The U.S. Geological Service says a 6.6-magnitude aftershock struck northeastern Japan today, exactly one month since the 9.0 earthquake that spawned the tsunami and nuclear crisis. The trembler is the second major aftershock in less than a week. At only eight miles deep, it was shallower than previous aftershocks, but shallow earthquakes tend to do the most damage. The quake, which had its epicenter 50 miles south of Fukushima and 101 miles northeast of Tokyo, briefly shut down power to pumps sending water to the troubled nuclear plant's three most badly damaged reactors before electricity was restored. Tokyo Electric Power Company temporarily ordered workers at the plant to withdraw and stay in a quakeproof building, but they are still not sure how many were involved.
Chief Cabinet Secretary Yukio Edano, the primary government spokesman since the tsunami, said Japan would order parts of five villages and cities outside the current evacuation zone to prepare to leave. Edano said those areas are in danger of being exposed to radiation levels equivalent to at least 20 millisieverts a year, which could be harmful over the long term. If the crisis at the plant worsens, five other areas will be told to evacuate, with orders expected within the month. Despite warnings about widening the evacuation zone from the International Atomic Energy Agency, Japanese leaders refused to follow the example of the United States and Australia, which both advised their citizens to stay 50 miles away from the plant. In fact, Edano said the chance of a large-scale radiation leak had decreased.
Broadening the evacuation zone can also assist with the eventual decontamination of farms and communities. Right now, as people and nonemergency vehicles move from contaminated to safe areas, there's a risk of spreading particles. Michael Friedlander, a specialist in emergency responses to nuclear accidents, told the New York Times, “Unless you gain control, it will be like trying to mop your kitchen floor with the kids running in and out of the house.”