Petersburg Borough, Alaska Natural Disaster Risk
FEMA National Risk Index assessment · AK
Very LowComposite Risk Score
National percentile: 15th
Petersburg Borough faces very low composite natural disaster risk (NRI Risk Index score 15.4, 15th national percentile), driven primarily by landslide and avalanche exposure. Expected annual loss across all 18 hazard types is $5M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Overall natural disaster risk in Petersburg Borough is very low, with a National Risk Index score of 15.4 out of 100 — placing it in the 15th national percentile and among the lowest-risk counties in the country. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
Risk here concentrates in landslide (downhill movement of rock, soil, and debris on unstable slopes) at High risk — $3M in expected annual loss and about 5.74 events per year; avalanche (fast-moving snow and debris sliding down steep mountain slopes) at High risk — $2M in expected annual loss and about 0.07 events per year; and volcanic activity (eruptions producing ashfall, lava, and pyroclastic hazards) at Low risk — $3K in expected annual loss and about 0.00 events per year. Across all hazards, FEMA estimates $5M in expected annual loss for a population of 3K.
Beyond physical exposure, Petersburg Borough has a medium 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.
History supports the rating: Petersburg Borough has received 3 federal disaster declarations since 2020, including 2 for biological events and 1 for mud/landslide events. The most recent was Severe Storm, Flooding, Landslides, and Mudslides (mud/landslide), declared in February 2021.
Among 30 Alaska counties, Petersburg Borough ranks #19 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Landslide | High | 5.74 / yr | $3M |
| Avalanche | High | 0.07 / yr | $2M |
| Volcanic Activity | Low | 0.00 / yr | $3K |
| Winter Weather | Low | 13.04 / yr | $26K |
| Earthquake | Very Low | 0.01 / yr | $20K |
| Ice Storm | Very Low | 0.01 / yr | $8K |
| Cold Wave | Very Low | 0.10 / yr | $6K |
| Wildfire | Very Low | 0.00 / yr | $991 |
| Riverine Flood | Very Low | 0.01 / yr | $187K |
| Lightning | Very Low | 2.61 / yr | $1K |
| Tornado | Very Low | 0.00 / yr | $0 |
| Coastal Flood | Very Low | 0.00 / yr | $0 |
| Drought | Very Low | 0.00 / yr | $0 |
| Hail | Very Low | 0.00 / 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 |
| Tsunami | Very Low | 0.00 / yr | $0 |
Disaster History
Petersburg Borough has received 3 federal disaster declarations since 2020, most recently Severe Storm, Flooding, Landslides, and Mudslides in February 2021. Most frequent causes: Biological (2), Mud/Landslide (1).
| Declared | Type | Disaster |
|---|---|---|
| February 2021 | Mud/Landslide | Severe Storm, Flooding, Landslides, and Mudslides |
| April 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Petersburg Borough?
Petersburg Borough has a composite FEMA National Risk Index score of 15.4 out of 100, placing it in the Very Low category and the 15th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Petersburg Borough?
The three highest-rated hazards are Landslide (High, $3M EAL), Avalanche (High, $2M EAL), Volcanic Activity (Low, $3K EAL). These account for most of the county's expected annual losses.
How does Petersburg Borough compare to other Alaska counties?
Petersburg Borough ranks #19 of 30 Alaska counties for overall natural disaster risk, with a very low rating.
How many federally declared disasters has Petersburg Borough had?
FEMA records 3 federal disaster declarations for Petersburg Borough since 2020, most often 2 for biological events and 1 for mud/landslide events. The most recent was Severe Storm, Flooding, Landslides, and Mudslides, declared in February 2021.
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. Petersburg Borough's $5M EAL is a statistical average, not a guarantee for any specific year or address.