This is a series of waves that are generated due to sudden movement of the seabed caused by earthquakes, underwater volcanic eruptions, landslides, meteorite impacts.
The majority of tsunamis occurring in the Pacific Ocean, affects limited portions of the coast, causing minor damage.
The most devastating Tsunami are caused by strong earthquakes generated by vertical movement (uplift or subsidence) of the Earth's crust along fault lines and edges of the plateau. Tidal waves destroy the towns their effects are felt throughout the Pacific Ocean basin.
Phenomena are rare and occur every year.
One of these occurred May 22, 1960 and brought death and destruction on the shores of the Pacific from Chile to Hawaii and from Japan to the Philippines.
Not all earthquakes generate tsunami and now there is no way of being able to predict.
Stations studying the wave characteristics of the waves come, however.
Tsunami is propagated from the epicenter in all directions, but with higher energy perpendicular to the fracture line that generated the earthquake.
The speed depends on depth.
In the open ocean with high depth, the speed varies between 500 and 1000 km / hour. The normal waves have speeds of 90 km / hour.
The maximum distance between two wave crests can vary from 500 to 650 km. The ocean waves have normal lengths around 100 meters.
Between the passage of a ridge and the next lag of 10 to 45 minutes. The movement may continue for hours and it is said that the first wave is the most intense.
The height of waves in the open ocean is only 30 - 60 cm.
With these dimensions and the enormous length, these waves pass unnoticed even by boats, ships and aircraft.
Are clearly visible in the open ocean only when the speed of propagation is particularly strong in one direction than the other.
The strength and power of the tsunami comes from the fact that it is waves that affect the entire water column from surface to bottom.
When the Tsunami reaches the coast, the wave velocity decreases and the height increases. Can form a veritable wall of water to heights that can easily exceed 10 meters. The wave of the highest of which we hear, 60 yards, struck the Lituya Bay in Alaska in 1958.
The effects vary depending on the type of coastline and the seabed bathymetry.
The first sign of the arrival of a tsunami is the backwash water out to sea or the slow rise in water level which continues for 10-15 minutes.
The power and destruction are linked both to the front turbulent wave that breaks both the power of the currents that are generated.
The boats and all that is on the coast, can be lifted and thrown against breakwaters or pressures on land.
The shallow waters of bays and ports to show the first arrival of the tsunami.
From 1900 to 2000 it occurred in the Pacific 796. There have been years without a tidal wave.
117 have caused damage only in the vicinity of the source.
9 have caused extensive devastation to the entire Pacific.
The 1938 was the year when there were more Tsunami (19), fortunately, all of low intensity, and without damage.
17% of the tsunami is generated near Japan. Following, South America 15%
New Guinea and Solomon Islands 13%, Indonesia 11%, 10% Kurile and Kamchatka, Mexico and Central America 10%, Philippines 9%, 7% of New Zealand and Tonga, Alaska and West Coast and Canada 7% United Satti, Hawaii 3% .
Recent Tsunami:
September 2, 1992 Nicaragua max height 10 m - 170 dead.
July 12, 1993 Hokkaido max height 30 m - 200 dead.
June 2, 1994 Java max height 14 m - 220 dead.
February 21, 1996 Peru max height 5 m - 12 dead
July 17, 1998 New Guinea Max height 15m - 2000 deaths
June 23, 2001 Peru max height 5 m - 50 dead
December 26, 2004
At 00:58 there was a catastrophic earthquake with its epicenter in the sea NW of Sumatra. (Lat 3.30N long 95.78 E).
The magnitude is about 9.0 Richter.
Over the past 100 years, earthquakes of similar intensity are only 2: Alaska 1964 9.2 Richetr and Chile 1960 9.5 Richter.
Following has formed a devastating tsunami that has affected all the Pacific coast, causing thousands of casualties.
The earthquake was caused by fracture (1000 km in length at 9-10 km depth) occurred in one of several faults that affect the area. The collapse of the plateau caused the Tsunami.
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