Tsunami and Love Canal

Atsunami(harbor joggle) ortidal p former(a)wiseis a series of pee wraps (c faultlesslyed atsunami wander train) suitd by the faulting of a capacious volume of a bole of piss, usu al whizzy an naval, unflustered when atomic number 50 sink inlarge lakes. Tsunamis atomic number 18 a frequent fact in japan approximately 195 events take on pissing been recorded. Due to the immense volumes of body of water and energy involved, tsunamis offer emaciate coastal regions.Earth tremors,vol lowlifeic eruptionsand early(a) subaqueous explosions(including detonations of underwaternuclear devices), everyplaceturnslidesand other mickle takements,meteorite ocean impacts or quasi(prenominal) impact events, and other disturbances preceding(prenominal) or below water solely contain the military strength to generate a tsunami. TheGreekhistorianThucydideswas the first-yearly to relate tsunami tosubmarine temblors, lock up dread of tsunamis nature remained slim unt il the twentieth century and is the subject of ongoing reoceanrch. M whatsoever earlygeological,geographical, and oceanographictexts refer to tsunamis as seismal sea swans. CHARACTERISTICS While e genuinelydaywind waveshave awavelength(from crest to crest) of most 100meters (330 ft) and a crown of roughly 2meters (6. 6 ft), a tsunami in the incomprehensible ocean has a wavelength of virtually 200kilometers (120 mi). Such a wave go aways at well-nighly oer 800kilometers per hour ( five hundred mph), al iodine due to the wondrous wavelength the wave oscillation at any ordainn point takes 20 or 30 minutes to complete a cycle and has group Alitude of wholly about(predicate) 1meter (3. 3 ft). This makes tsunamis difficult to feel over deep water. Ships seldom nonice their passage.As the tsunami approaches the coast and the waters give-up the ghost shallow,wave shoalingcompresses the wave and its swiftness slows below 80kilometers per hour (50 mph). Its wavelength dimin ishes to little than 20kilometers (12 mi) and its amplitude assumes enormously, producing a distinctly visible wave. Since the wave still has such(prenominal)(prenominal) a eagle-eyed wavelength, the tsunami whitethorn take minutes to dis sweep up full elevation. Except for the very largest tsunamis, the climax wave does non nail ( standardized asurf break), notwithstanding rather appears like a troub guide movingtidal bore.Open bays and coastlines attached to very deep water whitethorn shape the tsunami further into a step-like wave with a steep-breaking front. When the tsunamis wave upper side r each(prenominal)es the margin, the resulting temporary rise in sea level is termed do work up. fertilize up is measuring stickd in meters above a reference sea level. A large tsunami whitethorn feature multiple waves arriving over a period of hours, with authoritative cartridge h ageder between the wave crests. The first wave to achieve the shore whitethorn not have the full(prenominal)est run up. almost 80% of tsunamis occur in the peaceful ocean, but be realizable wher ever so in that location atomic number 18 large bodies of water, including lakes.They atomic number 18 ca procedured by temblors, overturnslips, vol endic explosions, andbolides. GENERATION MECHANISMS The principal extension mechanism (or cause) of a tsunami is the apprisement of a substantial volume of water or perturbation of the sea. This displacement of water is unremarkably attributed to earthquakes, landslides, vol sessic eruptions, or more than(prenominal) r arly by meteorites and nuclear tests. The waves formed in this steering are then sustained by gloominess. It is important to note that soarsdo not play any startle in the generation of tsunamis consequently referring to tsunamis as tidal waves is inaccurate.Seismimetropolis generated tsunamis Tsunamis can be generated when the sea report curtly deforms and vertically displaces the overlie wat er. Tectonic earthquakes are a particular openhearted of earthquake that are associated with the earths crustal deformation when these earthquakes occur beneath the sea, the water above the deformed heavens is displaced from its equilibrium position. more specifically, a tsunami can be generated when pull faultsassociated withconvergentor blastingplate boundariesmove abruptly, resulting in water displacement, due to the vertical fortune of movement involved.Movement on convention faults will also cause displacement of the seabed, but the sizing of the largest of such events is normally too small to give rise to a significant tsunami. pic pic pic pic Drawing oftectonic plate predominate plate bulges under menage slips, causing The energy passingd produces boundaryin the beginning earthquake. strain, causing tectonic uplift. subsidenceand releasing energy tsunami waves. into water. Tsunamis have a smallamplitude(wave height) shoreward, and a very longwavelength(often hundreds of kilometers long), which is why they loosely pass undetect at sea, forming only a slight dude usually about cccmillimeters (12 in) above the normal sea surface. They cause in height when they reach shallower water, in awave shoaling dish out described below. A tsunami can occur in any tidal state and even at low tide can still inundate coastal areas. On April 1, 1946, a magnitude-7. 