krf blogs: SQUID...SQUID...SQUID - Part 2

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the destiny: THE ESCAPE 1

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THE WORST EVER TSUNAMI IN ASIAN HISTORY

INDONESIAN TSUNAMI / 2004 INDIAN OCEAN TSUNAMI AND EARTHQUAKE

The 2004 Indian Ocean earthquake was an undersea megathrust earthquake that occurred at 00:58:53 UTC on Sunday, December 26, 2004, with an epicentre off the west coast of Sumatra, Indonesia. The quake itself is known by the scientific community as the Sumatra-Andaman earthquake.^[3][4] The resulting tsunami is given various names, including the 2004 Indian Ocean tsunami, South Asian Tsunami, Indonesian Tsunami, and Boxing Day Tsunami.

Whatever name they call it, the Tsunami had left a very big impact to the affected areas in Asian region which changed the lives of the survivors and the landscape forever.  

The earthquake was caused by subduction and triggered a series of devastating tsunamis along the coasts of most landmasses bordering the Indian Ocean, killing over 230,000 people in fourteen countries, and inundating coastal communities with waves up to 30 meters (100 feet) high.^[5] It was one of the deadliest natural disasters in recorded history. Indonesia was the hardest hit, followed by Sri Lanka, India, and Thailand.

With a magnitude of between 9.1 and 9.3, it is the third largest earthquake ever recorded on a seismograph. This earthquake had the longest duration of faulting ever observed, between 8.3 and 10 minutes. It caused the entire planet to vibrate as much as 1 centimetre (0.4 inches)^[6] and triggered other earthquakes as far away as Alaska.^[7] Its hypocentre was between Simeulue and mainland Indonesia.^[8]

The plight of the many affected people and countries prompted a worldwide humanitarian response. In all, the worldwide community donated more than $14 billion (2004 U.S. dollars) in humanitarian aid.^[9]

Perhaps it was the worst disaster ever suffered by the mankind in the modern world.






The disaster not only hit the countries in Asia but also countries in Africa. The tsunami hit the Indian Ocean and its huge waves destroyed any thing on its way up to the shore of South Africa.

According to the U.S. Geological Survey a total of 227,898 people died. Measured in lives lost, this is one of the ten worst earthquakes in recorded history, as well as the single worst tsunami in history. Indonesia was the worst affected area, with most death toll estimates at around 170,000.   However, another report by health minister of Indonesia, Fadilah Supari has estimated the death total to be as high as 220,000 in Indonesia alone, giving a total of 280,000 casualties.

TSAR BOMBA

WHAT IS TSAR BOMBA?

Tsar Bomba is the name of the largest nuclear weapon ever detonated in the World. Tsar Bomba (Russian: Царь-бомба) is the nickname for the AN602 hydrogen bomb, the most powerful nuclear weapon ever detonated. Also known as Kuz`kina Mat` (Russian: Кузькина мать, Kuzka's mother).

Developed by the Soviet Union, the bomb was originally designed to have a yield of about 100 megatons of TNT (420 PJ); however, the bomb yield was reduced to 50 megatons in order to reduce nuclear fallout. This attempt was successful, as it was one of the cleanest (relative to its yield) nuclear bombs ever detonated. Only one bomb of this type was ever built and it was tested on October 30, 1961, in the Novaya Zemlya archipelago.^[1]

The remaining bomb casings are located at the Russian Atomic Weapon Museum, Sarov (Arzamas-16), and the Museum of Nuclear Weapons, All-Russian Research Institute of Technical Physics, Snezhinsk (Chelyabinsk-70). Neither of these casings has the same antenna configuration as the actual device that was tested.

The Tsar Bomba is attributed with many names in literature: Project number – Project 7000; Product code – Product code 202 (Izdeliye 202); Article designations – RDS-220 (РДС-220), RDS-202 (РДС-202), RN202 (PH202), AN602 (AH602); Codename – Vanya; Nicknames – Big Ivan, Tsar Bomba, Kuzkina Mat' (Kuzya's Mother). The term "Tsar Bomba" was coined in an analogy with two other massive Russian objects: the Tsar Kolokol, the world's largest bell, and the Tsar Pushka, the world's largest cannon. Although the bomb was so named by Western sources, the name is now used in Russia as well.

