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A tsunami is a huge ocean wave that can travel at speeds up to 600 mi/hr (965 km/hr), hundreds of miles over open sea before it hits land. Sometimes incorrectly called a tidal wave, a tsunami is usually caused by an earthquake, volcanic eruption or coastal landslide.

Tsunami is Japanese for "harbor wave." It is, in fact, a series of waves which travel outward on the ocean surface in all directions in a kind of ripple effect. Since the waves can start out hundreds of miles long and only a few feet high, they would not necessarily be noticeable to a passing ship or a plane flying overhead.

As the waves get closer to shore, they decrease in speed and increase in height. They approach the coastline as a series of high and low water levels, approximately 10-45 minutes apart, with their speed decreasing to about 30-40 mi/hr (50-60 km/hr). The depth of the water and the layout of the coastal area can affect the tsunami's configuration when it hits the shore. It can grow to 30-50 meters high and smash into the shore as a wall of water or sweep over the land as a fast-moving flood. Although tsunamis can happen in any large body of water, most occur in the Pacific Ocean.

A tsunami that is generated from close-by can reach the shore in less than ten minutes. This does not allow authorities time to issue a warning. The only warning might be movement in the ground, which could alert people close to the shore that a tsunami is imminent. If a major earthquake gives cause to suspect a tsunami, one of the following warnings may be issued:
Tsunami information bulletin — announcing that a threat exists.
Tsunami watch — announcing that the tsunami is likely and residents should be alert.
Tsunami warning — giving expected arrival times of a tsunami.

Areas at greatest risk are usually within one mile (1.6 km) of the shoreline and less than 25 feet (7.6 meters) above sea level. Since the tsunami arrives as a series of waves, the danger exists even after the first wave hits. Often, subsequent waves may be more dangerous than the first one. The force of the tsunami is enormous, with waves carrying huge boulders, trees, buildings and vehicles in its wake. It can wrap around an island and be just as dangerous on the far side of the island as on the side facing the source of the tsunami.

What you need to know to prepare for a tsunami:
Since earthquakes frequently precipitate a tsunami, if an earthquake happens, expect a tsunami warning in its wake. Leave low-lying areas until the danger passes.
As a tsunami approaches there is often a noticeable drop in sea level; take it as nature's warning to leave the area. An incoming tsunami often sounds like an oncoming train — another of nature's warnings.
Though a tsunami may be small and harmless on one point on the shore, a little further away it could be much larger and carry far greater dangers.
Do not go to the shore to look for a tsunami; if you can see it, you are already too close to outrun it.
You should never try to surf a tsunami; the wave does not behave like a regular wave, curling or breaking.
If you are at the beach and feel the earth shake, immediately move to higher ground.
Drowning is the cause of most tsunami-related deaths. Other dangers to property and person include flooding, fires from ruptured tanks or gas lines, contaminated drinking water, and the loss of vital community infrastructure (police, fire, medical).

In 2004, an earthquake shook the ocean floor in the Indian Ocean near Indonesia. The resulting tsunami killed more than 200,000 people in Indonesia, Sri Lanka, Thailand, India and as far away as the African countries of Somalia and Madagascar. Waves reached a height of 65 feet (20 meters).

Other devastating tsunamis include one that took place in 1883, after Krakatoa erupted. Waves up to 100 feet (30 meters) high caused some 36,000 deaths. In Japan, in 1896, a wave that reached a height of about 65 feet (20 meters) killed about 26,000 people in villages around Sanriku. And in 1755, Lisbon, Portugal, was hit by an earthquake that precipitated a tsunami. More than 100,000 people were killed by the quake, tsunami and fires that broke out in the aftermath.Recommended Sites:
How to Donate to Tsunami Relief Programs
International Tsunami Information Center
How to Survive a Tsunami: US Geological Survey
American Red Cross's Tsunami Site Blogs:
Wave of Destruction: About the 2004 Asian Tsunami
The South-East Asia Earthquake and Tsunami Blog
Voice of America: Disaster News

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Dictionary
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tsu·na·mi (tsʊ-nä'mē)
n., pl. -mis.

A very large ocean wave caused by an underwater earthquake or volcanic eruption.

[Japanese : tsu, port + nami, wave.]
tsunamic tsu·na'mic (-mĭk) adj.
Sci-Tech Encyclopedia
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Tsunami

A set of ocean waves caused by any large, abrupt disturbance of the sea surface. If the disturbance is close to the coastline, tsunamis can demolish local coastal communities within minutes. A very large disturbance can both cause local devastation and export tsunami destruction thousands of miles away. Since 1850, tsunamis have been responsible for the loss of over 120,000 lives and billions of dollars of damage to coastal structures and habitats. Methods for predicting when and where the next tsunami will strike have not been developed; but once the tsunami is generated, forecasting its arrival and impact is possible through wave theory and measurement technology. See also Ocean waves.

Tsunamis are most commonly generated by earthquakes in marine and coastal regions. Major tsunamis are produced by large (greater than 7 on the Richter scale), shallow-focus (<30-km or 19-mi depth in the Earth) earthquakes associated with the movement of oceanic and continental plates. They frequently occur in the Pacific, where dense oceanic plates slide under the lighter continental plates. When these plates fracture, they cause a vertical movement of the sea floor that allows a quick and efficient transfer of energy from the solid earth to the ocean. The resulting tsunami propagates as a set of waves whose energy is concentrated at wavelengths corresponding to the earth movements (∼100 km or 60 mi), at wave heights determined by vertical displacement (∼1 m or 3 ft), and at wave directions determined by the adjacent coastline geometry. Because each earthquake is unique, every tsunami has unique wavelengths, wave heights, and directionality. From a warning perspective, this makes the problem of forecasting tsunamis in real time daunting. See also Earthquake; Plate tectonics.

