> This sounds like an eye-witness account of such an eruption, and it undoubtedly is, for Indian artifacts have been found buried in the Mazama ash. The eruption has been radiocarbon-dated to about 6500 years ago on the basis of Indian sandals found in the ash, but had no datable materials been found, this myth alone would have served to date the eruption as post-Pleistocene, because this part of the world was first inhabited by people who crossed the Bering Land Bridge and migrated down through Alaska and Canada into the northwestern United States.
Geomythology: geological origins of myths and legends https://sp.lyellcollection.org/content/specpubgsl/273/1/1.fu...
It didn't happen all in one day, or year. But there were many places where the water moved inland by three feet per year; any beach one knew as a child was gone by adulthood.
Millions of square miles of what was lowland is now underwater -- the region between Indonesian islands; for hundreds of miles out to sea from Viet Nam all the way up to Korea; all the space between Australia and New Guinea; thousands of square miles off India; the whole Persian Gulf; England and Ireland were not islands; from Florida to Louisiana; from Argentina out to the Falklands.
These places were prime habitat (possibly excepting near the Falklands, and northern England), so not unpopulated.
It seems significant that the oldest known civilizations, in Mesopotamia and the Indus valley, arose immediately uphill from especially major inundations. Australian oral records have precise accounts of conflict resolutions over people moving uphill into land already occupied for 40,000+ years.