Type	Thermonuclear weapon
Place of origin	Soviet Union
Production history
Designer	Julii Borisovich Khariton, Andrei Sakharov, Victor Adamsky, Yuri Babayev, Yuri Smirnov, and Yuri Trutnev
Number built	1 (plus one mock bomb)
Specifications
Weight	27,000 kilograms (60,000 lb)
Length	8 metres (26 ft)
Diameter	2.1 metres (6.9 ft)
Blast yield	50 megatons of TNT (210 PJ)

Design 

The tsar was a three-stage Teller–Ulam design hydrogen bomb with a yield of 50 megatons (Mt).^[2] This is equivalent to 1,400 times the combined power of the two nuclear explosives used in World War II (Little Boy (13–18 kilotons) and Fat Man (21 kilotons), the bombs that destroyed Hiroshima and Nagasaki),^[3] or 10 times the combined power of all the explosives used in WWII. But it is still only one quarter of the estimated yield of the 1883 eruption of Krakatoa. A three-stage H-bomb uses a fission bomb primary to compress a thermonuclear secondary, as in most H-bombs, and then uses energy from the resulting explosion to compress a much larger additional thermonuclear stage. However, there is evidence that the Tsar Bomba had a number of third stages rather than a single very large one.^[4]

The initial three-stage design was capable of approximately 100 Mt, but would have caused too much radioactive fallout. To limit fallout, the third stage and possibly the second stage had a lead tamper instead of a uranium-238 fusion tamper (which greatly amplifies the reaction by fissioning uranium atoms with fast neutrons from fusion reaction). This eliminated fast fission by the fusion-stage neutrons, so that approximately 97% of the total energy resulted from fusion alone (as such, it was one of the "cleanest" nuclear bombs ever created, generating a very low amount of fallout relative to its yield). There was a strong incentive for this modification since most of the fallout from a test of the bomb would have fallen on populated Soviet territory.^[4][5]

The components were designed by a team of physicists headed by Academician Julii Borisovich Khariton and including Andrei Sakharov, Victor Adamsky, Yuri Babayev, Yuri Smirnov, and Yuri Trutnev. Shortly after the Tsar Bomba was detonated, Sakharov began speaking out against nuclear weapons, which culminated in his becoming a dissident.^[1][5]

a Tsar Bomba-type casing on display at Sarov

The Test

The Tsar Bomba was flown to its test site by a specially modified Tu-95V release plane, flown by Major Andrei Durnovtsev. Taking off from an airfield in the Kola Peninsula, the release plane was accompanied by a Tu-16 observer plane that took air samples and filmed the test. Both aircraft were painted with a special reflective white paint to limit heat damage.

The bomb, weighing 27 tonnes, was so large (8 metres (26 ft) long by 2 metres (6.6 ft) in diameter) that the Tu-95V had to have its bomb bay doors and fuselage fuel tanks removed. The bomb was attached to an 800 kilogram fall-retardation parachute, which gave the release and observer planes time to fly about 45 kilometres (28 mi) from ground zero.

The Tsar Bomba detonated at 11:32 on October 30, 1961 over the Mityushikha Bay nuclear testing range (Sukhoy Nos Zone C), north of the Arctic Circle on Novaya Zemlya Island in the Arctic Sea. The bomb was dropped from an altitude of 10.5 kilometres (6.5 mi); it was designed to detonate at a height of 4 kilometres (2.5 mi) over the land surface (4.2 kilometres (2.6 mi) over sea level) by barometric sensors.^[1][4][5]

The original, November 1961 A.E.C. estimate of the yield was 55–60 Mt, but since 1991 all Russian sources have stated its yield as 50 Mt. Khrushchev warned in a filmed speech to the Communist Parliament of the existence of a 100 Mt bomb (technically the design was capable of this yield). Although simplistic fireball calculations predict a ground impact, its own shockwave reflected back to prevent this.^[6] The fireball reached nearly as high as the altitude of the release plane and was seen almost 1,000 kilometres (620 mi) from ground zero. 

Tsar Bomba's fireball, about 8 km (5miles) in diameter

 The subsequent mushroom cloud was about 64 kilometres (40 mi) high (nearly seven times the height of Mount Everest), which meant that the cloud was well inside the Mesosphere when it peaked. The base of the cloud was 40 kilometres (25 mi) wide. All buildings in the village of Severny (both wooden and brick), located 55 kilometres (34 mi) from ground zero, were completely destroyed. In districts hundreds of kilometers from ground zero, wooden houses were destroyed, and stone ones lost their roofs, windows and doors; and radio communications were interrupted for almost one hour. One participant in the test saw a bright flash through dark goggles and felt the effects of a thermal pulse even at a distance of 270 kilometres (170 mi). The heat from the explosion could have caused third-degree burns 100 km (62 miles) away from ground zero. 

