May 17, 2024
Contra Costa County, California
Summary
While reviewing this report, keep in mind that low risk is driven by lower loss due to natural hazards, lower social vulnerability, and higher community resilience.
For more information about the National Risk Index, its data, and how to interpret the information it provides, please review the About the National Risk Index and How to Take Action sections at the end of this report. Or, visit the National Risk Index website at hazards.fema.gov/nri/learn-more to access supporting documentation and links.
Risk Index
The Risk Index rating is Very High for Contra Costa County, CA when compared to the rest of the U.S.
Risk Index Legend
Hazard Type Risk Index
Hazard type Risk Index scores are calculated using data for only a single hazard type, and reflect a community's Expected Annual Loss value, community risk factors, and the adjustment factor used to calculate the risk value.
| Hazard Type | Risk Index Rating | Risk Index Score | National Percentile |
|---|---|---|---|
| Avalanche | Not Applicable | -- | |
| Coastal Flooding | Relatively Low | 57.5 | |
| Cold Wave | No Rating | 0 | |
| Drought | Relatively High | 99.3 | |
| Earthquake | Very High | 99.8 | |
| Hail | Very Low | 36 | |
| Heat Wave | Relatively High | 95.7 | |
| Hurricane | Not Applicable | -- | |
| Ice Storm | Not Applicable | -- | |
| Landslide | Relatively Moderate | 93.7 | |
| Lightning | Relatively Moderate | 89.3 | |
| Riverine Flooding | Relatively High | 96.2 | |
| Strong Wind | Very Low | 6.6 | |
| Tornado | Relatively Low | 55 | |
| Tsunami | Relatively Moderate | 66.2 | |
| Volcanic Activity | Not Applicable | -- | |
| Wildfire | Relatively Moderate | 95.9 | |
| Winter Weather | Very Low | 1.8 |
Risk Factor Breakdown
| Hazard Type | EAL Value | Social Vulnerability | Community Resilience | CRF | Risk Value | Risk Index Score |
|---|---|---|---|---|---|---|
| Earthquake | $566,466,572 | Relatively Moderate | Relatively High | 1.11 | $629,187,865 | 99.8 |
| Drought | $10,774,431 | Relatively Moderate | Relatively High | 1.11 | $11,839,427 | 99.3 |
| Riverine Flooding | $8,420,628 | Relatively Moderate | Relatively High | 1.11 | $9,924,052 | 96.2 |
| Wildfire | $5,828,404 | Relatively Moderate | Relatively High | 1.11 | $5,072,184 | 95.9 |
| Heat Wave | $2,645,169 | Relatively Moderate | Relatively High | 1.11 | $2,940,182 | 95.7 |
| Tornado | $1,291,507 | Relatively Moderate | Relatively High | 1.11 | $1,392,140 | 55 |
| Lightning | $552,279 | Relatively Moderate | Relatively High | 1.11 | $630,520 | 89.3 |
| Landslide | $232,345 | Relatively Moderate | Relatively High | 1.11 | $227,395 | 93.7 |
| Coastal Flooding | $188,681 | Relatively Moderate | Relatively High | 1.11 | $226,823 | 57.5 |
| Hail | $54,531 | Relatively Moderate | Relatively High | 1.11 | $58,214 | 36 |
| Tsunami | $40,671 | Relatively Moderate | Relatively High | 1.11 | $41,056 | 66.2 |
| Strong Wind | $20,594 | Relatively Moderate | Relatively High | 1.11 | $22,777 | 6.6 |
| Winter Weather | $0 | Relatively Moderate | Relatively High | 1.11 | $0 | 1.8 |
| Cold Wave | $0 | Relatively Moderate | Relatively High | 1.11 | $0 | 0 |
| Avalanche | -- | Relatively Moderate | Relatively High | 1.11 | -- | -- |
| Hurricane | -- | Relatively Moderate | Relatively High | 1.11 | -- | -- |
| Ice Storm | -- | Relatively Moderate | Relatively High | 1.11 | -- | -- |
| Volcanic Activity | -- | Relatively Moderate | Relatively High | 1.11 | -- | -- |
Expected Annual Loss
In Contra Costa County, CA, expected loss each year due to natural hazards is Very High when compared to the rest of the U.S.
Expected Annual Loss Legend
Expected Annual Loss for Hazard Types
Expected Annual Loss scores for hazard types are calculated using data for only a single hazard type, and reflect a community's relative expected annual loss for only that hazard type.
