Ann Finkbeiner writes in Slate about a story that caught fire over the summer: the likelihood of a major natural disaster in the Pacific Northwest at some point in the fairly near future. What’s fascinating is how she illustrates the value of folklore as a vehicle for knowledge. Indigenous peoples who relied on oral tradition for their histories passed along stories for centuries that traced their origin back to living memory of the most recent earthquake in or around 1700.

We moderns tend to discount folklore, placing it in the same category as fairytale. Yet any encounter with most folk stories demonstrates that most of them do contain fundamental knowledge in the form of history. Legend doesn’t have to mean legendary, in other words. And what the indigenous people of the Pacific Northwest have known since at least 1700, geologists have known only since 1984:

Geologists now know that the Pacific Northwest has been having these earthquakes and tsunamis irregularly every 500 years or so; their oldest record in sediments goes back at least 10,000 years. …the governments’ plans for the next earthquake and geologists’ understanding of the ancient ones—happened only in the past few decades. For the same 10,000-plus years that the Pacific Northwest has been having the earthquakes, indigenous groups have been living there. They have known forever that what the ground did was sudden and violent, that it came accompanied with catastrophic floods, and that it made people die. The questions for us, living in the present, are obvious. What was it like? And what was the impact of millennia of repeated catastrophes on the indigenous groups of the region? The answers seem obvious too, but they aren’t; this turns out to be a story about stories—how they merge into histories, how fragile they are, and how urgent.