Earthquake Fault Debate Impacts New and Older Construction

Industry News,

Should new construction be allowed on top of live earthquake faults? And, if not, what about the thousands of structures already perched upon these fearsome fissures? These are questions playing out in Hollywood and other parts of the Southland today, where a worrisome weave of active faults snakes its way through our communities.

About seven years ago, the City of Los Angeles put a stop to plans to build a pair of towering skyscrapers next to the Capitol Records building near Hollywood and Vine. The reason? An active fault – capable of triggering a magnitude 7 earthquake – ran directly underneath the site, according to the United States Geological Survey. The project developers of these 46- and 35-story giants have fought back, insisting that there is no active fault lurking below the site. Today, they are busy trenching underground to analyze the geological makeup of the earth below to prove – or disprove – that theory. This a scenario that plays out frequently in our earthquake-prone landscape.

“When a fault was discovered below a school site near Downtown Los Angeles, officials tore down a portion of the new school and reserved the area over the fault as a park. Buildings found to be on top of faults at Los Angeles Southwest College and San Bernardino Valley College have been razed; shopping center in Huntington Beach was demolished and rebuilt to avoid an earthquake fault. And in a suburb of Long Beach, developers took painstaking care to avoid building new homes atop a fault in Signal Hill, and instead put in a road, tennis courts and parking lots atop or around the fault,” the Los Angeles Times reported in April.

There are more than 500 active earthquake faults in California, according to the state Earthquake Authority. Apart from the mighty San Andreas and more recently discovered Puente Hills faults (both of which I have written about recently), there are more than a hundred smaller active faults in the Greater Los Angeles region, such as the Northridge, Raymond, Santa Monica, Hollywood, Newport-Inglewood, San Jacinto and Elsinore faults – many of which have triggered devastating disasters in the past.

A Matter of Local Concern

California law bans construction on live earthquake faults in most cases. Yet there are no statewide requirements for structures already perched upon them. Many cities, instead of focusing on active fault lines, consider the types of structures most vulnerable to earthquake damage when contemplating policies to make those structures safer. (Visit for list of these structures.)

Los Angeles, San Francisco, and Berkeley require seismic retrofits of structures proven to be at risk of failure or collapse in a major earthquake – not just along fault lines, but throughout their cities. Other cities provide guidelines that owners can decide to follow – or not. Buildings constructed farther from seismic faults may still be at risk. Damage happens more widely because of the jolting or rippling seismic waves that move across the landscape with tremendous ferocity.

Existing Buildings Also at Risk

If California bans new construction atop any earthquake faults, why are there no uniform regulations regarding existing buildings? This is where the responsibility for public safety and accountability falls in the hands of local government – and the building owner. Not building a skyscraper – or two – directly over an active earthquake fault is a matter of prudent precaution. But it is equally important to consider the vulnerability of structures farther from the fault – typically older commercial buildings constructed before the early 1980s.

Find out about the risks your apartment building may face with a complimentary building evaluation from Optimum Seismic. Visit or call (833) 978-7664. The fate of your building is in your hands.

Ali Sahabi, a licensed General Engineering Contractor (GEC), is an expert in seismic resilience and sustainability expert. 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.