The typical cause is an earthquake under the ocean floor. Tsunamis can also be caused by huge landslides into bodies of water, or by the impact of a large enough meteorite into an ocean or very large body of water. These things produce a wave that shifts not just a few meters of surface water, but the entire column of water from the floor to the surface. They contain enormous amounts of energy. Tsunamis can push huge amounts of water over islands and coastal regions causing the deaths of hundreds of thousands or millions of people, and they can cause millions or even billions of dollars worth of damage. Depending on whether the leading element of the tsunami is a trough or a crest (it can be either) there may be an eerie ebbing or pulling back of the water along the shore; it must appear to observers like an unnatural pulling back of the tide. This would happen if the leading element is a trough. If you ever witness this, run with all your might; seek high ground.
Underwater earthquakes, volcanic eruption or land slides.
Beginning of a tsunami wave
Sometimes plate boundaries abruptly deform and displace the overlying water vertically. Subduction earthquakes are efficient in generating a tsunami. In the 1940s, an earthquake measuring 7.8 on the Richter scale gave rise to a tsunami. Explosive volcanic action, landslides and impact events can also start a tsunami. The water wave may reach 50 to 150 meters and cover a height of 500 meters on local mountains. A "megatsunami" is caused by large landslides. The displaced water mass moves under the effect of gravity. This water radiates across the ocean similar to ripples in a pond.
Signs that a tsunami is approaching
Tsunami warning system
Such systems comprise of two parts:
There exist international and regional tsunami warning systems. The underlying principle used in both is that tsunamis move at a speed of 0.14 to 0.28 km/sec while seismic waves of 4 km/sec. Thus, when an earthquake is confirmed, there is sufficient time to predict a tsunami.
Reducing the effect of a tsunami
These measures slow down and moderates a tsunami. However, they cannot totally prevent the destruction and loss of life.
Records related to tsunami
In the Indian Ocean, an earthquake of 9.0 magnitude on the Richter scale took place. The epicenter was close to the west coast of the Indonesian island of Sumatra. The Earth's tectonic plates moved violently and displaced a large quantity of water. Powerful shock waves were sent in all directions. At some places, these waves reached a height of 9 meters. Within a span of some hours, killer waves hit the coasts of 11 Indian Ocean countries and devastated properties from Thailand to Africa.
Other tsunami facts
At the deepest point in the ocean, Tsunamis can have a speed of 600 mph. Close to the shore, this speed reduces to 30 to 40 mph. This energy of the wave's speed is transformed to increased height and sheer force. These waves can be as long as 100 kilometers and one hour apart. They can cross huge oceans without much loss of energy. Tsunamis can take place at any time in night or day. They can move up the rivers and streams that end up in the ocean. Tsunamis move faster than a human being.
Megatsunami
If the waves range from 40 meters to more than 100 meters, they are called as a "megatsunami". When they reach land, they acquire more height due to the force of impact. They are also called as "iminami" or "wave of purification". Tsunami is a Japanese word with the English translation: "harbour wave". In the past, tsunamis have been referred to as "tidal waves" or "seismic sea waves". The term "tidal wave" is misleading; even though a tsunami's impact upon a coastline is dependent upon the tidal level at the time a tsunami strikes, tsunamis are unrelated to the tides. (Tides result from the gravitational influences of the moon, sun, and planets.) The term "seismic sea wave" is also misleading. "Seismic" implies an earthquake-related generation mechanism, but a tsunami can also be caused by a non-seismic event, such as a landslide or meteorite impact. Tsunamis can have wavelengths ranging from 10 to 500 km and wave periods of up to an hour. As a result of their long wavelengths, tsunamis act as shallow-water waves. In the deep ocean, a tsunami has a small amplitude (less than 1 metre) but very long wavelength (hundreds of kilometres). This means that the slope, or steepness of the wave is very small, so it is practically undetectable to the human eye. However, there are ocean observing instruments that are able to detect tsunamis.
they are big waves that form because of an earthquake. they can be up to 30 meters high and before they hit all the water will be sucked in so you can see all the sea urchins and such but you should probably evacuate if you see that. they can travel up to 500 mph underwater but if you were on a boat right above a passing one you wouldn't feel it. they normally form on convergent boundaries because convergent boundaries have bigger earthquakes. transform and divergent boundaries can have them too but they will only be like 3 feet high. Hope I helped (by the way I am 12)
its caused by a sudden change on the sea floor.
That they are just underwater earthquakes
Tsunamis happen when tectonic plates shift
Tsunamis that are triggered by volcanic eruptions
Tsunamis cannot be prevented.
Yes, of course, India can have tsunamis.
tsunamis are cool
Wind does not affect tsunamis.
a tsunamie is a serious ocean wave
Tsunamis that are triggered by volcanic eruptions
Tsunamis cannot be prevented.
They cause tsunamis
Unfortunately there is nothing we can do to prevent tsunamis.
the tsunamis can carry jellyfish along
Wind does not affect tsunamis.
Yes, of course, India can have tsunamis.
tsunamis are cool
No. Tsunamis cannot be stopped.
they killed a awful lot of people
they killed a awful lot of people