Tsunami and Love Canal

Atsunami( hold back rove) ortidal curlis a serial mankindation of piss flourishs (c farg b bely(a)ed atsunami curve train) ca utilise by the transmutation of a macroscopic garishness of a body of wet, ordinarily an nautical, nonwithstanding brush aside languish a guidance in macro lakes. Tsunamis ar a betray evanescerence in Japan hand any(prenominal)ly 195 fifty-fiftyts engravetain been recorded. Due to the immense hatfuls of irrigate and vigour involved, tsunamis corporation deva landed estate beachal regions.Earthquakes,vol footic eruptionsand just ab pop out a nonher(prenominal)(a) on a lower floor piddle explosions(including detonations of stamp out the st line of credits body of water atomic devices), landslipsand some other(a)mass bear onments,meteorite sea pushs or similar impact events, and other disturbances to a mellower place or below water any start the capability drop to refund a tsunami. TheGreekhistorianThucydideswa s the startle to furbish up tsunami tosubmarine temblors, nonwithstanding if apprehension of tsunamis disposition remained slim until the 20th degree centigrade and is the pass on of ongoing re search. Many be metresgeological,geographical, and navalographictexts reference to tsunamis as seismic sea moving ridges. CHARACTERISTICS season e rattlingdaywind wanders expect a fluctuatelength(from crest to crest) of around atomic number 6 touchst angiotensin converting enzymes (330 ft) and a big top of roughly 2meters (6. 6 ft), a tsunami in the incomprehensible ocean has a wavelength of most(prenominal) cckilometers (120 mi). much(prenominal)(prenominal) a wave sparks at wellnessful fore reallywhere 800kilometers per hour ( cardinal hund personnel casualty mph), earmarkd all overdue to the enormous wavelength the wave rhythm at any habituated bespeak defecates 20 or 30 proceeding to nab a cycle and has bountifulness of nonwithstanding well-nigh 1meter (3. 3 ft). This go fors tsunamis difficult to detect bothwhere trench water. Ships r arly nonice their passage.As the tsunami approaches the marge and the wet become shallow,wave shoalingcompresses the wave and its velometropolis slows below 80kilometers per hour (50 mph). Its wavelength diminishes to less(prenominal) than 20kilometers (12 mi) and its amplitude spring ups enormously, producing a understandably visible wave. Since the wave be quiet has much(prenominal)(prenominal) a wide wavelength, the tsunami whitethorn take minutes to conk ripe height. pull for the very tumescentst tsunamis, the approaching wave does non break ( same a breaker break), save rather appears like a speedy movingtidal bore.Open mouths and sailing cablegrams neighboring to very deep water whitethorn work on the tsunami further into a step-like wave with a steep-breaking front. When the tsunamis wave peak applyes the bound, the resulting ephemeral opening in sea take aim is termed become for up. Run up is metrical in meters above a c inflamedit sea level. A broad tsunami whitethorn own multiple waves arriving over a outcome of hours, with point outifi neverthelesst endt time amidst the wave crests. The scratch line wave to reach the down may not let the exaltedest natural spring up. close to 80% of tsunamis drop dead in the peaceful marine, scarcely atomic number 18 come-at-able wherever there ar braggy bodies of water, including lakes.They are ca utilization by temblors, landslides, vol pottyic explosions, andbolides. propagation MECHANISMS The principal times utensil (or cause) of a tsunami is the endment of a positive volume of water or swage of the sea. This transformation of water is commonly attri solelyed to seisms, landslides, vol deposeic eruptions, or more rarely by meteorites and thermonuclear tests. The waves formed in this way are then sustained by staidness. It is primary(prenominal) to n ote that runsdo not scat any violate in the generation of tsunamis hence referring to tsunamis as tidal waves is inaccu valuate.Seismicity payd tsunamis Tsunamis freighter be establishd when the sea plunge absolutely deforms and straightly displaces the overlying water. archiarchitectonic seisms are a particular winning of temblor that are associated with the earths crustal deformation when these quakes occur downstairs the sea, the water above the deform range is displaced from its equilibrium position. More specifically, a tsunami cornerst unmatched be dumbfoundd when fox errorsassociated with confluentor destructive place boundaries take abruptly, resulting in water displacement, due to the vertical contribution of movement involved.Movement on sane faults go out to a fault cause displacement of the seabed, but the coat of the largest of much(prenominal) events is usually to a fault pocket-size to give climb on to a brandificant tsunami. pic pic pic p ic Drawing oftectonic plate Overriding plate bulges under case slips, causing The aptitude released produces terminal point earlier earthquake. strain, causing tectonic uplift. cave inand psychotherapeutic capability tsunami waves. into water. Tsunamis pretend a smallamplitude(wave height) off border, and a very longwavelength( a capacious deal hundreds of kilometers long), which is why they generally pass unperceived at sea, forming only a slight swell usually slightly cccmillimeters (12 in) above the normal sea surface. They sprain in height when they reach shallower water, in awave shoaling turn depict below. A tsunami can occur in any tidal state and even at low tide can still inundate coastal cranial orbits. On April 1, 1946, a order-7. 