Los Angeles County tops FEMA disaster risk list

2021 FEMA Hazard Risk Map. (Red and orange represent highest risks.)

Is your neighborhood at high risk of suffering from an earthquake? If you live in or near Los Angeles County, you could face greater than risk all other counties in the nation.

A new online tool, released in January by the Federal Emergency Management Agency, offers a comprehensive, searchable database that allows you to zoom in – down to even Census tracts – to determine a community’s risks, resilience, estimated loss from disaster, and more.

The National Risk Index pulls from an extensive compilation of data to illustrate risks on a color-coded map that is searchable by state, county or even neighborhood (as defined by the U.S. Census Bureau).

It provides a holistic view of community-level risk, combining multiple hazards with socioeconomic and built environmental factors. Access it at https://www.fema.gov/flood-maps/products-tools/national-risk-index.

Some of the information used in these calculations includes:

  • Risk level of experiencing 18 different natural hazards.
  • Identifying the vulnerability of populations based on age, income, living conditions, income, and education – and overlaying that with information on the number of hospitals, fire stations and ot­­­­her public infrastructure and services available to those populations.
  • Historical data on natural disasters of the past.

When calculating the risk score for each U.S. county, FEMA found that Los Angeles County is the community with the most risk in the nation.[1]

FEMA lists the following counties as the nation’s most at risk of natural disaster:[2]

  1. Los Angeles County (Score: 100)
  2. Bronx County, New York (Score: 85.63)
  3. New York County, New York (Score: 69.91)
  4. Miami-Dade County, Florida (Score: 58.25)
  5. Philadelphia County, Pennsylvania (Score: 57.72)
  6. Kings County, New York (Score: 56.52)
  7. Riverside County, California (Score: 55.80)
  8. San Bernardino County, California (Score: 52.56)
  9. Dallas County, Texas (Score: 52.45)
  10. St. Louis County, Missouri (Score: 52.35)

The county with the lowest risk in the country is Loudoun County in Virginia. The suburb of Washington D.C. has a score of 0. [3]

“It’s just that constant reminder,” Los Angeles resident Morgan Anderson told the Associated Press. “Oh yeah, we live somewhere where there’s natural disasters, and they can strike at any time.”[4]

The risks to L.A. and California are well-known. The state is notorious for earthquakes, and in 2020 California experienced its worst fire season on record in terms of area burned, as well as its largest single wildfire on record.[5]

Los Angeles County’s expected annual loss is very high, and its social vulnerability is relatively high while its community resilience is relatively low. Because of its population of nearly 10 million people and property value of more than $950 billion, any natural hazard can be costly.

The county is at very high risk for earthquakes, flooding, and wildfires.  It is at relatively high risk for drought, heat waves, ice storms, lightning, strong wind, and tornadoes.

Data-driven calculations

The Risk Index is a GIS tool designed to determine a variety of community resilience factors.

Color coding provides an easy, visual assessment of risks, challenges, and resilience.

Developed in partnership with Argonne National Laboratories, the analyses are derived from data drawn from 2013-2018. They incorporate 73 distinct methodologies for identifying community resilience, and use more than 100 community resilience indicators to come up with eight basic factors.

In analyzing hazards, the Index drew from historical hazard-specific data such as tornadoes, earthquakes, tropical storms, floods, and fire hazards. The tool looks at a community’s expected annual loss from natural hazards based on how many people and how much property could be affected.

This isn’t the first time L.A. has been listed as No. 1 in terms of risk.  The United States Geological Survey has ranked Los Angeles County as No. 1 for estimated annualized earthquake loss at 30.6 percent, and a recent study at U.C. Berkeley performed by the California Geological Survey supported that finding, ranking potential damage in Southern California higher than that of any other part of the state, including San Francisco.

The California Geological Survey found that in Southern California, a magnitude 7.1 quake along the Puente Hills fault would bring an estimated $69 billion in damages.

This would be much worse than any other quake in California’s history – killing more people and causing more damage than the San Andreas because it lies under vulnerable, older neighborhoods, and produces heavy reverberations that can be felt over a wide area.

A study by the University of Southern California says Puente Hills has the capacity to produce “the costliest disaster in U.S. history.”

