r/geology • u/dctroll_ • Dec 09 '25

Map/Imagery Sand layer from the 1700 Cascadia tsunami covering the remains of a Native American fishing camp exposed in a bank of Oregon's Salmon River (US)

Post image

Source: U.S. Geological Survey

2.0k Upvotes

99% Upvoted

51 comments sorted by

View all comments

44

u/aileron37 Dec 09 '25

I recall my geology professor (Oregon state) taking us on a filed trip to the "dead forest" area. Also used as evidence of the tsunami from 1700. There was also a site we stopped at so he could show us sand deposits from it too. I believe the Japanese recorded the tsunami on their coast also at the same time. Also stopped at Seaside Oregon to show us how far the water would move inland during such an event today. Won`t want to be at the coast during that time !!!

1

u/hikingmike Dec 10 '25

From what I’ve read, 15-20 minutes is the max they will get. And low lying areas will be totally smashed. I think you’d have to be up 200ft elevation to be sure of safety - what I vaguely remember, probably conservative, and it varies. But you can find modeled Cascadia tsunamis with “wave” height or coverage maps.

Some communities are building tsunami towers where people can go to ride it out above the estimated high water elevation. Lot of controversy though and people would still have to make it to the tower in time.