Two data sources are used in the Disaster Operations Map. First, the Social Vulnerability Index (SVI) is a public data base curated by the Center for Disease Control (CDC). Second, te Natural Hazard Housing Risk Index is a proprietary data set released by ATTOM Data Solutions.

Social Vulnerability Index (CDC 2018)
Natural Hazard Housing Risk Index (ATTOM 2016)

Methodology

We pull the data we need from these files and bring them into a .mbtiles file to use with Mapbox and D3.js. Full methodology on this data manipulation is available on the GitHub page.

Social Vulnerability Index

  • Level of disaggregation: U.S. Census Tract
  • Year: 2018
  • Source: CDC
  • Additional Information


    • The Overall Social Vulnerability Index (SVI) is a composite score of four broad vulnerability indicators: Socioeconomic Status, Household Composition, Minority Status/Language, and Housing and Transportation. Each sub-category is calculated from specific indicators described in the table below.

    Index scores range from 0 to 1; which depicts the percentiles of a particular county or tract relative to the rest of the USA. The higher the percentile ranking, the more vulnerable an area is in that category. A red flag indicates that an area is highly vulnerable, or in the top 90th percentile of a particular vulnerability.

    Indicator Vulnerability Category Description
    Below Poverty Socioeconomic Status Persons below poverty estimate
    Unemployed Socioeconomic Status Civilian (age 16+)
    Income Socioeconomic Status Per capita income
    No High School Diploma Socioeconomic Status Persons (age 25+) with no high school diploma
    Aged 65 or older Household Composition Persons aged 65 or older
    Aged 17 or younger Household Composition Persons aged 17 or younger
    Civilian with a disability Household Composition Civilian noninstitutionalized
    Single-Parent Households Household Composition Single parent household with children under 18
    Minority Minority Status/Language Minority (all persons except white, non-Hispanic)
    Speak English “Less than Well” Minority Status/Language Persons (age 5+) who speak English "less than well"
    Multi-Unit Structures Housing and Transportation Housing in structures with 10 or more units
    Mobile Homes Housing and Transportation Mobile homes
    Crowding Housing and Transportation At household level (occupied housing units), more people than rooms
    No Vehicle Housing and Transportation Households with no vehicle available estimate
    Population
    Location Text description of tract, county, and state

    Natural Hazard Housing Risk Index

  • Level of disaggregation: more than 3,000 USA counties
  • Year: 2016
  • Source: ATTOM Data Solutions
  • Additional Information


    • The Hazard Risk is an additive composite of six measures: Hurricane, Flood, Earthquake, Wildfire, Tornado, and Hail. Each hazard risk component is measured on a scale from 0-60, with a potential Overall Hazard Risk of 360.

    Indicator Description
    Overall Hazard Risk Descrip
    Hurricane Risk Data is from FEMA and the National Hurricane Center (NHC), and risk level is based on two factors with equal weight: number and intensity of hurricane strikes historically; and percentage of homes located in flood zones identified as having a risk of “storm-induced waves”
    Flood Risk Data is based on flood zones created by the Federal Emergency Management Agency (FEMA), and the level of risk was based on the percentage of homes in each county located in high-risk flood zones
    Earthquake Risk Data is from the United States Geological Survey (USGS), and the level of risk was based on the probability of a magnitude 5.0 earthquake in each county
    Wildfire Risk Data is from the United States Department of Agriculture Forest Service and Fire Modeling Institute, and risk level is based on the percentage of homes in each county located in “Very High” or “High” Wildfire Hazard Potential (WHP) areas.
    Tornado Risk Data is from the National Oceanic and Atmospheric Administration (NOAA), and level of risk was based on the Destruction Potential Index (DPI) for each county. DPI is calculated using number of tornadoes, path of tornadoes in square miles, and intensity of tornadoes on the Fujita scale.
    Hail Risk Data is from NOAA and the risk level is based on the average number of hail storms per year in each county with hail that exceeds 1-inch in size over the past 15 years.


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