>> o'brien: minoura didn't stop there. he dug deeper and found more marine layers, clear proof of similar giant tsunamis every thousand years or so, like geologic clockwork. over the course of the next 20 years, he would publish his findings in major scientific journals. >> i regret but nobody paid attention to anything to my thesis. >> o'brien: why not? >> i don't know. >> o'brien: so now people are coming and talking to you. >> but too late, yes. too late. >> o'brien: so what did tepco know and when did it know it? we spoke to a researcher who uncovered evidence of a very large tsunami in 869, which i know you're familiar with now. and he published this information 20 years ago. why was that not considered at fukushima? >> we don't know, but i heard that, you know, tepco and people in the education have been talking about, you know, considering that tsunami also. but i heard that we were... we were in the process of considering that, but this accident occurred during that process, i think. >> o'brien: but even if they ha