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The Resilience Divide Part 3: Modeling Inequity in Seattle, Washington

One Concern’s software helps uncover racial and socioeconomic disparities in earthquake impacts across the city

In every disaster event — whether a flood, an earthquake, or a global pandemic — populations are not impacted equally; disasters are not ‘the great equalizers.’ Rather, disasters expose the larger social inequities already present within society and exacerbate them, creating ripple effects that impact a community’s ability to recover, and to be resilient, for years to come. At One Concern, we believe that the first step to changing these outcomes — and building lasting resilience — involves bringing these inequities to light.

In the third and final installment of our Resilience Divide series, we highlight our project with the City of Seattle, which explored the potential impacts of multiple earthquakes in the Seattle region. Modeling the potential structural damage to buildings during three earthquakes, our software platform illuminated how these impacts vary in severity, location, and most importantly, how these impacts differ across racial and economic lines.

Project Background

Seattle’s local government is among the most progressive in the nation. As the first city in the country to design an initiative focused solely on eliminating institutional racism, known as the Race and Social Justice Initiative (RSJI), Seattle is a leader in the fight for equity in government and public policy. Across departments and organizations, teams work to bring awareness to inequalities throughout the city, and design comprehensive plans and programs for bridging these gaps. For the City of Seattle’s Office of Emergency Management (OEM), this drive is particularly focused on eliminating disparities in disaster resilience and building plans that are inclusive, relevant, and meaningful to the needs of each community.

In 2018, One Concern began an important project with the City of Seattle, to help the Seattle OEM better plan and prepare for the city’s seismic risks and to help provide data for the City’s Race and Social Justice Initiative. The Seattle OEM was particularly interested in understanding how earthquakes affect different demographic populations within the city, and our software platform provided insights to address the following questions:

How does the extent and the location of impact vary across the city for different types of earthquakes? Do these earthquakes produce different demographic-impact patterns?

Across these earthquake scenarios, are some population groups more likely to be adversely impacted than others? If yes, how?

To address these questions, the Seattle OEM used One Concern’s software platform to perform an impact analysis across three different earthquake scenarios, with the goal of identifying potential inequities of disaster impacts in the city. TJ McDonald, the Project Lead from Seattle OEM, presented the findings of this project to the City of Seattle in June of this year.

Methodology

Image source: Pacific Northwest Seismic Network

Seattle’s geographic location makes it highly susceptible to earthquakes. The city sits on the intersection of three different potential earthquake sources, representing three earthquake types: subduction zone, deep, and crustal. To understand Seattle’s vulnerability to future events, it is important to take into account the different potential impacts that can result from each type of earthquake.

One Concern’s software platform helps to illuminate these differences in impact. By modeling the probabilistic structural impact to buildings for multiple earthquake scenarios, our platform can paint a more holistic picture of risk — showcasing differences in impact at a census block level. With demographic data incorporated into our platform, the differences of impacts across various communities becomes clearer, and those who are most likely to experience severe damage are illuminated, as are the connections between impact disparities among racial and socioeconomic groups.

Using One Concern’s platform, the Seattle OEM conducted three earthquake impact analyses as indicated below:

  1. The 6.8 M 2001 Nisqually Earthquake simulation, which represents a deep earthquake.
  2. The Cascadia 9.0 M ‘L1 event’, which represents a subduction zone earthquake.
  3. The UASI THIRA** Scenario, 7.2 M Seattle Fault, which represents a crustal earthquake.

*UASI — Urban Areas Security Initiative; THIRA — Threat and Hazard Identification and Risk Assessment

Modeled structural damage for the 2001 Nisqually event, and the Cascadia L1 and 7.2 Seattle Fault scenarios. (Source: One Concern and the Seattle OEM)

These analyses show predicted structural damage ranging in 4 categories, called a Block Damage Index (BDI). The damage types range from BDI0 (blue-colored blocks; no damage) to BDI3 (red-colored blocks; severe damage), which are shown below in more detail:

Source: One Concern and the Seattle OEM

Next, the City used these impact analyses to examine the populations within severely damaged areas. Demographic categories covered race and ethnicity; which included the subcategories of Black, White, Asian, and Hispanic; age (seniors and children); and low-income.

