Folklore
I've been wondering about folklore in tsunami prone areas and your post inspired me to do some googling. Here's a couple o' links.
The November 18, 1929 offshore earthquake, slump and tsunami: Canada's most tragic historic seismic event.
University of Washington scientist probes Indian myth for tsunami clues
Hamaguchi--the oldest tsunami story
The people stood speechless on the side of the mountain. The village was gone; the temple was gone; the fields had been torn away. Nothing was left of their homes but a few straw roofs that floated on the water. But every man and woman and child was safe on the mountain side.
: Then the people knew why old Hamaguchi had set fire to the rice. There he stood among them, as poor as any. And they fell on their knees to thank him.