Seismic retrofit rates highlight inequitable efforts

Single-family homes in Los Angeles neighborhoods with predominantly Black, Hispanic, and low-income residents have fewer seismic retrofits than in other parts of the city.
 

By Rebecca Owen, Science Writer (@beccapox)
 

Citation: Owen, R., 2024, Seismic retrofit rates highlight inequitable efforts, Temblor, http://doi.org/10.32858/temblor.344
 

Editor’s note: This story references “cripple walls,” which is a common term used with respect to retrofitting. However, we will use “crawl space wall” instead.
 

In seismically active cities along the West Coast of the U.S., many older houses may not survive a strong earthquake. Take, for instance, houses built before 1980 with elevated front porches and crawl spaces. If these homes aren’t retrofitted properly, they could slide off their foundations or crumple during intense shaking.
 

 

Picture older bungalows, historically popular West Coast homes with steps leading up to the front porch. These houses have a small space between the ground and first floor — a crawl space instead of a full basement. In a house of this type, short wood stud walls in the crawl space between the main-floor framing and foundation provide vertical support and stability around the perimeter of the house, says BJ Cure, a structural engineer from Cascadia Risk Solutions. If a house’s crawl space wall collapses, it can “result in a total economic loss of the house, making it unusable in the immediate aftermath of the earthquake,” he says.

Two important retrofitting tasks include bolting the foundation to the frame of the house and bracing the crawl space wall with additional plywood. Though owners of susceptible properties might wish to make these safety upgrades to their homes, seismic retrofitting can be cost prohibitive. Costs for bolting and bracing can run from between $3,000 and $10,000, depending on a number of factors.

A recently published study examines the demographics of homeowners who have completed bracing retrofits of the crawl space in Los Angeles. The study’s results showed that households with lower retrofit rates correlated with disparities in race and ethnicity, as well as with lower income levels in neighborhoods across the city.

Temblor Earth News’ coverage of this study is the second part of a longer conversation about creating more equitable earthquake mitigation practices in the future. You can find the first part of this series of articles here.
 

Revealing information about retrofits

Making seismic retrofits “can actually mean the difference between your house being repairable and it being damaged beyond repair,” says Henry Burton, an author of the study and a professor of structural engineering at UCLA. “So you can imagine the significance, especially for low- to moderate-income families.”

Researchers examined records kept on the 5,400 homes, spanning 114 Los Angeles neighborhoods, that had crawl spaces retrofitted between 1999 and 2022. That data was obtained from the Los Angeles Department of Building and Safety, as well as the Los Angeles County Open Data Portal. Alongside the retrofit rate, researchers mapped sociodemographic information about these residents from census tract data.

“I wanted to look at how the retrofit is being distributed throughout L.A. and try to see if there any disparities, not just in terms of race and ethnicity, but in terms of income and education, too,” Burton says.

The team’s findings revealed that neighborhoods with higher Black and Hispanic households had lower retrofit rates. For instance, neighborhoods with the highest representation of Black residents had retrofit rates 33% lower than all of Los Angeles. City neighborhoods with the lowest median income had less than average retrofit rates compared to the rest of the city. White, Asian, and high-income households were overrepresented in the neighborhoods where homes had higher retrofit rates; Black and Hispanic households were underrepresented. The two neighborhoods with the highest retrofit rates — 22% and 44% percent, respectively — had residents with higher incomes and higher home values than the rest of Los Angeles.
 

 

One program’s impact

For homeowners in California, the Earthquake Brace and Bolt (EBB) program was introduced in 2013 by the California Earthquake Authority and the California Governor’s Office of Emergency Services. The EBB program provides funding for two necessary tasks: bolting the foundation to the frame of the house, and bracing the crawl space below the house with additional plywood for support.
 

 

EBB grants allot $3,000 for homeowners to retrofit wood-framed homes with raised foundations that were built before 1980. Furthermore, supplemental funding is available to low-income homeowners. To qualify for EBB funding, homes must also be located in specific at-risk zip codes in California. (In Oregon and Washington, where the possibility of destructive earthquakes also looms, no similar program exists to help homeowners cover the costs to retrofit their homes.)
 

 

The researchers compared data before and after the EBB’s implementation to see whether retrofit rates improved throughout Los Angeles. They paid attention to demographics. Their findings showed an approximately 37% increase in retrofits post-2013 in the ten neighborhoods with the highest percentage of Black households. After 2013, retrofit rates nearly doubled in Hispanic and low-income neighborhoods as well, suggesting the positive impact of the EBB program. Before 2013, the retrofit rate for these neighborhoods was 75% less than the rest of Los Angeles. After 2013, the retrofit rates are 46% lower than in other parts of the city, but this still marks an improvement from pre-EBB levels.

“The exciting thing is that the data shows an increase [of retrofits] in areas with high representation of Hispanic and Black homeowners,” says Janiele Maffei, California Earthquake Authority’s Chief Mitigation Officer, who was not involved in the study.

Although the initial $3,000 EBB grants help offset the cost of retrofitting, the grants are not awarded based on financial need. Grants, issued on a a first-come, first-served basis, are for homeowners who reside in their own homes in at-risk areas around California.

“We’re absolutely going to try and find out what we can do to assist people for whom that $3,000 wasn’t sufficient,” Maffei says. Households making under $87,360 a year now have another opportunity to receive supplemental funding to complete their retrofit. “In Southern California, where the study is, an EBB grant plus the supplemental grant may cover the entire cost of the retrofit for the vast majority of the retrofit jobs.”
 

Retrofitting for all

“The more the general public understands the problem and how to fix [it], more solutions become possible,” says Cure, who was not involved in the study.

“It’s actually better for you as a homeowner if you’re not the only person in the community that’s doing this retrofit,” says Burton. “My hope is that people who have that community mindset will not just do the retrofit but also make people aware that there’s this funding available.”

Even with the help of the EBB program in fortifying houses ahead of destructive earthquakes, disparities still exist throughout the city of Los Angeles for mitigation and preparedness. EBB funding is only available for homeowners who occupy their own properties. Renters in high-risk areas must depend on their landlords to make the necessary retrofits. In the aftermath of an earthquake, those residents would still be severely impacted by the loss of their rental homes.

The original funding requirements excluded renter-occupied houses in an effort to prevent EBB funding from being handed to large investment firms or corporations that own significant inventories of homes. “This year, our goal is to include houses that are occupied by renters, and I think by limiting the number of houses that a particular owner can [retrofit], we can,” Maffei says.

Before 2013, Burton explains, much of the retrofitting across neighborhoods in Los Angeles could be correlated with gentrification patterns, an avenue that researchers can keep exploring. “It’s not obvious how this should be interpreted. Retrofits are a good thing, right? But if with more retrofits comes a greater disparity, we need to think about that carefully as well as the types of policies that could help mitigate those disparities when communities start to change.”

Even as bolting and bracing retrofits continue to increase with more available funding, it will be crucial for policymakers to connect with homeowners and residents in the neighborhoods most at-risk to continue communicating mitigation efforts. The average retrofit rate in the ten Los Angeles neighborhoods with the highest representation of Hispanic households is one-third lower than the rest of the city. Directly after an earthquake, these neighborhoods may be the hardest hit and take the longest to recover. When this happens, displaced residents may never return, forever changing a community.

“Our results show that households from certain sociodemographic groups are less likely to mitigate their risk [because of economic barriers], and we need to have tailored policies to address this disproportionate impact,” says Sahar Derakhshan, one of the study’s authors and a professor of geography at Cal Poly Pomona. “Otherwise, these groups will have a larger burden when the earthquake happens.”
 

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