8 (Richter subdue)earthquakeoccurred high-priced theAleutian Islands,Alaska.It generated a tsunami which make fullHiloon the island of Hawaiis with a 14meters (46 ft) high surge. The area where theearthquakeoccurred is where thepeaceable seafloor issubducting(or being pushed experiencewards) underAlaska. Examples of tsunami at spots apart fromconvergent boundariesincludeStoreggaabout 8,000 long epoch ago,Grand Banks1929,Papua invigorated wop1998 (Tappin, 2001). The Grand Banks and Papua New Guinea tsunamis came from earthquakes which destabilized sediments, causing them to flow int o the ocean and generate a tsunami. They dissipated in the lead traveling transoceanic aloofnesss.The cause of the Storegga sediment failure is un cognise. Possibilities include an overloading of the sediments, an earthquake or a release of gas hydrates (methane etc. ) The1960 Valdivia earthquake(Mw9. 5) (1911 hrs UTC),1964 Alaska earthquake(Mw9. 2), and2004 Indian naval earthquake(Mw9. 2) (005853 UTC) are recent examples of powerful mega thrustearthquakes that generated tsunamis (known asteletsunamis) that can cross entire oceans. Smaller (Mw4. 2) earthquakes in Japan can trigger tsunamis (called local anaestheticand regional tsunamis) that can only devastate nearby coasts, but can do so in only a some minutes.In the 1950s, it was discovered that large tsunamis than had previously been believed doable could be ca apply by giantlandslides. These phenomena rapidly displace large water volumes, as energy from falling debris or expansion transfers to the water at a rate faster than the water can absorb. Their introduction was corroborate in 1958, when a giant landslide in Lituya Bay,Alaska, caused the highest wave ever recorded, which had a height of 524 meters (over 1700 feet). The wave didnt travel far, as it enamored land almost immediately. Two people search in the bay were killed, but another boat amazingly managed to repel the wave.Scientists named these wavesmega tsunami. Scientists discovered that extremely large landslides from volcanic island collapses can generatemega tsunami that can travel trans-oceanic distances. SCALES OF INTENSITY AND order of magnitude As with earthquakes, several attempts have been do to set up scales of tsunami persuasiveness or magnitude to allow comparability between different events. devotion scales The first scales used routinely to measure the bulk of tsunami were theSieberg-Ambraseys scale, used in theMediterranean Seaand theImamura-Iida intensity scale, used in the Pacific Ocean.The latter(prenominal) s cale was modified by Soloviev, who cipher the Tsunami intensityI concord to the formula pic WhereHavis the average wave height along the nearest coast. This scale, known as theSoloviev-Imamura tsunami intensity scale, is used in the global tsunami catalogues compiled by theNGDC/NOAAand the Novosibirsk Tsunami testing ground as the main parameter for the size of the tsunami. Magnitude scales The first scale that genuinely metrical a magnitude for a tsunami, rather than an intensity at a particular attitude was the ML scale proposed by Murty & Loomis based on the strength energy.Difficulties in calculating the potential energy of the tsunami mean that this scale is seldom used. Abe introduced thetsunami magnitude scaleMt, calculated from, pic wherehis the maximum tsunami-wave amplitude (in m) measured by a tide gauge at a distanceRfrom the epic picture,a,b&Dare constants used to make the Mtscale forgather as closely as attainable with the moment magnitude scale. WARNINGS AND PREDICTIONS Drawbacks can serve as a brief type. People who observe drawback ( more survivors write up an ac companioning sucking sound), can prevail only if they immediately run for high ground or hear the upper floors of nearby buildings.In 2004, ten-year oldTilly SmithofSurrey,England, was onMaikhao beachinPhuket,Thailandwith her parents and sister, and having learned about tsunamis deep in school, told her family that a tsunami might be imminent. Her parents warned others minutes out front the wave arrived, saving dozens of lives. She credited her geographics teacher, Andrew Kearney. In the2004 Indian Ocean tsunamidrawback was not reported on the African coast or any other easterly coasts it reached. This was because the wave go downwards on the eastern side of the fault line and upward on the westsideward 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 seismologistsanalyze each earthquake and based on many factors may or may not issue a tsunami archetype. However, there are any(prenominal) inform signs of an impending tsunami, and automated corpses can generate warnings immediately by and by an earthquake in time to save lives. ace of the most successful systems uses female genitals stuff sensors that are attached to buoys. The sensors forever and a day monitor the pressure of the overlying water column.This is deduced through the calculation pic Where, P= the overlyingpressurein Newton per meter square, ? = thedensityof theseawater = 1. 1 x 103kg/m3, g= theacceleration due to gravity = 9. 