Aftermath of ancient eruption offers lessons in adapting to disaster

It had to be an awesome sight. The fountain of fire would have been visible for dozens of miles around; the pillar of smoke could have been seen for hundreds of miles. Ash and steam would have generated fearsome thunder and lightning. Forests would have been set ablaze. Anybody in the Southwest who didn’t directly witness the Sunset Crater eruption definitely would have heard about it.

Sometime around 1085, a fissure opened up in the ground about 50 miles southeast of the Grand Canyon. A curtain of fire hundreds of meters high emerged from the crack, spreading lava across the landscape and shooting ash into the sky. Within a few weeks or months at most, the eruption had built a 300-meter-high cratered peak and buried 265 square kilometers of prime farmland under a foot or more of volcanic debris.

Today, such an event would be considered a major natural disaster. But the roughly 1,600 residents of the Sunset Crater area, known as the Sinagua, adapted to the event surprisingly well. With no Red Cross or FEMA to help, they managed within decades to found a new settle­ment that prospered for more than a century. The resilience of those people contains lessons for those who find their lives upended by natural disasters today, says volcanologist Michael Ort of Northern Arizona University in Flagstaff.

Ort works on a team of archaeologists, soil scientists and dendrochronologists that has drawn a remarkably detailed picture of what the Sinagua did during and after the Sunset Crater eruption. The first thing they probably did was pray, Ort reported in Flagstaff on October 17 at a symposium for science writers sponsored by the Council for the Advancement of Science Writing. At a site a few kilometers west of Sunset Crater, archaeologists have found hunks of lava rock with the impressions of corn cobs on their surfaces. These “corn rocks” were probably created when people tried to stop the eruption by placing offerings of the sacred plant next to holes in the advancing flows and then retrieving the ears after molten lava had splashed over them and cooled.

Dimpled features of the corn impressions suggest the ears were about three weeks shy of ripeness, a clue that puts the eruption in the fall, just before harvest. With their crops ruined and homes buried under volcanic ash, the Sinagua did the same thing that many residents of New Orleans did after Hurricane Katrina: They moved in with out-of-town relatives (according to local oral tradition of the Sinagua’s Hopi descendants).

But as anyone who has been forced to live with in-laws knows, that kind of arrangement isn’t going to last long. Within a few decades, new settlements began to crop up around Sunset Crater — but in sites where people had never lived before. The biggest of those new settlements, Wupatki Pueblo, was founded around 1100 along a dry wash 20 kilometers north of Sunset Crater.

At an elevation of about 5,200 feet, Wupatki would have been uninhabitable before the eruption. Below about 6,200 feet in northern Arizona, conditions are too dry to grow unirrigated corn.

Yet during its first quarter century of existence, Wupatki Pueblo and its outlying settlements had an estimated 1,600 inhabitants. That’s almost exactly the population that is thought to have been driven off by the eruption.

The people of Sunset Crater must have learned fairly quickly what Ort has discovered by studying other eruptions and by doing experiments. Though deep volcanic ash ruins the land for agriculture, a shallow layer less than 10 centimeters deep provides a valuable mulch that holds in moisture and provides nutrients.

When examining the locations of the settlements that arose in the decades after the Sunset Crater eruption, Ort and colleagues found that virtually all were at lower elevations where the volcano’s ash ranged from 3 centimeters to 8 centimeters deep. In fields around those settlements, rock barriers can still be found that were designed to hold the ash in place and protect young corn plants from the spring winds.

Within decades, people had figured out how to live in an environ­ment that had been completely transformed. They must have kept in touch with what was going on in their old neighborhood, perhaps by returning occasionally to hunt or collect wild foods. They kept track of where in the landscape plants and animals were coming back, which led surprisingly quickly to a strategy for restoring their way of life. Rather than stubbornly trying to grow corn on ruined land, or just pulling up stakes and moving on, people adapted.

That reaction to an eruption a millennium ago provides a valuable lesson for people today. Though volcanic eruptions may be rare events, environmental disruptions in general are more frequent than ever, as both natural and man-made forces change the world in unexpected and unprecedented ways. As the people of Sunset Crater knew, it pays to work with nature in such circumstances rather than against it.

SN Prime | November 21 & 28 2011 | Vol.1 , No. 22