A shock wave was observed in the air at Dikson settlement 700 kilometres (430 mi) away; windowpanes were partially broken to distances of 900 kilometres (560 mi). Atmospheric focusing caused blast damage at even greater distances, breaking windows in Norway and Finland. The seismic shock created by the detonation was measurable even on its third passage around the Earth.^[7] Its seismic body wave magnitude was about 5 to 5.25.^[6] The energy yield was around 7.1 on the Richter scale but, since the bomb was detonated in air rather than underground, most of the energy was not converted to seismic waves. The TNT equivalent of the 50 MT test could be represented by a cube of TNT 312 metres on a side, approximately the height of the Eiffel Tower.

Since 50 Mt is 2.1×10¹⁷ joules, the average power produced during the entire fission-fusion process, lasting around 39 nanoseconds^{[citation needed]}, was about 5.4×10²⁴ watts or 5.4 yottawatts (5.4 septillion watts). This is equivalent to approximately 1.4% of the power output of the Sun.^[8]

The Tsar Bomba is the single most physically powerful device ever used by humanity. Its size and weight precluded a successful delivery in case of a real war.^[9] By contrast, the largest weapon ever produced by the United States, the now-decommissioned B41, had a predicted maximum yield of 25 Mt, and the largest nuclear device ever tested by the US (Castle Bravo) yielded 15 Mt (this was due to an unexpected runaway lithium-7 reaction; the design yield was approximately 5 Mt). The largest weapons deployed by the Soviet Union were also around 25 Mt, as in the SS-18 Mod. 2 ICBM warheads.


Analysis

The weight and size of the Tsar Bomba limited the range and speed of the specially modified bomber carrying it and ruled out its delivery by an ICBM (although on December 24, 1962, a 50 Mt ICBM warhead developed by Chelyabinsk-70 was detonated at 24.2 Mt to reduce fallout).^[10] In terms of physical destructiveness, much of its high yield was inefficiently radiated upwards into space. It has been estimated that detonating the original 100 Mt design would have released fallout amounting to about 25 percent of all fallout emitted since the invention of nuclear weapons.^[11] Hence, the Tsar Bomba was an impractically powerful weapon. It was decided that such a test blast would create too great a risk of nuclear fallout and a near certainty that the release plane would be unable to reach safety before detonation.^[12]

The Tsar Bomba was the culmination of a series of high-yield thermonuclear weapons designed by the USSR and USA during the 1950s (examples include the Mark-17^[13] and B41). Such bombs were designed because:

• The nuclear bombs of the day were large and heavy, regardless of yield, and could only be delivered by strategic bombers. Hence yield was subject to dramatic economies of scale;
• It was feared that many bombers would fail to reach their targets because their size and low speed made detection and interception easy. Hence maximizing the firepower carried by any single bomber was considered vital;
• Prior to satellite intelligence, each side lacked precise knowledge of the location of the other's military and industrial facilities;
• A bomb dropped without benefit of advanced inertial navigation systems could easily miss its intended target. Parachute retardation would only worsen the bomb's accuracy.

Thus certain bombs were designed to destroy an entire large city even if dropped five to ten kilometres from its centre. This objective meant that yield and effectiveness were positively correlated, at least up to a point. However, the advent of ICBMs accurate to 500 metres or better made such a design philosophy obsolete. Subsequent nuclear weapon design in the 1960s and 1970s focused primarily on increased accuracy, miniaturization, and safety. The standard practice for many years has been to employ multiple smaller warheads (MIRVs) to "carpet" an area, resulting in greater ground damage.

Footage from a Soviet documentary about the bomb is featured in Trinity and Beyond: The Atomic Bomb Movie (Visual Concept Entertainment, 1995), where it is referred to as the Russian monster bomb.^[14] The movie incorrectly states that the Tsar Bomba project broke the moratorium on nuclear tests. Soviets restarted their tests two months before Tsar Bomba, and there was no de jure moratorium in place at the time (the U.S. had already announced that it considered itself free to resume testing without further notice).^[1]

Comparative fireball radii for a selection of nuclear weapons, including the Tsar Bomba. Full blast effects extend many times beyond the radii of the fireballs themselves.

Zone of total destruction of the Tsar Bomba (as an example – over a map of Paris): red circle = total destruction (radius 35 kilometres (22 mi)), yellow circle = fireball (radius 3.5 kilometres (2.2 mi)).

TSUNAMIS

MEGATSUNAMIS

What is Megatsunami? Megatsunami (also known as iminami or "purification wave") ^[1] is an informal term to describe a tsunami that has initial wave heights that are much larger than normal tsunamis. Unlike usual tsunamis, which originate from tectonic activity and the raising or lowering of the sea floor, known megatsunamis have originated from large scale landslides or impact events.

