Where are America’s volcanoes? Hawaii, Alaska, the Pacific Northwest and Yellowstone National Park might spring to mind, but there are more than 150 potentially active volcanoes across the U.S. and its territories, including in Arizona, Utah and Colorado — and many have erupted in the geologically recent past.
In 2018, the U.S. Geological Survey (USGS) identified 57 volcanoes it considers “Very High” or “High” threats based on factors such as the likelihood of future eruptions and their proximity to population hubs. For example, Washington State’s Mount Rainier is less than 60 miles from Seattle. Some of these higher risk volcanoes pose very real dangers to large numbers of people. Others, such as those in the sparsely populated Aleutian Islands, which arc between Alaska and Russia, could pose a significant aircraft hazard. (In 2010, ash particles from the eruption of Iceland’s Eyjafjallajökull disrupted international air traffic for weeks.)