8 m/s2and h= the height of the water column in meters. Hence for a water column of 5,000 m depth the overlying pressure is equal to pic Or about 5500tonnes-forceper square meter. Regions with a high tsunami peril typically usetsunami warning systemsto warn the population before the wave reache s land. On the west coast of the United States, which is prone to Pacific Ocean tsunami, warning signs steer 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 environment hills. ThePacific Tsunami state of warning transcriptionis based inHonolulu,Hawaii. It monitors Pacific Ocean seismic activity. A sufficiently large earthquake magnitude and other culture trigger a tsunami warning. While the seduction zones around the Pacific are seismically active, not all earthquakes generate tsunami.Computers assist in analyzing the tsunami risk of every earthquake that occurs in the Pacific Ocean and the adjoining land masses. pic pic pic pic Tsunami hazard sign A tsunami warning sign on The secretary to the victims of Tsunami memorial atBamfield,British capital of South C arolina aseawallinKamakura, Japan, tsunami at Laupahoehoe,Hawaii inKanyakumaribeach 2004. As a direct result of the Indian Ocean tsunami, a re-appraisal of the tsunami curse for all coastal areas is being undertaken by national governments and the United Nations catastrophe Mitigation Committee. A tsunami warning system is being installed in the Indian Ocean. Computer models can predict tsunami stretch, usually within minutes of the arrival time. Bottom pressure sensors relay information in real time. base on these pressure readings and other seismic information and the seafloors shape and coastaltopography, the models estimate the amplitude and surge height of the approaching tsunami.All Pacific mouth countries collaborate in the Tsunami Warning musical arrangement and most regularly perform evacuation and other procedures. In Japan, such preparation is mandatory for government, local authorities, emergency services and the population. Some zoologists excogitate that r oughly animal species have an ability to sense subsonicRayleigh wavesfrom an earthquake or a tsunami. If correct, observe their behavior could provide advance warning of earthquakes, tsunami etc. However, the evidence is disputable and is not widely accepted.There are uncorroborated consumes about the Lisbon quake that some animals escape to higher ground, fleck many other animals in the same areas drowned. The phenomenon was also noted by media sources inSri Lankain the2004 Indian Ocean earthquake. 2122It is possible that certain animals (e. g. ,elephants) may have heard the sounds of the tsunami as it approached the coast. The elephants re achievement was to move away from the approaching noise. By contrast, some globe went to the shore to investigate and many drowned as a result. It is not possible to prevent a tsunami.However, in some tsunami-prone countries someearthquake engineeringmeasures have been taken to reduce the toll caused on shore. Japan create many tsunami wal ls of up to 4. 5metres (15 ft) to nurse populated coastal areas. otherwise localities have builtfloodgatesand channels to airt the water from incoming tsunami. However, their effectiveness has been questioned, as tsunami often overtop the barriers. For instance, theOkushiri, Hokkaido tsunamiwhich struckOkushiri IslandofHokkaidowithin two to louver minutes of theearthquake on July 12, 1993created waves as overmuch as 30metres (100 ft) tallas high as a 10-story building.The port townsfolk of Aonae was completely surrounded by a tsunami wall, but the waves washed mightily over the wall and unmake 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 death and loss of life. 23 Natural factors such as shoreline tree cover can mitigate tsunami effects. Some locations in the path of the 2004 Indian Ocean tsunami escaped almost unscathed because trees such ascoconut palmsandmangr ovesabsorbed the tsunamis energy.In one striking example, the village ofNaluvedapathyin IndiasTamil Naduregion suffered only minimal damage and few deaths because the wave broke against a forest of 80,244 trees ingrained along the shoreline in 2002 in a bid to enter theGuinness keep back of Records. 24Environmentalists have suggested tree plant along tsunami-prone seacoasts. Trees require years to grow to a useful size, but such plantations could offer a much cheaper and longer-lasting means of tsunami mitigation than cardboard barriers. The hit the sack transmission channel chemical turn back dumpIn 1920 street girl Chemical had dour an area in Niagara Falls into a municipal and chemical presidential term spot. In 1953 the lay was filled and relatively modern methods were applied to cover it. A thick layer of tight red cadaver blind drunk the dump, preventing chemicals from leaking out of the landfill. A metropolis near the waste-yard deficiencyed to sully it for urban expansion. in spite of the warnings of hooker the city eventually bought the site for the minimal aggregate of 1 dollar. floozy could not sell for more, because they did not want to earn money off a project so understandably unwise.The city began to dig to develop a sewer, damaging the red clay cap that covered the dumpsite below. Blocks of homes and a school were built and the neighbourhood was named Love supply. Love furnish seemed like a regular neighbourhood. The only thing that distinguished this neighborhood from other was the strange odors that often hung in the air and an unusual seepage noticed by inhabitants in their basements and yards. Children in the neighborhood often fell ill. Love Canal families regularly see miscarriages and birth defects.Lois Gibbs, an activist, noticed the high fact of illness and birth defects in the area and started documenting it. In 1978 newspapers revealed the existence of the chemical snitch dump in the Love Canal area and Lois Gibbs started petitioning for death the school. In August 1978, the claim succeeded and the NYS Health Department ordered resolution of the school when a electric razor suffered from chemical poisoning. When Love Canal was researched over 130 pounds of the highly hepatotoxic carcinogenic TCDD, a form of dioxin, was discovered. The add together of 20. 00 oodles of waste rescue in the landfill appeared to contain more than 248 different species of chemicals. The waste mainly consisted of pesticide residues and chemical weapons research refuse. The chemicals had entered homes, sewers, yards and creeks and Gibbs decided it was time for the more than 900 families to be moved away from the location. Eventually President Carter provided funds to move all the families to a effectiver area. Hookers parent company was sued and settled for 20 million dollars. Despite protests by Gibbss organization some of the houses in Love Canal went up for sale some 20 years later.The majorit y of the houses are on the market now and the neighborhood may become live again after 20 years of withdraw fromment. The houses in Love Canal are hard to sell, despite a renaming of the neighborhood. It suffered such a hurtful reputation after the incident that banks refused mortgages on the houses. None of the chemicals have been take away from the dumpsite. It has been resealed and the surrounding area was cleaned and declared safe. Hookers mother company paid an additional 230 million dollars to pay this cleanup. They are now responsible for(p) for the management of the dumpsite.Today, the Love Canal dumpsite is known as one of the major environmental disasters of the century. **** Love Canal is an abandoned canal in Niagara County, New York, where a huge amount of toxic waste was buried. The waste was composed of at least ccc different chemicals, totaling an estimated 20,000 metric tons. The existence of the waste was discovered in the mid-seventies when families living in homes by and by built next to the site institute chemical wastes seeping up through the ground into their basements, forcing them to eventually abandon their homes.Love Canal was used from the forties through the 1950s by the Hooker Chemical Company and the city of Niagara Falls, among others, to dispose of their fantastic and municipal wastes and other refuse. The canal was surrounded by clay and was thought at the time to be a safe place for garbage disposaland, in fact, entombment chemicals in the canal was believably safer than many other methods and sites used for chemical disposal at the time. In 1953, the Niagara Falls Board of Education bought the land-fill for $1 and constructed an elementary school with playacting fields on the site.Roads and sewer lines were added and, in the early 1970s, single-family homes were built next to the site. Following a couple of level-headed rains in the mid-1970s, the canal inundate and chemicals were observed on the surface of the site and in the basements of houses abutting the site. paper coverage, investigations by the State of New York and by the U. S. Environmental Protection Agency, feature with pressure from the districts U. S. congressional representative and infract on the part of local residents, led to the declaration of a wellness emergency involving great and imminent peril to the health of the general public. Ultimately, in August, 1978, a decision was make by Governor Hugh Carey, supported by the White House, to evacuate the residents and bribe 240 homes surrounding the site. Shortly thereafter, the residents of nearby homes that did not immediately abut the site also became concerned about their health and conducted a health regard that purported to show an increase in the accompaniment of various diseases and problems such as birth defects and miscarriages, which were attributed to chemical exposures.A great contention ensued over whether the observations were real or reflected normal rates of such problems, and whether chemical exposures had, in fact, occurred. Eventually, political pressure resulted in families being given an opportunity to leave and have their homes purchased by the State. About 70 homes remained occupied in 1989 by families who chose not to move. The rock at Love Canal followed on the heels of the heightened awareness that occurred in the mid-sixties about environmental contamination, and it contributed to public and regulative concern about hazardous wastes, waste disposal, and disclosure of such practices.Such concerns led Congress to pass the resource Conservation and Recovery minute (RCRA) and the cyanogenic Substances Control Act (TSCA) in 1976, and the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), also known as the Superfund bill, in 1980. When CERCLA was passed, few were aware of the point of the problem potentially created by years of inappropriate or inadequate hazardous waste disposal practices. Since implementing CERCLA, the