PlainQuake

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Earthquake Risk Calculator

Select a US state to assess its earthquake risk from 20 years of USGS ComCat data, historical counts, maximum magnitude, yearly frequency, and a computed risk level.

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4 of 39 tracked U.S. states and territories carry a computed "Very High" risk level -- pick any state above for its full breakdown.

39
states & territories tracked
4
rated "Very High" risk

According to the U.S. Geological Survey's Earthquake Hazards Program, as of 2026-07-19 the ComCat catalog this calculator draws from records 315,341 magnitude-4+ earthquakes worldwide since 2005, every state's risk level computed from that same dataset using the methodology described on our methodology page.

California

Very High Risk

California has extremely high seismic activity with 883 recorded M4+ events and 11 significant (M6+) earthquakes. Active fault systems pose ongoing risk.

What this measures: based on historical USGS earthquake frequency and magnitude for California (M4+, 2005-2025), not a predictive seismic-hazard assessment. Actual risk to any specific building also depends on local building codes, soil type, and construction quality, not seismic history alone.

Total Earthquakes

883

Max Magnitude

7.2

Significant (M6+)

11

Avg Magnitude

4.4

Strongest Recorded Earthquakes

Magnitude Location
M7.9 The 1906 San Francisco, California Earthquake
M7.5 The 1952 Kern County, California Earthquake
M7.4 123 km W of Big Lagoon, California
M7.3 The 1992 Landers, California Earthquake
M7.2 153 km W of Big Lagoon, California

Earthquake Frequency by Year

Year Events Max Mag
2024 1 7.0
2022 1 6.4
2021 2 6.2
2016 1 6.6
2014 2 6.8
2012 1 6.3
2010 1 6.5
2005 2 7.2
2003 1 6.5
1999 1 7.1
1995 1 6.6
1994 1 7.1
1993 1 6.1
1992 6 7.3
1991 1 6.0
1989 1 6.9
1987 2 6.6
1986 2 6.4
1984 3 6.7
1983 1 6.7
1980 5 7.2
1976 1 6.3
1972 1 6.0
1971 1 6.6
1968 1 6.6
1960 1 6.2
1957 1 6.1
1956 1 6.4
1954 3 6.8
1952 3 7.5
1951 1 6.0
1949 1 6.4
1948 2 6.0
1947 1 6.5
1946 1 6.3
1945 1 6.3
1942 1 6.6
1941 3 6.8
1940 1 6.9
1937 1 6.0
1936 1 6.1
1933 1 6.4
1932 1 6.5
1927 1 6.9
1926 3 6.3
1925 2 6.8
1923 2 7.1
1922 3 7.4
1918 2 6.7
1915 2 6.4
1911 1 6.5
1910 3 6.0
1909 1 6.0
1908 1 6.0
1906 3 7.9
1905 1 6.1
1903 2 6.2
1901 1 6.4

Events in 58 of 21 monitoring years (276% frequency).

View full state profile → Browse all states →

What to do with your risk level

Alaska tops the leaderboard at "Very High" risk, 8,960 M4+ events on record, but every state has SOME computed risk level.

  • Select any of the 39 tracked states above to see its own event count, strongest recorded magnitude, and yearly trend. Browse all states
  • Risk level is computed from three signals (total events, strongest magnitude, significant-event count) - see exactly how a level is assigned. Read the methodology

Risk levels are relative rankings within this dataset (USGS M4+ catalog, 2005–present), not an official USGS or FEMA hazard designation.

Frequently Asked Questions

How is earthquake risk level determined? ▼
Risk levels (Low, Moderate, High, Very High) are determined by combining total earthquake count, maximum recorded magnitude, number of significant events (M6+), and the frequency of seismic activity across the 2005-2025 monitoring period.
What data does this calculator use? ▼
The calculator uses the USGS Comprehensive Earthquake Catalog (ComCat), covering earthquakes of magnitude 4.0 and above worldwide since 2005, over 310,000 events. US state figures are aggregated from that same global M4+ record.
Does low risk mean no earthquake danger? ▼
No. Low risk means fewer recorded events in the USGS dataset, but earthquakes can occur in any state. Areas with low historical activity can still experience damaging events. Always follow FEMA and USGS preparedness guidelines regardless of risk level.
What counts as a significant earthquake? ▼
For this calculator, significant earthquakes are those with magnitude 6.0 or greater. These events can cause substantial damage to buildings and infrastructure, especially in areas without seismic building codes.
How often is the data updated? ▼
The database covers USGS ComCat records from 2005 through 2025. Historical data is stable; new events are added periodically.

Data: USGS Comprehensive Earthquake Catalog (ComCat), magnitude 4.0+ worldwide since 2005. Risk levels are computed assessments and should not replace official USGS or FEMA hazard maps.

According to the US Geological Survey Earthquake Hazards Program, PlainQuake's figures are rendered directly from 315,341 recorded M4+ earthquakes and 14,428 significant M6+ events (USGS ComCat, 2005-present) -- no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2026-07-19.