TOKYO: Japanese nuclear regulators trusted that the reactors at the Fukushima Daiichi complex were safe from the worst waves an earthquake could muster based on a single-page memo from the plant operator nearly 10 years ago.

In the December 19, 2001, document - a double-sized page obtained under Japan's public records law - Tokyo Electric Power Company (Tepco) rules out the possibility of a tsunami large enough to knock the plant offline, and gives scant details to justify this conclusion.

Despite advances in earthquake and tsunami science, the document was never updated. When Tepco revisited tsunami preparedness last year, it was a cursory check.

''There was an attitude of disrespecting nature,'' said Kobe University professor emeritus Katsuhiko Ishibashi, who has sat on government nuclear safety advisory panels.

Associated Press