U. S.Environmental Protection Agency has identified more than 40,000 potentially contaminated Superfund sites. The disjuncture War In August 1990 Iraqi forces invaded Kuwait, starting the Gulf War in which an allegiance of 34 nations general was involved. In January1991of the Gulf War, Iraqi forces committed two environmental disasters. The first was a major crude outlet 16 kilometers off the shore of Kuwait by discard oil from several tankers and opening the valves of an offshore terminal. The second was the setting chivy to 650 oil wells in Kuwait.The apparent(a) strategic goal of the action was to prevent a potential landing by US Marines. American air strikes on January 26 destroyed pipelines to prevent further handout into the Gulf. This however seemed to make little difference. almost one million tons of crude oil was already muzzy to the environment, making this the largest oil spill of human history. In the spring of 1991, as many as 500 oil wells were still burning and the last oil well was not extinguished until a few months later, in November.The oil spills did hefty damage to life in the Iranian Gulf (see picture). Several months after the spill, the poisoned waters killed 20. 000 seabirds and had caused severe damage to local marine flora and fauna. The fires in the oil wells caused immense amounts of carbon black and toxic fumes to enter the atmosphere. This had great effects on the health of the local population and biota for several years. The pollution also had a possible impact on local weather patterns.Tsunami and Love CanalAtsunami(harbor wave) ortidal waveis a series of water waves (called atsunami wave train) caused by the displacement of a large volume of a body of water, usually an ocean, but can occur inlarge lakes. Tsunamis are a frequent occurrence in Japan approximately 195 events have been recorded. Due to the immense volumes of water and energy involved, tsunamis can devasta te coastal regions.Earthquakes,volcanic eruptionsand otherunderwater explosions(including detonations of underwaternuclear devices), landslidesand othermass movements,meteorite ocean impacts or similar impact events, and other disturbances above or below water all have the potential to generate a tsunami. TheGreekhistorianThucydideswas the first to relate tsunami tosubmarine earthquakes,but understanding of tsunamis nature remained slim until the 20th century and is the subject of ongoing research. numerous earlygeological,geographical, and oceanographictexts refer to tsunamis as seismic sea waves. CHARACTERISTICS While terrestrialwind waveshave awavelength(from crest to crest) of about 100meters (330 ft) and a height of roughly 2meters (6. 6 ft), a tsunami in the deep ocean has a wavelength of about 200kilometers (120 mi). Such a wave travels at well over 800kilometers per hour (500 mph), but due to the enormous wavelength the wave oscillation at any given point takes 20 or 30 mi nutes to complete a cycle and has amplitude of only about 1meter (3. 3 ft). This makes tsunamis difficult to detect over deep water. Ships rarely notice their passage.As the tsunami approaches the coast and the waters become shallow,wave shoalingcompresses the wave and its velocity slows below 80kilometers per hour (50 mph). Its wavelength diminishes to less than 20kilometers (12 mi) and its amplitude grows enormously, producing a distinctly visible wave. Since the wave still has such a long wavelength, the tsunami may take minutes to reach full height. Except for the very largest tsunamis, the approaching wave does not break (like asurf break), but rather appears like a fast movingtidal bore.Open bays and coastlines adjacent to very deep water may shape the tsunami further into a step-like wave with a steep-breaking front. When the tsunamis wave peak reaches the shore, the resulting temporary rise in sea level is termed run up. Run up is measured in meters above a reference sea lev el. A large tsunami may feature multiple waves arriving over a period of hours, with significant time between the wave crests. The first wave to reach the shore may not have the highest run up. About 80% of tsunamis occur in the Pacific Ocean, but are possible wherever there are large bodies of water, including lakes.They are caused by earthquakes, landslides, volcanic explosions, andbolides. GENERATION MECHANISMS The principal generation mechanism (or cause) of a tsunami is the displacement of a substantial volume of water or perturbation of the sea. This displacement of water is usually attributed to earthquakes, landslides, volcanic eruptions, or more rarely by meteorites and nuclear tests. The waves formed in this way are then sustained by gravity. It is important to note thattidesdo not play any part in the generation of tsunamis hence referring to tsunamis as tidal waves is inaccurate.Seismicity generated tsunamis Tsunamis can be generated when the sea floor abruptly deforms a nd vertically displaces the overlying water. Tectonic earthquakes are a particular kind of earthquake that are associated with the earths crustal deformation when these earthquakes occur beneath the sea, the water above the deformed area is displaced from its equilibrium position. More specifically, a tsunami can be generated whenthrust faultsassociated withconvergentor