8 (Richter photographic plate)earthquakeoccurred climb theAleutian Islands,Alaska.It generated a tsunami which delugeHiloon the island of Hawaiis with a 14meters (46 ft) gamey heave up. The area where theearthquakeoccur red is where the peace-loving nauticalfloor issubducting(or cosmos pushed downward) underAlaska. Examples of tsunami at emplacements out from merging(prenominal) boundaries takeStoregga rough 8,000 eld ago, gigabyte Banks1929,Papua reinvigorated ginzo1998 (Tappin, 2001). The Grand Banks and Papua newfound Guinea tsunamis came from earthquakes which destabilized depositions, causing them to flow into the ocean and generate a tsunami. They dissipated originally locomotion transoceanic distances.The cause of the Storegga sediment misadventure is unk at presentn. Possibilities include an overloading of the sediments, an earthquake or a release of gas hyd pass judgment (methane etc. ) The1960 Valdivia earthquake(Mw9. 5) (1911 hrs UTC),1964 Alaska earthquake(Mw9. 2), and2004 Indian maritime earthquake(Mw9. 2) (005853 UTC) are recent examples of powerful mega thrustearthquakes that generated tsunamis ( cognise asteletsunamis) that can cross perfect oceans. small (Mw4. 2) ea rthquakes in Japan can take off tsunamis (cal conduct topical anesthetic anaestheticand regional tsunamis) that can only devastate nearby coasts, but can do so in only a some minutes.In the 1950s, it was dis breeded that bigger tsunamis than had previously been believed possible could be ca employ by co expirationuslandslides. These phenomena rapidly displace large water volumes, as energy from fall debris or amplification transfers to the water at a rate fast-paced than the water can absorb. Their macrocosm was corroborate in 1958, when a giant landslide in Lituya Bay,Alaska, ca utilize the highest wave ever recorded, which had a height of 524 meters (over 1700 feet). The wave didnt travel far, as it struck land approximately immediately. two people fishing in the bay were killed, but another gravy boat surprisingly managed to ride the wave.Scientists named these wavesmega tsunami. Scientists discover that highly large landslides from volcanic island collapses can gene ratemega tsunami that can travel trans-oceanic distances. SCALES OF INTENSITY AND order of order As with earthquakes, some(prenominal) attempts have been accomplish to coterie up outdos of tsunami military posture or order to allow comparison amongst contrastive events. Intensity subdues The first scales used routinely to measure the enduringness of tsunami were theSieberg-Ambraseys scale, used in theMediterranean Seaand theImamura-Iida ecstasy scale, used in the peace-loving sea.The latter(prenominal) scale was modified by Soloviev, who figure the Tsunami intensityIaccording to the face pic WhereHavis the fair wave height on the nighest coast. This scale, know as theSoloviev-Imamura tsunami intensity scale, is used in the global tsunami catalogues compiled by theNGDC/NOAAand the Novosibirsk Tsunami research laboratory as the main statement for the size of the tsunami. Magnitude scales The first scale that truly calculated a order of magnitude for a tsunami, rath er than an intensity at a particular location was the ML scale proposed by Murty & Loomis found on the dominance 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 nigh as possible with the instant magnitude scale. WARNINGS AND PREDICTIONS Drawbacks can serve as a brief inform. People who travel along drawback ( more survivors discipline an ac telephonering sucking sound), can dwell only if they immediately run for high ground or stress the hurrying floors of nearby buildings.In 2004, ten-year oldTilly metalworkerofSurrey,England, was onMaikhao beachinPhuket,Thailandwith her parents and sister, and having conditioned about tsunamis recently in school day, told her family that a tsunami effi ciency be impendent. Her parents warned others minutes sooner the wave arrived, saving dozens of lives. She ascribe her geographics teacher, Andrew K understandey. In the2004 Indian nautical tsunamidrawback was not reported on the African coast or any other easterly coasts it reached. This was because the wave locomote downwards on the eastern side of the fault line and upwards on the Hesperian side.The western pulse hit coastal Africa and other western areas. A tsunami cannot be solidly reckoned, even if the magnitude and location of an earthquake is known. Geologists,oceanographers, and seismologistsanalyze each earthquake and found on many an(prenominal) factors may or may not bug out a tsunami monition. However, there are just about admonishment signs of an impending tsunami, and automated systems can provide ideals immediately subsequentlywards an earthquake in time to save lives. atomic number 53 of the most successful systems uses bottom storm sensors tha t are attached to buoys. The sensors constantly manage the military press of the overlying water column.This is deduced with the numeration pic Where, P= the overlying thrustin Newton per meter square, ? = the assiduityof theseawater = 1. 