So, the native survivors of that eruption had a Christian calendar and kept records of the event? Or is that just a semi-educated guess?
AD1100, plus or minus a few decades.
I feel like it’s so cute that someone had the notion to include the comment that 1100AD was like 1000 years ago. That’s so cool, I would never have guessed that many! /S
“So, the native survivors of that eruption had a Christian calendar and kept records of the event?”
No, but Western scientists do, and they have techniques like carbon dating to estimate when last eruptions occurred. It’s likely that a lazy journalist used an exact year, when the experts probably gave an approximation.