Jump to content

Tsunami: Difference between revisions

Edit links
From Wikipedia, the free encyclopedia
Browse history interactively
← Previous editNext edit →
Content deleted Content added
VisualWikitext
MikeLeeds (talk | contribs)
325 edits
rvv
No edit summary
Line 288: Line 288:
* [http://archives.cbc.ca/IDD-1-75-1561/science_technology/earthquakes_and_tsunamis/ CBC Digital Archives – Canada's Earthquakes and Tsunamis]
* [http://archives.cbc.ca/IDD-1-75-1561/science_technology/earthquakes_and_tsunamis/ CBC Digital Archives – Canada's Earthquakes and Tsunamis]
* [http://citizenxpress.com/blog/view/244/ 2nd Anniversary Of Tsunami: Many Questions Remain Unanswered ]
* [http://citizenxpress.com/blog/view/244/ 2nd Anniversary Of Tsunami: Many Questions Remain Unanswered ]
* [http://youtube.com/watch?v=P6PvqLaT8jE Rare footage of the 2004 Tsunami]


=== Fiction ===
=== Fiction ===

Revision as of 16:03, 19 February 2007

For other meanings of tsunami, see Tsunami (disambiguation).
The tsunami that struck Malé in the Maldives on December 26, 2004.

A tsunami (pronounced /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 meaning harbor ("tsu", 津) and wave ("nami", 波). 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

Tsunami can be generated when the sea floor abruptly deforms and vertically displaces 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.

Submarine landslides (which are sometimes triggered by large earthquakes) as well as collapses of volcanic edifices may also disturb the overlying water column as sediment and rocks slide downslope and are redistributed across the sea floor. Similarly, a violent submarine volcanic eruption can uplift the water column and form a tsunami.

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

In the 1950s it was discovered that larger tsunami than previously believed possible could be caused by landslides, explosive volcanic action, and impact events. 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. These tsunami were so large that they caused landslides on the opposite coast triggering another massive tsunami, or "bounce back" tsunami. An example today would be a landslide equivalent to everything west of Portland, Oregon falling into the Pacific Ocean, resulting in a tsunami that would then hit the Chinese coast with enough force to erode the coast, triggering a landslide large enough to send a tsunami that would in turn inundate the U.S. West Coast and would wipe out Portland.

Characteristics

There is a common misconception that tsunami behave like wind-driven waves or swells (with air behind them, as in this celebrated 19th century woodcut by Hokusai, The Great Wave at Kanagawa). In fact, a tsunami is better understood as a new and suddenly higher sea level, which manifests as a shelf or shelves of water. The leading edge of a tsunami superficially resembles a breaking wave but behaves differently: the rapid rise in sea level, combine with the weight and pressure of the ocean behind it, has far greater force.

Often referred to as "tidal waves", a tsunami does not look like the popular impression of "a normal wave, only much bigger". Instead, it looks rather like an endlessly onrushing tide which forces its way around and through any obstacle. Most of the damage is caused by the huge mass of water behind the initial wave front, as the height of the sea keeps rising fast and floods power in the coastal area. The sheer weight of water is enough to pulverize objects in its path, often reducing buildings to their foundations and scouring exposed ground to the bedrock. Large objects such as ships and boulders can be carried several miles inland before the tsunami subsides.

Tsunami act very differently from typical surf swells: they contain immense energy, propagate at high speeds and can travel great transoceanic distances with little overall energy loss. Tsunami can cause damage thousands of kilometers from their origin, so there may be several hours between creation and impact on a coast arriving long after the seismic wave generated by the originating event arrives. Although the total or overall loss of energy is small, the total energy is spread over a larger and larger circumference as the wave travels. The energy per linear meter in the wave proportional to the inverse of the distance from the source.[citation needed] (In other words, it decreases linearly with distance.) This is the two-dimensional equivalent of the inverse square law, which is obeyed by waves which propagate in three dimensions (in a sphere instead of a circle).

A single tsunami event may involve a series of waves of varying heights, so the set of waves is called a train. In open water, tsunami have extremely long periods (the time for the next wave top to pass a point after the previous one), from minutes to hours, and long wavelengths of up to several hundred kilometers. This is a very different from typical wind-generated swells on the ocean, which might have periods of about 10 seconds and wavelengths of 150 meters.

