A tsunami is a large ocean wave usually caused by an underwater earthquake or a volcanic explosion. Tidal waves are caused by the forces of the moon, sun, and planets upon the tides, as well as the wind as it moves over the water. Tsunamis are generated by any large, impulsive displacement of the sea level.
With typical waves, water flows in circles, but with a tsunami, water flows straight. The most common cause of a tsunami is sea floor uplift associated with an earthquake.
In some cases, a wall of water or series of breaking waves may form.
How is a tsunami different from a wind-generated wave?
Can strike-slip (horizontal motion) earthquakes trigger tsunamis?
Yes, approximately 10-15% of damaging tsunamis are triggered by strike-slip earthquakes.
Also, wind-generated waves break as they shoal and lose energy offshore. A twenty foot tsunami is a twenty foot rise in sea level.
What are nature’s signs that a tsunami may be imminent?
Did you know…A tsunami travels from the central Aleutian Islands to Hawaii in about 5 hours and to California in about 6 hours, or from the Portugal coast to North Carolina in about 8.5 hours. Tsunamis range in size from inches to over a hundred feet.
In deep water (greater than 600 feet), tsunamis are rarely over 3 feet and are not normally noticed by ships due to their long period or time between crests.