[silence]
Disasters do not impact all individuals, neighborhoods, or communities equally
across all members. Today, I will look at an example of disparate risk due to
earthquakes through the lens of potentially vulnerable communities.
The HayWired scenario, which recently presented its societal consequences
research to the public on the anniversary of the 1868 Hayward earthquake,
comprehensively analyzed many facets of earthquake hazard.
This talk will focus on communities at risk to earthquake hazards
and their aftermath, specifically where these communities may be found,
who may be residents of these communities,
and what these communities may experience.
Disasters have differential impacts on the land, buildings,
and those who reside in them. Where concentrations of building
damage are seen, longer and more complex recoveries result.
These complexities extend beyond just the blocks with
concentrated building damage into the surrounding neighborhoods.
An example of this effect was seen in Los Angeles following the
1994 Northridge earthquake, where concentrated multi-family housing
damage led to more and more residents leaving, blighting the neighborhoods.
In the HayWired scenario, the initial event produces sudden slip
along the Hayward Fault and widespread ground shaking.
The fault slip and ground shaking cause ground movement
in the forms of surface rupture, landslides, and liquefaction.
Damages from these earthquake hazards initiate fires following the earthquake,
and fault slip continues as afterslip with time as the plates re-equalize.
Aftershocks and their related hazards then continue over the course of
two years following the main shock. Each unique hazard can exacerbate
existing damage in addition to causing new damage.
To illustrate spatially where damages may be overwhelming, we took the
square footage of buildings damaged, according to FEMA’s Hazus
loss estimation software, and integrated square footage damage
due to fire to identify potential areas of concentrated damage.
These areas of concentrated building damage are mapped as census tracts
with 20% or more of their total building square footage
classified as extensively or completely damaged.
Further, these areas of concentrated damage were divided into
seven economic sub-areas – four in Alameda County
and one each in Contra Costa, Marin, and Solano Counties.
Concentrated damage areas in Marin and Solano Counties stand out specifically
due to the integration of fire damage. The area of concentrated damage
identified for the HayWired scenario, which is shown in orange and red
in the map here, contains roughly 203,000 residential buildings
with around 46,000 of these buildings potentially experiencing
extensive or complete damage. Nearly 50% of the region’s residential
buildings with extensive or complete damage in the HayWired scenario
are located in areas of concentrated building damage, yet this area contains
less than 8% of the census tracts in the nine-county region as a whole.
As a result, these areas are likely to have longer recovery trajectories and
more long-term community recovery challenges than other parts of the region.
Following a major disaster, individuals in the area may leave for several reasons,
either voluntary or forced. These reasons may include lack of
community services and uncertainty regarding additional
exposure to hazards. Residents with school-age children
will need access to schools to return to normalcy, while individuals with
access and functional needs will need stable access to healthcare.
Low-income residents will need inexpensive rental or repair
options for their housing situations. Disparate risk can lead to disparate
recovery, with more vulnerable populations tending to be more prone
to longer and more difficult recovery.
In order to gain some understanding of the different population groups that
may be exposed to HayWired hazards, several population demographic
categories were identified as historically more vulnerable.
For HayWired, the Association of Bay Area Governments and
San Francisco Bay Conservation and Development Commission’s
Community Vulnerability Indicators from 2015 were used as one metric,
along with additional demographic characteristics defined by the authors
of the HayWired Communities at Risk chapter.
The Community Vulnerability Indicator is defined by ABAG and BCDC look at
10 different demographic characteristics, including housing cost burden,
transportation cost burden, home ownership status, household income,
education level, racial or cultural composition, transit dependence,
primary language spoken at home, presence of young children,
and presence of the elderly. The additional author-defined
characteristics focused on how likely a population would need neighborhood
stability in order to remain in their current residences.
These characteristics include school-age children, households with at least one
resident with access or functional needs, homeless populations, and younger
residents with limited ties to the region due to home ownership status, lack of
children or family ties, or financial freedom to move from the region.
In particular, young and moderate- to high-income renters may have
enhanced means in mobility, allowing them to more easily permanently
leave the region if a disaster temporarily displaces them.
For the HayWired scenario, residents in census block groups with
concentrations of at least five Community Vulnerability Indicators
make up a disproportionate amount of total residents in areas with concentrated
damage, especially in portions of Alameda and Contra Costa Counties.
Nearly one in five Alameda County residents live in block groups
in concentrated damage areas that also have concentrations of at least five
Community Vulnerability Indicators. Specifically, the central Alameda
County and western Costra County sub-areas house around 40 and 26%
of their total populations, respectively, in these areas of concentrated damage,
also supporting concentrations of five or more Community Vulnerability
Indicators. Housing- and income-related indicators, like lack of home ownership,
high housing cost burden, and lower household incomes are relatively
more present in block groups where concentrations of at least
five Community Vulnerability Indicators are found, as are literacy
indicators like lower levels of education and more non-English speakers.
In the HayWired scenario areas of concentrated damage, there are also
more than 64,000 school-age children, more than 31,000 households with
at least one resident with access or functional needs, and more than
24,000 renters householders between the ages of 25 and 34 in 2010 census
block groups where the concentrations of these demographics are higher than
other block groups. For young renter householders, more than 14,000
also reside in block groups where concentrations of more wealthy young
householders, individuals with no families or children,
or higher rental costs are found. While detailed data for homeless
populations were not available, several cities with areas of concentrated
damage have identified homeless populations via point-in-time surveys.