14 of 18 hazard types contribute to the expected annual loss for Contra Costa County, CA.
| Hazard Type | Expected Annual Loss Rating | EAL Value | Score |
|---|---|---|---|
| Earthquake | Very High | $566,466,572 | 99.8 |
| Drought | Relatively High | $10,774,431 | 99.4 |
| Riverine Flooding | Relatively High | $8,420,628 | 96.3 |
| Wildfire | Relatively Moderate | $5,828,404 | 96.7 |
| Heat Wave | Relatively High | $2,645,169 | 96.1 |
| Tornado | Relatively Low | $1,291,507 | 58.8 |
| Lightning | Relatively High | $552,279 | 89.2 |
| Landslide | Relatively Moderate | $232,346 | 94.6 |
| Coastal Flooding | Relatively Low | $188,681 | 56.8 |
| Hail | Very Low | $54,531 | 40.1 |
| Tsunami | Relatively Moderate | $40,671 | 82.0 |
| Strong Wind | Very Low | $20,594 | 9.4 |
| Winter Weather | Very Low | $0 | 4.5 |
| Cold Wave | $0 | 0.0 | |
| Avalanche | |||
| Hurricane | |||
| Ice Storm | |||
| Volcanic Activity |
Expected Annual Loss Values
| Hazard Type | Total | Building Value | Population Equivalence | Population | Agriculture Value |
|---|---|---|---|---|---|
| Avalanche | -- | -- | -- | -- | -- |
| Coastal Flooding | $188,681 | $186,564 | $2,118 | 0.00 | n/a |
| Cold Wave | $0 | $0 | $0 | 0.00 | $0 |
| Drought | $10,774,431 | n/a | n/a | n/a | $10,774,431 |
| Earthquake | $566,466,572 | $410,055,680 | $156,410,893 | 13.48 | n/a |
| Hail | $54,531 | $42,961 | $10,280 | 0.00 | $1,290 |
| Heat Wave | $2,645,169 | $485 | $2,625,904 | 0.23 | $18,780 |
| Hurricane | -- | -- | -- | -- | -- |
| Ice Storm | -- | -- | -- | -- | -- |
| Landslide | $232,345 | $207,224 | $25,121 | 0.00 | n/a |
| Lightning | $552,279 | $37,680 | $514,599 | 0.04 | n/a |
| Riverine Flooding | $8,420,628 | $4,123,781 | $4,005,211 | 0.35 | $291,636 |
| Strong Wind | $20,594 | $5,591 | $14,927 | 0.00 | $76 |
| Tornado | $1,291,507 | $930,045 | $361,249 | 0.03 | $213 |
| Tsunami | $40,671 | $38,659 | $2,012 | 0.00 | n/a |
| Volcanic Activity | -- | -- | -- | -- | -- |
| Wildfire | $5,828,404 | $5,667,293 | $161,110 | 0.01 | $0 |
| Winter Weather | $0 | $0 | $0 | 0.00 | $0 |
Exposure Values
| Hazard Type | Total | Building Value | Population Equivalence | Population | Agriculture Value |
|---|---|---|---|---|---|
| Avalanche | -- | -- | -- | -- | -- |
| Coastal Flooding | $81,282,240,960 | $2,103,515,194 | $79,178,725,766 | 6,825.75 | n/a |
| Cold Wave | $0 | $0 | $0 | 0.00 | $0 |
| Drought | $65,624,093 | n/a | n/a | n/a | $65,624,093 |
| Earthquake | $13,743,211,720,000 | $218,458,520,000 | $13,524,753,200,000 | 1,165,927.00 | n/a |
| Hail | $13,737,961,980,754 | $218,460,912,694 | $13,519,405,600,000 | 1,165,466.00 | $95,468,060 |
| Heat Wave | $13,737,961,980,754 | $218,460,912,694 | $13,519,405,600,000 | 1,165,466.00 | $95,468,060 |
| Hurricane | -- | -- | -- | -- | -- |
| Ice Storm | -- | -- | -- | -- | -- |
| Landslide | $4,071,872,848,712 | $70,779,338,524 | $4,001,093,510,188 | 344,921.85 | n/a |
| Lightning | $13,737,866,512,694 | $218,460,912,694 | $13,519,405,600,000 | 1,165,466.00 | n/a |
| Riverine Flooding | $353,166,916,090 | $7,173,753,922 | $345,939,994,512 | 29,822.41 | $53,167,656 |
| Strong Wind | $13,737,961,980,754 | $218,460,912,694 | $13,519,405,600,000 | 1,165,466.00 | $95,468,060 |
| Tornado | $13,737,961,980,754 | $218,460,912,694 | $13,519,405,600,000 | 1,165,466.00 | $95,468,060 |
