Dr. Amanda Clarke; Professor, Arizona State University
Eruption of very fluid, dark magma called basalt, dominates volcanism on Earth, Mars, the Moon, and Venus. About 900 years ago the largest and one of the most recent eruptions of a basaltic volcano in the contiguous USA took place at Sunset Crater, about 15 miles NE of Flagstaff, AZ. The eruption produced lava flows, which are observable in the Sunset Crater National Monument, but most of the erupted lava was ejected as ash in a series of explosive eruptions that produced plumes ranging from 7 to 25 kms high. The eruption clearly impacted prehistoric inhabitants over a wide area, causing them to move away from the volcano and dramatically alter their settlement style and food production. A similar modern eruption scenario would significantly affect the Southwest US, potentially causing major disruption to air traffic at multiple major hubs. The exact cause of such a highly explosive basaltic eruption is hotly debated in the literature and is the topic of our ongoing multi-pronged research which includes field observations, high-temperature solubility experiments, numerical modeling, and expansion into other field sites. These eruptions also serve as excellent analogues for better understanding explosive volcanic activity on Mars and the role of its modern and ancient atmospheric structure in controlling the dispersal of scoria and ash.