Japan Quake • A Timeline

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Following the 8.9 magnitude earthquake and subsequent tsunami on the east coast of Japan, the country is now racing to prevent a nuclear disaster at a major nuclear power plant. Below is a time line of events in Japan local time. (Updated 8:30 p.m. EST) •

  • Friday  March 11

2:00 p.m.

8.9 earthquake strikes off coast of Honshu 15 miles below surface

11 nuclear power reactors shutdown

3:45 p.m.

Tokyo Electric Power Co (Tepco) reports emergency generators for reactors 1, 2 and 3 at the Fukushima Daiichi power plant have failed and there were reports that the diesel-powered back up systems was also affected by the Tsunami.

7:30 p.m.

Prime Minister Naoto Kan declares "nuclear emergency status," but officials say this is standard procedure and that no radioactive material was detected in the area.

10:00 p.m.

The government begins to evacuate residents within a 3-kilometer radius from the area

(GRAPHIC:International Nuclear and Radiological Event Scale. The Fukushima plant in Japan was upgraded to a 6 on the scale. Chernobyl ranked a 7. Three Mile Island was a 5. - Photo Illustration/WNYC)

  • Saturday - March 12

5:30 a.m.

After the automatic shutdown of the reactors, pressure builds as the cooling system fails to work properly and the decision is made to release the pressure by venting some of the steam. The steam contains trace amounts of radioactive material.

11:00 a.m.

Pressure builds in reactor unit 2 and the steam is vented, releasing more radioactive material into the air.

3:30 p.m.

There is a massive explosion at the power station, in which one of the four buildings collapses and injures four workers.

8:00 p.m.

Officials confirm that the concrete building surrounding the plant’s steel reactor container has collapsed, but the steel container has not been damaged.

To avoid a nuclear meltdown Tepco deciced to flood the reactor with seawater, effectively destroying the 40-year old plant. They also prepare to flood reactor 3 to cool it and reduce pressure.

  • Sunday - March 13

3:20 a.m.

The World Health Organization announces that the risk of a radiation leak to the pubic is quite low. Meanwhile, Japan's official nuclear agency rates the incident a 4 out of 7 on the scale of severity. For context, the disaster at Chernobyl was rated a 7, while Three Mile Island was a 5. 

6:00 a.m.

The cooling system of reactor 2 failed. Tepco says it will release more steam and more radioactive material and considers injecting seawater.

8:30 a.m.

There are reports that reactor 3 is facing a partial meltdown and that radiation has risen to unsafe levels.


Japanese officials say another explosion is possible, but another official says the reactor core is protected and that the radioactivity that has been released does not pose a health threat to the public.


The International Atomic Energy Agency (IAEA) announced a state of emergency has been declared for another nuclear power plant, Onagawa, which is over 100 miles north of the Fukushima Daiichi power plant.

Later, Japan's nuclear safety agency announces the cooling system at the Onagawa plant is fine.


  •   Monday - March 14


There was a second massive explosion at reactor 2. In an effort to cool reactor 2, as officials were venting the reactor to prevent a complete nuclear meltdown.

9:00 p.m.

The ministry of Foreign Affairs says 94 countries and 9 international aid organizations have pledged assistance. Foreign rescue teams have begun to arrive.

  • Tuesday - March 15


6:20 a.m.

There was a third explosion at reactor 2. The power plant accidents have so far injured 15 workers and exposed up to 190 people to higher levels of radiation than is considered safe.

6:30 a.m.

TEPCO begins rolling blackouts in an effort to conserve energy in service regions across the country, with the exception of Central Tokyo. The blackouts will continue until Friday March 18.

10:00 a.m.

Officials urge the evacuation of residents living 20-30 miles of Fukushima Daiichi plant. Japanese officials have also distributed iodine tablets at evacuation centers.

8:25 p.m.

The IAFC said the levels of radioactivity have been decreasing at the nuclear power plant. They added that 150 people have been tested for radioactivity and 23 of those have had to undergo decontamination. 

Correction: An earlier version of this article erroneously reported that the tsunami was on the west coast of Japan. That is incorrect. The tsunami was on the east coast of the country. WNYC regrets the error.