Tsunami - Trabajo de Inglés

Presentation Tsunamis:

Good afternoon to everyone , thank you all for coming to my presentation, my name is Nicolás Parra and today I will speak about Tsunamis. I will be talking about the countries that have been frecuent victims of this natural disaster, and also about the biggest tsunamis in the history of mankind.

Tsunamis are giant waves caused by earthquakes or volcanic eruptions under the sea. Out in the depths of the ocean, tsunami waves do not dramatically increase in height. But as the waves travel inland, they build up to higher and higher heights as the depth of the ocean decreases. The speed of tsunami waves depends on ocean depth rather than the distance from the source of the wave. Tsunami waves may travel as fast as jet planes over deep waters, only slowing down when reaching shallow waters.

The energy of a tsunami depends on the height, the length of the wave and its front. The total energy discharged on a coastal area also depends on the number of peaks that carry the train of waves. Often a tsunami that travels long distances, reduces the height of the waves, but it will always keep a certain speed, determined by the depth where the tsunami travels. Normally, in the case of tectonic tsunamis, the height of the tsunami wave in deep water is about 1.0 meters, but the wave height may reach several hundred kilometres. This is what allows, even when the length in the open ocean is low, that the height of this wave will aggressively grow with decreasing depth, which, by reducing the speed of the front of the tsunami, will necessarily grow up by transformation kinetic energy into potential energy. That is why the mass of water can raze its path inland, only by being some meters long.

History has left us more than 13 major tsunamis in the world since 1960 to the present. Each of them has had a very important significance and magnitude especially regarding to victims, casualties and material damage. Here you can see in the map below the countries where tsunamis have occurred and how many times they have been affected. After that, we will detail the ten largest in history.

Number 10: Hokkaido Tsunami , 1993:

After an 7.8 degrees (Richter scale) earthquake, the japanese island of Hokkaido was strike by 30 meters waves leaving more than 197 death victims and more than 250 harmed by the earthquake and tsunami

Number 9:  Java Tsunami, 2006:

A 7 meters wave raze throw the indonesian coast including java 150km of surface. 668 people where found dead, 65 never appeared and more than 9000 people was damaged.

Number 8: Tsunami of Papua New Guinea, 1998:

The earthquake of 7.0 degrees on the Richter scale, triggered a tsunami with waves of 15 meters high, causing at least 2,183 deaths, over 500 missing and about 10 thousand victims

Number 7: Tumaco Tsunami 1979:

The tsunami of December 12, which began with an earthquake of 7.9 on the Richter scale, struck with great force off the coast of Colombia. In total, 259 people died, while 798 were injured and 95 missing.

Number 6: Alaska Tsunami 1964:

The tsunami triggered by an earthquake measuring 9.2 on the Richter scale, devastated the western coast of North America, the 30-meter waves killed 121 people in places like Alaska and California.

Number 5: Tsunami Moro Gulf, 1976:

On August 16 waves of 5 meters high hit the coast of the Philippines. They were produced by an earthquake of 7.9 magnitude on the Richter scale which produced extensive damage, as 90,000 people homeless. Instead 5,000 people were killed and another 9,500 wounded.

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