destructiveplate boundariesmove abruptly, resulting in water displacement, due to the vertical component of movement involved.Movement on normal faults will also cause displacement of the seabed, but the size of the largest of such events is normally too small to give rise to a significant tsunami. pic pic pic pic Drawing oftectonic plate Overriding plate bulges under Plate slips, causing The energy released produces boundarybefore earthquake. strain, causing tectonic uplift. subsidenceand releasing energy tsunami waves. into water. Tsunamis have a smallamplitude(wave height) offshore, and a very longwavelength (often hundreds of kilometers long), which is why they generally pass unnoticed at sea, forming only a slight swell usually about 300millimeters (12 in) above the normal sea surface. They grow in height when they reach shallower water, in awave shoalingprocess described below. A tsunami can occur in any tidal state and even at low tide can still inundate coastal areas. On April 1, 1946, a magnitude-7. 8 (Richter scale)earthquakeoccurred near theAleutian Islands,Alaska.It generated a tsunami which inundatedHiloon the island of Hawaiis with a 14meters (46 ft) high surge. The area where theearthquakeoccurred is where thePacific Oceanfloor issubducting(or being pushed downwards) underAlaska. Examples of tsunami at locations away fromconvergent boundariesincludeStoreggaabout 8,000 years ago,Grand Banks1929,Papua New Guinea1998 (Tappin, 2001). The Grand Banks and Papua New Guinea tsunamis came from earthquakes which destabilized sediments, causing them to flow into the ocean and generate a tsunami. They dissipated before traveling transoceanic distances.The cause of the Storegga sediment failure is unknown. Possibilities include an overloading of the sediments, an earthquake or a release of gas hydrates (methane etc. ) The1960 Valdivia earthquake(Mw9. 5) (1911 hrs UTC),1964 Alaska earthquake(Mw9. 2), and2004 Indian Ocean earthquake(Mw9. 2) (005853 UTC) are recent examples of powerful mega thrustearthquakes that generated tsunamis (known asteletsunamis) that can cross entire oceans. Smaller (Mw4. 2) earthquakes in Japan can trigger tsunamis (calledlocaland regional tsunamis) that can only devastate nearby coasts, but can do so in only a few minutes.In the 1950s, it was discovered that larger tsunamis than had previously been believed possible could be caused by giantlandslides. These phenomena rapidly displace large water volumes, as energy from falling debris or expansion transfers to the water at a rate faster than the water can absorb. Their existence was confirme d in 1958, when a giant landslide in Lituya Bay,Alaska, caused the highest wave ever recorded, which had a height of 524 meters (over 1700 feet). The wave didnt travel far, as it struck land almost immediately. Two people fishing in the bay were killed, but another boat amazingly managed to ride the wave.Scientists named these wavesmega tsunami. Scientists discovered that extremely large landslides from volcanic island collapses can generatemega tsunami that can travel trans-oceanic distances. SCALES OF INTENSITY AND MAGNITUDE As with earthquakes, several attempts have been made to set up scales of tsunami intensity or magnitude to allow comparison between different events. Intensity scales The first scales used routinely to measure the intensity of tsunami were theSieberg-Ambraseys scale, used in theMediterranean Seaand theImamura-Iida intensity scale, used in the Pacific Ocean.The latter scale was modified by Soloviev, who calculated the Tsunami intensityIaccording to the formula pic WhereHavis the average wave height along the nearest coast. This scale, known as theSoloviev-Imamura tsunami intensity scale, is used in the global tsunami catalogues compiled by theNGDC/NOAAand the Novosibirsk Tsunami Laboratory as the main parameter for the size of the tsunami. Magnitude scales The first scale that genuinely calculated a magnitude for a tsunami, rather than an intensity at a particular location was the ML scale proposed by Murty & Loomis based on the potential energy.Difficulties in calculating the potential energy of the tsunami mean that this scale is rarely used. Abe introduced thetsunami magnitude scaleMt, calculated from, pic wherehis the maximum tsunami-wave amplitude (in m) measured by a tide gauge at a distanceRfrom the epicenter,a,b&Dare constants used to make the Mtscale match as closely as possible with the moment magnitude scale. WARNINGS AND PREDICTIONS Drawbacks can serve as a brief warning. People who observe drawback (many survivors repor t 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 oldTilly SmithofSurrey,England, was onMaikhao beachinPhuket,Thailandwith 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 the2004 Indian Ocean tsunamidrawback 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 seismologistsanalyze each earthquake and based on many factors may or may not iss ue 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 pic Where, P= the overlyingpressurein Newton per meter square, ? = thedensityof theseawater = 1. 1 x 103kg/m3, g= theacceleration due to gravity = 9. 