On February 28, 2023, and in the wake of the devastating earthquakes that rocked the country of Turkey just a few weeks prior, the Los Angeles County Board of Supervisors voted unanimously to require the retrofitting of older, so-called “non-ductile concrete” buildings that are at a high risk of collapse during a powerful earthquake. The U.S. Geological Survey has said that such buildings “pose the greatest risk to life safety” and that the collapsed of even a single large concrete building can not only take many lives, but also devastate an entire city’s economic core for a generation or more.
What are “non-ductile” buildings?
Buildings that are “non-ductile” are those considered to be so brittle and prone to collapse, that their method of construction has literally been banned since the 1980s. Such buildings are deficient because an inadequate amount of steel reinforcement bars was used in the construction of their concrete frames and columns, and this flaw allows concrete to explode out of columns shaken during an earthquake, which can lead to a catastrophic collapse. This same non-ductile flaw was the cause of the collapse of freeways in the 1989 Loma Prieta and the 1994 Northridge earthquakes.
Despite the knowledge of how unsafe such buildings may prove to be in a strong earthquake, local governments have traditionally done little to evaluate and strengthen such buildings, including those owned by the County of Los Angeles. For example, a Los Angeles Times investigation published in 2013 explained how the City of Los Angeles knew for decades about the flaws in the construction of non-ductile concrete buildings, yet did little to address such flaws. Following up on the investigation, Mayor Eric Garcetti proposed, and the City Council approved, a law requiring property owners in Los Angeles to retrofit non-ductile concrete and soft-story buildings.
What will happen after the Board of Supervisors vote?
The Board of Supervisors has now directed its public works staff to draft an update to the County’s building code, that would require retrofitting non-ductile buildings within 10 years, if they are located in unincorporated areas or those areas owned by the County. The code update would require owners of such buildings to submit structural evaluation reports within three years, and building plans to retrofit or demolish such buildings within five years.
Importantly, County Supervisors also ordered officials to create an inventory of all so-called “soft-story” residential buildings in unincorporated areas, as well as those areas owned by the County. Such buildings are also considered weak and potentially unsafe during an earthquake. While the Supervisors stopped short of calling for a mandatory retrofit program for soft-story apartments, local governments have sometimes ordered such an inventory first, as a prelude to a mandatory retrofit order.
Why the sudden urgency to retrofit now?
The Board of Supervisors opined that the County must insist on a renewed urgency to retrofit and repair non-ductile vulnerable structures, as a recent USGS simulation showed that a magnitude 7.8 earthquake in Southern California could cause 50 such buildings to collapse with as many as 7,500 people in them.
It was the collapse of two such non-ductile concrete buildings in the 2011 Christchurch, New Zealand earthquake that caused the vast majority of the deaths in that unfortunate event. Of the 185 people who died in the New Zealand earthquake, 133 died in the collapse of only two non-ductile buildings.
Will the County support property owners who can’t afford to retrofit?
County Supervisors have asked County officials to identify programs that may support property owners with the cost of such seismic retrofits, including zero-interest loan programs, and subsidies for low-income homeowners. One such program already exists, namely the Earthquake Brace + Bolt Program, which helps homeowners retrofit their homes at no cost by providing free government assistance for doing so.
Top seismologists and building scientists all agree that there now is an urgent need to retrofit residential and commercial properties in the County of Los Angeles and safeguard such buildings from the destructive forces of earthquakes. Property owners should prepare today for the real and very imminent threat of seismic activity. If you wish to discuss or schedule a free inspection of your property, call us at (800) 862-6582. Be prepared and have peace of mind when the next “Big One” hits!
City News Service, “LA County Moves Toward Requirement for Seismic Retrofit of Older Buildings”, February 28, 2003.
Los Angeles Times, “L.A. County moves to require quake retrofits as Turkey-Syria death toll exceeds 50,000”, Rebecca Ellis, Rong-Gong Lin II, February 28, 2023.