Saturday, 21 April 2012
TSUNAMI - ENVIRONMENTAL DISASTER
Tsunami Means:
A tsunami (pronounced sue-nahm-ee) is a series of huge waves that can cause great destruction to human's life, constructions etc when they strike a coastal area. Tsunami waves do not resembles normal sea waves, because their wavelength is very long. Instead of appearing as a breaking wave, a tsunami may instead initially resemble a rapidly rising tide, and for this reason they are often referred to as tidal waves.
The Word Tsunami: The word tsunami comes from the Japanese word meaning "harbor wave." Tsunamis are sometimes incorrectly called "tidal waves" -- tsunamis are not caused by the tides (tides are caused by the gravitational force of the moon on the sea). Regular waves are caused by the wind.
Causes of Tsunami:
Tsunamis are caused by an underwater earthquake, a volcanic eruption, an sub-marine rock slide, or, more rarely, by an asteroid or meteoroid crashing into in the water from space. Most tsunamis are raised by underwater earthquakes, but not all underwater earthquakes cause tsunamis - An earthquake which has to be over about magnitude of 6.75 Richter scale causes a tsunami. Mostly 90% of all tsunamis occur in the Pacific Ocean.
Tsunami generated by seismicity
The principal of generation of a tsunami is the displacement of a substantial volume of water or perturbation of the sea. This displacement of water is mainly due to earthquakes, landslides, volcanic eruptions, glacier calving or more rarely by meteorites and nuclear tests. The waves formed in this way are then sustained by gravity. Tides do not play any part in the generation of tsunamis.
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| Development of a Tsunami |
A tsunami starts when a huge volume of water is quickly shifted. This rapid movement makes an underwater earthquake (when the sea floor quickly moves up or down), a rock slide, a volcanic eruption, or another high-energy event. After the huge volume of water has moved, the resulting wave is very long (the distance from crest to crest can be hundred of miles long) but not very tall (roughly 3 feet tall). The wave propagates (spreads) across the sea in all directions; it can travel great distances from the source at tremendous speeds.
The Size of a Tsunami:
Tsunamis have an extremely long wavelength (wavelength is the distance between the crest (top) of one wave and the crest of the next wave) up to several hundred miles long. The period (the time between two successive waves) is also very long about an hour in deep water. In the deep sea, a tsunami's height can be only about 1 m (3 feet) tall. Tsunamis are often barely visible when they are in the deep sea. This makes tsunami detection in the deep sea very difficult.
Tsunamis have an extremely long wavelength (wavelength is the distance between the crest (top) of one wave and the crest of the next wave) up to several hundred miles long. The period (the time between two successive waves) is also very long about an hour in deep water. In the deep sea, a tsunami's height can be only about 1 m (3 feet) tall. Tsunamis are often barely visible when they are in the deep sea. This makes tsunami detection in the deep sea very difficult.
The Speed of a Tsunami:
A tsunami can travel at well over 970 kph (600 mph) in the open ocean - as fast as a jet flies. It can take only a few hours for a tsunami to travel across an entire ocean. A regular wave (generated by the wind) travels at up to about 90 km/hr.
A tsunami can travel at well over 970 kph (600 mph) in the open ocean - as fast as a jet flies. It can take only a few hours for a tsunami to travel across an entire ocean. A regular wave (generated by the wind) travels at up to about 90 km/hr.
Tsunami Warning Systems:
Tsunami warning systems exist in many places around the world. As scientists continuously monitor seismic activity (earthquakes), a series of buoys float off the coast and monitor changes in sea level. Unfortunately, since tsunamis are not very tall in height when they are out at sea, detection is not easy and there are many false alarms. Sirens at affected beaches may be activated -- do not ignore them!
Tsunami warning systems exist in many places around the world. As scientists continuously monitor seismic activity (earthquakes), a series of buoys float off the coast and monitor changes in sea level. Unfortunately, since tsunamis are not very tall in height when they are out at sea, detection is not easy and there are many false alarms. Sirens at affected beaches may be activated -- do not ignore them!
Tsunami all over the world
| PERIOD | PLACE | REASON | TSUNAMI EFFECTS |
| 65 million years ago | Chicxulub crater at the tip of Mexico's Yucatán Peninsula | Meteoroid impact | Impact and tsunami may have triggered the K-T mass extinction |
| 1490 B.C. | Greece (Aegean Sea) | Eruption/collapse of the volcano of Santorini | end of the Minoan civilization in Greece. |
| January 26, 1700 | Japan (Pacific Ocean) | | Earthquake of magnitude 9.0 off the western coast of Vancouver Island, Canada |
| August 26, 1883 | Indonesia | Eruption/collapse of the volcano Krakatoa | Almost 40,000 people died. |
| June 15, 1896 | Honshu, Japan | Offshore earthquake of magnitude 7.2 | 28,000 people killed |
| November 18, 1929 | Grand Banks, Canada (Atlantic Ocean) | Offshore earthquake of magnitude 7.2 | 27 people died. |
| April 1, 1946 | Aleutian Islands, Alaska (Pacific Ocean) | Earthquake of magnitude 7.8 in the Aleutian Islands of Alaska | Over 170 people died |
| November 4, 1952 | Kamchatka Peninsula, Russia (Pacific Ocean) | An earthquake of magnitude 8.2 off the coast of the Kamchatka Peninsula (Russia) | No lives lost |
| March 9, 1957 | Aleutian Islands, Alaska (Pacific Ocean) | Earthquake of magnitude 8.3 that occurred south of the Andreanof Islands (in the Aleutian Islands of Alaska) | No lives lost |
| July 9, 1958 | Lituya Bay, Alaska | Landslide | Initial wave up to 520 meters ( 1,720 feet) high traveling at 160 kph (100 mph) |
| May 22, 1960 | Chile (Pacific Ocean) | Earthquake of magnitude 8.3 that occurred off the coast of South Central Chile | Up to 2,290 people died (due to the Earthquake and tsunami) |
| March 28, 1964 | Prince Williams Sound, Alaska (Pacific Ocean) | An earthquake of magnitude 8.4 in Prince William Sound (Alaska) | 122 people died |
| November 29, 1975 | Hawaii (Pacific Ocean) | Earthquake of magnitude 7.2 (and subsequent rock slide) | 2 people died |
| Ssptember 1, 17, 1992 | Nicaragua (Pacific Ocean) | Offshore earthquake of magnitude 7.0 | About 200 people killed |
| July 17, 1998 | Papua-New Guinea | Underwater landslide that was triggered by an earthquake | Thousands of people killed |
| June 23, 2001 | Southern Peru (Pacific Ocean) | Earthquake | |
| December 26, 2004 | Indonesia, W Thailand, Sri Lanka, SE India (Indian Ocean) | Earthquake of magnitude 9.0 in the southern Indian Ocean | About 150,000 people died in the tsunamis |
| 25 October 2010 | Bengkulu and West Sumatra | Sumatra earthquake was a magnitude 7.7 | Displaced more than 20,000 people and affected about 4,000 households. 435 people were killed, with over 100 more still missing |
| March 11, 2011 | Japan | A 9.0 magnitude earthquake, that triggered a deadly 23-foot tsunami in the country's north | Disasters left 15,839 dead, 5,950 injured, and 3,642 missing |
| April 2012 | Indonesia | 7.3 quake strikes off coast of Indonesia | Few killed |
KEYWORD: Natural disasters, Environmental Harzards, Environment disasters, earthquakes and tsunami, tsunami means, reason for tsunami, tsunami in india, tsunami in all over world, recent tsunami struck area, Disaster in Tsunami, Tsunami causes and effects.
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