Volcanic Activity

Hazard in Geological and Other Natural Hazards

A regional hazard of ashfall, lahars and gas that can close airspace and bury valleys, with warning that is real but uncertain.

Plans also call it: volcano, volcanic eruption, lahar, lava flow, volcanic ashfall, ash fall, tephra, vog

Talk to us about Volcanic ActivityAll 73 hazards →

What you’d hand your council

The first page of a Volcanic Activity evidence brief: likelihood, impact and readiness on your own scale, every figure sourced.

Evidence brief for Cedar Ridge County (example)

September 14, 2026

Volcanic Activity

Hazard in Geological and Other Natural Hazards, on the established threats & hazards list

Impact
5432112345

Likelihood

Likelihood
3

Possible — Expected occasionally — roughly once in 10 to 50 years (2–10% chance in any year).

Impact
5

Catastrophic — Overwhelming effects — mass casualties possible, widespread destruction, essential services out for a month or more, long-term recovery requiring state and federal assistance.

Readiness
2

Low — Some elements of capability are in place, but important gaps remain that could significantly limit the organization's ability to perform effectively. Additional development is needed before the capability can be relied upon.

  • 2source documents
  • 58verified mentions
  • 2federal declarations
  • 91.6NRI score, relatively high
Worked example: Cedar Ridge County is fictional. The scores illustrate the format and are nobody's decision. Open a full sample brief →

The national record

FEMA National Risk Index: Volcanic Activity

$60M
expected loss a year, nationally
10
counties rated high or very high

Your county’s own rating is the first thing we pull.

How it maps

The same hazard in the vocabularies your plan and FEMA already use.

FEMA National Risk Index
Volcanic Activity (VLCN)one of the 18 hazards NRI scores per county
FEMA declaration incident type
Volcanic Eruption6 declarations on record
NOAA Storm Events type
Volcanic Ash
Hazzard category
Geological and Other Natural Hazards, natural hazards

The national record

What the federal data says about Volcanic Activity

The same national sources a Hazzard brief starts from. For your jurisdiction we narrow each one to your county and its neighbors.

Where Volcanic Activity is rated high

Share of each state's counties FEMA rates Relatively High or Very High

Alabama: not rated for Volcanic ActivityAlaska: 2 of 26 counties rated high (8%) · $4M expected loss a yearArizona: 0 of 9 counties rated high (0%) · $3K expected loss a yearArkansas: not rated for Volcanic ActivityCalifornia: 1 of 46 counties rated high (2%) · $2M expected loss a yearColorado: 0 of 32 counties rated high (0%) · $3K expected loss a yearConnecticut: not rated for Volcanic ActivityDelaware: not rated for Volcanic ActivityDistrict of Columbia: not rated for Volcanic ActivityFlorida: not rated for Volcanic ActivityGeorgia: not rated for Volcanic ActivityHawaii: 2 of 3 counties rated high (67%) · $29M expected loss a yearIdaho: 0 of 34 counties rated high (0%) · $1K expected loss a yearIllinois: not rated for Volcanic ActivityIndiana: not rated for Volcanic ActivityIowa: not rated for Volcanic ActivityKansas: not rated for Volcanic ActivityKentucky: not rated for Volcanic ActivityLouisiana: not rated for Volcanic ActivityMaine: not rated for Volcanic ActivityMaryland: not rated for Volcanic ActivityMassachusetts: not rated for Volcanic ActivityMichigan: not rated for Volcanic ActivityMinnesota: not rated for Volcanic ActivityMississippi: not rated for Volcanic ActivityMissouri: not rated for Volcanic ActivityMontana: 0 of 7 counties rated high (0%) · $0K expected loss a yearNebraska: not rated for Volcanic ActivityNevada: 0 of 16 counties rated high (0%) · $4K expected loss a yearNew Hampshire: not rated for Volcanic ActivityNew Jersey: not rated for Volcanic ActivityNew Mexico: 0 of 17 counties rated high (0%) · $0K expected loss a yearNew York: not rated for Volcanic ActivityNorth Carolina: not rated for Volcanic ActivityNorth Dakota: not rated for Volcanic ActivityOhio: not rated for Volcanic ActivityOklahoma: not rated for Volcanic ActivityOregon: 0 of 32 counties rated high (0%) · $2M expected loss a yearPennsylvania: not rated for Volcanic ActivityRhode Island: not rated for Volcanic ActivitySouth Carolina: not rated for Volcanic ActivitySouth Dakota: not rated for Volcanic ActivityTennessee: not rated for Volcanic ActivityTexas: not rated for Volcanic ActivityUtah: 0 of 23 counties rated high (0%) · $1K expected loss a yearVermont: not rated for Volcanic ActivityVirginia: not rated for Volcanic ActivityWashington: 5 of 29 counties rated high (17%) · $23M expected loss a yearWest Virginia: not rated for Volcanic ActivityWisconsin: not rated for Volcanic ActivityWyoming: 0 of 9 counties rated high (0%) · $0K expected loss a year
  • None
  • Up to 10%
  • 10–25%
  • 25–50%
  • Over 50%
  • Not rated
FEMA National Risk Index v1.20.0, county table

