Interactive tool
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.
California
Very High RiskCalifornia has extremely high seismic activity with 877 recorded M4+ events and 8 significant (M6+) earthquakes. Active fault systems pose ongoing risk.
Total Earthquakes
877
Max Magnitude
7.2
Significant (M6+)
8
Avg Magnitude
4.4
Strongest Recorded Earthquakes
| Magnitude | Location |
|---|---|
| M7.4 | 123 km W of Big Lagoon, California |
| M7.2 | 153 km W of Big Lagoon, California |
| M7.1 | 121 km W of Ferndale, California |
| M6.8 | 123 km W of Ferndale, California |
| M6.8 | 77 km WNW of Indianola, California |
Earthquake Frequency by Year
| Year | Events | Max Mag |
|---|---|---|
| 2022 | 1 | 6.4 |
| 2021 | 2 | 6.2 |
| 2016 | 1 | 6.6 |
| 2014 | 1 | 6.8 |
| 2012 | 1 | 6.3 |
| 2005 | 2 | 7.2 |
| 2003 | 1 | 6.5 |
| 1995 | 1 | 6.6 |
| 1994 | 1 | 7.1 |
| 1993 | 1 | 6.1 |
| 1992 | 2 | 6.6 |
| 1991 | 1 | 6.0 |
| 1984 | 2 | 6.7 |
| 1980 | 4 | 6.2 |
| 1976 | 1 | 6.3 |
| 1972 | 1 | 6.0 |
| 1971 | 1 | 6.6 |
| 1960 | 1 | 6.2 |
| 1957 | 1 | 6.1 |
| 1956 | 1 | 6.4 |
| 1954 | 1 | 6.8 |
| 1952 | 2 | 6.2 |
| 1951 | 1 | 6.0 |
| 1949 | 1 | 6.4 |
| 1948 | 1 | 6.0 |
| 1945 | 1 | 6.3 |
| 1941 | 3 | 6.8 |
| 1937 | 1 | 6.0 |
| 1936 | 1 | 6.1 |
| 1926 | 3 | 6.3 |
| 1925 | 1 | 6.0 |
| 1923 | 1 | 6.2 |
| 1922 | 2 | 7.4 |
| 1918 | 1 | 6.5 |
| 1915 | 2 | 6.4 |
| 1911 | 1 | 6.5 |
| 1910 | 2 | 6.0 |
| 1909 | 1 | 6.0 |
| 1908 | 1 | 6.0 |
| 1906 | 1 | 6.4 |
| 1905 | 1 | 6.1 |
| 1903 | 2 | 6.2 |
Events in 42 of 21 monitoring years (200% frequency).
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.