21. Yellowstone caldera, Wyoming
> Overall threat score: 115
> Population within 30 km (approx. 18 miles): 234
> Population within 100 km (approx. 30 miles): 20,692
> Most recent eruption year: -1350
20. Iliamna Volcano, Cook Inlet, Alaska
> Overall threat score: 115
> Population within 30 km (approx. 18 miles): 01
> Population within 100 km (approx. 30 miles): 7,564
> Most recent eruption year: 1876
19. Mount Okmok, Aleutian Islands, Alaska
> Overall threat score: 117
> Population within 30 km (approx. 18 miles): Not available
> Population within 100 km (approx. 30 miles): 04
> Most recent eruption year: 2008
18. Long Valley Caldera, California
> Overall threat score: 129
> Population within 30 km (approx. 18 miles):
> Population within 100 km (approx. 30 miles):
> Most recent eruption year:
17. Crater Lake, Oregon
> Overall threat score: 129
> Population within 30 km (approx. 18 miles): 366
> Population within 100 km (approx. 30 miles): 272,674
> Most recent eruption year: -2850