Other large-scale disturbances of the sea surface that can generate tsunamis are explosive volcanoes and asteroid impacts. The eruption of the volcano Krakatoa in the East Indies on August 27, 1883, produced a 30-m (100-ft) tsunami that killed over 36,000 people. See also Asteroid; Volcano.
Geography Dictionary
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tsunami

A huge sea wave. Most are formed from earthquakes of 5.5 or more on the Richter scale. Other causes include the eruption of submarine volcanoes, very large landslides off coastal cliffs, or the calving of very large icebergs from glaciers in fiords. The most active source region of tsunamis between 1900 and 1983 was along the Japan-Taiwan island arc, where over a quarter of all tsunamis were generated.

A submarine earthquake off the north-east coast of Honshu generated the 1933 tsunami, producing a wave crest of up to 24 m. The death toll was 3008, with 1152 injured. While sea walls of up to 16 m offer some protection against tsunamis, the Japanese government have also offered subsidies for villagers to relocate on higher ground.
Britannica Concise Encyclopedia
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tsunami

Catastrophic ocean wave, usually caused by a submarine earthquake. Underwater or coastal landslides or volcanic eruptions also may cause tsunamis. The term tsunami is Japanese for "harbour wave." The term tidal wave is a misnomer, because the wave has no connection with the tides. Perhaps the most destructive tsunami ever occurred in 2004 in the Indian Ocean, after an earthquake struck the seafloor off the Indonesian island of Sumatra. More than 200,000 people were killed in Indonesia, Thailand, India, Sri Lanka and other countries as far away as Somalia on the Horn of Africa.

For more information on tsunami, visit Britannica.com.
Columbia Encyclopedia
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tsunami (tsʊnä'mē) , series of catastrophic ocean waves generated by submarine movements, which may be caused by earthquakes, volcanic eruptions, landslides beneath the ocean, or an asteroid striking the earth. Tsunamis are also called seismic sea waves or, popularly, tidal waves.

In the open ocean, tsunamis may have wavelengths of up to several hundred miles and travel at speeds up to 500 mi per hr (800 km per hr), yet have wave heights of less than 3 ft (1 m), which pass unnoticed beneath a ship at sea. The period between the crests of a tsunami's waves varies from 5 min to about 1 hr. When tsunamis approach shallow water along a coast, they are slowed, causing their length to shorten and their height to rise sometimes as high as 100 ft (30 m). When they break, they often destroy piers, buildings, and beaches and take human life. The wave height as they crash upon a shore depends almost entirely upon the submarine topography offshore. Waves tend to rise to greater heights along gently sloping shores, along submarine ridges, or in coastal embayments.

There is little warning of approach; when a train of tsunami waves approaches a coastline, the first indication is often a sharp swell, not unlike an ordinary storm swell, followed by a sudden outrush of water that often exposes offshore areas as the first wave trough reaches the coast. After several minutes, the first huge wave crest strikes, inundating the newly exposed beach and rushing inland to flood the coast. Generally, the third to eighth wave crests are the largest.

Since tsunamis principally occur in the Pacific Ocean following shallow-focus earthquakes over magnitude 6.5 on the Richter scale, one of the best means of prediction is the detection of such earthquakes on the ocean floor with a seismograph network (see seismology). Tsunamis may be detected by wave gauges and pressure monitors, such as those emplaced as part of the U.S. Tsunami Warning System; established in 1949 and originally confined to the Pacific region, the system has been expanded to the Caribbean and the W North Atlantic. An early warning system for the Indian Ocean began operating in 2006. Measurement of sudden sea level changes from satellites are also used to warn of a potential tsunami.

One of the most destructive tsunamis to occur during historical times followed the explosive eruption of the volcano Krakatoa in the East Indies on Aug. 27, 1883, when over 36,000 people were killed as a result of the wave. Waves were up to 100 ft (30 m) high. Its passage was traced as far away as Panama. On Dec. 26, 2004, a 9.1–9.3 earthquake off NW Sumatra, Indonesia, caused a tsunami with waves as high as 65 ft (20 m) nearest the epicenter. At least 200,000 people are believed to have died. The waves devastated many areas in the E Indian Ocean basin, particularly the nearby coast of N Sumatra, the Andaman and Nicobar Islands, and the E and S coasts of Sri Lanka. Areas of SE India and SW Thailand were also hard hit. Deaths and destruction occurred as far away as the coasts of Somalia and Madagascar in Africa, and minor sea level changes were measured as far away as San Diego, Calif., Iquique, Chile, and Atlantic City, N.J. It is believed that a 0.6-mi-wide (1-km-wide) asteroid that struck the ocean SW of New Zealand about A.D. 1500 created a tsunami that reached heights of more than 425 ft (130 m).

Science Dictionary
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tsunami (tsooh-nah-mee)


A large wave on the ocean, usually caused by an undersea earthquake, a volcanic eruption, or coastal landslide. A tsunami can travel hundreds of miles over the open sea and cause extensive damage when it encounters land. Also called tidal waves.
Obscure Words
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tsunami

[Jap.] a great sea wave produced by submarine earth movement or volcanic eruption
Wikipedia
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tsunami

The tsunami that struck Malé in the Maldives on December 26, 2004.

