The Sunset Crater Volcano erupted around 1300, right in the middle of their civilization. I wonder if it played a role in their demise. I know I would be pretty upset if an active volcano (even a small one) started erupting in my neighborhood.
"Sunset Crater Volcano was born in a series of eruptions sometime between 1040 and 1100. Powerful explosions profoundly affected the lives of local people and forever changed the landscape and ecology of the area. Lava flows and cinders still look as fresh and rugged as the day they formed. But among dramatic geologic features, you'll find trees, wildflowers, and signs of wildlife – life returns."