Colorado volcanic activity risk
Eagle County has the highest volcanic activity risk in Colorado, scoring 82.7 out of 100 — rated "Very Low" by FEMA's National Risk Index.
| # | County | NRI score | Rating |
|---|---|---|---|
| 1 | Eagle County | 82.7 | Very Low |
| 2 | Denver County | 73.6 | Very Low |
| 3 | Arapahoe County | 73 | Very Low |
| 4 | El Paso County | 71.7 | Very Low |
| 5 | Jefferson County | 71 | Very Low |
| 6 | Adams County | 69.4 | Very Low |
| 7 | Boulder County | 64.8 | Very Low |
| 8 | Douglas County | 64.2 | Very Low |
| 9 | Larimer County | 62.5 | Very Low |
| 10 | Weld County | 61.2 | Very Low |
| 11 | Garfield County | 52.1 | Very Low |
| 12 | Fremont County | 51.8 | Very Low |
| 13 | Broomfield County | 48.9 | Very Low |
| 14 | Summit County | 38.8 | Very Low |
| 15 | Teller County | 36.8 | Very Low |
| 16 | Elbert County | 35.8 | Very Low |
| 17 | Chaffee County | 35.5 | Very Low |
| 18 | Routt County | 35.2 | Very Low |
| 19 | Grand County | 32.9 | Very Low |
| 20 | Park County | 32.6 | Very Low |
| 21 | Pitkin County | 32.2 | Very Low |
| 22 | Clear Creek County | 28.7 | Very Low |
| 23 | Lake County | 27 | Very Low |
| 24 | Gilpin County | 25.7 | Very Low |
| 25 | Rio Blanco County | 25.4 | Very Low |
| 26 | Gunnison County | 25.1 | Very Low |
| 27 | Jackson County | 19.9 | Very Low |
| 28 | Mesa County | 18.6 | Very Low |
| 29 | Pueblo County | 17.6 | Very Low |
| 30 | Delta County | 17.3 | Very Low |
| 31 | Moffat County | 14.7 | Very Low |
| 32 | Saguache County | 12.1 | Very Low |
| 33 | Conejos County | 0 | No Rating |
| 34 | Costilla County | 0 | No Rating |
| 35 | Huerfano County | 0 | No Rating |
| 36 | Las Animas County | 0 | No Rating |
Source: FEMA National Risk Index v1.20.0, December 2025. Scores are 0–100 percentile rankings among all US counties. See the methodology page for definitions. Download the full CSV for all counties.
Volcanic Activity risk nationally:
Other hazard risks in Colorado:
Frequently asked questions
What is the highest volcanic activity risk county in Colorado?
Eagle County, CO has the highest volcanic activity risk in Colorado, with a FEMA National Risk Index score of 82.7 out of 100 (rated "Very Low").
What causes volcanic activity risk in Colorado?
Volcanic activity risk reflects expected losses from lava flows, tephra fall, lahars (volcanic mudflows), and volcanic gases. The highest-risk counties are in Washington (Mt. Rainier), Oregon (Mt. Hood), and Hawaii (Kilauea, Mauna Loa). Alaska's Aleutian chain contains many active volcanoes affecting nearby communities and trans-Pacific air traffic. Volcanic ashfall events are reported at forecast-zone level in NOAA Storm Events and are not included in county-level counts.