An accented declivity less in the side-sea makes the waves to lose force, attenuating tsunami

A bigger depth in the hillside plays the waves for top, amplifying its power

Volcanic eruptions inject tons of wash in the oceanic soil, generating devastating waves

Submarine earthquakes dislocate the crust oceanic, pushing the water mass for top

A tsunami (soo-nah-mee; IPA: /tsʊˈnɑːmi/) is a series of waves created when a body of water, such as an ocean, is rapidly displaced on a massive scale. Earthquakes, mass movements above or below water, volcanic eruptions and other underwater explosions, landslides, large meteorite impacts and testing with nuclear weapons at sea all have the potential to generate a tsunami. The effects of a tsunami can range from unnoticeable to devastating. The term tsunami comes from the Japanese words(津波、つなみ) meaning harbor ("tsu", 津) and wave ("nami", 波). [a. Jap. tsunami, tunami, f. tsu harbour + nami waves. - Oxford English Dictionary] Although in Japanese tsunami is used for both the singular and plural, in English tsunamis is often used as the plural. The term was created by fishermen who returned to port to find the area surrounding their harbor devastated, although they had not been aware of any wave in the open water. Tsunami are common throughout Japanese history; approximately 195 events in Japan have been recorded.

A tsunami has a much smaller amplitude (wave height) offshore, and a very long wavelength (often hundreds of kilometers long), which is why they generally pass unnoticed at sea, forming only a passing "hump" in the ocean. Tsunami have been historically referred to as tidal waves because as they approach land, they take on the characteristics of a violent onrushing tide rather than the sort of cresting waves that are formed by wind action upon the ocean (with which people are more familiar). Since they are not actually related to tides the term is considered misleading and its usage is discouraged by oceanographers. [1] Since not all tsunami occur in harbors, however, that term is equally misleading, although it does have the benefit of being misleading in a different language.

Causes

Generation of a tsunami

A tsunami can be generated when the plate boundaries abruptly deform and vertically displace the overlying water. Such large vertical movements of the Earth’s crust can occur at plate boundaries. Subduction earthquakes are particularly effective in generating tsunami.

Tsunami are surface gravity waves that are formed as the displaced water mass moves under the influence of gravity and radiates across the ocean like ripples on a pond.

In the 1950s it was discovered by that larger tsunami than previously believed possible could be caused by landslides, explosive volcanic action, and impact events when they contact water. These phenomena rapidly displace large volumes of water, as energy from falling debris or expansion is transferred to the water into which the debris falls. Tsunami caused by these mechanisms, unlike the ocean-wide tsunami caused by some earthquakes, generally dissipate quickly and rarely affect coastlines distant from the source due to the small area of sea affected. These events can give rise to much larger local shock waves (solitons), such as the landslide at the head of Lituya Bay which produced a water wave estimated at 50 – 150 m and reached 524 m up local mountains. However, an extremely large landslide could generate a “megatsunami” that might have ocean-wide impacts.

The geological record tells us that there have been massive tsunami in Earth's past.

Signs of an approaching tsunami

There is often no advance warning of an approaching tsunami. However, since earthquakes are often a cause of tsunami, an earthquake felt near a body of water may be considered an indication that a tsunami will shortly follow.

When the first part of a tsunami to reach land is a trough rather than a crest of the wave, the water along the shoreline may recede dramatically, exposing areas that are normally always submerged. This can serve as an advance warning of the approaching crest of the tsunami, although the warning arrives only a very short time before the crest, which typically arrives seconds to minutes later.[2] In the 2004 tsunami that occurred in the Indian Ocean the sea receding was not reported on the African coast or any other western coasts it hit, when the tsunami approached from the east.

Warnings and prevention

Tsunami hazard sign at The Wedge in Balboa Peninsula, Newport Beach, California.

Tsunami wall at Tsu, Japan


Tsunami cannot be prevented or precisely predicted, but there are some warning signs of an impending tsunami, and there are many systems being developed and in use to reduce the damage from tsunami.

In instances where the leading edge of the tsunami wave is its trough, the sea will recede from the coast half of the wave's period before the wave's arrival. If the slope is shallow, this recession can exceed many hundreds of meters. People unaware of the danger may remain at the shore due to curiosity, or for collecting fish from the exposed seabed.

Tsunami warning sign on seawall in Kamakura, Japan, 2004. In the Muromachi period, a tsunami struck Kamakura, destroying the wooden building that housed the colossal statue of Amida Buddha at Kotokuin. Since that time, the statue has been outdoors.

Regions with a high risk of tsunami may use tsunami warning systems to detect tsunami and warn the general population before the wave reaches land. In some communities on the west coast of the United States, which is prone to Pacific Ocean tsunami, warning signs advise people where to run in the event of an incoming tsunami. Computer models can roughly predict tsunami arrival and impact based on information about the event that triggered it and the shape of the seafloor (bathymetry) and coastal land (topography). [3]

One of the early warnings comes from nearby animals. Many animals sense danger and flee to higher ground before the water arrives. The Lisbon quake is the first documented case of such a phenomenon in Europe. The phenomenon was also noted in Sri Lanka in the 2004 Indian Ocean earthquake. [4] Some scientists speculate that animals may have an ability to sense subsonic Rayleigh waves from an earthquake minutes or hours before a tsunami strikes shore (Kenneally, [5]). More likely, though, is that the certain large animals (e.g., elephants) heard the sounds of the tsunami as it approached the coast. The elephants reactions were to go in the direction opposite of the noise, and thus go inland. Humans, on the other hand, head down to the shore to investigate.

While it is not possible to prevent tsunami, in some particularly tsunami-prone countries some measures have been taken to reduce the damage caused on shore. Japan has implemented an extensive programme 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 are 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 10-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.