| Tsunami | $112,040,238,956 | $3,886,066,775 | $108,154,172,181 | 9,323.64 | n/a |
| Volcanic Activity | -- | -- | -- | -- | -- |
| Wildfire | $356,109,882,333 | $6,520,975,903 | $349,587,475,435 | 30,136.85 | $1,430,995 |
| Winter Weather | $657,587,479 | $57,001,091 | $599,615,107 | 51.69 | $971,280 |
Annualized Frequency Values
| Hazard Type | Annualized Frequency | Events on Record | Period of Record |
|---|---|---|---|
| Avalanche | -- | -- | -- |
| Coastal Flooding | 1.5 events per year | n/a | Various (see documentation) |
| Cold Wave | 0 events per year | 0 | 2005-2021 (16 years) |
| Drought | 52 events per year | 1,386 | 2000-2021 (22 years) |
| Earthquake | 0.970% chance per year | n/a | 2021 dataset |
| Hail | 0 events per year | 2 | 1986-2021 (34 years) |
| Heat Wave | 1.8 events per year | 27 | 2005-2021 (16 years) |
| Hurricane | -- | -- | -- |
| Ice Storm | -- | -- | -- |
| Landslide | 0 events per year | 12 | 2010-2021 (12 years) |
| Lightning | 0.4 events per year | 9 | 1991-2012 (22 years) |
| Riverine Flooding | 1.3 events per year | 31 | 1996-2019 (24 years) |
| Strong Wind | 0 events per year | 2 | 1986-2021 (34 years) |
| Tornado | 0.1 events per year | 5 | 1950-2021 (72 years) |
| Tsunami | 0 events per year | 5 | 1800-2021 (222 years) |
| Volcanic Activity | -- | -- | -- |
| Wildfire | 0.306% chance per year | n/a | 2021 dataset |
| Winter Weather | 0 events per year | 0 | 2005-2021 (16 years) |
Historic Loss Ratios
| Hazard Type | Overall Rating |
|---|---|
| Avalanche | -- |
| Coastal Flooding | Very Low |
| Cold Wave | No Rating |
| Drought | Relatively High |
| Earthquake | Relatively High |
| Hail | Relatively Low |
| Heat Wave | Very Low |
| Hurricane | -- |
| Ice Storm | -- |
| Landslide | Very Low |
| Lightning | Very High |
| Riverine Flooding | Very Low |
| Strong Wind | Very Low |
| Tornado | Very Low |
| Tsunami | Relatively Moderate |
| Volcanic Activity | -- |
| Wildfire | Relatively Low |
| Winter Weather | Very High |
Expected Annual Loss Rate
| Hazard Type | Building EAL Rate (per building value) |
Population EAL Rate (per population) |
Agriculture EAL Rate (per agriculture value) |
|---|---|---|---|
| Avalanche | -- | -- | -- |
| Coastal Flooding | $1 per $1.17M | 1 per 6.38B | -- |
| Cold Wave | -- | -- | -- |
| Drought | -- | -- | $1 per $8.86 |
| Earthquake | $1 per $532.76 | 1 per 86.44K | -- |
| Hail | $1 per $5.09M | 1 per 1.32B | $1 per $74.00K |
| Heat Wave | $1 per $450.53M | 1 per 5.15M | $1 per $5.08K |
| Hurricane | -- | -- | -- |
| Ice Storm | -- | -- | -- |
| Landslide | $1 per $1.05M | 1 per 538.16M | -- |
| Lightning | $1 per $5.80M | 1 per 26.27M | -- |
| Riverine Flooding | $1 per $52.98K | 1 per 3.38M | $1 per $327.35 |
| Strong Wind | $1 per $39.07M | 1 per 905.69M | $1 per $1.26M |
| Tornado | $1 per $234.89K | 1 per 37.42M | $1 per $447.77K |
| Tsunami | $1 per $5.65M | 1 per 6.72B | -- |
| Volcanic Activity | -- | -- | -- |
| Wildfire | $1 per $38.55K | 1 per 83.91M | $1 per $27.93B |
| Winter Weather | $1 per $2.56T | 1 per 359.20T | $1 per $4.62P |
Social Vulnerability
Social groups in Contra Costa County, CA have a Relatively Moderate susceptibility to the adverse impacts of natural hazards when compared to the rest of the U.S.