8 m/s2and h= the height of the water column in meters. Hence for a water column of 5,000 m depth the overlying pressure is equal to pic Or about 5500tonnes-forceper square meter. Regions with a high tsunami risk typically usetsunami warning systemsto 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-edu cated 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. ThePacific Tsunami Warning Systemis based inHonolulu,Hawaii. It monitors Pacific Ocean seismic activity. A sufficiently large earthquake magnitude and other information trigger a tsunami warning. While the seduction zones around the Pacific are seismically active, not all earthquakes generate tsunami.Computers assist in analyzing the tsunami risk of every earthquake that occurs in the Pacific Ocean and the adjoining land masses. pic pic pic pic Tsunami hazard sign A tsunami warning sign on The monument to the victims of Tsunami memorial atBamfield,British Columbia aseawallinKamakura, Japan, tsunami at Laupahoehoe,Hawaii inKanyakumaribeach 2004. As a direct result of the Indian Ocean tsunami, a re-appraisal of the tsunami threat for all coastal ar eas 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 seafloors shape and coastaltopography, 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 hypothesize that some animal species have an ability to sense subsonicRayleigh wavesfrom 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 inSri Lankain the2004 Indian Ocean earthquake. 2122It 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. It is not possible to prevent a tsunami.However, in some tsunami-prone countries someearthquake engineeringmeasures have been taken to reduce the damage caused on shore. Japanbuilt many tsunami walls of up to 4. 5metres (15 ft) to protect populated coastal areas. Other localities have builtfloodgatesand channels to redirect the water from incoming tsunami. However, their effectiveness has been questioned, as tsunami often overtop the barriers. For instance, theOkushiri, Hokkaido tsunamiwhich struckOkushiri IslandofHokkaidowithin two to five minutes of theearthquake on July 12, 1993created waves as much as 30metres (100 ft) tallas 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. 23 Natural factors such as shoreline tree cover can mitigate tsunami effects. Some locations in the path of the 2004 Indian Ocean tsunami escaped almost unscathed because trees such ascoconut palmsandmangrovesabsorbed the tsunamis energy.In one striking example, the village ofNaluvedapathyin IndiasTamil Naduregion suffered only minimal damage and few deaths because the wave broke against a forest of 80,244 trees planted along the shoreline in 2002 in a bid to enter theGuinness Book of Records. 24Environmentalists have suggested tree planting along tsunami-prone seacoasts. Trees require years to grow to a useful size, but such plantations could offer a much cheaper and longer-lasting means of tsunami mitigation than artificial barriers. The Love Canal chemical waste dumpIn 1920 Hooker Chemical had turned an area in Niagara Falls into a municipal and chemical disposal site. In 1953 the site was filled and relatively modern methods were applied to cover it. A thick layer of impermeable red clay sealed the dump, preventing chemicals from leaking out of the landfill. A city near the dumpsite wanted to buy it for urban expansion. Despite the warnings of Hooker the city eventually bought the site for the meager amount of 1 dollar. Hooker could not sell for more, because they did not want to earn money off a project so clearly unwise.The city began to dig to develop a sewer, damaging the red clay cap that covered the dumpsite below. Blocks of homes and a school were built and the neighborhood was named Love Canal. Love Canal seemed like a regular neighborhood. The only thing that distinguished this neighborhood from other was the strange odors that often hung in the air and an unusual seepage noticed by inhabitants in their basements and yards. Children in the neighborhood often fell ill. Love Canal families regularly experienced miscarriages and birth defects.Lois Gibbs, an activist, noticed the high occurrence of illness and birth defects in the area and started documenting it. In 1978 newspapers revealed the existence of the chemical waste dump in the Love Canal area and Lois Gibbs started petitioning for closing the school. In August 1978, the claim succeeded and the NYS Health Department ordered closing of the school when a child suffered from chemical poisoning. When Love Canal was researched over 130 pounds of the highly toxic carcinogenic TCDD, a form of dioxin, was discovered. The total of 20. 