Concept

A megatsunami is meant to refer to a tsunami with an initial wave amplitude (height) measured in several tens, hundreds, or possibly thousands of meters.

Normal tsunamis generated at sea result from movement of the sea floor. They have a small wave height offshore, and a very long wavelength (often hundreds of kilometers long), and generally pass unnoticed at sea, forming only a slight swell usually of the order of 30 cm (12 in) above the normal sea surface. When they reach land the wave height increases dramatically as the base of the wave pushes the water column above it upwards.

By contrast, megatsunamis are caused by giant landslides and other impact events. Underwater earthquakes or volcanic eruptions do not normally generate such large tsunamis, but landslides next to bodies of water resulting from earthquakes can, since they cause a massive amount of displacement. If the landslide or impact occurs in a limited body of water, as happened at the Vajont Dam (1963) and Lituya Bay (1958) then the water may be unable to disperse and one or more exceedingly large waves may result.

Two heights are sometimes quoted for megatsunamis - the height of the wave itself (in water), and the height to which it washes when it reaches land, which depending upon the locale, can be several times larger.

History of the hypothesis

Main article: 1958 Lituya Bay megatsunami

Geologists searching for oil in Alaska in 1953 observed that in Lituya Bay, mature tree growth did not extend to the shoreline as it did in many other bays in the region. Rather, there was a band of younger trees closer to the shore. Forestry workers, glaciologists, and geographers call the boundary between these bands a trim line. Trees just above the trim line showed severe scarring on their seaward side, whilst those from below the trim line did not. The scientists hypothesized that there had been an unusually large wave or waves in the deep inlet. Because this is a recently deglaciated fjord with steep slopes and crossed by a major fault, one possibility was a landslide-generated tsunami.^[2]

On 9 July 1958, an earthquake of magnitude 7.7 (on the Richter scale), caused 90 million tonnes of rock and ice to drop into the deep water at the head of Lituya Bay. The block fell almost vertically and hit the water with sufficient force to create a wave approximately 524 metres (1,719 ft) high. Howard Ulrich and his son, Howard Jr., were in the bay in their fishing boat when they saw the wave. They both survived and reported that the wave carried their boat "over the trees" on one of the initial waves which washed them back into the bay, though the larger wave did not harm them a great lot. A similar tsunami out at sea could come tens of kilometers inland.

This event and evidence of a potentially similar past event at the same location inspired the term megatsunami.

List of Megatsunami

Prehistoric

1-The asteroid which created the Chicxulub crater in Yucatan approximately 65 million years BP would have generated some of the largest megatsunami in Earth's history.

2-A series of megatsunami were generated by the bolide impact that created the Chesapeake Bay impact crater, about 35.5 million years BP.^[3]

3-At Seton Portage, British Columbia, Canada, a freshwater megatsunami may have occurred approximately 10,000 BP.^[4] A huge block of the Cayoosh Range suddenly slid northwards into what had been a large lake spanning the area from Lillooet, British Columbia to near Birken, in the Gates Valley or Pemberton Pass to the southwest. The event has not been studied in detail, but the proto-lake (freshwater fjord) may have been at least as deep as the two present-day halves, Seton and Anderson Lakes, on either side of the Portage, suggesting that the surge generated by the giant landslide in the narrow mountain confines of the fjord valley may have been comparable in scale to Lituya Bay. Another more recent landslide on the south shore of Anderson Lake dropped a large portion of high mountainside down a debris chute, creating a rockwall "fan" which must have made a megatsunami-type wave, though not as large as the main one at the Portage.

4-Approximately 8,000 BP, a massive volcanic landslide off of Mt. Etna, Sicily caused a megatsunami which devastated the eastern Mediterranean coastline on three continents.^[5] 

5-In the Norwegian Sea, the Storegga Slide caused a megatsunami approximately 7,000 years BP.^[6] 

6-Approximately 6000 years ago, a landslide on Réunion island, to the east of Madagascar, may have caused a megatsunami.^[7] 

7-The recently discovered undersea Burckle Crater located at the bottom of the Indian Ocean would have caused a megatsunami at the time of impact estimated to be c. 3000–2800 BCE. It is unknown whether the Burckle Crater is connected to the Fenambosy Chevron which provides evidence of another megatsunami.

