World’s Biggest Tsunami
On
the night of July 9, 1958 an earthquake along the Fairweather Fault in the
Alaska Panhandle loosened about 40 million cubic yards (30.6 million cubic
meters) of rock high above the northeastern shore of Lituya Bay. This mass of rock plunged from an altitude of
approximately 3000 feet (914 meters) down into the waters of Gilbert Inlet (see
map below). The impact generated a local tsunami that crashed against the
southwest shoreline of Gilbert Inlet. The wave hit with such power that it
swept completely over the spur of land that separates Gilbert Inlet from the
main body of Lituya Bay. The wave then contiuned down the entire length of
Lituya Bay, over La Chaussee Spit and into the Gulf of Alaska. The force of the
wave removed all trees and vegetation from elevations as high as 1720 feet (524 meters) above sea level.
Millions of trees were uprooted and swept away by the wave. This is the highest
wave that has ever been known.
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| Tsunami wave |
World’s deadliest Tsunami
The
deadliest tsunami in recorded history was the 2004 Asian tsunami, which
killed almost 230,000 people in eleven countries across the Indian Ocean.
World’s first Tsunami
The
first Tsunami occurred in 6100 B.C.
The Storegga Slides occurred 100 km north-west of the Møre coast in the Norwegian Sea, causing a very large
tsunami in the North Atlantic Ocean. This collapse involved an estimated
290 km length of coastal shelf, with a total volume of 3,500 km3
of debris. Based on carbon dating of plant material recovered from sediment deposited by
the tsunami, the latest incident occurred around 6100 BC. In Scotland, traces
of the subsequent tsunami have been recorded, with deposited sediment being
discovered in Montrose Basin, the Firth of Forth, up to 80 km inland and 4
metres above current normal tide levels.
Advanced Tsunami Warning system
Australian scientists are building an advanced tsunami warning
system. The tsunami warning system contains a seismic array which is a network
of interconnected seismographs that measure and record the force and duration
of earthquakes. The system being installed in the red dust of the Pilbara
region in Western Australia will monitor earthquakes around the Indian
Ocean. In particular, it will look for signs of underground ruptures
along the Indonesian archipelago to the north. It will not only predict tsunami
but even predict the place it will hit.
Walls for preventing Tsunami
Japan has implemented an extensive program of
building tsunami walls of up to 4.5 m (13.5 ft) high in front of populated
coastal areas. Other localities have built floodgates and channels to redirect
the water from incoming tsunami. However, their effectiveness has been questioned,
as tsunami is often higher than the barriers. For instance, the tsunami which
struck the island of Hokkaidō on July 12, 1993 created waves as much as 30 m
(100 ft) tall - as high as a ten-story building. The port town of Aonae was
completely surrounded by a tsunami wall, but the waves washed right over the
wall and destroyed all the wood-framed structures in the area. The wall may
have succeeded in slowing down and moderating the height of the tsunami, but it
did not prevent major destruction and loss of life.
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| Tsunami wall, Japan |
Country with highest tsunami rate
Japan is the nation with the most recorded tsunami
in the world. The earliest recorded disaster was the tsunami associated with
the 684 C.E. Hakuho Earthquakes. The number of tsunami in Japan totals 195 over
a 1,313 year period, averaging one event every 6.7 years, the highest rate of
occurrence in the world. These waves have hit with such violent fury that entire
towns have been destroyed.
References
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