As many as 18,000 people would die, 735,000 would lose their homes, and up to 100,000 tons of debris would be generated. The total economic loss would be as high as $252 billion.[6]

A 7.5 quake on this fault in the center of urban Los Angeles could be so intense it would lift heavy objects in the air, like the 1989 Loma Prieta Earthquake in Northern California, where shaking was so bad, “We found an upside-down grand piano,” seismologist Lucy Jones told the Los Angeles Times.[7]

A quake of that magnitude would “hit all of downtown and everywhere from La Habra to Hollywood,” Jones said.

The United States Geological Survey presented similar projections, noting that Puente Hills’ destructive power is five times that of the San Andreas. A 7.5 magnitude Puente Quake would cause the same destruction as an 8.0 on the San Andreas – with an 8.0 releasing 16 times the energy of a 7.5

The Puente Hills fault runs about 25 miles through the Los Angeles Basin, from downtown L.A., through La Mirada, creating a cross-stitch pattern under South Gate, Downey, Norwalk, and surrounding communities extending into Orange and San Bernardino counties.

The 6.0 magnitude Whittier Narrows earthquake (1987) was what led to this discovery. This was followed by quakes in Chino Hills (2008), Pico Rivera (2010), and La Habra (2014).

A team of scientists from Harvard, USC, and the University of California, Los Angeles, in 2017 produced a report showing accelerating slip rates along this fault.

“This increase in rate implies that the magnitudes and/or the frequency of earthquakes on this fault segment have increased over time,” the report concluded. “This challenges the characteristic earthquake model and presents an evolving and potentially increasing seismic hazard to metropolitan Los Angeles[8].

Other calculations for Southern California include: $49 billion from a 6.9 magnitude quake on the Newport-Inglewood fault; $30 billion from a 7.1 magnitude event along the Palos Verdes fault; $29 billion from a 6.8 event on the Whittier fault; and $24 billion for a 6.7 event on the Verdugo fault.[9]

Major reasons the USGS put L.A. County at the top of annualized earthquake loss has to do with the population density, the types of buildings located here and the likelihood that they may be damaged when a major quake strikes.

Deadly faults

California has always feared the mighty San Andreas – an earthquake fault stretching from the Salton Sea north to Eureka.

It was the cause of many of the state’s most devastating quakes:[10]

  • 1857: A 7.9-magnitude quake stretching 220 miles in Southern and central California.
  • 1906: The infamous 7.8-magnitude San Francisco earthquake, rupturing along 270 miles, killing 3,000 and sparking devastating fires.
  • 1989: The devastating 6.9-magnitude Loma Prieta earthquake near Santa Cruz, which damaged much of San Francisco as well.

If a 7.8-magnitude earthquake were to strike along the San Andreas Fault in Los Angeles today, one in every 16 buildings in the region would be damaged, according to the U.S. Geological Survey.[11]

That’s 300,000 structures.

Other USGS projections for this scenario include[12]:

  • 800 deaths
  • 50,000 injuries
  • $213 billion in property and infrastructure losses
  • 121,339 displaced households (3.5 million individuals)

This USGS “ShakeOut” study anticipates that at least five pre-1994 steel moment-frame high-rise buildings would collapse under this scenario, with about 5,000 people inside them if the quake strikes during regular business hours. As many as 50 low- and mid-rise concrete moment-frame buildings would collapse, and 900 unreinforced masonry buildings would be irreparably damaged.

Los Angeles has suffered under other seismic faults – most notably, the Northridge Blind Thrust Fault (discovered following the devastating quake of 1994), and the 1971 Sylmar quake along the Sierra Madre fault.

The threat of these faults, coupled with L.A.’s densely concentrated areas of aging buildings, makes the city especially vulnerable to earthquakes.

A recent Stanford University study found that older buildings that predate modern codes are “by far the dominant source of natural-hazard risk today…These results show that society can cost-effectively protect itself from natural hazard risk in multiple ways, both by mitigating past problems and by preventing future ones.”[13]

Many West Coast cities, from San Diego to Seattle, recognize the economic value of preserving structures by retrofitting them in a manner that will safeguard them during an earthquake. Financial incentives such as density bonuses, reductions in development standards and relief from nonconforming provisions can incentivize building owners to perform upgrades that promote building safety and revitalize communities for greater economic impacts.