The effects of a tsunami can be mitigated by natural factors such as tree cover on the shoreline. Some locations in the path of the 2004 Indian Ocean tsunami escaped almost unscathed as a result of the tsunami’s energy being sapped by a belt of trees such as coconut palms and mangroves. In one striking example, the village of Naluvedapathy in India's Tamil Nadu region suffered minimal damage and few deaths as the wave broke up on a forest of 80,244 trees planted along the shoreline in 2002 in a bid to enter the Guinness Book of Records. [6] Environmentalists have suggested tree planting along stretches of seacoast which are prone to tsunami risks. While it would take some years for the trees to grow to a useful size, such plantations could offer a much cheaper and longer-lasting means of tsunami mitigation than the costly and environmentally destructive method of erecting artificial barriers.

Historic tsunami


See also: List of natural disasters by death toll#Tsunamis

Tsunami occur most frequently in the Pacific Ocean, but are a global phenomenon; they are possible wherever large bodies of water are found, including inland lakes, where they can be caused by landslides. Very small tsunami, non-destructive and undetectable without specialized equipment, occur frequently as a result of minor earthquakes and other events.

Japan is the nation with the most recorded tsunami in the world. The earliest recorded disaster being that of the A.D. 684 Kakuho Earthquake. 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.

On December 26, 2004, an undersea earthquake measuring 9.3 on the Earthquake Magnitude scale occurred 160 km (100 mi) off the western coast of Sumatra, Indonesia. It was the second largest earthquake in recorded history and generated massive tsunamis, which caused widespread devastation when they hit land, leaving an estimated 230,000 people dead in countries around the Indian Ocean. [7]

Bristol Channel floods resulted in the drowning of an estimated 2,000 or more people, with houses and villages swept away, farmland inundated and livestock destroyed, wrecking the local economy along the coasts of the Bristol Channel, UK. Some churches have plaques up to 8ft above sea level to show how high the waters rose.

The cause of the flood is not yet proven, but a research paper published in the journal Archaeology in the Severn Estuary [8] in 2002 following investigations by Professor Simon Haslett, from Bath Spa University, and Australian geologist Ted Bryant, from the University of Wollongong, proposed that the flooding was caused by a tsunami.

The British Geological Survey has suggested an earthquake on a known unstable fault off the coast of Ireland causing the vertical displacement of the sea floor as the possible cause.

1700 - Vancouver Island, Canada

January 26, 1700 - The Cascadia Earthquake, one of the largest earthquakes on record (estimated MW 9 magnitude), ruptured the Cascadia subduction zone (CSZ) offshore from Vancouver Island to northern California, and caused massive tsunami across the Pacific Northwest logged in Japan and oral traditions of the Native Americans. Brian F. Atwater, Musumi-Rokkaku Satoko, Satake Kenji, Tsuji Yoshinobu, Ueda Kazue, and David K. Yamaguch prepared a "scientific detective story" investigating this tsunami entitled The Orphan Tsunami of 1700—Japanese Clues to a Parent Earthquake in North America. This document is downloadable and available online.

1755 - Lisbon, Portugal

Tens of thousands of Portuguese who survived the Great Lisbon Earthquake on November 1 were killed by a tsunami which followed a half hour later. Many townspeople fled to the waterfront, believing the area safe from fires and from falling debris from aftershocks. Before the great wall of water hit the harbour, waters retreated, revealing lost cargo and forgotten shipwrecks. These people did not know that a Tsunami is a succession of waves, rather than just a single one.

The earthquake, tsunami, and many forest fires killed between 60,000 and 100,000 of Lisbon's pre-quake population of 275,000. Historical records of explorations by Vasco da Gama and other early navigators were lost, and countless buildings were destroyed (including most examples of Portugal's Manueline architecture). Europeans of the 18th century struggled to understand the disaster within religious and rational belief systems. Philosophers of the Enlightenment, notably Voltaire, wrote about the event. The philosophical concept of the sublime, as described by philosopher Immanuel Kant in the Observations on the Feeling of the Beautiful and Sublime, took inspiration in part from attempts to comprehend the enormity of the Lisbon quake and tsunami.

The tsunami took just over 4 hours to travel over 1,000 miles to Cornwall in the United Kingdom. An account by Arnold Boscowitz (a century later) claimed "great loss of life."

1771 - Yaeyama Islands, Okinawa, Japan

An undersea earthquake of estimated magnitude 7.4 occurred near Yaeyama Islands in Okinawa, Japan on 4 April, 1771 at about 8 A.M.. The earthquake is not believed to have directly resulted in any deaths, but a resulting tsunami is thought to have killed about 12,000 people, (9313 on the Yaeyama Islands and 2548 on Miyako Islands according to one source([9]). Estimates of the highest seawater runup on Ishigaki Island, range between 30 meters and 85.4 meters. The tsunami put an abrupt stop to population growth on the islands, and was followed by malaria epidemics and crop failures which decreased the population further. It was to be another 148 years before population returned to its pre-tsunami level.

1792 - Tsunami in Kyūshū, Japan

Tsunami were the main cause of death for Japan's worst-ever volcanic disaster, due to an eruption of Mount Unzen in Nagasaki Prefecture, Kyūshū, Japan. It began towards the end of 1791 as a series of earthquakes on the western flank of Mount Unzen which gradually moved towards Fugen-daké, one of Mount Unzen's peaks. In February 1792, Fugen-daké started to erupt, triggering a lava flow which continued for two months. Meanwhile, the earthquakes continued, shifting nearer to the city of Shimabara. On the night of 21st May, two large earthquakes were followed by a collapse of the eastern flank of Mount Unzen's Mayuyama dome, causing an avalanche which swept through Shimabara and into Ariake Bay, triggering a tsunami. It is not known to this day whether the collapse occurred as a result of an eruption of the dome or as a result of the earthquakes. The tsunami struck Higo Province on the other side of Ariake Bay before bouncing back and hitting Shimabara again. Out of an estimated total of 15,000 fatalities, around 5,000 is thought to have been killed by the landslide, around 5,000 by the tsunami across the bay in Higo Province, and a further 5,000 by the tsunami returning to strike Shimabara.