The height of a tsunami wave in open water is often less than one meter, and the height is spread over the wavelength of the tsunami which is multiple kilometers. This is unnoticeable to people on ships in deep water. Because it has such a large wavelength, the energy of a tsunami mobilizes the entire water column down to the sea bed. Typical ocean surface waves in deep water cause water motion to a depth equal to half their wavelength. This means that ocean surface wave motion will only reach down to a depth of a few 100 m or less. Tsunami, by contrast, behave as shallow-water waves in the deep ocean.

Because a tsunami behaves like a shallow-water wave, its speed is based on the depth of the water. Typically, a tsunami wave will travel across a deep ocean at an average speed of 400 to 500 mph.([2]). As the wave approaches land, the sea shallows and the tsunami wave no longer travels as quickly, so it begins to 'pile-up': the wave front becomes steeper and taller, and there is less distance between crests. While a person at the surface of deep water would probably not even notice the tsunami, the wave can increase to a height of six stories or more as it approaches the coastline and compresses. The steepening process is analogous to the cracking of a tapered whip. As a wave goes down the whip from handle to tip, the same energy is carried by less and less material, which as a consequence then moves more violently.

A wave becomes a shallow-water wave when the ratio between the water depth and its wavelength gets very small, and since a tsunami has an extremely large wavelength (hundreds of kilometers), tsunami act as a shallow-water wave even in deep oceanic water. Shallow-water waves move at a speed that is equal to the square root of the product of the acceleration of gravity (9.8 m/s2) and the water depth. For example, in the Pacific Ocean, where the typical water depth is about 4000 m, a tsunami travels at about 200 m/s (720 km/h or 450 mph) with little energy loss, even over long distances. At a water depth of 40 m, the speed would be 20 m/s (about 72 km/h or 45 mph), which is much slower than the speed in the open ocean, but the wave would still be difficult to outrun.

Tsunami propagate outward from their source, so coasts in the "shadow" of affected land masses are usually fairly safe. However, tsunami waves can diffract around land masses (as shown in this Indian Ocean tsunami animation as the waves reach southern Sri Lanka and India). They are also not necessarily symmetrical; tsunami waves may be much stronger in one direction than another, depending on the nature of the source and the surrounding geography.

Local geographic peculiarities can lead to seiche (standing waves) forming, which can amplify the onshore damage. For instance, the tsunami that hit Hawaii on April 1, 1946 had a fifteen-minute interval between wave fronts. The natural resonant period of Hilo Bay is about thirty minutes. That meant that every second wave was in phase with the motion of Hilo Bay, creating a seiche in the bay. As a result, Hilo suffered worse damage than any other place in Hawaii, with the tsunami/seiche reaching a height of 14 m and killing 159 inhabitants.

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 approach crest of the tsunami, although the warning arrives only a very short time before the crest, which typically arrives seconds to minutes later.[3] Although in the 2004 tsunami in the Indian Ocean the sea receding was not reported on the African coast or any other western coasts that it hit, when the tsunami approached from the east.

Warnings and prevention

File:Tsunamihazardzonesign.jpg
"Tsunami Hazard Zone" sign at the University of California, Santa Barbara
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). [4]

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. [5] 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, [6]).

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. [7] 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.

Historical tsunami

See also List of historic tsunami by death toll.

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 684 A.D. Hakuho 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

[8]

1700 - Vancouver Island, Canada

January 26 - 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 1755 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.

The earthquake, tsunami, and many forest fires killed more than 1,000 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.

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 Kyushu, Japan caused by a collapsing volcano

Tsunami were the main cause of death for Japan's worst-ever volcanic disaster, due to an eruption of Mount Unzen in Nagasaki Prefecture, Kyushu, 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 avelanche 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 5000 is thought to have been killed by the landslide, around 5000 by the tsunami across the bay in Higo Province, and a further 5000 by the tsunami returning to strike Shimabara.

1868 - Hawai’ian 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 cocoanut 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.

