About a thousand years ago, a crater that now stands on the outskirts of Flagstaff erupted for somewhere between 23 and 115 days. How can volcanologists be so sure of the elapsed time of an event that occurred so long ago? Michael Ort’s reconstruction of the Sunset Crater eruption is a marvel of historical and scientific detective work. He also knows that about 1,600 people were forced to move away. Ort has analyzed every scrap of evidence concerning the eruption, and he has learned even more by studying the similar eruption of Paricutín in Michoacán, Mexico between 1943 and 1952.

He has concluded that, in some respects, the ancient dwellers of the region around Sunset Crater might have done a better job of responding to the disaster than did the Mexican government 60 years ago. For more information...