More than 6.6 million homes on the Atlantic and Gulf coasts are at risk of hurricane storm surge inundation with a total reconstruction cost value (RCV) of nearly $1.5 trillion (see Table 1 below).
The CoreLogic analysis examines risk from hurricane-driven storm surge for homes along the Atlantic and Gulf coastlines of 19 states and the District of Columbia, as well as for 84 metro areas. Homes are categorized among five risk levels, including Low, Moderate, High, Very High and Extreme. In addition to the number of homes at risk, the analysis provides RCVs, which indicate how much is required to rebuild the property, including labor and materials, and assuming worst-case scenario at 100-percent destruction.
At the regional level, the Atlantic Coast has more than 3.8 million homes at risk of storm surge in 2015 with an RCV of $939 billion, and the Gulf Coast has just under 2.8 million homes at risk and nearly $549 billion in potential exposure to total destruction damage (Table 2). Said Dr. Tom Jeffery, senior hazard risk scientist for CoreLogic:
The number of hurricanes each year is less important than the location of where the next hurricane will come ashore. It only takes one hurricane that pushes storm surge into a major metropolitan area for the damage to tally in the billions of dollars. With new home construction, and any amount of sea-level rise, the number of homes at risk of storm surge damage will continue to increase.
Table 3 shows that six states account for more than three-quarters of all at-risk homes nationally. Florida has the highest total number of properties at various risk levels (2,509,812), followed by Louisiana (760,272), New York (464,534), New Jersey (446,148), Texas (441,304) and Virginia (420,052). Even though Louisiana has the second most homes at risk of storm surge, only one-quarter of these homes are in the extreme or very high storm surge category due, in large part, to the upgrade and expansion of levees in Louisiana. Said Jeffery:
The levee system in and around New Orleans is one of the most extensive in the world. After Hurricane Katrina in 2005, upgrades were planned for the network of levees and pumping stations to reduce the potential devastation from future storms. Upgrades were completed in 2013, and CoreLogic analysis shows a significant number of homes are now protected from all but the higher category hurricanes as a result.
At the local level, five Core Based Statistical Areas (CBSAs) rank the highest in both number of homes at risk and total RCV. They include New York-Newark, NY-NJ-PA; Miami-Fort Lauderdale-West Palm Beach, FL; Tampa-St. Petersburg-Clearwater, FL; Virginia Beach-Norfolk-Newport News, VA-NC; and New Orleans-Metairie, LA (Table 5).
Additional findings in the CoreLogic storm surge analysis:
- The five states with the highest RCV for homes at risk include: Florida ($491,119,183,016), New York ($177,398,620,779), Louisiana ($162,096,659,527) New Jersey ($126,829,146,685) and Virginia ($91,049,049,641).
- The five states (including the District of Columbia) with the lowest RCV for homes at risk include: District of Columbia ($351,443,177), New Hampshire ($3,215,714,570) Maine ($5,807,400,656), Rhode Island ($7,476,741,658) and Alabama ($9,954,390,796).
- The five states (including the District of Columbia) with the lowest total number of properties at risk include: the District of Columbia (3,668), New Hampshire (12,409), Maine (22,491), Rhode Island (26,490) and Delaware (49,716).
- Virginia Beach-Norfolk-Newport News, VA-NC has the highest percentage of homes (87 percent) at risk of storm surge, but not designated in a FEMA flood zone. Philadelphia-Camden-Wilmington, PA-NJ-DE-MD and Jacksonville, Fla. also top the list at 85 percent and 77 percent, respectively.
The CoreLogic storm surge analysis also complements Federal Emergency Management Agency (FEMA) flood zone information to provide a snapshot of potential damage exposure at the property level, as many properties located outside designated FEMA flood zones are still at risk for storm surge damage. Standard FEMA flood zones are designed to identify areas at risk for both freshwater flooding, as well as storm surge, based on the likelihood of either a 100-year or 500-year flood event. They do not differentiate risk based on storm severity, and as a result, do not accurately define the total extent of potential risk along coastal areas. Homeowners who live outside the FEMA flood zones frequently do not carry flood insurance, given that there is no mandate to do so, and therefore may not be aware of the potential risk storm surge poses to their properties.
To illustrate varying degrees of flood risk exposure, the analysis compares homes that are not located within FEMA 100-year floodplains against the number of homes located in surge inundation zones, as well as those located in both surge and FEMA Special Flood Hazard Areas (SFHA). This data can be found in the full report at: http://www.corelogic.com/about-us/researchtrends/storm-surge-report
Table 1 – Residential Exposure by Storm Category for the Entire U.S.
|Storm Surge Risk Level|
|Total Homes Potentially Affected||Total Estimated|
|Extreme (Affected by a Category 1-5 storm)||1,651,978||$393,494,752,074|
|Very High (Category 2-5)||1,438,526||$324,225,419,007|
|High (Category 3-5)||1,654,925||$371,135,087,394|
|Moderate (Category 4-5)||1,178,196||$267,395,972,220|
|Low (Category 5)||685,391||$132,090,242,053|
Table 2 – Residential Exposure by Coastal Region
|Region||Atlantic Coast Homes||Atlantic Coast RCV (U.S. Dollars)||Gulf Coast Homes||Gulf Coast RCV (U.S. Dollars)|
|Extreme (Affected by a Category 1-5 storm)||1,018,371||$264,963,399,509||633,607||$128,531,352,565|
|Very High (Category 2-5)||911,091||$223,821,396,433||527,435||$100,404,022,574|
|High (Category 3-5)||860,657||$212,741,476,684||794,268||$158,393,610,710|
|Moderate (Category 4-5)||686,061||$172,277,118,076||492,135||$95,118,854,144|
|Low (Category 5)||332,984||$65,334,507,800||352,407||$66,755,734,253|
Table 3 – State Table (Ranked by Number of Homes at Risk)
|20||District of Columbia||N/A**||N/A**||545||3,123||N/A||3,668|
* The “Low” risk category is based on Category 5 hurricanes, which are not likely along the northeastern Atlantic coast. States in that area have N/A designated for the Low category due to the extremely low probability of a Category 5 storm affecting that area.
** Washington, D.C. has no Atlantic coastal properties, but can be affected by larger hurricanes that push storm surge into the Potomac River. Category 1 and 2 storms will likely not generate sufficient storm surge to affect properties in Washington, D.C.
Table 4 – Reconstruction Value of Properties at Risk by State (U.S. Dollars)
|20||District of Columbia||N/A||N/A||$62,715,469||$288,727,708||N/A||$351,443,177|
Table 5 – Storm Surge Risk for Top 5 Metro Areas
|Rank||Metropolitan Area||Total Properties Potentially Affected by All Categories of Hurricane||Total RCV (U.S. Dollars)|
|1||New York, NY||685,152||$244,312,501,442|
|4||Virginia Beach, VA-NC||395,341||$86,393,517,790|
|5||New Orleans, LA||380,120||$84,242,355,537|
Additional CBSA data, market rankings, regional, state and local-level maps are available upon request.
The 2015 CoreLogic storm surge analysis encompasses single-family residential structures including mobile homes, duplexes, manufactured homes and cabins, among other non-traditional home types. Year-over-year changes in the number of homes at risk and RCV can be the result of several variables, including new home construction, improved public records, enhanced modeling techniques, fluctuation in labor, equipment and material costs, and even potential rise in sea level. As a result, direct year-over-year comparisons should be avoided. To estimate the value property exposure of the single-family residences CoreLogic utilized it’s proprietary Marshall & Swift/Boeckh reconstruction cost valuation methodology. This methodology estimates the cost to rebuild the property in the event of a total loss and is not to be confused with property market values or new construction cost estimation. Reconstruction cost estimates more accurately reflect the actual cost of damage or destruction of residential buildings that would occur from hurricane-driven storm surge since they include the cost of materials, equipment and labor needed to rebuild, and also factor in geographical pricing differences. Actual land values are not included in the estimates. The values are based on 100-percent or total destruction of the residential structure. Depending upon the amount of surge water from a given storm, there may be less than 100 percent damage to the residence, which would result in a lower realized reconstruction cost value.
Storm surge is triggered primarily by the high winds and low pressure associated with hurricanes, which cause water to amass inside a storm as it moves across the ocean before releasing as a powerful rush overland when the hurricane moves onshore. In addition to the property damage and potential lives lost to flooding, the speed and force associated with storm surge waves can significantly increase geographic and economic impact in hurricane disaster areas.