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Earthquake Retrofitting

California’s cities are getting ready for the next major earthquake – Los Angeles is set to have the toughest earthquake safety standards in the whole nation, while Santa Monica is about to take on a massive retrofitting effort.

Seismic retrofitting

Los Angeles County, Santa Monica, West Hollywood and Beverly Hills have adopted or are in the process of adopting city ordinances that mandate earthquake retrofits for specific buildings.

An estimated 100,000 buildings are facing seismic retrofitting mandates in Southern California as more cities follow suit. Cities in Northern California are taking similar measures.

About 13,500 buildings are due for a retrofit in LA. So far, 1,200 engineering plans have been submitted to the city while 125 buildings have undergone complete retrofitting so that they can better withstand earthquakes.

While the figures seem low, it is important to note that retrofitting is a lengthy process that involves multiple reviews and steps before construction can even begin. The process of getting engineering plans approved by the city has turned out to be quite slow, although a special unit has been tasked to oversee the whole retrofitting process.

Moreover, the city is still sending out notices to property owners affected by the new retrofitting laws.

In Santa Monica, over 2,000 buildings have been tagged for seismic evaluations and earthquake safety improvements.

LA has singled out pre-1978 wood-framed soft-story buildings as posing the most risk for the loss of life during a major earthquake. Owners of such buildings have two years from the date they receive a notice to comply to submit engineering plans.

Meanwhile, Santa Monica has required not only concrete and wood-frame buildings to undergo retrofitting, but steel-frame structures as well.

Earthquake-prone areas

A World Geological Survey predicted that there is more than a 99% likelihood that the state will be struck with an earthquake that ranks higher than a 6.7 magnitude within the next 30 years.  

In 2016, a study by the University of Hawaii Manoa also found that the state was at risk for a major earthquake. The San Andreas Fault – which has been responsible for some of the most devastating earthquakes in U.S. history, most notably the 1906 San Francisco earthquake – runs through a large portion of the state.

A newly mapped fault, the Salton Trough Fault, runs parallel to San Andreas. The fault was discovered in 2016 after a series of small earthquakes shook the Colorado Desert and sparked fears of a bigger earthquake.

Experts also believe that the Cascadia Subduction Zone, a 600-mile fault that cuts through Northern California all the way to British Columbia, has the capacity to unleash a much more devastating earthquake than the San Andreas Fault – one that could hit 9.0 on the Richter Scale.  

The challenges of seismic retrofitting

There isn’t a one-size-fits-all solution for retrofitting buildings. Even two buildings that seem identical will have various underlying conditions that affect how well they hold up during an earthquake. These include the building’s overall structure, materials, the quality of the soil on which it stands and even the placement of doors and windows.  

Building owners have expressed concern over having to pay for their tenants to relocate while retrofitting construction takes place on their properties. The City of Los Angeles Housing and Community Investment Department (HCIDLA) has said that tenants may stay in rental properties as long as construction efforts don’t make the building uninhabitable and that they will not be exposed to hazardous or toxic materials.  
For more information on mandatory retrofit programs in LA and Santa Monica, click here and here.