File:Burnintsunami.jpg
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 Honshu, 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 Honshu, 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, tsunami being the leading cause of 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 Hawaii and five in Alaska (the lighthouse keepers at the Scotch Cap Light in the Aleutians) resulted in the creation of a tsunami warning system (specifically The PTWC), established in 1949 for Pacific Ocean area countries. The tsunami is locally known in Hawaii as the April Fools Day Tsunami in Hawaii due to people thinking the warnings were an April Fools prank.

1958 - Lituya Bay Megatsunami

In 1958 an earthquake with a magnitude of 8.3 on the Richter scale rocked a small inlet of 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 524m (1740ft) making it the largest wave in recorded history. It swept up 3 boats, 1 managed to ride the wave the other 2 were swpet into the Pacific Ocean, where they were completely destroyed, killing 4 people.

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]

1964 - Good Friday tsunami

After the magnitude 9.2 Good Friday Earthquake (Friday, March 27, 1964), tsunami struck Alaska, British Columbia, California, and coastal Pacific Northwest towns, killing 121 people. 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 6, 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 tsunami

File:1993 Okushiri EB NHK.jpg
Map of Hokkaidō shown on NHK during an emergency broadcast.

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

Within minutes, the Japan Durka Durka Agency issued a tsunami warning which was broadcast on NHK in English and Japanese (archived at YouTube[10]). However, this was too late for the small island of Okushiri near the epicenter, which was struck with extremely big waves, some reaching 30 meters, within 2 to 5 minutes after the quake. The village of Aonae at the southern tip of the island, which is surrounded by the sea in three directions, was devastated over the course of the next hour by a total of 13 waves over 2 meters high coming from multiple directions, including waves which had bounced back off Hokkaidō, despite being surrounded by tsunami barriers. Out of the 250 people killed as a result of the quake, 197 of them were killed by the tsunami on Okushiri; the waves also caused deaths on the coast of Hokkaidō. While many residents, remembering the 1983 tsunami (see above) ten years previous, 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 31m (about 93ft) tall.

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, which had a magnitude of 9.3, 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 aproximately 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.

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 a 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 600 people were reported killed, with around 150 others still missing. 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.

2006 - Crescent City, California tsunami

On November 15 2006 according to the United States Geological Survey, an 8.3 magnitude earthquake struck off coast of the Kuril´sk, Kuril Islands, about 1,000 miles northeast of Japan. The quake triggered a tsunami that struck the Pacific Northwest. There were no fatalities. The resulting tsunami did cause approximately $700,000 in damage to Crescent City, California's harbor. The quake sent a wave surge of 5-6 feet. The tsunami struck five hours after warnings had been lifted and an initial wave of 3-5 feet struck earlier in the morning. Surges also struck Santa Cruz, California.

Other tsunami in South Asia

Tsunami in South Asia
(Source: Amateur Seismic Centre, India)[12]
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
26 December 2004 Banda Aceh, Indonesia; Tamil Nadu, Kerala, Andhra Pradesh, Andaman and Nicobar Islands (India); Sri Lanka; Thailand; Malaysia; Maldives; Somalia; Kenya; Tanzania

North American and Caribbean tsunami

Possible tsunami

Source: NOAA National Weather Service Forecast Office

European tsunami

Other historical tsunami

Other tsunami that have occurred include the following:

  • ca. 1600 B.C.: The Israelite crossing 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 by 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. The cause of the flood remains disputed, it is quite possible that it was caused by a combination of meteorological extremes and tidal peaks.(discussion).
  • July 9, 1958: A huge landslip caused a tsunami in the fjörd-shaped Lituya Bay, Alaska, USA. It traveled at over 150 km/h. It was the world’s tallest recorded tsunami at 524 m (1719 ft).

See also

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
  1. ^ ""Emergency & Disasters Data Base"". CRED. Retrieved 2006-05-30.
Wikimedia Commons has media related to Tsunami.

Articles and websites

Images and video

See also: Images and video, 2004 Indian Ocean earthquake

Fiction

Template:Link FA Template:Link FA Template:Link FA

Retrieved from "https://en.wikipedia.org/enwiki/w/index.php?title=Tsunami&oldid=109319759"