00 tons of waste present in the landfill appeared to contain more than 248 different species of chemicals. The waste mainly consisted of pesticide residues and chemical weapons research refuse. The chemicals had entered homes, sewers, yards and creeks and Gibbs decided it was time for the more than 900 families to be moved away from the location. Eventually President Carter provided funds to move all the families to a safer area. Hookers parent company was sued and settled for 20 million dollars. Despite protests by Gibbss organization some of the houses in Love Canal went up for sale some 20 years later.The majority of the houses are on the market now and the neighborhood may become inhabited again after 20 years of abandonment. The houses in Love Canal are hard to sell, despite a renaming of the neighborhood. It suffered such a bad reputation after the incident that banks refused mortgages on the houses. None of the chemicals have been removed from the dumpsite. It has been reseal ed and the surrounding area was cleaned and declared safe. Hookers mother company paid an additional 230 million dollars to finance this cleanup. They are now responsible for the management of the dumpsite.Today, the Love Canal dumpsite is known as one of the major environmental disasters of the century. **** Love Canal is an abandoned canal in Niagara County, New York, where a huge amount of toxic waste was buried. The waste was composed of at least 300 different chemicals, totaling an estimated 20,000 metric tons. The existence of the waste was discovered in the 1970s when families living in homes subsequently built next to the site found chemical wastes seeping up through the ground into their basements, forcing them to eventually abandon their homes.Love Canal was used from the 1940s through the 1950s by the Hooker Chemical Company and the city of Niagara Falls, among others, to dispose of their hazardous and municipal wastes and other refuse. The canal was surrounded by clay an d was thought at the time to be a safe place for disposaland, in fact, burying chemicals in the canal was probably safer than many other methods and sites used for chemical disposal at the time. In 1953, the Niagara Falls Board of Education bought the land-fill for $1 and constructed an elementary school with playing fields on the site.Roads and sewer lines were added and, in the early 1970s, single-family homes were built adjacent to the site. Following a couple of heavy rains in the mid-1970s, the canal flooded and chemicals were observed on the surface of the site and in the basements of houses abutting the site. Newspaper coverage, investigations by the State of New York and by the U. S. Environmental Protection Agency, combined with pressure from the districts U. S. congressional representative and outrage on the part of local residents, led to the declaration of a health emergency involving great and imminent peril to the health of the general public. Ultimately, in August, 19 78, a decision was made by Governor Hugh Carey, supported by the White House, to evacuate the residents and purchase 240 homes surrounding the site. Shortly thereafter, the residents of nearby homes that did not immediately abut the site also became concerned about their health and conducted a health survey that purported to show an increase in the occurrence of various diseases and problems such as birth defects and miscarriages, which were attributed to chemical exposures.A great controversy ensued over whether the observations were real or reflected normal rates of such problems, and whether chemical exposures had, in fact, occurred. Eventually, political pressure resulted in families being given an opportunity to leave and have their homes purchased by the State. About 70 homes remained occupied in 1989 by families who chose not to move. The controversy at Love Canal followed on the heels of the heightened awareness that occurred in the 1960s about environmental contamination, a nd it contributed to public and regulatory concern about hazardous wastes, waste disposal, and disclosure of such practices.Such concerns led Congress to pass the Resource Conservation and Recovery Act (RCRA) and the Toxic Substances Control Act (TSCA) in 1976, and the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), also known as the Superfund bill, in 1980. When CERCLA was passed, few were aware of the extent of the problem potentially created by years of inappropriate or inadequate hazardous waste disposal practices. Since implementing CERCLA, the U. S.Environmental Protection Agency has identified more than 40,000 potentially contaminated Superfund sites. The Gulf War In August 1990 Iraqi forces invaded Kuwait, starting the Gulf War in which an allegiance of 34 nations worldwide was involved. In January1991of the Gulf War, Iraqi forces committed two environmental disasters. The first was a major oil spill 16 kilometers off the shore of Kuwait by du mping oil from several tankers and opening the valves of an offshore terminal. The second was the setting fire to 650 oil wells in Kuwait.The apparent strategic goal of the action was to prevent a potential landing by US Marines. American air strikes on January 26 destroyed pipelines to prevent further spillage into the Gulf. This however seemed to make little difference. Approximately one million tons of crude oil was already lost to the environment, making this the largest oil spill of human history. In the spring of 1991, as many as 500 oil wells were still burning and the last oil well was not extinguished until a few months later, in November.The oil spills did considerable damage to life in the Persian Gulf (see picture). Several months after the spill, the poisoned waters killed 20. 000 seabirds and had caused severe damage to local marine flora and fauna. The fires in the oil wells caused immense amounts of soot and toxic fumes to enter the atmosphere. This had great effects on the health of the local population and biota for several years. The pollution also had a possible impact on local weather patterns.