You’ve probably never heard of the Jogan event. But according to Japanese paleontologist Koji Minoura, it was an ancient tsunami that devastated northeast Japan in 869 AD, killing more than 1,000 people.

He was tipped off to Jogan from a most unlikely place: a poem.

Minoura researched this event and ones like it for more than 20 years, publishing his findings in major scientific journals. Giant tsunamis occurred in northeast Japan about every thousand years, he warned — meaning the area was overdue for another one prior to the devastating March 2011 wave.

Minoura’s story, as reported by Arun Rath for The World and featured in tonight’s FRONTLINE film Nuclear Aftershocks, is a tale of too little, too late. A spokesman from the Tokyo Electric Power Corporation [TEPCO] told FRONTLINE that the company was aware of Minoura’s work and was in the process of considering plant modifications in case of a massive tsunami.

Then came the March 2011 earthquake, tsunami and subsequent nuclear meltdown at the Fukushima Daiichi plant. Thousands of people were killed and entire communities were evacuated.

Minoura’s work has received a higher profile since the disaster, but he feels like his warnings were ignored: “I regret it, but no one paid attention to my thesis,” he says.

Listen to the full piece from The World below: