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Copyright Red Cross Nuclear Disaster Resource Center

Great East Japan Earthquake and Tsunami, Fukushima Daiichi NPP Accident (1/5)

1. Overview of the earthquake

Distribution of JMA* Seismic Intensity Source: JMA website

Date and Time: March 11, 2011 14:46 JSTEpicenter: Off the Sanriku coast

(38°6.2′ N, 142°52′ E)Depth 24Km

Magnitude: 9.0

2. Overview of the Tsunami

The 2011 Great East Japan Earthquake (JMA):http://www.jma.go.jp/jma/en/2011_Earthquake/Information_on_2011_Earthquake.html

On March 11, 2011, the earthquake occurred centered offthe Sanriku coast. The magnitude was 9.0, far beyond thescale of the Kanto Great Earthquake (M7.9) in 1923 andShowa Sanriku Earthquake (M8.4) in 1933, the biggestearthquake ever in and around Japan.Soon after the earthquake, the JMA named it as “2011 off

the Pacific coast of Tohoku Earthquake”. On April 1, 2011,the cabinet decided to call the disaster caused by theearthquake and the following Fukushima Daiichi NuclearPower Plant accident “Great East Japan Earthquake”.

The JMA seismic intensities observed in Fukushima Prefecture are as follows:

The tsunami which followed the earthquake caused much more damage. In a widearea from Hokkaido to Okinawa, particularly along the Pacific coast mainly fromTohoku to North Kanto, the tsunami was observed. In Fukushima, the maximumheight of the tsunami observed was higher than 9.3m. The tsunami inundated as wideas 112km2 and caused enormous damage.The tsunami data observed at the observation stations in Fukushima Prefecture are

as follows:

Area Date Time Type Height Date Time HeightSoma*1 *2 *3 *4Onahama, Iwaki *3 March 11, 2011 15：08 Anaseism 2.6m March 11, 2011 15：39 3.3m

(Translation of JMA report, March 2011)

First Wave Maximum Height

March 11, 2011 14：-- Backwash 1.2m March 11, 2011 15：51 >=9.3m

Note: Since the observation stations were damaged by the tsunami, data could not be retrieved for some time and the subsequent waves may have been higher than the data listed.

*1 Data could not be retrieved for some time.*2 Observed by a massive tsunami observation instrument (per 0.1m).*3 Readings of the first wave may have been inaccurate due to the land subsidence effect.*4 The beginning time of the first wave could not be identified by the sea-level fluctuations caused by the earthquake.

However, the occurrence of land subsidence along the Pacific coast after the earthquake is estimated by Geospatial Information Authority of Japan. Therefore, it is estimated that the coast was included in the source area of tsunami.

* Japan Meteorological Agency

JMA Seismic Intensity Location

6 Upper Shirakawa, Sukagawa, Kunimi, Tenei, Tomioka, Okuma, Namie, Kagamiishi, Naraha, Futaba and Shinchi

6 Lower Fukushima, Nihonmatsu, Motomiya, Koriyama, Koori, Kawamata, Nishigo, Yabuki, Nakajima, Tamakawa, Ono, Tanagura, Date, Hirono, Asakawa, Tamura, Iwaki, Kawauchi, Iitate, Soma, Minamisoma and Inawashiro

5 Upper Otama, Izumizaki, Yamatsuri, Hirata, Ishikawa, Miharu, Katsurao, Furudono, Aizuwakamatsu, Aizubange, Kitakata, Yugawa, Aizumisato and Bandai

(Translation of Fukushima Prefecture report)

< About Great East Japan Earthquake and Tsunami >


Situation soon after the accident occurrenceThe massive earthquake automatically shut down the Units 1, 2 and 3 which were being operated at TEPCO’s Fukushima Daiichi Nuclear Power

Plant (Fukushima Daiichi NPP). At that time, Units 4, 5 and 6 were not operated because they were being checked or tested.Since the earthquake lost all external power sources at the Fukushima Daiichi NPP, the emergency diesel generators automatically started running

and maintained the cooling function of the reactors and spent fuel pools. However, the subsequent tsunami discontinued the operation of theemergency generators resulting in all AC power sources lost for Units 1 to 4. TEPCO took measures to recover power source in cooperation with thegovernment, but they faced difficulties.The isolation condenser of Unit 1 became inoperable. At Units 2 and 3, DC power source ran out and the supply of cooling water stopped. These led

to dysfunction of core cooling system at each Unit. As a result, the water level of the reactors lowered and the reactor cores were exposed. Thereactors began to be damaged and were finally melt down. After that, there were hydrogen explosions at Unit 1 and 3 around the roof top of the reactorbuilding. The explosions are estimated to have been caused by hydrogen leaked from the containment. The explosions destroyed the operation floor ofeach building. These explosions released a huge amount of radioactive materials into the atmosphere. Following the explosion at the Unit 3 building,there was another explosion at Unit 4 where all reactor fuel had been moved to its spent fuel pool due to a regular check. The explosion is estimated tohave been caused by hydrogen. The upper part of the reactor building was destroyed. During this period of time, a large damage is estimated to haveoccurred at Unit 2 probably around its suppression chamber room.The Japanese government issued “Declaration of Fukushima Daiichi Emergency Situation”, followed by evacuation order to residents within the 3km

