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California earthquake risk

58 counties scored 7 rated Very High

Alameda County has the highest earthquake risk in California, scoring 100 out of 100 — rated "Very High" by FEMA's National Risk Index.

# County NRI score Rating
1 Alameda County 100 Very High
2 Los Angeles County 100 Very High
3 Orange County 99.9 Very High
4 Santa Clara County 99.9 Very High
5 Riverside County 99.8 Very High
6 San Bernardino County 99.8 Very High
7 San Francisco County 99.8 Very High
8 Contra Costa County 99.7 Relatively High
9 San Diego County 99.7 Relatively High
10 San Mateo County 99.7 Relatively High
11 Ventura County 99.7 Relatively High
12 Sonoma County 99.5 Relatively High
13 Kern County 99.4 Relatively High
14 Monterey County 99.4 Relatively High
15 Santa Barbara County 99.4 Relatively High
16 San Joaquin County 99.3 Relatively High
17 Santa Cruz County 99.3 Relatively High
18 Fresno County 99.2 Relatively High
19 Imperial County 99.2 Relatively High
20 Humboldt County 99 Relatively High
21 Solano County 99 Relatively High
22 Sacramento County 98.9 Relatively High
23 Marin County 98.7 Relatively High
24 Merced County 98.5 Relatively High
25 Stanislaus County 98.5 Relatively High
26 Napa County 98.4 Relatively High
27 Mendocino County 98.3 Relatively High
28 San Luis Obispo County 97.9 Relatively Moderate
29 Tulare County 97.9 Relatively Moderate
30 Butte County 97.5 Relatively Moderate
31 Yolo County 97.4 Relatively Moderate
32 San Benito County 97.3 Relatively Moderate
33 Kings County 97 Relatively Moderate
34 Lake County 97 Relatively Moderate
35 Madera County 96.9 Relatively Moderate
36 Shasta County 96.5 Relatively Moderate
37 Placer County 95.2 Relatively Moderate
38 Inyo County 94.3 Relatively Moderate
39 Tehama County 94.3 Relatively Moderate
40 Del Norte County 94.2 Relatively Moderate
41 Sutter County 94.1 Relatively Moderate
42 Glenn County 92.5 Relatively Moderate
43 Plumas County 92.2 Relatively Moderate
44 Nevada County 92.1 Relatively Moderate
45 El Dorado County 91.6 Relatively Moderate
46 Colusa County 90.8 Relatively Moderate
47 Yuba County 90.1 Relatively Low
48 Lassen County 89.7 Relatively Low
49 Mono County 89 Relatively Low
50 Siskiyou County 88.2 Relatively Low
51 Trinity County 85 Relatively Low
52 Calaveras County 76.7 Relatively Low
53 Tuolumne County 71 Relatively Low
54 Modoc County 68.8 Relatively Low
55 Mariposa County 67.5 Relatively Low
56 Sierra County 66.8 Relatively Low
57 Amador County 64.5 Relatively Low
58 Alpine County 53 Very Low

Source: FEMA National Risk Index v1.20.0, December 2025. Scores are 0–100 percentile rankings among all US counties. See the methodology page for definitions. Download the full CSV for all counties.

Earthquake risk nationally:

Top 50 US counties

Other hazard risks in California:

WildfireInland FloodingCoastal FloodingHeat WaveTornadoHurricaneHailStrong WindWinter WeatherIce StormCold WaveLightningDroughtLandslideAvalancheTsunamiVolcanic Activity

Frequently asked questions

What is the highest earthquake risk county in California?

Alameda County, CA has the highest earthquake risk in California, with a FEMA National Risk Index score of 100 out of 100 (rated "Very High").

How many counties in California are rated Very High for earthquake risk?

7 of 58 scored California counties are rated "Very High" for earthquake risk by FEMA's National Risk Index.

What causes earthquake risk in California?

Earthquake risk reflects expected annual losses from ground shaking. High scores concentrate in California, the Pacific Northwest, Alaska, and the New Madrid Seismic Zone (spanning Missouri, Arkansas, Tennessee, and neighboring states). NOAA's Storm Events Database does not track earthquakes, so recorded event counts are not shown.