6 federal declarations since 1955

Declarations FEMA filed as “Volcanic Eruption”, by year (2026 to date)

0121955: 1 declaration1980: 2 declarations1990: 1 declaration2014: 1 declaration2018: 1 declaration1980: 21960197019801990200020102020
OpenFEMA Disaster Declarations Summaries, as of 2026-09-27. Counts distinct disasters; major, emergency and fire-management declarations.

In your plan

What a Volcanic Activity profile needs, and where each part comes from

A local hazard mitigation plan profiles each hazard the same way (44 CFR 201.6). Here is how Hazzard fills each part for Volcanic Activity.

  1. Location

    44 CFR 201.6(c)(2)(i)

    National data

    FEMA's National Risk Index rates Volcanic Activity for every county. We place yours against its neighbors and the state, then add what your plans map in more detail.

  2. Extent

    44 CFR 201.6(c)(2)(i)

    Your documents

    The magnitude your plans use for Volcanic Activity (a scale, a depth, an acreage, a duration), read from your documents and cited, so the profile states the strength you plan for.

  3. Previous occurrences

    44 CFR 201.6(c)(2)(i)

    National data

    Every FEMA declaration filed as Volcanic Eruption that included your county, back to 1953, alongside the events your own records and after-action reports describe.

  4. Probability of future events

    44 CFR 201.6(c)(2)(i)

    National data

    NRI's annualized frequency for your county, and the declaration history, drafted into a likelihood on your own scale for your team to accept or change.

  5. Vulnerability and impacts

    44 CFR 201.6(c)(2)(ii)

    National data

    NRI's expected annual loss and social vulnerability for your county, the Census population profile and HHS emPOWER counts, with the impacts your plans already describe.

  6. The assessment itself

    Your team decides

    Likelihood, impact and readiness for Volcanic Activity are drafted with every source attached, and a person on your team accepts each one. Hazzard never records a score on its own.

How we can help

How we’d help you prepare for Volcanic Activity

  1. 1

    We pull what the national record holds

    NRI ratings where FEMA models Volcanic Activity, any declarations, and the drought-relevant climate record. Where nothing models it, we say so.

  2. 2

    We read your plans and studies

    Mitigation plan, geologic or drought studies you already have, so the evidence you own is cited alongside the federal figures.

  3. 3

    You leave with a cited brief

    Likelihood, impact and readiness for Volcanic Activity on your own scale, every figure tied to its source, ready for the planning team or the council.

Also in Geological and Other Natural Hazards

Preparing for Volcanic Activity

Give Volcanic Activity the profile it deserves, even if it rarely makes the news.

Slow and rare hazards are the ones plans skim. We show what the national record says about yours, and where your plan has to rely on local knowledge instead. A person replies within one business day.

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