Resilience isn’t just good for society, it’s good for business.

Learn more at our webinar series

Optimum Seismic has teamed up with a coalition of leading business organizations and government officials to launch a monthly webinar series, “The Resilience Advantage,” to help educate communities about the threats they face and the approaches to take to avoid social and economic disaster.

“We know that earthquakes can have devastating impacts on vulnerable buildings, people and our economy, but they don’t have to be disasters,” explained U.S. Resiliency Council Executive Director Evan Reis, who hosts the program.

The webinars explain why investing in resilience is good economics, good business, responsible public policy, and good for the environment.

Each episode in the webinar series features a panel of national experts addressing risks, building safety, social concerns, and business and economic impacts.

Partners in the series include the Los Angeles Area Chamber of Commerce, Los Angeles County Economic Development Corporation, Los Angeles County Business Federation and U.S. Resiliency Council.

Upcoming webinars will be held from 11 a.m. to 12:30 p.m. on the following dates, with others planned throughout the year:

Feb. 17:  Benefits of Resilient Communities.  Episode champions are California Building Officials and Long Beach Chamber of Commerce.

March 17:  Earthquake Retrofits Safeguard Existing Buildings.  Episode champions are Los Angeles County Business Federation and Los Angeles Conservancy.

April 21:  Sustainability and Resilience – a Natural Connection.  Episode champions are United States Green Building Council Los Angeles and Los Angeles Conservancy.

For more information, visit optimumseismic.com/the-resilience-advantage. Past webinars are also posted there for those who missed any of the series.

What will happen when the next major earthquake strikes urban Los Angeles? And what is being done to boost community resilience to them?

Much of society has embraced resilience, recognizing that the strength of the built environment affects the physical, economic, and social well-being of communities by preserving lives, property, investments, business continuity, public services, and communities’ fiscal stability.

Commercial and industrial building owners and managers, architects, attorneys, business owners, builders, community leaders, engineers, lenders, and many others are among those expected to benefit from information presented in The Resilience Advantage webinars.

Find out more by tuning into the webinar series.

Visit optimumseismic.com for more information, or call us at 323-978-7664.

Ali Sahabi, a licensed General Engineering Contractor (GEC), is an expert in seismic resilience and sustainability. He is Co-Founder of Optimum Seismic, Inc., which has completed more than 3,500 seismic retrofitting and adaptive reuse projects for multifamily residential, commercial, and industrial buildings throughout California.

[1] The Hill, FEMA announces the riskiest counties in the U.S., https://thehill.com/changing-america/resilience/natural-disasters/532512-fema-announces-the-riskiest-counties-in-the-us

[2] The Weather Channel, https://weather.com/news/news/2021-01-04-fema-national-risk-index-riskiest-counties-in-the-us-los-angeles-new-york

[3] The Hill, FEMA announces the riskiest counties in the U.S., https://thehill.com/changing-america/resilience/natural-disasters/532512-fema-announces-the-riskiest-counties-in-the-us

[4] Ibid.

[5] Vox, California’s August Complex ‘gigafire’ breaks record, https://www.vox.com/2020/10/5/21502397/august-complex-gigafire-wildfire-california-record

[6] University of Southern California, “Loss Estimates for a Puente Hills Blind-Thrust Earthquake in Los Angeles, California,” Edward H. Field, et. al., 2005.

[7] Ibid.

[8] Geo Science World, “Accelerating slip rates on the Puente Hills blind thrust fault system beneath metropolitan Los Angeles, California, USA. Kristian Bergen et al, 2017.

[9] CBS News, Puente Hills Fault Could be Disastrous, https://losangeles.cbslocal.com/2014/03/30/7-5-quake-on-puente-hills-thrust-fault-could-be-disastrous/

[10] Wikipedia, San Andreas Fault, https://en.wikipedia.org/wiki/San_Andreas_Fault

[11] United States Geological Survey, https://pubs.usgs.gov/of/2008/1150/

[12] USGS, https://pubs.usgs.gov/of/2008/1150/

[13] Stanford University Urban Resilience Initiative, http://urbanresilience.stanford.edu/