8-Evidence for large landslides has been found in the form of extensive underwater debris aprons around many volcanic ocean islands which are composed of the material which has slid into the ocean. The island of Molokai had a catastrophic collapse over a million years ago; this underwater landslide likely caused large tsunamis. In recent years, five such debris aprons have been located around the Hawaiian Islands. The Canary Islands have at least 14 such debris aprons associated with the archipelago.

Modern

1792: Mount Unzen, Japan

Main article: Mount Unzen

In 1792, Mount Unzen in Japan erupted, causing part of the volcano to collapse into the sea. The landslide caused a megatsunami that reached 100 meters (328 ft) high and killed 15,000 people in the local fishing villages.

1958: Lituya Bay, Alaska, USA

 

Main articles: 1958 Lituya Bay megatsunami and Lituya Bay

 

Damage from the 1958 Lituya Bay megatsunami can be seen in this oblique aerial photograph of Lituya Bay, Alaska as the lighter areas at the shore where trees have been stripped away.

On 9 July 1958, a giant landslide at the head of Lituya Bay in Alaska, caused by an earthquake, generated a wave with an initial amplitude of 524 meters (1,719 ft). This is the highest wave ever recorded, and surged over the headland opposite, stripping trees and soil down to bedrock, and surged along the fjord which forms Lituya Bay, destroying a fishing boat anchored there and killing two people. Howard Ulrich and his son managed to ride the wave in their boat, and both survived.

1963: Vajont Dam, Italy

Main article: Vajont Dam

On 9 October 1963, a landslide above Vajont Dam in Italy produced a 250 m (820 ft) surge that overtopped the dam and destroyed the villages of Longarone, Pirago, Rivalta, Villanova and Faè, killing nearly 2,000 people.

1980: Spirit Lake, Washington, USA

Main articles: Spirit Lake (Washington), 1980 eruption of Mount St. Helens, and Mount St. Helens

On May 18, 1980, the upper 460 meters of Mount St. Helens failed and detached in a massive landslide. This released the pressure on the magma trapped beneath the summit bulge which exploded as a lateral blast, which then released the over-pressure on the magma chamber and resulted in a plinian eruption. One lobe of the avalanche surged onto Spirit Lake, causing a megatsunami which pushed the lake waters in a series of surges, which reached a maximum height of 260 metres^[8] above the pre-eruption water level (~975 m asl). Above the upper limit of the tsunami, trees lie where they were knocked down by the pyroclastic surge; below the limit, the fallen trees and the surge deposits were removed by the megatsunami and deposited in Spirit Lake.^[9]

Potential Future Megatsunami

Experts interviewed by the BBC think that a massive landslide on a volcanic ocean island is the most likely future cause of a megatsunami.^[10] The size and power of a wave generated by such means could produce devastating effects, travelling across oceans and inundating up to 25 kilometres (16 mi) inland from the coast.

British Columbia

Some geologists consider an unstable rock face at Mount Breakenridge, above the north end of the giant fresh-water fjord of Harrison Lake in the Fraser Valley of southwestern British Columbia, Canada, to be unstable enough to collapse into the lake, generating a megatsunami that might destroy the town of Harrison Hot Springs (located at its south end).^[11]

Canary Islands

Geologists S. Day and S. Ward consider that a megatsunami could be generated during a future eruption involving the Cumbre Vieja on the volcanic ocean island of La Palma, in the Canary Islands.^[12][13] In 1949, the Cumbre Vieja volcano erupted at its Duraznero, Hoyo Negro and San Juan vents. During this eruption, an earthquake with an epicentre near the village of Jedy occurred. The following day Rubio Bonelli, a local geologist, visited the summit area and discovered that a fissure about 2.5 kilometers (2 mi) long had opened on the eastern side of the summit. As a result, the western half of the Cumbre Vieja (which is the volcanically active arm of a triple-armed rift) had slipped about 2 meters (7 ft) downwards and 1 meters (3 ft) westwards towards the Atlantic Ocean.

The Cumbre Vieja volcano is currently in a dormant stage, but will almost certainly erupt again in the future. Day and Ward hypothesize^[12][13] that if such an eruption causes the western flank to fail, a megatsunami will be generated.

