HUMAN ADAPTATION TO THE 11TH CENTURY ERUPTION OF SUNSET CRATER VOLCANO, NORTHERN ARIZONA

The Sunset Crater eruption (~1075+/-25 CE) dramatically altered the physical and cultural landscape of northern Arizona. The eruption produced a >300-m-high cinder cone, two lava flows, and a cinder blanket >1-cm-thick covering ~2,300 km˛. The eruption destroyed human settlements and agricultural fields, and disrupted long-established production zones and trade networks.

This project is dating Sunset Crater using dendrochemistry, changes in ring morphology, and paleomagnetic analyses. An accurate date for the eruption will elucidate the relation between alterations in cultural behavior and significant regional changes occurring at about the same time.

The Sunset Crater area was inhabited by small groups of subsistence farmers who were pre-adapted to successfully deal with the eruption. Cinder deposits deeper than 30 cm, a depth at which farming is no longer possible, cover ~400 km2, necessitating migration. In contrast, lower elevation areas previously too dry to farm but with 3-10 cm cinder cover now became inhabitable because the tephra acted as moisture-retaining mulch. This shift in human adaptation and settlement is visible in the archaeological record by the establishment of lower-elevation habitation sites and agricultural field areas, the use of new agricultural techniques, a shift in ceramic production and trade, and the adoption of new ritual practices.

The Sunset Crater eruption affected the landscape, ecosystems, and the human population. Choices made by affected groups resulted in adaptive responses based upon a complex mix of variables, including cultural practices, the nature of the eruption, and the environment. Technological changes and risk-minimization strategies allowed affected groups to survive and even thrive. Geological and archaeological analysis of human response to natural disaster in prehistory allows an understanding of culture history, and can be analogous to modern responses/adaptations to an environment in crisis.