The New York Times reports a strong aftershock in northeast Japan disrupted cooling operations at the Fukushima Daiichi nuclear power plant for nearly an hour, as workers were yet again evacuated from the site during a tsunami warning. Meanwhile, exactly one month after the nuclear catastrophe began, the Japanese federal government has begun plans to expand the mandatory evacuation zone from 20 to 30 km, in recognition of the risks of prolonged exposure to elevated radiation levels.