18 volcanoes in the USA are classified as “very high threat”, many are in the Pacific Northwest.
The United States has 161 young, active volcanoes within its borders. Since 1980, there have been 120 eruptions and 52 episodes of notable volcanic unrest at 44 U.S. volcanoes.
The U.S. Geological Survey systematically assesses U.S. volcanoes considered to be active or potentially active, and publishes a volcanic threat assessment that ranks the volcanoes based on 24 hazard and exposure factors. Last published in 2005, this 2018 update considers (1) field and laboratory research that adds or removes volcanoes from the list of potentially active volcanoes, and (2) updates the hazard and exposure factors used to produce a relative threat ranking of volcanoes.
The 2018 update of the 2005 assessment adds or raises the threat level for 12 volcanoes and reduces or removes threat level status from 20 volcanoes. The threat ranking is not an indication of which volcano will erupt next. Rather, it is an indicator of the potential severity of impacts that could result from future eruptions at any given volcano.
The volcanic threat assessment is used by the USGS to help guide and prioritize risk mitigation efforts at U.S. volcanoes through volcano research, hazard assessment, emergency planning and preparation and monitoring efforts with federal, state and local government partners. The prioritization of risk mitigation efforts is a cornerstone in the development of the National Volcano Early Warning System.
The 2018 Update to the U.S. Geological Survey National Volcanic Threat Assessment is available online.
This revised threat assessment includes 18 very high threat, 39 high threat, 49 moderate threat, 34 low threat, and 21 very low threat volcanoes. The total of 161 volcanoes is a decrease of 8 from the total reported by Ewert and others (2005)
Here is a table of the top threats: