Tsunami: An Introduction
Tsunamis are huge waves that come against land with little or no warning. Caused by earthquakes or volcanoes that move the land on the bottom of the ocean, these waves are the most powerful and vicious waves produced in the ocean. They can cross great distances at speeds of 650 to 800 kilometers per hour, losing very little energy as they move. While they may be only a meter high as they travel across the open ocean, tsunamis can become terribly tall as they approach the coast. If the trough of a tsunami hits land first, the water is sucked away from harbors and beaches so rapidly that it leaves flopping fish and boats behind. This tsunami wave can be a wall of water 7 meters to 33 meters high. The crest of the wave, which eventually slams into the coast, generally within about fifteen minutes, can move much faster than a person can run. Water moving inland has the ability to displace everything in its path. The retreating wave drags people, buildings, boats, vegetation, and even the sand from the beach out to sea.
Tsunami is a Japanese word with the English translation, "harbor wave." Represented by two characters, the top character, "tsu," means harbor, while the bottom character, "nami," means, "wave." Formerly, the scientific community sometimes referred to tsunamis as “tidal waves” by the general public, and as “seismic sea waves”. The term "tidal wave" is a misnomer; though a tsunami's influence upon a coastline is conditional upon the tidal level at the time a tsunami strikes, tsunamis are not related to the tides. Tides result from the excessive, extraterrestrial, gravitational influences of the moon, sun, and planets. The term "seismic sea wave" is also ambiguous. "Seismic" means an earthquake-related generation mechanism, however a tsunami can also be caused by a nonseismic event, such as a earthquake or meteorite impact.........
