A question I get asked a lot (and I mean a lot) is what I think the most dangerous volcano in the United States might be. Now, that is a loaded question in more ways than one. Even defining what we mean by "dangerous" is fraught with peril. Is a volcano more dangerous if it erupts frequently but smaller eruptions? Or maybe it only has infrequent large blasts and happens to be near a populated area? Could it be one that might be a hazard even when it is not erupting?
Really, it comes down to a mix between a few traits of any volcano:
How often has it erupted in the past?
How big were these eruptions?
What kind of eruptions were they? Lava flows, explosions, pyroclastic flows, etc.?
How close is the volcano to populated areas?
How close is the volcano to major flight routes?
When you try to look at the volcanoes of the United States with these lenses, a list can begin to form. The US Geological Survey publishes a "Threat Assessment" for US volcanoes, the last one in 2018. Using their rankings, Hawaii's Kīlauea is considered the most hazardous thanks to a mix of people living near the volcano and how frequently it erupts. Mount St. Helens comes in second because it is the only Cascade volcano to have erupted over the past 100 years.
