There are 161 known active volcanoes in the United States, and 18 of them pose a "very high threat" of death and destruction to Americans living nearby, according to a new volcanic risk report released by the U.S. Geological Survey (USGS).
Kilauea volcano, which rained destruction on Hawaii's Big Island this summer and forced the evacuation of some 1,700 people, ranked No. 1 on the list due to its recent eruptive history and proximity to heavily populated areas.
Rounding out the top five highest-risk volcanoes were Mount St. Helens and Mount Rainier in Washington, Redoubt volcano in Alaska, and Mount Shasta in California. [History's Most Destructive Volcanoes]
The new USGS report, published online Monday (Oct. 22), is an update on a similar report released in 2005. According to the authors, the report's threat rankings are "not a forecast or [an] indication of which volcanoes are most likely to erupt next," but rather an indicator of the "potential severity of impacts" that could result from future eruptions at a given volcano. The higher a volcano landed on the list, the more disastrous an eruption could be to people, cities and U.S. infrastructure. Anticipating which volcanoes around the country will have the most destructive potential should help guide research, monitoring and emergency preparation, the authors wrote.
To calculate a threat score for each volcanic region, the report's authors weighed the combined effects of 24 risk factors. These included the type of volcano, its explosive potential, recent activity, the number of people living in the vicinity and the potential disruption to air traffic of an eruption. The resulting scores were then used to separate the volcanoes into five risk categories: very low threat (21 volcanoes), low threat (34), moderate threat (49), high threat (38) and very high threat (18).
The complete list of "very high threat" volcanoes includes:
1. Kilauea (Hawaii)
2. Mount St. Helens (Wash.)
3. Mount Rainier (Wash.)
4. Redoubt volcano (Alaska)
5. Mount Shasta (Calif.)
6. Mount Hood (Ore.)
7. Three Sisters (Ore.)
8. Akutan Island (Alaska)
9. Makushin volcano (Alaska)
10. Mount Spur (Alaska)
11. Lassen volcanic center (Calif.)
12. Augustine volcano (Alaska)
13. Newberry volcano (Ore.)
14. Mount Baker (Wash.)
15. Glacier Peak (Wash.)
16. Mauna Loa (Hawaii)
17. Crater Lake (Ore.)
18. Long Valley Caldera (Calif.)
That these 18 volcanoes pose particular dangers to the surrounding communities is no news to volcanologists; the exact same group appears at the top of the 2005 USGS report.
Several volcanoes were added to the master list based on new information collected since 2005, however, including one new "high risk" volcano (the Salton Buttes lava domes in Southern California). Overall, however, the list of 161 known active sites includes eight fewer volcanoes than the 2005 report.
"This report may come as a surprise to many, but not to volcanologists," Janine Krippner, a volcano expert at Concord University in West Virginia not involved in the study, told The Guardian. "The USA is one of the most active countries in the world when it comes to [volcanoes]."
According to the new report, there have been 120 volcanic eruptions in the United States since 1980.
Originally published on Live Science.