MattieGeorgeMorisettEarthScience13December 2017Sendai Earthquake At 2:46 P.M.
on March 11, 2011, oneof the most powerful earthquakes ever recorded in history hit northeasternJapan. An earthquake so powerful that it triggered a series of large tsunamisthat destroyed many coastal areas of the country and instigated a major nuclearaccident a power station along the coast. This earthquake has come to be knownas the Great Sendai Earthquake.
The Great Sendai Earthquake, also referred toas the Great T?hoku Earthquake, was a magnitude-9.0 earthquake occurred innortheastern Japan, off the country’s main island, Honshu (Pletcher). The epicenter,or the middle of the earthquake, was located 130 kilometers east of the city ofSendai, and the focus occurred at a depth of thirty kilometers below the floorof the Pacific Ocean (Pletcher). It was felt as far away as Russia, Taiwan, andChina (Pletcher).
The natural disaster was preceded by several foreshocks,including a magnitude-7.2 event that centered roughly forty kilometers awayfrom epicenter, and followed by multiple aftershocks in the weeks after thatwere measured magnitude-6.0 (Pletcher). The earthquakewas caused by a rupture of the subduction zone associated with the JapaneseTrench, which separates the Eurasian plate from the Pacific plate whichdisplaced the water that sat above it which created a series of highlydestructive tsunami waves that measured approximately over thirty feet tall andreached as far as ten kilometers inland (Pletcher). Sendai wasn’t the only cityaffected by the tsunami waves; other communities, including Kamaisha and Miyakoin Iwate; Ishinomaki, Kensennuma, and Shiogama in Miyagi; and Hitachinaka andKitaibaraki in Ibaraki were also devastated (Pletcher). Tsunami warnings were triggered bythe main quake throughout the Pacific basin (Pletcher). The natural oceanicdisaster raced from the epicenter towards the land at about 800 kilometers perhour, generating waves that affected many other areas of the world, includingthe Hawaiian Islands chain, Aleutian Islands chain, and the west coast of NorthAmerica (Pletcher). Eighteen hours after, waves also reached Antarctica andcaused the outer-shell of the Sulzberger Shelf to break (Pletcher).
Within two weeks of the disaster,the Japanese government’s official count of death surpassed 10,000; more thanone and a half times that number were still listed as missing and presumed dead(Pletcher). The numbers in both categories, missing or dead, dramaticallyincreased in the following days which sprung multiple rescue operations alongthe Japanese coast (Pletcher). The official count for those who are confirmed dead orstill missing rose to approximately 28,500, but by the end of 2011, the numberreduced to 19,300 as more and more people were found to be alive (Pletcher). Morethan half the victims were age 65 years or older (Pletcher). Out of all theprefectures in Japan that were in the effected area, Miyagi suffered thegreatest of losses as 10,800 were officially pronounced dead or missing andanother 4,100 were injured (Pletcher). Although nearlyall the human casualties were caused by the large tsunami waves along the coast,the earthquake was responsible for a considerable amount of damage over a widerarea (Pletcher). Fires took place in many cities such as a petrochemical plantin Sendai, a portion of the city of Kensennuma, and an oil refinery at Ichihara(Pletcher).
Infrastructure throughouteastern T?hoku was heavily affected with roads and rail lines damaged, waterand sewage systems disrupted, and electric power knocked out (Pletcher). A dam,near the prefectural capital, Fukushima city, burst due to the earthquake causingthe destruction of thousands of homes in Fukushima, Ibaraki, and Chiba prefectures(Pletcher). Another result from the natural disasterincluded the significant concern of the status of several nuclear powerstations in the T?hoku region (Pletcher).
Three nuclear power plants shut downtheir reactors at they were closest to the epicenter (Pletcher). Theaftershocks from the earthquake cut the main power and the tsunami wavesdamaged the back up generators at some of the plants, most notably the FukushimaDaiichi plant, also known as “Number One” plant, a plant situated in the northeasternFukushima prefecture about 100 kilometers south of Sendai (Pletcher). With the power gone, the coolingsystems failed and a few days after the disaster, the cores overheated which ledto partial meltdowns of the fuel rods (Pletcher). The melted material fell andburned sizable holes in the bottom of the containment vessels in reactors oneand two, exposing nuclear materials in the cores (Pletcher). Pressurized hydrogengas in the outer containment buildings enclosing the reactors caused multipleexplosions to erupt (Pletcher). Fuel rods stored in reactor four were touchedoff by the fire resulting from the explosions in the first three reactors(Pletcher). The facility released significant levels of radiation in the weeksfollowing the earthquake; workers sought to stabilize the damaged reactors bycooling them with seawater and boric acid (Pletcher).
Japanese officials were afraid of possible radiationexposure, so they established a thirty kilometer no-fly zone and created anarea of twenty kilometers around the Fukushima Daiichi plant (Pletcher). Therewas a spike in levels of radiation found in the local food and water suppliesthat prompted officials in Japan and overseas to issue warnings about theirconsumption (Pletcher). Towards the end of March 2011, seawater near the Daiichifacility was discovered to have been contaminated with high levels of radioactiveiodine-131 which stemmed from the exposure of pumped-in seawater that workersused to cool the fuel coils (Pletcher). The water later had leaked inwater-filled trenches and tunnels between the facility and the ocean(Pletcher).
Japanese nuclear regulators, in mid-April, elevatedthe security level of the nuclear emergency at the Fukushima Daiichi from fiveto seven—the highest level on the scale created by the International AtomicEnergy Agency (Pletcher). This placed the Fukushima accident in the samecategory as the Chernobyl accident, which happened in the Soviet Union in 1986).Evaluation zones were thought to be uninhabitable for decades, due to radiationlevels remaining high for many weeks after the accident (Pletcher).
However,several months after the accident, government officials announced radiationlevels in five towns just beyond the twenty kilometer radius had declinedenough to allow residents to reenter their homes, but some former residents stayedaway, concerned about the amount of radiation in the soil (Pletcher).In December 2011, Japanese Prime Minister NodaYoshihiko declared the Fukushima Daiichi facility stable, but numerous leaksfollowed the accident (Pletcher). Years later, a significant leak happened inAugust 2013, which was severe enough to prompt Japan’s Nuclear RegulationAuthority to classify it as a level-3 nuclear incident (Pletcher). In the first hours of the earthquake,the Japanese Prime Minister Kan Naoto moved to set up an emergency commandcenter to be located in Tokoyo (Pletcher). In result, many rescue workers and approximately100,000 members of the Japanese Self-Defense Force were mobilized quickly todeal with the disaster (Pletcher). The country also requested U.S.
militarypersonnel stationed in the country to be a part of the relief efforts, and inturn a U.S. Navy aircraft was dispatched to the area (Pletcher).
Several other countries, such asAustralia, China, Indian, New Zealand, South Korea, and U.S., helped by sendingsearch-and-rescue teams, while dozens of other countries and majorinternational relief organizations, such as Red Cross and Red Crescent, helpedwith financial and material support (Pletcher). Private and other nongovernmentalorganizations from all over the world established relief funds to aid in therescue and recovery efforts (Pletcher). WorksCited Pletcher, Kenneth, and John P.Rafferty.
“Japan earthquake and tsunami of 2011.” Encyclopœdia Britannica, Encyclopœdia Britannica, inc. 22 Nov.2016, www.