Introduction:
when a body of water, such as an ocean is rapidly displaced on a massive scale then we call it tsunami. It Is a series of waves. The effects of a tsunami can range from unnoticeable to devastating. There are various reasons behind the tsunami.
1.earthquakes. 2.mass movements. 3.Volcanic erosions. 4.Under water explosions. 5.Meteorite impacts. The term tsunami comes from the Japanese language meaning harbour. tsunami is used for both the singular and plural. The term was created by fishermen.
Causes:
1.it happens when the sea floor abruptly deforms and vertically displaces the overlying water. 2.it also happens because of the large vertical movements of the Earth's crust can occur at plate boundaries. 3.Subduction earthquakes are particularly effective in generating tsunamis. 4.too much stress is put on the lip and it snaps back, sending shockwaves through the Earth's crust, causing a tremor under the sea, known as an Undersea Earthquake. 5.Sub-marine landslides and collapses of volcanic edifices may also disturb the overlying water column. 6.violent submarine volcanic eruption can uplift the water column and form a tsunami.
Tsunami wave:
The ocean waves are divided into three groups. They are characterized by depth.
1.Deep water.
2.Intermediate water.
3.Shallow water.

tsunami waves are considered shallow-water waves. As the wave approaches the shallow waters of shore, its time period remains the same, but its wavelength decreases rapidly, thus causing the water to pile up to form tremendous crests, in an effect known as "shoaling".
Signs of an approaching tsunami:
1.An earthquake may be felt. 2.Large quantities of gas may bubble to the water surface and make the sea look as if it is boiling. 3.The water in the waves may be unusually hot. 4.The water may smell of rotten eggs or of petrol or oil. 5.A thunderous boom may be heard then a roaring noise as of a jet plane or a whistling sound. 6.The water may sting the skin. 7.A flash of red light might be seen near the horizon. 8.The sea may recede to a considerable distance.
Warnings and prevention:
Tsunamis cannot be prevented or precisely predicted
1.Regions with a high risk of tsunamis may use tsunami warning systems to detect tsunamis and warn the general population before the wave reaches land.
2.Computer models can roughly predict tsunami arrival and impact based on information about the event that triggered it and the shape of the seafloor and coastal land. 3.the early warnings comes from nearby animals. 4.building tsunami walls of up to 4.5 m (13.5 ft) high in front of populated coastal areas. 5.floodgates and channels to redirect the water from incoming tsunamis. 6.Environmentalists have suggested tree planting along stretches of sea coast which are prone to tsunami risks, it would take some years for the trees to grow to a useful size. And such plantations could offer a much cheaper and longer-lasting means of tsunami mitigation.

Author: Pacific Disaster Center
The Pacific Disaster Center's mission is to provide applied information research and support for the development of more effective policies and, programs, for the disaster management. PDC give information and help during times of natural disaster. PDC Helps people during Natural calamities