What is a tsunami?
The phenomenon we call tsunami is a series of large waves of extremely long wavelength and period usually generated by a violent, impulsive undersea disturbance or activity near the coast or in the ocean. When a sudden displacement of a large volume of water occurs, or if the sea floor is suddenly raised or dropped by an earthquake, big tsunami waves can be formed by forces of gravity. The waves travel out of the area of origin and can be extremely dangerous and damaging when they reach the shore. The word tsunami (pronounced tsoo-nah’-mee) is composed of the Japanese words “tsu” (which means harbor) and “nami” (which means “wave”). Often the term, “seismic or tidal sea wave” is used to describe the same phenomenon, however the terms are misleading, because tsunami waves can be generated by other, non seismic disturbances such as volcanic eruptions or underwater landslides, and have physical characteristics different of tidal waves. The tsunami waves are completely unrelated to the ast
Tsunamis are sea waves generated by an abrupt displacement of large volumes of water. Large subduction zone earthquakes of magnitude 7.5 or greater are the most frequent cause of tsunamis, as the vertical displacement of the sea floor along the subduction zone fault results in displacement of the water above. A tsunami can also be generated by other types of submarine faults, as well as by large coastal or submarine landslides. Not all submarine earthquakes will cause tsunamis. A submarine earthquake with pure strike-slip motion may not produce a tsunami, because water is less likely to be displaced unless the ocean bottom is rough. Click here for a more in depth discussion on tsunamis. • Q: Is any place safe from earthquakes? A: No place is completely safe from natural hazards. We choose what kinds of hazards we are willing to live with, and to prepare for. Regions of the U.S. that have almost no earthquake hazard, like the midwest, may instead have hazards from floods, tornados, or h
A tsunami is a series of waves with a long wavelength and period (time between crests) generated by a large, impulsive displacement of sea water. Time between crests of the wave can vary from a few minutes to over an hour. Tsunamis are often incorrectly called tidal waves; they have no relation to the daily ocean tides. How are tsunamis generated? Tsunamis are generated by any large, impulsive displacement of the sea level. Tsunamis are also triggered by landslides into or under the water surface, and can be generated by volcanic activity and meteorite impacts. How often do tsunamis occur? On the average, two tsunamis occur per year throughout the world which inflict damage near the source. Approximately every 15 years a destructive, ocean-wide tsunami occurs. Can strike-slip (horizontal motion) earthquakes trigger tsunamis? Yes, approximately 15% of all damaging tsunamis were triggered by strike-slip earthquakes. This type of earthquake is less likely to trigger a tsunami than one wit
A tsunami (pronounced “soo-nahm’ee”) is a series of waves generated by an undersea disturbance such as an earthquake. From the area of the disturbance, the waves will travel outward in all directions, much like the ripples caused by throwing a rock into a pond. The time between wave crests may be from 5 to 90 minutes, and the wave speed in the open ocean will average 450 miles per hour. Tsunamis reaching heights of more than 100 feet have been recorded. As the waves approach the shallow coastal waters, they appear normal and the speed decreases. Then as the tsunami nears the coastline, it may grow to great height and smash into the shore, causing much destruction. • Tsunamis are caused by an underwater disturbance usually an undersea earthquake. Landslides, volcanic eruptions, and even meteorites can also generate a tsunami. • Tsunamis can originate hundreds or even thousands of miles away from coastal areas. Local geography may intensify the effect of a tsunami. Areas at greatest risk
