On 16 July 2007, following an earthquake that measured 6.8 on the Richter scale, the world's largest nuclear plant (seven reactors with total generating capacity of 8,000 megawatts), at Kashiwazaki-Kariwa in Niigata prefecture, had to be shut down indefinitely. The plant's operators (Tokyo Electric Power Company) admitted that the quake had been more than twice as strong as the design had allowed for, and that it had been built directly atop a fault line that they had not detected. Oops!