La Palma is currently the most volcanically active island in the Canary Islands Archipelago. It is likely that several eruptions would be required before failure would occur on Cumbre Vieja.^[12][13] However, the western half of the volcano has an approximate volume of 500 cubic kilometres (120 cu mi) and an estimated mass of 1,500,000,000,000 metric tons (1.7×10¹² short tons) If it were to catastrophically slide into the ocean, it could generate a wave with an initial height of about 1,000 metres (3,300 ft) at the island, and a likely height of around 50 metres (164 ft) at the Caribbean and the Eastern North American seaboard when it runs ashore eight or more hours later. Tens of millions of lives would be lost as New York, Boston, Baltimore, Washington, D.C., Miami, Havana, and many other cities near the Atlantic coast are leveled. The likelihood of this happening is a matter of vigorous debate.^[14]

The last Cumbre Vieja eruption occurred in 1971 at the southern end of the sub-aerial section without any movement. The section affected by the 1949 eruption is currently stationary and does not appear to have moved since the initial rupture.^[15]

Geologists and volcanologists also disagree about whether an eruption on the Cumbre Vieja would cause a single large gravitational landslide or a series of smaller landslides.

Hawaii

Prehistoric sedimentary deposits on the Kohala Volcano, Lanai and Molokai controversially indicates that landslides from the flank of the Kilauea and Mauna Loa volcanoes in Hawaii may have triggered past megatsunamis, most recently at 120,000 BP.^[16][17][18] A future tsunami event is also possible, with the tsunami potentially reaching up to about 1 kilometre (3,300 ft) in height.^[19][20] According to a documentary called National Geographic's Ultimate Disaster: Tsunami, if a big landslide occurred at Mauna Loa, a 30 metres (98 ft) tsunami would take only thirty minutes to reach Honolulu, Hawaii. There, hundreds of thousands of people would be killed as the tsunami leveled Honolulu and traveled 25 kilometres (16 mi) inland.

HISTORIC TSUNAMIS

Recorded Historic Tsunamis - Part 1

This article is telling about the lists of notable historic tsunamis, which are sorted by the date and location that the tsunami occurred, the earthquake that generated it, or both.

Because of seismic and volcanic activities at tectonic plate boundaries along the Pacific Ring of Fire, tsunamis occur most frequently in the Pacific Ocean, but are also worldwide natural phenomena. Tsunamis are possible wherever large bodies of water are found, including inland lakes, where they can be caused by landslides and glacier calving. Very small tsunamis, non-destructive and undetectable without specialized equipment, occur frequently as a result of minor earthquakes and other events.

As early as 426 BC, the Greek historian Thucydides inquired in his book History of the Peloponnesian War (3.89.1-6) about the causes of tsunamis. He argued rightly that it could only be explained as a consequence of ocean earthquakes, and could see no other possible causes for the phenomenon.^[1]

Crete and the Argolid and other locations were destroyed by a tsunami caused by the eruption of Thira, which destroyed Minoan civilization on Crete and related cultures in the Cyclades and in areas facing the eruption on the Greek mainland such as the Argolid.

During the Persian siege of the sea town Potidaea, Greece, in 479 BC,^[2] the Greek historian Herodotus reports how the Persian attackers who tried to exploit an unusual retreat of the water were suddenly surprised by "a great flood-tide, higher, as the people of the place say, than any one of the many that had been before". Herodotus attributes the cause of the sudden flood to the wrath of Poseidon.^[3]

Here are some facts provided by the history about the tsunamis:

Tsunamis - Before 1000 AD

 

1) 6100 BC: Norwegian Sea

Main article: Storegga Slide

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.^[4] Based on carbon dating of plant material recovered from sediment deposited by the tsunami, the latest incident occurred around 6100 BC.^[5] 

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.

 

2) 1600 BC: Santorini, Greece

Main article: Minoan eruption

The volcanic eruption on Santorini, Greece is assumed to have caused severe damage to cities around it, most notably the Minoan civilization on Crete. A tsunami is assumed to be the factor that caused the most damage.

 

3) 426 BC: Maliakos Gulf, Greece

Main article: 426 BC Maliakos Gulf tsunami

In the summer of 426 BC, a tsunami hit hard the Maliakos bay in Eastern Greece.^[6] The Greek historian Thucydides (3.89.1-6) described how the tsunami and a series of earthquakes intervened with the events of the raging Peloponnesian War (431-404 BC) and correlated for the first time in the history of natural science quakes and waves in terms of cause and effect.^[7]

 

4) 373 BC: Helike, Greece

An earthquake and a tsunami destroyed the prosperous Greek city Helike, lying 2 km away from the sea. The fate of the city, which remained permanently submerged, was often commented upon by ancient writers^[8] and may have inspired the contemporary Plato to the myth of Atlantis.

