Matanuska-Susitna Borough, Alaska Natural Disaster Risk
FEMA National Risk Index assessment · AK
MediumComposite Risk Score
National percentile: 93th
Matanuska-Susitna Borough faces medium composite natural disaster risk (NRI Risk Index score 93.3, 93th national percentile), driven primarily by avalanche and earthquake exposure. Expected annual loss across all 18 hazard types is $161M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
FEMA's National Risk Index rates Matanuska-Susitna Borough at medium composite risk, with a National Risk Index score of 93.3 out of 100 — placing it in the 93rd national percentile and near the national midpoint for natural-disaster risk. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
Most of Matanuska-Susitna Borough's expected losses come from avalanche (fast-moving snow and debris sliding down steep mountain slopes) at Very High risk — $15M in expected annual loss and about 1.33 events per year; earthquake (ground shaking from sudden movement along geologic faults) at High risk — $131M in expected annual loss and about 0.20 events per year; and landslide (downhill movement of rock, soil, and debris on unstable slopes) at Medium risk — $304K in expected annual loss and about 91.40 events per year. Across all hazards, FEMA estimates $161M in expected annual loss for a population of 107K.
Beyond physical exposure, Matanuska-Susitna Borough has a very low social vulnerability rating (how susceptible the population is to harm) and a very low community resilience rating (its capacity to prepare for and recover from disasters). Both measures sit toward the lower end, indicating relatively modest population sensitivity.
The county's disaster history tells the same story: Matanuska-Susitna Borough has received 20 federal disaster declarations since 1986, including 5 for severe storm events and 5 for flood events. The most recent was Severe Storm (winter storm), declared in April 2026.
Among 30 Alaska counties, Matanuska-Susitna Borough ranks #2 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Avalanche | Very High | 1.33 / yr | $15M |
| Earthquake | High | 0.20 / yr | $131M |
| Landslide | Medium | 91.40 / yr | $304K |
| Wildfire | Medium | 0.00 / yr | $4M |
| Winter Weather | High | 11.16 / yr | $620K |
| Volcanic Activity | Very Low | 0.02 / yr | $915 |
| Cold Wave | Low | 4.02 / yr | $2M |
| Lightning | Low | 17.98 / yr | $329K |
| Riverine Flood | Low | 0.01 / yr | $8M |
| Ice Storm | Very Low | 0.01 / yr | $14K |
| Tsunami | Very Low | 0.30 / yr | $56K |
| Hail | Very Low | 0.01 / yr | $8K |
| Tornado | Very Low | 0.00 / yr | $7 |
| Coastal Flood | Very Low | 0.01 / yr | $0 |
| Drought | Very Low | 1.14 / yr | $0 |
| Heat Wave | Very Low | 0.00 / yr | $0 |
| Hurricane | Very Low | 0.00 / yr | $0 |
| Strong Wind | Very Low | 0.00 / yr | $0 |
Disaster History
Matanuska-Susitna Borough has received 20 federal disaster declarations since 1986, most recently Severe Storm in April 2026. Most frequent causes: Severe Storm (5), Flood (5), Fire (4).
| Declared | Type | Disaster |
|---|---|---|
| April 2026 | Winter Storm | Severe Storm |
| March 2022 | Severe Storm | Severe Winter Storm and Straight-Line Winds |
| April 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| August 2019 | Fire | Deshka Landing Fire |
| August 2019 | Fire | Mckinley Fire |
| January 2019 | Earthquake | Earthquake |
| November 2018 | Earthquake | Earthquake |
| September 2018 | Flood | Flooding |
| June 2015 | Fire | Sockeye Fire |
Showing the 10 most recent of 20 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Matanuska-Susitna Borough?
Matanuska-Susitna Borough has a composite FEMA National Risk Index score of 93.3 out of 100, placing it in the Medium category and the 93th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Matanuska-Susitna Borough?
The three highest-rated hazards are Avalanche (Very High, $15M EAL), Earthquake (High, $131M EAL), Landslide (Medium, $304K EAL). These account for most of the county's expected annual losses.
How does Matanuska-Susitna Borough compare to other Alaska counties?
Matanuska-Susitna Borough ranks #2 of 30 Alaska counties for overall natural disaster risk, with a medium rating.
How many federally declared disasters has Matanuska-Susitna Borough had?
FEMA records 20 federal disaster declarations for Matanuska-Susitna Borough since 1986, most often 5 for severe storm events and 5 for flood events. The most recent was Severe Storm, declared in April 2026.
What does Expected Annual Loss (EAL) mean?
EAL is FEMA's estimate of average annual dollar losses from natural hazards, calculated from historical event data and exposure models. Matanuska-Susitna Borough's $161M EAL is a statistical average, not a guarantee for any specific year or address.