1868 - Hawaiian Islands local tsunami generated by earthquake

On April 2, 1868, a local earthquake with a magnitude estimated between 7.25 and 7.75 rocked the southeast coast of the Big Island of Hawai’i. It triggered a landslide on the slopes of the Mauna Loa volcano, five miles north of Pahala, killing 31 people. A tsunami then claimed 46 additional lives. The villages of Punaluu, Ninole, Kawaa, Honuapo, and Keauhou Landing were severely damaged. According to one account, the tsunami "rolled in over the tops of the coconut trees, probably 60 feet high .... inland a distance of a quarter of a mile in some places, taking out to sea when it returned, houses, men, women, and almost everything movable." This was reported in the 1988 edition of Walter C. Dudley's book "Tsunami!" (ISBN 0-8248-1125-9).

1883 - Krakatoa explosive eruption

The island volcano of Krakatoa in Indonesia exploded with devastating fury on August 26-27, 1883, blowing its underground magma chamber partly empty so that much overlying land and seabed collapsed into it. A series of large tsunami waves was generated from the collapse, some reaching a height of over 40 meters above sea level. Tsunami waves were observed throughout the Indian Ocean, the Pacific Ocean, the American West Coast, South America, and even as far away as the English Channel. On the facing coasts of Java and Sumatra the sea flood went many miles inland and caused such vast loss of life that one area was never resettled but went back to the jungle and is now the Ujung Kulon nature reserve.

The aftermath of the tsunami that struck Newfoundland in 1929.

1896 - Sanriku coast, Japan

On 15 June, 1896, at around 19:32 local time, a magnitude 8.5 undersea earthquake off the Sanriku coast of northeastern Honshū, Japan, triggered tsunami waves which struck the coast about half an hour later. Although the earthquake itself is not thought to have resulted in any fatalities, the waves, the highest recorded measurement of which reaching 38.2 meters, killed approximately 20,000 people.

1917 - Halifax Explosion and tsunami

The Halifax Explosion occurred on Thursday, December 6, 1917 at 9:04:35 A.M. local time in Halifax, Nova Scotia in Canada, when the French munitions ship Mont-Blanc, bound for World War I France, collided with the Norwegian ship Imo, chartered to carry Belgian relief supplies. In the aftermath of the collision, Mont-Blanc caught fire and exploded. The explosion caused a tsunami, and a pressure wave of air.

1923 - The Great Kanto Earthquake, Japan

The Great Kanto Earthquake, which occurred in Eastern Japan on 1 September, 1923, and devastated Tokyo, Yokohama and the surrounding areas, caused tsunami which struck the Shonan coast, Boso Peninsula, Izu Islands and the east coast of Izu Peninsula, within minutes in some cases. In Atami, waves reaching 12 meters were recorded. Examples of tsunami damage include about 100 people killed along Yui-ga-hama beach in Kamakura and an estimated 50 people on the Enoshima causeway. However, tsunami only accounted for a small proportion of the final death toll of over 100,000, most of whom were killed in fire.

1929 - Newfoundland tsunami

On November 18, 1929, an earthquake of magnitude 7.2 occurred beneath the Laurentian Slope on the Grand Banks. The quake was felt throughout the Atlantic Provinces of Canada and as far west as Ottawa and as far south as Claymont, Delaware. The resulting tsunami measured over 7 meters in height and took about 2½ hours to reach the Burin Peninsula on the south coast of Newfoundland, where 29 people lost their lives in various communities. It also snapped telegraph lines laid under the Atlantic.

1933 - Sanriku coast, Japan

On March 3, 1933, the Sanriku coast of northeastern Honshū, Japan which had already suffered a devastating tsunami in 1896 (see above) was again stuck by tsunami waves as a result of an offshore magnitude 8.1 earthquake. The quake destroyed about 5,000 homes and killed 3,068 people, the vast majority as a result of tsunami waves. Especially hard hit was the coastal village of Taro (now part of Miyako city) in Iwate Prefecture, which lost 42% of its total population and 98% of its buildings. Taro is now protected by an enormous tsunami wall, currently 10 meters in height and over 2 kilometers long. The original wall, constructed in 1958, saved Taro from yet another destruction from the 1960 Chilean tsunami (see below).

1944 - Tonankai Earthquake, Japan

A magnitude 8.0 earthquake on 7 December, 1944, about 20 km off the Shima Peninsula in Japan, caused tsunami which struck the Pacific coast of central Japan, mainly Mie, Aichi, and Shizuoka Prefectures. News of the event was downplayed by the authorities in order to protect wartime morale, and as a result the full extent of the damage is not known, but the quake is estimated to have killed 1223 people, the tsunami being the leading cause of the fatalities.

1946 - Nankai Earthquake, Japan

The Nankai earthquake, a periodic earthquake of around magnitude 8.0 which occurs off the southern coast of Kii Peninsula and Shikoku, Japan every 100 to 150 years, last struck on 21 December, 1946. The resulting tsunami hit the Pacific coast of western Japan. Particularly hard hit were the coastal towns of Kushimoto and Kainan on the Kii Peninsula. The quake led to more than 1400 deaths, tsunami being the leading cause .

