Day 3 – Sunday, March 13
- Fukushima reactor No. 3 is vented again.
- There is believed to have been a partial meltdown in the reactor.
- A company spokesman states that the radiation released thus far does not pose a health risk to humans.
- The cooling system in reactor 2 fails and more radioactive steam is released.
- The government evacuates more than 200,000 residents from homes within a 20-kilometer (12.4-mile) radius of the plant and tests 160 people for radiation exposure, authorities said Sunday.
- IAEA rates the accident as a level four out of seven on the scale of international nuclear disasters. Three-Mile-Island was rated a five, Chernobyl a seven.
- Meanwhile, in southwestern Japan, Shinmoedake volcano erupts for the second time in 2011, sending ash and rock more than two miles into the air. Analysts say it was the biggest volcanic activity there in 52 years.
Day 4 – Monday, March 14
- An explosion caused by pressure buildup blows away the roof and walls of the building housing the Fukushima Daiichi plant's No. 3 reactor and injured 11 people. The plant's No. 2 reactor loses its cooling capabilities after the explosion. Workers begin injecting seawater and boric acid into that reactor.
- A fire is extinguished, but Chief Cabinet Secretary Yukio Edano says that more radiation was released as a result and that "now we are talking about levels that can damage human health."
- The US Geological Survey upgrades the earthquake from an 8.9 to a 9.0.