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HOW DOES TUSNAMI COME ?PLEASE SEND A PICTURE ALSO
A tsunami is a wave or series of waves generated at sea by the abrupt movement of a mass of seawater. This is usually caused by the sea floor moving suddenly. Tsunamis may also occur in large lakes.A number of natural phenomena can cause the initial displacement of water that generates a tsunami.

Earthquakes that push up or depress the sea floor by a metre or more, large slippages of the sea floor down slopes, volcanic eruptions, and large volumes of ice breaking off glaciers or ice sheets can all cause tsunamis.

Even large meteorite impacts may generate complex tsunamis as they enter the sea and then hit the sea floor.Out in the open ocean a tsunami is only about 1m high and the distance between its crests or troughs (its wavelength) is typically 200km. In comparison, waves whipped up by winds during storms have peaks about 100m apart and heights ranging from a few metres up to 15m or more when generated by hurricanes.

Tsunamis travel fast in the open ocean, reaching 700km per hour or more. Wind-generated waves travel at only 30 to 100km per hour.Tsunamis are generally unrecognisable at sea because the heights of their crests are relatively small, up to 1m, and successive crests are 15 to 20 minutes apart. However, when a tsunami enters shallower water near the coast it slows down dramatically and becomes compressed. The distance between peaks reduces by 10 times or more and its height increases up to 20 to 30m.

A tsunami doesn't generally break on a beach like a typical wave. Instead, it moves rapidly over the coastline as a steep surging mass of water, destroying or damaging whatever is in its path as it moves forward and then retreats.

Significant tsunamis often affect areas tens of metres above sea level. Some have reached even higher elevations.

If the trough of the tsunami reaches land first, the sea retreats dramatically before rising. If the crest arrives first, it causes a rush of water across the land with little or no warning. It can be travelling up to 100km per hour.

Since tsunamis are usually a series of waves, multiple surges may flow across the coastline and the danger can last for many hours. The shape of coastlines may also deflect or reflect the tsunami causing complex arrivals of waves.


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