radius of Fukushima Daiichi NPP. Next day (March 12), at 5:44, the government expanded the evacuation order area from 3km to 10km after theradiation level in the center control room of Unit 1 rose. Following the hydrogen explosion at Unit 1 at 15:36 on that day, the evacuation order area wasfurther expanded to 20km at 18:25. At 11:01 on March 14, another hydrogen explosion was confirmed at Unit 3. At 6;10 on March 15, an explosion washeard at Unit 4 and then the government ordered sheltering indoors to 140,000 residents within the 20-30km radius area of the power plant at 11:00.

(as of Mar. 11, 2011) (as of Mar. 12, 2011) (as of Mar. 15, 2011)

Extended evacuation order areas

< About TEPCO’s Fukushima Daiichi Nuclear Power Plant Accident >



< Fukushima Daiichi NPP Accident: Timeline from the accident occurrence (2011) >

Reports (The National Diet of Japan Fukushima Nuclear Accident Independent Investigation Commission) http://warp.da.ndl.go.jp/info:ndljp/pid/3856371/naiic.go.jp/en/

Reports (Investigation Committee on the Accident at the Fukushima Nuclear Power Stations of Tokyo Electric Power Company established by the cabinet decision) http://www.cas.go.jp/jp/seisaku/icanps/eng/

Translation of the following references and websites:Reports (The National Diet of Japan Fukushima Nuclear Accident Independent Investigation Commission); Reports (Investigation Committee on the Accident at the Fukushima Nuclear Power Stations of Tokyo Electric Power Company established by the cabinet decision); Prime Minister’s Office website; Cabinet Office’s website; Ministry of Economy, Trade and Industry’s website; Japan Meteorological Agency’s website; and excerpts from “Great East Japan Earthquake and Tsunami –Record Document of Fukushima –“ published by JRCS Fukushima Chapter.

14:46 "2011 off the Pacific Coast of Tohoku Earthquake" occurred. Magnitude: 9.0; Seismic intensity observed: 6 lower (Fukushima City); Maximum intensity observed: 7 (North Miyagi Prefecture).

The following reactors were automatically shut down: Units No. 1 to 3 at Fukushima Daiichi NPP and Units No. 1 to 4 at Fukushima Daini NPP.Units 4 to 6 at Fukushima Daiichi NPP were in a regular check.

The disaster response headquarters were established by Fukushima Prefecture and the disaster security headquarters by Fukushima Prefectural Police. (49 municipalities in Fukushima Prefectures also established their own disaster response headquarters.)

14:49 The Japan Meteorological Agency issued a major tsunami warning to the Pacific coastal regions of the following prefectures: Aomori; Iwate; Miyagi; and Fukushima.

14:50 The Japanese Government established the Response Office at the Prime Minister's Office. => The government established the Disaster Management Headquarters at 15:14.

15:37 Fukushima Daiichi NPP lost its power source due to the tsunami.=> 15:42 TEPCO notified the government of the event based on Act on Special Measures concerning Nuclear Emergency Preparedness

19:03 The government issued "Declaration of Fukushima Daiichi NPP Emergency Situation".

20:50 The Fukushima Prefecture Nuclear Disaster Headquarters "requested evacuation" to residents within a radius of 2 km from Unit 1 of Fukushima Daiichi NPP.

21:23 The government ordered evacuation to 5,862 residents within 3 km radius of Fukushima Daiichi NPP, and ordered sheltering indoors to residents of the radius of 3 - 10 km from the NPP.

5:44 The government ordered evacuation to 51,207 residents within 10km radius of Fukushima Daiichi NPP.

7:45 The government issued "Declaration of Fukushima Daini NPP Emergency Situation".

7:45 The government ordered evacuation to 8,049 residents within 3km radius of Fukushima Daini NPP and sheltering indoors to residents within 3-10km radius of the power plant.

15:36 Hydrogen explosion at Unit 1 of Fukushima Daiichi NPP.17:39 The government ordered evacuation to 32,426 residents within

10km radius of Fukushima Daini NPP.18:25 The government ordered evacuation to about 80,000 residents

within 20km radius of Fukushima Daiichi NPP.19:04 Seawater injection into the reactor of Fukushima Daiichi NPP

started.

2011/03/11

2011/03/12

11:01 Hydrogen explosion in the Unit 3 building of Fukushima Daiichi NPP.

18:22 All fuel rods at Unit 2 of Fukushima Daiichi NPP were exposed due to shortage of cooling water.

around 6:00

An impulsive sound presumably from damage around the pressure suppression room in Unit 2 of Fukushima Daiichi NPP was confirmed.A significant impulsive sound was heard from Unit 4 of the NPP. The roof top area on the fifth floor of the reactor building was damaged.

11:00 Residents within 20-30km radius of Fukushima Daiichi NPP were ordered to stay indoors.

5:45 Fire occurrence around the north-west part of the third floor of Unit 4 reactor building of Fukushima Daiichi NPP was confirmed.

8:34 A large grey smoke rising from Unit 3 was observed.2011/03/17 Water spraying into the Unit 3 spent fuel pool was conducted by

police and Self-Defense Forces.Water spraying into the Unit 3 spent fuel pool was carried out by Self-Defense Forces and the U.S. Army using high-pressure water cannon vehicles.Nuclear and Industrial Safety Agency issued Level 5 (Accident with off-site risk) INES provisional rating for Units 1 to 3.

2011/03/19 Emergency Fire Rescue Team of Fire and Disaster Management Agency sprayed water to the Unit 3 spent fuel pool.

Unit 5 at Fukushima Daiichi NPP was in cold shutdown.Unit 6 at Fukushima Daiichi NPP was in cold shutdown.

2011/03/23 Estimates for radioactive effects using SPEEDI was announced.

2011/03/25 The government requested mayors of municipalities in the areas where sheltering order was issued (20-30 km radius of Fukushima Daiichi NPP) for active encouragement of voluntary evacuation to their citizens and for beginning preparations on the assumption evacuation order issuance.

2011/04/01 The government named the disaster as "Great East Japan Earthquake".

2011/04/04 Low-level radioactive contaminated water was discharged into the ocean.

2011/04/12 The INES provisional rating was raised to Level 7 (Major accident) for Units 1-3.

2011/04/17 TEPCO released "Roadmap towards Restoration from the Accident at Fukushima Daiichi Nuclear Power Station".

2011/03/20

2011/03/14

2011/03/15

2011/03/16

2011/03/18



Results of aircraft monitoring by MEXT* and Miyagi Prefecture(Total surface deposition of Cs‐134 and Cs‐137 inside 100 and120 km zone of TEPCO Fukushima Daiichi NPP and in northern Miyagi Prefecture) (as of July 2, 2011)* Ministry of Education, Culture, Sports, Science and Technology

Source: Excerpts from aircraft monitoring readings released by MEXT

The Fukushima Daiichi NPP accident released radioactive materials such as Cs-134 and Cs-137 whose half-life period is long over a wide area. Due to this, there are still many areas with high ambient dose rate as of February 2013, about two years on from the accident.

TEPCOFukushima Daiichi NPP

Fukushima

Akita Iwate

Yamagata

Niigata

Gunma

Tochigi

Ibaraki

Saitama

TokyoChibaYamanashi

Miyagi

Air dose rate map (Air dose rate over 1 meter above ground level)(Combination of the 6th aircraft monitoring results and readings of air dose monitoring outside 80km zone of TEPCO Fukushima Daiichi NPP) (as of February 28, 2013)

TEPCOFukushima Daiichi NPP

< Spread of radioactive materials from Fukushima Daiichi NPP >



Miyagi Pref.

Note: The charts were prepared based on thedata of the Reconstruction Agency website.

Extended evacuation order areas

March 11, 2011(3km radius of the Fukushima NPP)

April 21, 2011 (Extended to 20km radius)

April 22, 2011(Redefined evacuation areas made residents outside a 30km

radius of the NPP evacuate.)

Fukushima Pref.

(Some descriptions are added to the evacuation area maps posted on the METI*website)

The unprecedented complicated disaster of the huge earthquake and tsunami which occurred on March 11, 2011 and the subsequent nuclear accidentextended evacuation order areas. Finally, evacuation order was issued over a wide area and this forced a large number of residents to flee their homes.Many Fukushima citizens including families with children evacuated to other prefectures, because they were concerned about radiation effects.

As of March 2015, there were 71,399evacuees inside Fukushima Pref. 46,902Fukushima citizens were evacuated outsideof the prefecture. The number of theevacuees to other prefectures was muchhigher than that for other affected prefectures.

Fukushima

Evacuation order area

Sheltering indoors

Fukushima Daiichi NPP Fukushima Daiichi NPP

Fukushima Daini NPP

Evacuation order areaSheltering

indoors

FukushimaDaiichi NPP

FukushimaDaini NPP

Evacuation order area

Evacuation‐Prepared Area in Case of Emergency

Evacuation‐Prepared Area in Case of EmergencyDeliberate

Evacuation Area

Iwate Pref.Number of evacuees by year

< Wide-area evacuation caused by the Fukushima Daiichi NPP accident >


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