 

5) 365 AD: Alexandria, Eastern Mediterranean

Main article: 365 Crete earthquake

In the morning of July 21, 365 AD, an earthquake of great magnitude caused a huge tsunami more than 100 feet high. It devastated Alexandria and the eastern shores of the Mediterranean, killing thousands and hurling ships nearly two miles inland.^[9][10] The Roman historian Ammianus Marcellinus (Res Gestae 26.10.15-19) describes in his vivid account the typical sequence of the tsunami including an incipient earthquake, the sudden retreat of the sea and a following gigantic wave:

Slightly after daybreak, and heralded by a thick succession of fiercely shaken thunderbolts, the solidity of the whole earth was made to shake and shudder, and the sea was driven away, its waves were rolled back, and it disappeared, so that the abyss of the depths was uncovered and many-shaped varieties of sea-creatures were seen stuck in the slime; the great wastes of those valleys and mountains, which the very creation had dismissed beneath the vast whirlpools, at that moment, as it was given to be believed, looked up at the sun's rays. Many ships, then, were stranded as if on dry land, and people wandered at will about the paltry remains of the waters to collect fish and the like in their hands; then the roaring sea as if insulted by its repulse rises back in turn, and through the teeming shoals dashed itself violently on islands and extensive tracts of the mainland, and flattened innumerable buildings in towns or wherever they were found. Thus in the raging conflict of the elements, the face of the earth was changed to reveal wondrous sights. For the mass of waters returning when least expected killed many thousands by drowning, and with the tides whipped up to a height as they rushed back, some ships, after the anger of the watery element had grown old, were seen to have sunk, and the bodies of people killed in shipwrecks lay there, faces up or down. Other huge ships, thrust out by the mad blasts, perched on the roofs of houses, as happened at Alexandria, and others were hurled nearly two miles from the shore, like the Laconian vessel near the town of Methone which I saw when I passed by, yawning apart from long decay.^[9]

The tsunami in 365 AD was so devastating that the anniversary of the disaster was still commemorated annually at the end of the 6th century in Alexandria as a "day of horror."^[11]

Researchers at the University of Cambridge recently carbon dated corals on the coast of Crete which were lifted 10 metres and clear of the water in one massive push. This indicates that the tsunami of 365 AD was generated by an earthquake in a steep fault in the Hellenic trench near Crete. The scientists estimate that such a large uplift is only likely to occur once in 5,000 years, however the other segments of the fault could slip on a similar scale - and could happen every 800 years or so. It is unsure whether "one of the contiguous patches might slip in the future."^[12]

 

6) 684 AD: Hakuho, Japan (白鳳大地震)

Japan is the nation with the most recorded tsunamis in the world. The number of tsunamis in Japan totals 195 over a 1,313 year period (thru 1997), averaging one event every 6.73 years, the highest rate of occurrence in the world.

The Great Hakuho Earthquake was the first recorded tsunami in Japan. It hit in Japan on November 29, 684. It occurred off the shore of the Kii Peninsula, Nankaido, Shikoku, Kii, and Awaji region. It has been estimated to be a magnitude 8.4 ^[13] It was followed by a huge tsunami, but no estimates on how many deaths.^[14]

 

7) 869 AD: Sendai, Japan

Main article: 869 Sanriku earthquake and tsunami

The Sendai region was struck by a major tsunami that caused flooding extending 4 km inland from the coast. The town of Tagajō was destroyed, with an estimated 1,000 casualties.

 

8) 887 AD: Ninna Nankai, Japan (仁和南海地震)

On August 26 of the Ninna era, there was a strong shock in the Kyoto region, causing great destruction and some victims. At the same time, there was a strong earthquake in Osaka, Shiga, Gifu, and Nagano prefectures. A tsunami flooded the coastal locality, and some people died. The coast of Osaka and primarily Osaka Bay suffered especially heavily from the tsunami. The tsunami was also observed on the coast of Hyuga-Nada.^[13]

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KRF Kak Mie: Local Fruits - Nangka/Jackfruit

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TSUNAMI - Part 5

Warnings and Predictions

See also: Tsunami warning system

 

Tsunami warning sign

 

 

One of the deep water buoys used in the DART tsunami warning system

Drawbacks can serve as a brief warning. People who observe drawback (many survivors report an accompanying sucking sound), can survive only if they immediately run for high ground or seek the upper floors of nearby buildings. In 2004, ten-year old Tilly Smith of Surrey, England, was on Maikhao beach in Phuket, Thailand with her parents and sister, and having learned about tsunamis recently in school, told her family that a tsunami might be imminent. Her parents warned others minutes before the wave arrived, saving dozens of lives. She credited her geography teacher, Andrew Kearney.