Social Vulnerability Legend
Community Resilience
Communities in Contra Costa County, CA have a Relatively High ability to prepare for anticipated natural hazards, adapt to changing conditions, and withstand and recover rapidly from disruptions when compared to the rest of the U.S.
Community Resilience Legend
About the National Risk Index
The National Risk Index is a dataset and online tool to help illustrate the United States communities most at risk for 18 natural hazards: Avalanche, Coastal Flooding, Cold Wave, Drought, Earthquake, Hail, Heat Wave, Hurricane, Ice Storm, Landslide, Lightning, Riverine Flooding, Strong Wind, Tornado, Tsunami, Volcanic Activity, Wildfire, and Winter Weather.
The National Risk Index leverages available source data for Expected Annual Loss due to these 18 hazard types, Social Vulnerability, and Community Resilience to develop a baseline relative risk measurement for each United States county and Census tract. These measurements are calculated using average past conditions, but they cannot be used to predict future outcomes for a community. The National Risk Index is intended to fill gaps in available data and analyses to better inform federal, state, local, tribal, and territorial decision makers as they develop risk reduction strategies.
Explore the National Risk Index Map at hazards.fema.gov/nri/map.
Visit the National Risk Index website at hazards.fema.gov/nri/learn-more to access supporting documentation and links.
Calculating the Risk Index
Risk Index scores are calculated using an equation that combines scores for Expected Annual Loss due to natural hazards, Social Vulnerability and Community Resilience:
Risk Index = Expected Annual Loss × ÷ Community Resilience
Risk Index scores are presented as a composite score for all 18 hazard types, as well as individual scores for each hazard type.
For more information, visit hazards.fema.gov/nri/determining-risk.
Calculating Expected Annual Loss
Expected Annual Loss scores are calculated using an equation that combines values for exposure, annualized frequency, and historic loss ratios for 18 hazard types:
Expected Annual Loss = Exposure × Annualized Frequency × Historic Loss Ratio
Expected Annual Loss scores are presented as a composite score for all 18 hazard types, as well as individual scores for each hazard type.
For more information, visit hazards.fema.gov/nri/expected-annual-loss.
Calculating Social Vulnerability
Social Vulnerability is measured using the Social Vulnerability Index (SVI) published by the Centers for Disease Control and Prevention (CDC).
For more information, visit hazards.fema.gov/nri/social-vulnerability.
Calculating Community Resilience
Community Resilience is measured at the County level using the Baseline Resilience Indicators for Communities (HVRI BRIC) published by the University of South Carolina's Hazards and Vulnerability Research Institute (HVRI).
For more information, visit hazards.fema.gov/nri/community-resilience.
How to Take Action
There are many ways to reduce natural hazard risk through mitigation. Communities with high National Risk Index scores can take action to reduce risk by decreasing Expected Annual Loss due to natural hazards, decreasing Social Vulnerability, and increasing Community Resilience.
For information about how to take action and reduce your risk, visit hazards.fema.gov/nri/take-action.
Disclaimer
The National Risk Index (the Risk Index or the Index) and its associated data are meant for planning purposes only. This tool was created for broad nationwide comparisons and is not a substitute for localized risk assessment analysis. Nationwide datasets used as inputs for the National Risk Index are, in many cases, not as accurate as available local data. Users with access to local data for each National Risk Index risk factor should consider substituting the Risk Index data with local data to recalculate a more accurate risk index. If you decide to download the National Risk Index data and substitute it with local data, you assume responsibility for the accuracy of the data and any resulting data index. Please visit the Contact Us page if you would like to discuss this process further.
The methodology used by the National Risk Index has been reviewed by subject matter experts in the fields of natural hazard risk research, risk analysis, mitigation planning, and emergency management. The processing methods used to create the National Risk Index have produced results similar to those from other natural hazard risk analyses conducted on a smaller scale. The breadth and combination of geographic information systems (GIS) and data processing techniques leveraged by the National Risk Index enable it to incorporate multiple hazard types and risk factors, manage its nationwide scope, and capture what might have been missed using other methods.
The National Risk Index does not consider the intricate economic and physical interdependencies that exist across geographic regions. Keep in mind that hazard impacts in surrounding counties or Census tracts can cause indirect losses in your community regardless of your community's risk profile.
Nationwide data available for some risk factors are rudimentary at this time. The National Risk Index will be continuously updated as new data become available and improved methodologies are identified.
The National Risk Index Contact Us page is available at hazards.fema.gov/nri/contact-us.