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Volcanic Hazards from the Region Around Craters of the Moon Lava Field

When the Craters of the Moon volcanic field erupts again, it will likely display a variety of eruption styles from high lava fountaining to quiet outpouring of lava flows.

Craters of the Moon Lava Field, Idaho, Landsat 7 natural-color image. Lava flows black and dark brown, agricultural town of Carey and Pioneer Mountains to west. (Public domain.)

Through time, magma at the Craters of the Moon has become higher in silica content. If that trend continues, future eruptions may include explosive events with more viscous lava. The earlier phases of eruptive activity often produce high lava fountains that build up cinder cones. Resulting tephra may be ejected into the lower part of the atmosphere, posing a risk to civil aviation, but probably not high enough to threaten commercial aviation routes.

The clearest eruption hazard is the production of a large basalt lava field, which could flow east or west from the alignment of the Great Rift. Depending on the exact location of future vents, the lava flows will take advantage of local topography and flow through lava tubes to move as much as 20 miles from vent locations. Therefore, the lava flows can threaten rangeland and farms at some distance from the Great Rift and cause significant property loss. Three national highways (US 20, 26, and 93) pass through Craters of the Moon volcanic field, and they may become blocked by eruption products. The nearest populated communities (Arco and Carey, Idaho) are far from the area of future eruptions, and unlikely to experience eruptive phenomena. The Idaho National Laboratory lies on the eastern margin of the Great Rift, and its nuclear reactors and radioactive waster storage facility, which lies in a topographic basin, may be impacted by future lava flow eruptions.

If the next eruption occurs in the northern part of the Great Rift (as is predicted), the infrastructure and populace of the Craters of the Moon National Monument are all at high risk. Evacuation of people from the area at the earliest sign of activity is a primary goal.