In the 2004 Indian Ocean tsunami drawback was not reported on the African coast or any other eastern coasts it reached. This was because the wave moved downwards on the eastern side of the fault line and upwards on the western side. The western pulse hit coastal Africa and other western areas.

A tsunami cannot be precisely predicted, even if the magnitude and location of an earthquake is known. Geologists, oceanographers, and seismologists analyse each earthquake and based on many factors may or may not issue a tsunami warning. However, there are some warning signs of an impending tsunami, and automated systems can provide warnings immediately after an earthquake in time to save lives. One of the most successful systems uses bottom pressure sensors that are attached to buoys. The sensors constantly monitor the pressure of the overlying water column. This is deduced through the calculation:

where
P = the overlying pressure in newtons per metre square,
ρ = the density of the seawater= 1.1 x 10³ kg/m³,
g = the acceleration due to gravity= 9.8 m/s² and
h = the height of the water column in metres.
Hence for a water column of 5,000 m depth the overlying pressure is equal to

or about 5500 tonnes-force per square metre.

Regions with a high tsunami risk typically use tsunami warning systems to warn the population before the wave reaches land. On the west coast of the United States, which is prone to Pacific Ocean tsunami, warning signs indicate evacuation routes. In Japan, the community is well-educated about earthquakes and tsunamis, and along the Japanese shorelines the tsunami warning signs are reminders of the natural hazards together with a network of warning sirens, typically at the top of the cliff of surroundings hills.^[27]

The Pacific Tsunami Warning System is based in Honolulu, Hawaiʻi. It monitors Pacific Ocean seismic activity. A sufficiently large earthquake magnitude and other information triggers a tsunami warning. While the subduction zones around the Pacific are seismically active, not all earthquakes generate tsunami. Computers assist in analysing the tsunami risk of every earthquake that occurs in the Pacific Ocean and the adjoining land masses.

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  Tsunami hazard sign at Bamfield, British Columbia
  
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  A tsunami warning sign on a seawall in Kamakura, Japan, 2004
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  The monument to the victims of tsunami at Laupahoehoe, Hawaii
  
  
  

  

  Tsunami memorial in Kanyakumari beach
  

A seawall at Tsu, Japan

 

 

Tsunami Evacuation Route signage along U.S. Route 101, in Washington

As a direct result of the Indian Ocean tsunami, a re-appraisal of the tsunami threat for all coastal areas is being undertaken by national governments and the United Nations Disaster Mitigation Committee. A tsunami warning system is being installed in the Indian Ocean.

Computer models can predict tsunami arrival, usually within minutes of the arrival time. Bottom pressure sensors relay information in real time. Based on these pressure readings and other seismic information and the seafloor's shape (bathymetry) and coastal topography, the models estimate the amplitude and surge height of the approaching tsunami. All Pacific Rim countries collaborate in the Tsunami Warning System and most regularly practice evacuation and other procedures. In Japan, such preparation is mandatory for government, local authorities, emergency services and the population.

Some zoologists hypothesise that some animal species have an ability to sense subsonic Rayleigh waves from an earthquake or a tsunami. If correct, monitoring their behavior could provide advance warning of earthquakes, tsunami etc. However, the evidence is controversial and is not widely accepted. There are unsubstantiated claims about the Lisbon quake that some animals escaped to higher ground, while many other animals in the same areas drowned. The phenomenon was also noted by media sources in Sri Lanka in the 2004 Indian Ocean earthquake.^[28][29] 

It is possible that certain animals (e.g., elephants) may have heard the sounds of the tsunami as it approached the coast. The elephants' reaction was to move away from the approaching noise. By contrast, some humans went to the shore to investigate and many drowned as a result.

Along the United States west coast, in addition to sirens, warnings are sent on television & radio via the National Weather Service, using the Emergency Alert System.

Mitigation

See also: Tsunami barrier

In some tsunami-prone countries earthquake engineering measures have been taken to reduce the damage caused onshore. Japan, where tsunami science and response measures first began following a disaster in 1896, has produced ever-more elaborate countermeasures and response plans.^[30] That country has built many tsunami walls of up to 4.5 metres (15 ft) to protect 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 often overtop the barriers. For instance, the Okushiri, Hokkaidō tsunami which struck Okushiri Island of Hokkaidō within two to five minutes of the earthquake on July 12, 1993 created waves as much as 30 metres (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.^[31]

As a weapon

There have been studies and at least one attempt to create tsunami waves as a weapon. In World War II, the New Zealand Military Forces initiated Project Seal, which attempted to create small tsunamis with explosives in the area of today's Shakespear Regional Park; the attempt failed.^[32]