Japan Tsunami

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japan tsunami


he2011 earthquake off the Pacific coast of Thoku(Thoku-chih Taiheiy Oki Jishin?)was amagnitude9.0 (Mw)underseamegathrust earthquakeoff the coast ofJapanthat occurred at 14:46JST(05:46UTC) on Friday 11 March 2011,[2][3][8]with theepicentreapproximately 70 kilometres (43mi) east of theOshika PeninsulaofThokuand thehypocenterat an underwater depth of approximately 30km (19mi).[2][9]The earthquake is also often referred to in Japan as theGreat East Japan Earthquake(Higashi nihon daishinsai?)[10][11][12][fn 1]and also known as the2011 Tohoku earthquake,[13]and the3.11 Earthquake. It was the most powerfulearthquake ever recorded to have hit Japan, and the fifthmost powerful earthquake in the worldsince modern record-keeping began in 1900.[8][14][15]The earthquake triggered powerfultsunamiwaves that reached heights of up to 40.5 metres (133ft) inMiyakoin Thoku'sIwate Prefecture,[16][17]and which, in theSendaiarea, travelled up to 10km (6mi) inland.[18]The earthquake movedHonshu(the main island of Japan) 2.4m (8ft) east and shifted the Earth on its axis by estimates of between 10cm (4in) and 25cm (10in),[19][20][21]and generated sound waves detected by the low orbitingGOCEsatellite.[22]On 10 February 2014, a JapaneseNational Police Agencyreport confirmed 15,885 deaths,[23]6,148 injured,[24]and 2,623 people missing[25]across twentyprefectures, as well as 127,290 buildings totally collapsed, with a further 272,788 buildings 'half collapsed', and another 747,989 buildings partially damaged.[26]The earthquake and tsunami also caused extensive and severe structural damage in north-eastern Japan, including heavy damage to roads and railways as well as fires in many areas, and a dam collapse.[18][27]Japanese Prime MinisterNaoto Kansaid, "In the 65 years after the end of World War II, this is the toughest and the most difficult crisis for Japan."[28]Around 4.4million households in northeastern Japan were left without electricity and 1.5million without water.[29]The tsunami causednuclear accidents, primarily thelevel 7meltdownsat three reactors in theFukushima Daiichi Nuclear Power Plantcomplex, and the associated evacuation zones affecting hundreds of thousands of residents.[30][31]Many electrical generators were taken down, and at least three nuclear reactorssuffered explosionsdue to hydrogen gas that had built up within their outer containment buildings after cooling system failure. Residents within a 20km (12mi) radius of the Fukushima Daiichi Nuclear Power Plant and a 10km (6.2mi) radius of theFukushima Daini Nuclear Power Plantwere evacuated. In addition, the U.S. recommended that its citizens evacuate up to 80km (50mi) of the plant.[32]Early estimates placed insured losses from the earthquake alone at US$14.5 to $34.6billion.[33]TheBank of Japanoffered15trillion (US$183billion) to the banking system on 14 March in an effort to normalize market conditions.[34]TheWorld Bank's estimated economic cost was US$235billion, making it the costliest natural disaster in world history.[35][36]Contents 1Earthquake 1.1Geology 1.2Energy 1.3Geophysical effects 1.4Aftershocks 2Tsunami 2.1Japan 2.2Elsewhere across the Pacific 3Land subsidence 4Casualties 5Damage and effects 5.1Ports 5.2Dams and water problems 5.3Electricity 5.4Oil, gas and coal 5.5Nuclear power plants 5.5.1Fukushima meltdowns 5.5.2Incidents elsewhere 5.6Wind power 5.7Transport 5.8Telecommunications 5.9Defense 5.10Space center 5.11Cultural properties 6Aftermath 7Humanitarian response 8Media coverage 9Scientific and research response 10See also 11Notes 12References 13Further reading 14External links 14.1Tsunami videosEarthquake[edit]