To measure how different groups experience exposure to heavy damage, One Concern’s software platform uses a ratio formula that allows users to compare a specific population’s impact to other groups, by quantifying how over- or under-represented a particular group is (shown as a percentage) in the overall impact experienced by the city.

Using our demographic analysis feature, the Seattle OEM performed an analysis for the groups listed above for each modeled scenario.

Findings

The results of the analysis were disconcerting, but not surprising, given the broader pattern of institutional inequality in the United States.

Results of Seattle OEM study, showing severe damage exposure patterns. Percentages indicate a population’s under- (negative percentage) or over-representation (positive percentage) in heavily damaged census blocks.

Across all three scenarios, the project found that the bigger the simulated earthquake, the more drastic the inequity. As earthquake magnitude increased, so did the burden felt by minorities and lower-income groups. For the Cascadia scenario in particular, low-income groups had an extremely high exposure to BDI3 (severe) damage, compared with those in higher-income groups.

But perhaps the most eye-opening finding was in the Seattle Fault scenario, where Black residents were predicted to have almost double the BDI3 exposure as white residents. Further, One Concern’s platform predicted that 61% of the Black population lives in areas likely to experience severe damage.

The implications of this finding are staggering. If an earthquake similar to the simulated magnitude 7.2 Seattle Fault scenario were to occur, Black residents are not only more likely to experience severe damage to their homes — over half of the Black population in Seattle would experience this impact.

Conclusion

The findings from this study expose a vast amount of inequity in the ways Seattle residents may experience impact from earthquakes. Armed with this knowledge, Seattle’s OEM will be transforming their strategies in outreach, planning, mitigation, response and recovery, to reflect and address the disparities showcased by our platform.

This study also highlights the importance of incorporating multiple earthquake scenarios into overall assessments of risk. In addition to the racial and socioeconomic disparities detailed in this project, one of the most prominent findings was the projected devastation from an earthquake on the Seattle Fault. For the Seattle OEM, this information will be crucial to formulate comprehensive preparedness plans, demonstrating that they need to plan more tactfully and engage with different communities in order to build holistic resilience. In the absence of these insights, the most relevant and natural protocol is to rely on data from previous experienced earthquakes (such as Seattle’s 2001 Nisqually earthquake, which most earthquake planning in the city has been based off of) or formulate plans based on traditional and static assessments of risk.

This project with the Seattle OEM demonstrates that investigating these differences can have significant implications for how cities prepare for and respond to disaster events. By adding the analyses of the Cascadia and Seattle Fault lines, the City of Seattle gained tangible, quantitative insights into how certain earthquakes disproportionately affect Black residents and low-income groups — providing the data necessary to start taking steps towards mitigating these outcomes and building equity into the City’s disaster preparedness and mitigation programs.

Closing the Resilience Divide

Above all, the work we highlighted in this series underscores the pressing and critical need for further research in these areas. Building resilience is not a “one-size-fits-all” solution, and in order to build equitable, holistic resilience in our communities, we need to understand risk in the context of broader society. We need tools to understand how larger, systemic inequalities are related to differences in disaster risk.

Quantifying these differences in risk has historically been difficult, especially considering how difficult it can be to obtain data that meaningfully represents a community, as we saw in OutRight Action International’s research on the LGBTIQ population. But this work is essential to building a more just and resilient world.

Moving forward, as a global community of scientists we must work to build data sets that are inclusive, and use these data sets in conjunction with innovative technologies to capture the true, everyday realities of people living in America and in other parts of the world. With this data, we can highlight disparities, concretely — not only validating the experiences of so many people across the globe, but also giving agencies, governments and organizations the tools they need to address these inequalities head-on.

The Resilience Divide will not be closed until we work to bring light to its existence. At One Concern, we believe that exposing these inequalities can be a first step in driving action towards bridging them — one analysis, report, and data set at a time.

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