AP: A 5.3-magnitude earthquake hit Japan's Fukushima Prefecture.
The 2011 [earthquake and tsunami] caused three reactors to melt and damaged a fuel cooling pool at another. Officials have acknowledged that radiation-contaminated groundwater has been seeping into the Pacific Ocean since soon after the meltdowns.
The region lies on the ‘‘Ring of Fire’’ — an arc of earthquake and volcanic zones that stretches around the Pacific Rim. About 90 percent of the world’s quakes occur in the region.