High concentrations of these additional demographic characteristics and areas
with Community Vulnerability Indicator scores of at least 5 overlap
the central Alameda County, western Contra Costa County,
and Vallejo sub-areas for school-age children, the western Contra Costa
County and central Alameda County economic sub-areas for households
with at least one resident with access or functional needs, and Vallejo, Pinole,
areas near Lake Merritt, near the west side of Oakland,
and in Union City for young renter householders.
For people displaced from inhabitable homes or neighborhoods,
interim and permanent housing needs resulting from building damage,
utility outages, and environmental health threats following a major
earthquake are less well-addressed by current government and
non-government plans compared to their focus on short-term needs.
Extended utility outages can push residents out of otherwise
structurally sound housing. For example, residents who rely on
medical equipment to stay in their homes will be forced to relocate
due to extended electric power outage, even if structural damage to their
houses was minimal. And lack of in-house access
to potable water could lead residents in otherwise sound areas
to move elsewhere, potentially permanent.
Renters, particularly lower-income renters, and people with access or
functional needs may have more difficulty finding alternative housing.
Households relying on public housing, Housing Choice Vouchers, or other
housing subsidies may be especially vulnerable to displacement and
insufficient long-term interim housing, especially in the San Francisco Bay
Area, where housing shortages and high rental prices have dramatically affected
individuals using Housing Choice Vouchers and other housing subsidies.
Estimates of populations and households at risk of displacement
owing to building damage and other physical impacts of the HayWired
scenario varied depending on the method used to obtain the estimate.
The low-end household and population displacement estimates use a customized
Hazus analysis to estimate displacement due to shaking and liquefaction
damages to buildings by the HayWired scenario main shock.
The next estimate assumes, based on prior earthquakes,
that utility outages will increase displacement estimates by 20%.
The high displacement estimates include damage due to landslides
and fires and the compounding effects of concentrated damage
by the HayWired main shock.
For the HayWired scenario, the high-end household and
population displacement estimates show that as many as 520,000 households
and 1.45 million people are at risk of displacement from the HayWired
main shock, which is about 20% of the nine-county region total.
Due to Alameda County’s position as the central point of the event,
as much as 23% of households and population in the county reside
in the areas of concentrated damage. A larger portion of the total
displacement in the region is likely
to come from these areas. While aftershocks would not result
in substantial increases in emergency shelter or interim housing demands,
there could be ripple effects for mental health,
population displacement, and housing.
These ripple effects may include mortgage defaults, reduced property
values, population relocation, neighborhood blight,
and decreases in property tax revenues in affected jurisdictions.
The COVID-19 pandemic has highlighted disparities for some
minority populations, front-line workers, and people living in close quarters,
which have seen a disproportionate number of deaths in the last two years.
Housing, infrastructure, social, and financial vulnerabilities to
a major earthquake are a serious issue throughout the San Francisco Bay Area.
And, without changes in investment and focus on reducing seismic risk,
at least some of these vulnerabilities will likely continue to grow.
During the pandemic, socially cohesive communities have fared better.
With the San Jose State University anthropology department,
HayWired has engaged with communities to identify hazards
and social vulnerability characteristics of local concern and compare them
with available HayWired analyses to see what may be missing
and what would help their community.
Through this engagement, they found that LGBTQIA+ populations
were lacking representation in HayWired research.
Similarly, the bulk of HayWired communications are currently
only available in English and only available online.
Were more of the research available in languages other than English,
or perhaps in non-digital formats, a wider audience could be reached.
During the HayWired Communities at Risk webinar, Janiele Maffei
of the California Earthquake Authority described a program to concentrate free
building retrofits in lower-income ZIP codes as an antidote to disproportionate
effects on underserved populations in concentrated damage areas.
Maziar Movassaghi of the California Housing and Community Development
department, expressed concern around the gaps in reconstruction resources
and costs, the time it takes for funding to become available, and the lack of
community planning to leverage Community Development Block Grant
Disaster Recovery resources, all of which are differentially longer
for multi-family housing. An example of this delay is shown in
the graph here, which highlights the drop in subsequent lack of housing
stock recovery for Butte County following the Camp Fire in 2018.
Many low-income neighborhoods are already experiencing displacement,
and high-income neighborhoods are also rapidly losing their
existing low-income populations.
Neighborhoods with rail stations, historical housing stock, and rising
housing prices are especially at risk of losing low-income households.
Many of these at-risk neighborhoods correspond with areas of concentrated
damage in the East Bay in the HayWired scenario, making planning all the
more important to avoid exacerbating replacement trends.
Other factors affect whether displaced residents that are an important part of
our workforce return to their homes following a major disaster like the
HayWired earthquake scenario. Extended housing restoration times,
particularly for multi-family housing, lack of community services,
lack of social ties, and flexibility of job locations, among other things,
could delay population return or exacerbate population-out migration.
In addition, some displaced people may prefer the amenities available
in their receiving communities and choose to stay there rather than return.
Post-disaster changes in the demographic composition of impacted
communities is common, with new people, notably recovery workers
and the reconstruction labor force moving in, sometimes permanently.
I would like to acknowledge my co-authors for the HayWired
Communities at Risk Analysis work. First and foremost, lead author
Laurie Johnson, along with USGS’s Anne Wein and Jeff Peters.
For further information about the Hayward scenario,
please refer to the URL shown here or do an internet search for
"USGS HayWired" to find the main website,
or "HayWired connection" for access to the webinar archive. Thank you.