Some time around 1978--give or take a year--I read an account written by one of the fisherman anchored in the bay at the time of the landslide and wave, as published in "National Fisherman" magazine.
I remember reading how the chain to his anchor flew out of his boat's chain locker as the wave carried his boat backward, until the chain reached the end and snapped.
He said that as he looked over the stern of his boat, he could see the tops of pine trees below him, as the wave carried him over them.
He also mentioned early in the article that long before this incident happened, he had seen in earlier visits to the place, marks high up the sides of the surrounding mountainsides, which appeared to be caused by water--he said before he witnessed it for himself, he would never have believed those marks could have been caused by water.
Apparently chunks of that mountain had fallen and caused waves before.