1946 - Pacific tsunami

Residents run from an approaching tsunami in Hilo, Hawai’i

The April 1 Aleutian Island earthquake tsunami that killed 159 people on Hawai’i and five in Alaska (the lighthouse keepers at the Scotch Cap Light in the Aleutians) resulted in the creation of a tsunami warning system known as the Pacific Tsunami Warning System (specifically the PTWC), established in 1949 for Pacific Ocean area countries. The tsunami is known as the April Fools Day Tsunami in Hawai’i due to people thinking the warnings were an April Fools prank.

1958 - Lituya Bay megatsunami

On July 9, 1958, an earthquake with a magnitude of 8.3 on the Richter scale rocked a small inlet in Alaska called Lituya Bay. It then caused part of a mountain at the back of the bay to collapse, causing a monstrous tsunami (an iminami) to fly headlong through the bay. At a mountain at the mouth of the bay, the run was measured to be 524 m (about 1742 ft) making it the largest wave in recorded history. It swept up three boats; one managed to ride the wave, but the other two were swept into the Pacific Ocean, where they were completely destroyed and four people aboard them were killed.

1960 - Chilean tsunami

The magnitude 9.5 Great Chilean Earthquake of May 22, 1960 is the strongest earthquake ever recorded. Its epicenter, off the coast of South Central Chile, generated one of the most destructive tsunami of the 20th Century.

It spread across the entire Pacific Ocean, with waves measuring up to 25 meters high. The first tsunami arrived at Hilo approximately 14.8 hrs after it originated off the coast of South Central Chile. The highest wave at Hilo Bay was measured at around 10.7 m (35 ft). 61 lives were lost allegedly due to people's failure to heed warning sirens.

Almost 22 hours after the quake, the waves hit the ill-fated Sanriku coast of Japan, reaching up to 3 m above high tide, and killed 142 people. Up to 6,000 people died in total worldwide due to the earthquake and tsunami.[1]

The Vajont Dam as seen from Longarone today, showing approximately the top 60-70 metres of concrete. The 200-250 metre wall of water (megatsunami) that over-topped the dam would have obscured virtually all of the sky in this picture.

1963 Vajont Dam Megatsunami

The Vajont Dam was completed in 1961 under Monte Toc, 100 km north of Venice, Italy. At 262 metres, it was one of the highest dams in the world. On October 9, 1963 an enormous landslide of about 260 million cubic metres of forest, earth, and rock, fell into the reservoir at up to 110 km per hour (68 mph). The resulting displacement of water caused 50 million cubic metres of water to overtop the dam in a 250-metre high wave. The flooding destroyed the villages of Longarone, Pirago, Rivalta, Villanova and Faè, killing 1,450 people. Almost 2,000 people (some sources report 1,909) perished in total.

1964 - Good Friday tsunami

After the magnitude 8.6 Good Friday Earthquake (Friday, March 27, 1964), tsunami struck Alaska, British Columbia, California, and coastal Pacific Northwest towns, killing 121 people. The waves caused by the Tsunami were up to 23 m tall, and killed 11 people as far away as Crescent City, California.

1976 - Moro Gulf tsunami

On August 16, 1976 at 12:11 A.M., a devastating earthquake of 7.9 hit the island of Mindanao, Philippines. It created a tsunami that devastated more than 700 km of coastline bordering Moro Gulf in the North Celebes Sea. An estimated number of victims for this tragedy left 5,000 dead, 2,200 missing or presumed dead, more than 9,500 injured and a total of 93,500 people were left homeless. It devastated the cities of Cotabato, Pagadian, and Zamboanga, and the and provinces of Basilan, Lanao del Norte, Lanao del Sur, Maguindanao, Sultan Kudarat, Sulu, and Zamboanga del Sur.

1979 - Tumaco tsunami

A magnitude 7.9 earthquake occurred on December 12, 1979 at 7:59:4.3 UTC along the Pacific coast of Colombia and Ecuador. The earthquake and the resulting tsunami caused the destruction of at least six fishing villages and the death of hundreds of people in the Colombian province of Nariño. The earthquake was felt in Bogotá, Cali, Popayán, Buenaventura, and several other cities and towns in Colombia and in Guayaquil, Esmeraldas, Quito, and other parts of Ecuador. When the Tumaco Tsunami hit the coast, it caused huge destruction in the city of Tumaco, as well as in the small towns of El Charco, San Juan, Mosquera, and Salahonda on the Pacific coast of Colombia. The total number of victims of this tragedy was 259 dead, 798 wounded and 95 missing or presumed dead.

1983 - Sea of Japan tsunami

On May 26, 1983 at 11:59:57 local time, a magnitude-7.7 earthquake occurred in the Sea of Japan, about 100 km west of the coast of Noshiro in Akita Prefecture, Japan. Out of the 107 fatalities, all but four were killed by the resulting tsunami, which struck communities along the coast, especially Aomori and Akita Prefectures and the east coast of Noto Peninsula. Footage of the tsunami hitting the fishing harbor of Wajima on Noto Peninsula was broadcast on TV. The waves exceeded 10 meters in some areas. Three of the fatalities were along the east coast of South Korea (whether North Korea was affected is not known).

1993 - Okushiri, Hokkaido tsunami
Map of Hokkaidō shown on NHK during an emergency broadcast.

A devastating tsunami wave occurred along the coasts of Hokkaidō in Japan as a result of a magnitude 7.8 earthquake, 80 miles offshore, on July 12, 1993.

Within minutes, the Japan Meteorological Agency[citation needed] issued a tsunami warning that was broadcast on NHK in English and Japanese (archived at YouTube[10]). However, it was too late for Okushiri, a small island near the epicenter, which was struck with extremely big waves, some reaching 30 meters, within two to five minutes of the quake. Aonae, a village on a low-lying peninsula at the southern tip of the island, was devastated over the course of the following hour by 13 waves of over two meters’ height arriving from multiple directions, including waves that had bounced back off Hokkaidō—despite being surrounded by tsunami barriers. Of 250 people killed as a result of the quake, 197 were victims of the series of tsunamis that hit Okushiri; the waves also caused deaths on the coast of Hokkaidō. While many residents, remembering the 1983 tsunami (see above), survived by quickly evacuating on foot to higher ground, it is thought that many others underestimated how soon the waves would arrive (the 1983 tsunami took 17 minutes to hit Okushiri) and were killed as they attempted to evacuate by car along the village’s narrow lanes. The highest wave of the tsunami was a staggering 31 meters (102 feet) high.

1998 - Papua New Guinea

On 17 July, 1998, a Papua New Guinea tsunami killed approximately 2200 people [11]. A 7.1 magnitude earthquake 24 km offshore was followed within 11 minutes by a tsunami about 12 m tall. While the magnitude of the quake was not large enough to create these waves directly, it is believed the earthquake generated an undersea landslide, which in turn caused the tsunami. The villages of Arop and Warapu were destroyed.

2004 - Indian Ocean tsunami

The 2004 Indian Ocean earthquake; Tsunami strikes Ao Nang, Thailand.

The 2004 Indian Ocean earthquake, which had a magnitude of 9.0[12], triggered a series of lethal tsunami on December 26, 2004 that killed approximately 300,000 people (including 168,000 in Indonesia alone), making it the deadliest tsunami as well as one of the deadliest natural disasters in recorded history. It also had the second largest earthquake in recorded history. The initial surge was measured at a height of approximately 108 feet, making it the largest earthquake-generated tsunami in recorded history. The tsunami killed people over an area ranging from the immediate vicinity of the quake in Indonesia, Thailand and the northwestern coast of Malaysia to thousands of kilometers away in Bangladesh, India, Sri Lanka, the Maldives, and even as far away as Somalia, Kenya, and Tanzania in eastern Africa. This is an example of a teletsunami which can travel vast distances across the open ocean, in this case, it is an inter-continential tsunami. Tsunami waves 2.6 meters tall were reported even in places such as Mexico, nearly 13,000 km away from the epicenter. The energies for these waves travel along fault lines and becoming concentrated therefore traveling further.

Unlike in the Pacific Ocean, there was no organized alert service covering the Indian Ocean. This was in part due to the absence of major tsunami events since 1883 (the Krakatoa eruption, which killed 36,000 people). In light of the 2004 Indian Ocean tsunami, UNESCO and other world bodies have called for an international tsunami monitoring system.

2006 - South of Java Island tsunami

A 7.7 magnitude earthquake rocked the Indian Ocean seabed on July 17,2006, 200 km south of Pangandaran, a beautiful beach famous to surfers for its perfect waves. This earthquake triggered tsunami whose heights varied from 2 meters at Cilacap to 6 meters at Cimerak beach, where it swept away and flattened buildings as far as 400 meters away from the coastline. More than 800 people were reported missing or dead. See July 2006 Java earthquake.

2006 - Kuril Islands tsunami

On November 15, 2006, an 8.1 magnitude quake struck an area claimed by both Russia and Japan, but the waves near Japan did not swell higher than 23 inches. There were no immediate reports of casualties or damage. Six hours later, tsunami waves up to nearly 5 feet high caused by the quake crashed into Crescent City, California and Santa Cruz, California causing considerable damage. See 2006 Kuril Islands tsunami.

2007 - Solomon Islands tsunami
Main article: 2007 Solomon Islands earthquake

On April 2, 2007, a powerful magnitude 8.1 (initially 7.6) earthquake hit the East Pacific region about 25 miles (40 km) northwest of the Solomon Islands at 7:39 a.m., resulting in a tsunami that was up to 17 feet (5 meters) tall. The wave, which struck the coast of Solomon Islands (mainly Gizo), triggered region-wide tsunami warnings and watches extending from Japan to New Zealand to Hawaii and the eastern seaboard of Australia. So far, at least 39 people are confirmed dead with the toll expected to rise. Dozens more have been injured with entire towns inundated by the sweeping water which travelled 300 meters inland in some places. Simbo, Choiseul and Ranunga islands were also affected. A state of national emergency was declared for the Solomon Islands. On the island of Choiseul, a wall of water reported to be 30 feet high swept almost 400 meters inland destroying everything in its path. Officials estimate that the tsunami displaced more than 5000 residents all over the archipelago.

Other tsunami in South AsiaTsunami in South Asia
(Source: Amateur Seismic Centre, India)[13]
Date Location
1524 Near Dabhol, Maharashtra
02 April 1762 Arakan Coast, Myanmar
16 June 1819 Rann of Kachchh, Gujarat, India
31 October 1847 Great Nicobar Island, India
31 December 1881 Car Nicobar Island, India
26 August 1883 Krakatoa volcanic eruption
28 November 1945 Mekran coast, Balochistan


North American and Caribbean tsunami
1690 - Nevis
14 November 1840 - Great Swell on the Delaware River
18 November 1867 - Virgin Islands
17 November 1872 - Maine
11 October 1918 - Puerto Rico
18 November 1929 - Newfoundland
9 January 1926 - Maine
4 August 1946 - Dominican Republic
18 August 1946 - Dominican Republic
27 March 1964 - Crescent City, CA
15 November 2006 - Crescent City, CA