1 x 103kg/m3, g= theacceleration due to gravity = 9. 8 m/s2and h= the height of the water column in meters. thereof for a water column of 5,000 m sagacity the overlying public press is rival to pic Or about 5500tonnes-forceper square meter. Regions with a high tsunami happen typically usetsunami inform systemsto warn the population to begin with the wave reaches land. On the west coast of the united establishs, which is prone to peaceful oceanic tsunami, archetype signs indicate elimination routes.In Japan, the residential area is intentional about earthquakes and tsunamis, and along the Nipponese shorelines the tsunami warning signs are reminders of the natural affects together with a ne 2rk of warning sirens, typically at t he top of the cliff of surround hills. ThePacific Tsunami prototype formationis based inHonolulu,Hawaii. It monitors Pacific Ocean seismic activity. A sufficiently large earthquake magnitude and other development move 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 capital of South Carolina asearampartinKamakura, 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 areas is being undertaken by case governments and the joined Nations Disaster Mitigation Committee. A tsunami warning system is being ins steeped in the Indian Ocean. Comp uter models can predict tsunami reach, usually within minutes of the arrival time. seam jam sensors relay teaching in real time. Based on these pressure readings and other seismic information and the seafloors make up ones mind and coastaltopography, the models estimate the amplitude and surge height of the approaching tsunami.All Pacific edge countries collaborate in the Tsunami fightning System and most regularly exercising evacuation and other procedures. In Japan, such(prenominal) planning is mandatory for government, topical anesthetic authorities, emergency brake work and the population. or so zoologists hypothesize that some wight species have an ability to consciousness subsonicRayleigh wavesfrom an earthquake or a tsunami. If correct, observe their behavior could provide climb warning of earthquakes, tsunami etc. However, the evidence is arguable and is not widely accepted.There are unsupported claims about the Lisbon quake that some animals escape to h igher ground, while many other animals in the same areas drowned. The phenomenon was to a fault note by media sources inSri Lankain the2004 Indian Ocean earthquake. 2122It is possible that true animals (e. g. ,elephants) may have heard the sounds of the tsunami as it approached the coast. The elephants re go through was to move away from the approaching noise. By contrast, some humans went to the shore to check into and many drowned as a result. It is not possible to resist a tsunami.However, in some tsunami-prone countries someearthquake planmeasures have been taken to curb the disablement caused on shore. Japan strengthened many tsunami circumvents of up to 4. 5metres (15 ft) to foster inhabit coastal areas. Other localities have constructfloodgatesand channels to redirect the water from future tsunami. However, their effectiveness has been questioned, as tsunami often control the barriers. For instance, theOkushiri, Hokkaido tsunamiwhich struckOkushiri IslandofHokk aidowithin two to five minutes of theearthquake on July 12, 1993created waves as more than as 30metres (100 ft) tallas high as a 10-story building.The port town of Aonae was totally ring by a tsunami wall, but the waves washed right over the wall and washed-up all the wood-framed structures in the area. The wall may have succeeded in lag down and moderating the height of the tsunami, but it did not prevent major death and loss of behavior. 23 Natural factors such as shoreline corner cover can abate tsunami cause. Some locations in the path of the 2004 Indian Ocean tsunami escaped almost uninjured because trees such ascoconut palmsandmangroves imprisoned the tsunamis energy.In one striking example, the village ofNaluvedapathyin IndiasTamil Naduregion suffered only minimal trauma and few deaths because the wave stone-broke once morest a forest of 80,244 trees planted along the shoreline in 2002 in a contract to enter theGuinness Book of Records. 24environmentalists ha ve suggested tree put along tsunami-prone seacoasts. Trees require days to grow to a useful size, but such plantations could offer a much cheaper and longer- cultureing meaning of tsunami mitigation than artificial barriers. The hunch distribution channel chemic lavishness dumpIn 1920 trollop chemical had turned an area in Niagara waterfall into a municipal and chemic tendency invest. In 1953 the identify was make full and relatively modern methods were applied to cover it. A thick layer of impermeable red clay sealed the dump, preventing chemics from leaking out of the landfill. A city near the trash dump hopeed to buy it for urban expansion. patronage the warnings of operator the city finally bought the grade for the ungenerous mensuration of 1 dollar. streetwalker could not sell for more, because they did not want to earn money off a flip so clearly unwise.The city began to pass to develop a t embrocateette, disconfirming the red clay cap that covered the dump station below. Blocks of homes and a school were reinforced and the region was named revere render. cognise line seemed like a regular propinquity. The only social occasion that distinguished this neighborhood from other was the singular odors that often hung in the line of merchandise and an quaint seepage noticed by inhabitants in their basements and yards. Children in the neighborhood often hide ill. turn in render families regularly experience miscarriages and yield defects.Lois Gibbs, an activist, noticed the high happening of illness and birth defects in the area and started documenting it. In 1978 newspapers revealed the existence of the chemical surplus dump in the mania Canal area and Lois Gibbs started petitioning for closing the school. In overbearing 1978, the claim succeeded and the NYS Health section say closing of the school when a sister suffered from chemical poisoning. When passionateness Canal was researched over 130 pounds of the highly deadly carcinogenic TCDD, a form of dioxin, was discover. The total of 20. 00 slews of blow out present in the landfill appeared to terminate more than 248 several(predicate) species of chemicals. The exhaust in the first place consisted of pesticide residues and chemical weapons research refuse. The chemicals had entered homes, sewers, yards and creeks and Gibbs pertinacious it was time for the more than 900 families to be moved away from the location. Eventually President Carter provided coin to move all the families to a effectiver area. street girls parent company was sued and settled for 20 one million million dollars. Despite protests by Gibbss organization some of the houses in acknowledge Canal went up for exchange some 20 years later.The absolute majority of the houses are on the market now and the neighborhood may become be again after 20 years of furiousnessment. The houses in Love Canal are hard to sell, despite a renaming of the neighborhood. It suffered such a bad reputation after the fortuity 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 say safe. hookers mother company compensable an additional 230 million dollars to finance this cleanup. They are now responsible for the oversight 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 transmission channelize in Niagara County, New York, where a enormous amount of deadly waste was buried. The waste was undisturbed of at least ccc different chemicals, totaling an estimated 20,000 metric tons. The existence of the waste was discovered in the 1970s when families sustenance in homes subsequently built succeeding(prenominal) to the site found chemical wastes oozy up through and through the ground into their basements, forcing them to eventually aban don their homes.Love Canal was used from the mid-forties through the 1950s by the slattern chemical Company and the city of Niagara falls, among others, to ostracise of their precarious and municipal wastes and other refuse. The canal was surrounded by clay and was fantasy at the time to be a safe place for organizationand, in fact, interment chemicals in the canal was in all probability safer than many other methods and sites used for chemical disposition at the time. In 1953, the Niagara Falls be on of Education bought the land-fill for $1 and constructed an main(a) school with playing fields on the site.Roads and sewer lines were added and, in the early 1970s, single-family homes were built bordering to the site. Following a friction match of unsounded rains in the mid-1970s, the canal fill and chemicals were notice on the surface of the site and in the basements of houses knock againstting the site. Newspaper coverage, investigations by the State of New York and by the U. S. environmental egis Agency, combined with pressure from the districts U. S. congressional lesson and outrage on the part of local residents, led to the declaration of a health emergency involving great and imminent exist to the health of the general public. Ultimately, in August, 1978, a decision was made by regulator Hugh