David Hill