Possible tsunami
35 million years ago - Chesapeake Bay impact crater, Chesapeake Bay
9 June 1913 - Longport, NJ
6 August 1923 - Rockaway Park, Queens, NY .
8 August 1924 - Coney Island, NY .
19 August 1931 - Atlantic City, NJ
22 June 1932 - Cuyutlán, Colima, Mexico
19 May 1964 - Northeast USA
4 July 1992 - Daytona Beach, FL

Source: NOAA National Weather Service Forecast Office, [14]

European tsunami
6100 BC - Storegga Slide, Norway
16 October 1979 - 23 people died when the coast of Nice, France, was hit by a tsunami. This may have had a man-made cause: construction at the new Nice airport creating an undersea landslide. [15] [16] [17] [18]

Other historic tsunami

Other tsunami that have occurred include the following:
ca. 1600 B.C.: The Israelite passage of the Red Sea has been linked by some researchers to a tsunami following the volcanic explosion of the Greek island of Santorini.
ca. 500 B.C.: Poompuhar, Tamil Nadu, India, Maldives
ca. 450 B.C.: The Greek historian Thucydides in his book History of the Peloponnesian Wars, speculated about the causes of tsunami. He argued that it could only be explained as a consequence of ocean earthquakes, and could see no other possible causes for the phenomenon.
1541: a tsunami struck the earliest European settlement in Brazil, São Vicente. There is no record of deaths or injuries, but the town was almost completely destroyed.
January 20, 1606/1607: along the coast of the Bristol Channel thousands of people were drowned, houses and villages swept away, farmland was inundated and flocks were destroyed by a flood that might have been a tsunami. While it is quite possible that it was caused by a combination of meteorological extremes and tidal peaks, recent evidence points more strongly towards a tsunami. ([19]).(discussion).

See also
Higher Ground Project
List of earthquakes
Meteotsunami
Megatsunami
Freak wave
Sneaker wave
Tidal bore
Tsunami Society
List of Deadliest Tsunami
Earthquake
Tsunami warning system

References
Iwan, W.D., editor, 2006, Summary report of the Great Sumatra Earthquakes and Indian Ocean tsunamis of 26 December 2004 and 28 March 2005: Earthquake Engineering Research Institute, EERI Publication #2006-06, 11 chapters, 100 page summary, plus CD-ROM with complete text and supplementary photographs, EERI Report 2006-06. [www.eeri.org] ISBN 1-932884-19-X
Dudley, Walter C. & Lee, Min (1988: 1st edition) Tsunami! ISBN 0-8248-1125-9 link
Kenneally, Christine (December 30 2004). "Surviving the Tsunami". Slate. link
Macey, Richard (January 1 2005). "The Big Bang that Triggered A Tragedy", The Sydney Morning Herald, p 11 - quoting Dr Mark Leonard, seismologist at Geoscience Australia.
Lambourne, Helen (March 27 2005). "Tsunami: Anatomy of a disaster". BBC News. link
abelard.org. tsunamis: tsunamis travel fast but not at infinite speed. Website, retrieved March 29 2005. link
The NOAA's page on the 2004 Indian Ocean earthquake and tsunami
^ "Emergency & Disasters Data Base". CRED. Retrieved on 2006-05-30.

External links

Wikimedia Commons has media related to:
Tsunami

Articles and websites
Tsunami database with detailed statistics
ImanusT (Crisis Relief Non-Profit Organization)
Tsunami education and outreach site
Tsunami Information from the Coastal Ocean Institute, Woods Hole Oceanographic Institution
NOVA: Wave That Shook The World — Site and special report shot within days of the 2004 Indian Ocean tsunami.
NOAA Tsunami — General description of tsunamis and the United States agency NOAA's role in Tsunami hazard assessment, preparedness, education, forecasts & warnings, response and research.
Can HF Radar detect Tsunamis? — University of Hamburg HF-Radar.
The Higher Ground Project — Stories of children who survived the tsunami.
The International Centre for Geohazards (ICG)
ITIC tsunami FAQ
NOAA Center for Tsunami Research (incorporates the PMEL Tsunami Research Program) (United States)
USGS: Surviving a tsunami (United States)
ITSU — Coordination Group for the Pacific Tsunami Warning System.
Pacific Tsunami Museum
Tsunamis and Earthquakes
Tsunami Centers — United States National Weather Service.
Science of Tsunami Hazards journal
The International Centre for Geohazards (ICG)
Envirtech Tsunami Warning System — Based on seabed seismics and sea level gauges.
What Causes a Tsunami?
Scientific American Magazine (January 2006 Issue) Tsunami: Wave of Change What we can learn from the Indian Ocean tsunami of December 2004.

Images and video

See also: Images and video, 2004 Indian Ocean earthquake
[20] 5 Amateur Camcorder Video Streams of the December 26 2004 tsunami that hit Sri Lanka, Thailand and Indonesia (search on tsunamis).
"After the Tsunami" Danish writer and photographer Thorsten Overgaard's documentary after the SE Asia tsunami December 26 2004.
2004 Asian Tsunami Satellite Images (Before and After)
Satellite Images of Tsunami Affected Areas High resolution satellite images showing the effects of the 2004 tsunami on the affected areas in Indonesia, Thailand and Nicobar island of India.
Computer-generated animation of a tsunami
Animations of actual and simulated tsunami events from the NOAA Center for Tsunami Research
Animation of 1960 tsunami originating outside coast of Chile
The Survivors - A moving travelogue full of stunning images along the tsunami ravaged South-Western Coast of India [Unavailable]
Origin of a Tsunami - animation showing how the shifting of continental plates in the Indian Ocean created the catastrophe of December 26th 2004.
CBC Digital Archives – Canada's Earthquakes and Tsunamis
Tsunami Aftermath in Penang and Kuala Muda, Kedah.