U.S. Geological Survey via Getty Images
Hawaii's Kilauea volcano erupted on on May 4, 2018.
The federal government's ranking of which volcanoes pose the most threat to the US has been more updated for the first time since 2005.
Each one gets two scores: an overall threat score and an aviation threat score.
The overall threat score looks at 24 factors including how often it erupts, how powerful its eruptions are, the nearby population size, and how many people have been killed or evacuated before.
The aviation threat score is similar but focuses on factors like how close a volcano is to airports, and which flight paths go nearby.
Here are the 20 volcanoes that post the biggest risk: