Special Report

50 Most Dangerous Volcanoes in America

Thomas C. Frohlich

Source: U.S. Fish and Wildlife Service / Wikimedia Commons

20. Veniaminof, Alaska
> Threat score: 109
> Last eruption year: 2013
> Pop. within 30 km: 0
> Pop. within 100 km: 542

Source: ChrisBoswell / Getty Images

19. Adams, Washington
> Threat score: 113
> Last eruption year: 950
> Pop. within 30 km: 4,019
> Pop. within 100 km: 393,303

Source: Vipersniper / Getty Images

18. Augustine, Alaska
> Threat score: 123
> Last eruption year: 2006
> Pop. within 30 km: 0
> Pop. within 100 km: 759

Source: Samson1976 / Getty Images

17. Newberry, Oregon
> Threat score: 126
> Last eruption year: 690
> Pop. within 30 km: 16,437
> Pop. within 100 km: 180,091

Source: Photographersnature / Wikimedia Commons

16. Long Valley Caldera, California
> Threat score: 128
> Last eruption year: 14,000-15,000 B.C.
> Pop. of Mammoth Lakes, the closest town: 8,234