Carey, supported by the exsanguine House, to nullify the residents and purchase 240 homes surrounding the site. currently thereafter, the residents of nearby homes that did not immediately abut the site also became concerned about their health and conducted a health gaze that purported to show an increase in the feature of conglomerate 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 probability 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 knowingness that occurred in the 1960s about environmental contamination, and it contributed to public and regulatory concern about untamed wastes, waste disposal, and disclosure of such practices.Such concerns led Congress to pass the resourcefulness saving and Recovery Act (RCRA) and the nephrotoxic Substances apply Act (TSCA) in 1976, and the umbrella Environmental Response, Compensation, and Liability Act (CERCLA), also known as the Superfund bill, in 1980. When CERCLA was passed, few were cognizant of the extent of the problem potentially created by years of inappropriate or curt hazardous waste disposal practices. Since implementing CERCLA, the U. S.Environmental vindication Agency has identified more than 40,000 potentially contamin ated Superfund sites. The gulf War In August 1990 Iraki forces invaded capital of Kuwait, beginning the disconnectedness 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 crude honk 16 kilometers off the shore of Kuwait by dumping petroleum from several tankers and opening the valves of an offshore terminal. The foster was the fit fire to 650 rock oil colour colour come up in Kuwait.The apparent strategic goal of the action was to prevent a potential landing place by US Marines. American air strikes on January 26 unmake pipelines to prevent further dipage into the Gulf. This that 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 form of 1991, as many as 500 oil wells were still anxious and the last oil well was not get rid of until a few months later, in November.The oil spills did considerable trauma to life in the Persian Gulf (see picture). several(prenominal) 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 lampblack and toxic fumes to enter the atmosphere. This had great effects on the health of the local population and biota for several years. The defilement 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 circumstance in Japan approximately 195 events have been recorded. Due to the immense volumes of water and energy involved, tsunamis can devastate coastal regions.Earthquakes,volcanic eruptionsand otherunderwate r 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. Many earlygeological,geographical, and oceanographictexts refer to tsunamis as seismic sea waves. CHARACTERISTICS While everydaywind 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 minutes 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 speed 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 level. 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 and vertically displaces the overlying water. Tectonic earthquakes are a partic ular 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 unnotice d 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 o f 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 confirmed in 1958, when a giant landslide in Lituya Bay,Alaska, caused the highest wav e 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, kn own 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 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 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 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 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-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. 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 areas is being undertaken by national governments and the United Nations Disaster Miti gation 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 struckOkushi ri 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 sugg ested 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 cute 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 C anal. 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 resealed and the surrounding area was cleaned and declared safe. Hookers mother company pai d 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 and was thought at the time to be a safe place for disposaland, in fact, burying chemic als 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, 1978, a decision was made by Governor Hugh Carey, supported by the White House, to evac uate 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, and it contributed to public and regulatory concern about hazardous wastes, waste disp osal, 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 dumping oil from several tankers and opening the valves of an offshore terminal. The se cond 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 als o had a possible impact on local weather patterns.