SendaiMap showing the epicenter of the earthquake

USGS centroid moment tensor solution of the main tremor showing a visual representation offocal mechanismThe 9.0magnitude(MW)underseamegathrust earthquakeoccurred on 11 March 2011 at 14:46JST(05:46 UTC) in the north-western Pacific Ocean at a relatively shallow depth of 32km (19.9mi),[37]with itsepicenterapproximately 72km (45mi) east of theOshika PeninsulaofThoku, Japan, lasting approximately six minutes.[1][2]The earthquake was initially reported as 7.9MWby the USGS before it was quickly upgraded to 8.8 MW, then to 8.9 MW,[38]and then finally to 9.0 MW.[3][39]Sendaiwas the nearest major city to the earthquake, 130km (81mi) from the epicenter; the earthquake occurred 373km (232mi) fromTokyo.[2]The main earthquake was preceded by a number of largeforeshocks, with hundreds ofaftershocksreported. The first major foreshock was a 7.2MWevent on 9 March, approximately 40km (25mi) from the epicenter of the 11 March earthquake, with another three on the same day in excess of 6.0MW.[2][40]Following the main earthquake on 11 March, a 7.0MWaftershock was reported at 15:06 JST (6:06 UTC), succeeded by a 7.4 MWat 15:15 JST (6:16 UTC) and a 7.2 MWat 15:26 JST (6:26 UTC).[41]Over eight hundred aftershocks of magnitude 4.5 MWor greater have occurred since the initial quake,[42]including one on 26 October 2013 (local time) of magnitude 7.3.[43]Aftershocks followOmori's Law, which states that the rate of aftershocks declines with the reciprocal of the time since the main quake. The aftershocks will thus taper off in time, but could continue for years.[44]One minute before the earthquake was felt in Tokyo, theEarthquake Early Warningsystem, which includes more than 1,000seismometersin Japan, sent out warnings of impending strong shaking to millions. It is believed that the early warning by theJapan Meteorological Agency(JMA) saved many lives.[45][46]The warning for the general public was delivered about 8 seconds after the firstP wavewas detected, or about 31 seconds after the earthquake occurred. However, the estimated intensities were smaller than the actual ones in some places in Kanto and Tohoku regions. This was thought to be because of smaller estimated earthquake magnitude, smaller estimated fault plane, shorter estimated fault length, not having considered the shape of the fault, etc.[47]There were also cases where large differences between estimated intensities by the Earthquake Early Warning system and the actual intensities occurred in the aftershocks and triggered earthquakes.[48]Geology[edit]

Map of the Thoku earthquake and aftershocks on 1114 March

Hypocentral region boundaries (Source: The Japanese Headquarters for Earthquake Research Promotion)This earthquake occurred where thePacific Plateissubductingunder the plate beneath northern Honshu; which plate is a matter of debate amongst scientists.[20][49]The Pacific plate, which moves at a rate of 8 to 9cm (3.1 to 3.5 in) per year, dips under Honshu's underlying plate building large amounts of elastic energy. This motion pushes the upper plate down until the accumulated stress causes a seismic slip-rupture event. The break caused the sea floor to rise by several meters.[49]A quake of this magnitude usually has a rupture length of at least 500km (300mi) and generally requires a long, relatively straight fault surface. Because the plate boundary andsubduction zonein the area of the Honshu rupture is not very straight, it is unusual for the magnitude of its earthquake to exceed 8.5; the magnitude of this earthquake was a surprise to some seismologists.[50]Thehypocentral regionof this earthquake extended from offshoreIwate Prefectureto offshoreIbaraki Prefecture.[51]TheJapanese Meteorological Agencysaid that the earthquake may have ruptured the fault zone from Iwate to Ibaraki with a length of 500km (310mi) and a width of 200km (120mi).[52][53]Analysis showed that this earthquake consisted of a set of three events.[54]The earthquake may have had a mechanism similar to that ofanother large earthquake in 869with an estimatedsurface wave magnitude(Ms) of 8.6, which also created a large tsunami.[55]Other major earthquakes with tsunamis struck theSanriku Coastregionin 1896andin 1933.In a study of N. Uchida and T. Matsuzawa, it was pointed out that the source area of this earthquake has a relatively high coupling coefficient surrounded by areas of relatively low coupling coefficients in the west, north, and south. From the averaged coupling coefficient of 0.50.8 in the source area and the seismic moment, it was estimated that the slip deficit of this earthquake was accumulated over a period of 260880 years, which is consistent with the recurrence interval of such great earthquakes estimated from the tsunami deposit data. The seismic moment of this earthquake accounts for about 93% of the estimated cumulative moment from 1926 to March 2011. Hence, earthquakes with magnitudes about 7 since 1926 in this area only had released part of the accumulated energy. In the area near the trench, the coupling coefficient is high, which could act as the source of the large tsunami.[56]Most of the foreshocks are interplate earthquakes with thrust-type focal mechanisms. Both interplate and intraplate earthquakes appeared in the aftershocks offshore Sanriku coast with considerable proportions.[57]The strong ground motion registered at the maximum of 7 on theJapan Meteorological Agency seismic intensity scaleinKurihara,Miyagi Prefecture.[58]Three other prefecturesFukushima,IbarakiandTochigirecorded an upper 6 on the JMA scale. Seismic stations inIwate,Gunma,SaitamaandChiba Prefecturemeasured a lower 6, recording an upper 5 in Tokyo.InRussia, the main shock could be felt inYuzhno-Sakhalinsk(MSK 4) andKurilsk(MSK 4). The aftershock at 06:25 UTC could be felt inYuzhno-Kurilsk(MSK 5) and Kurilsk (MSK 4).[59]Energy[edit]

Damage to the antenna ofTokyo TowerThis energy of the seismic waves from the earthquake wassurface energy(Me)1.9 0.51017joules,[60]which is nearly double that of the 9.1-magnitude2004 Indian Ocean earthquake and tsunamithat killed 230,000 people. If harnessed, the seismic energy from this earthquake would power a city the size of Los Angeles for an entire year.[44]Theseismic moment(M0), which is represents a