In this “ring,” in the Pacific Northwest in America, two large tectonic plates (thousands of miles) meet - this area is called the Cascadia Subduction Zone. Written history from that part of America hadn’t recorded anything about it, as the area’s written history doesn’t go back very far.
In Japan, however, written records do go back very far - and they have records of a tsunami in early 1700 despite no earthquake having happened nearby.
Back in the Pacific North West, along the coast, there is a “ghost forest” on the shore, which is basically a bunch of dead cedar stumps. The assumption initially was that they had died over time. But in the 80s, paleogeologists found evidence in the soil that their deaths had been caused by a sudden drop in the ground level causing them to be submerged in seawater. Looking at the rings in the tree stumps, they were able to date them all to just before the Japanese tsunami. Crazy to think that “forest” had been dead 300 years but was still hanging around.
They now think what happened is there was a huge earthquake in that zone, which caused the massive tsunami that travelled all the way to Japan, and another huge tsunami that travelled east into America.
To really cement it, this lines up exactly with various stories passed down through generations in different Native American peoples in the area - of a huge earthquake and tsunami that wiped out several villages, with some recording it as reaching as far inland as 80 miles. Through shared details in the Native American spoken records (e.g., it happening when people were going to bed), and the written records in Japan, they were even able to estimate the time at which it occurred - about 9PM -and calculate the time it took to get to Japan. Some people think this massive event is the root of Native American myths in the area of a fight between a thunderbird and a whale - the description of it does line up with what the earthquake and tsunami would have been like.
I just think it’s absolutely insane how by looking at the earth, dead trees, and histories of different people thousands of miles apart, scientists and humanities researchers were able to reconstruct something that a) was mostly missing from written records and b) happened three hundred years ago. All this led seismologists to a much greater understanding about the zone & to realise there is a chance something like this could happen again in that area over the next 50-100 years.
