On March 11, an earthquake that measures 9.0 on the Richter scale strikes off the coast of Japan and launches a tsunami that rages over the northern part of the country. The destruction sets off the worst nuclear emergency since Chernobyl. Explosions and leaks of radioactive gas occur in three reactors at the Fukushima Daiichi Nuclear Power Station, which sustains partial meltdowns. Spent fuel rods at a fourth reactor overheat and catch fire, resulting in the release of radioactive material into the atmosphere. Radiation is detected in Tokyo’s water as well as water from the reactors that was released into the ocean.