Is Your Building on Stable Ground? By Ali Sahabi

Is Your Building on Stable Ground?

BY ALI SAHABI

How vulnerable is your apartment to earthquake damage?

If it is located within a fault, landslide, or liquefaction zone, it may be at risk — and a combination of any of these could be disastrous.

Active earthquake faults in Orange County run along the coast and mountain ranges, hitting places such as Huntington Beach and Yorba Linda.

And the hillside communities of Laguna Beach, San Clemente and Santiago Canyon are prone to landslides that can be triggered in a major earthquake, potentially undermining the foundation of a home, or sliding into one.

Liquefaction areas can be found throughout the county, most notably wherever water flows either above or below the ground: In the aquifer-rich region of central and coastal Orange County, Garden Grove, Santa Ana, Irvine, Huntington Beach, and Yorba Linda, to name a few.

Liquefaction amplifies the impacts of seismic waves produced during an earthquake. The ground reacts like Jello-O: jiggling, undulating, and putting the structures built upon it in jeopardy.

The United States Geological Survey has published an interactive map online, enabling the public to search by property address to determine the earthquake risks associated with specific land parcels.

Properties located on or near a fault or liquefaction zone are particularly at risk of damage in an earthquake. Visit the California Earthquake Hazards Zone Application Map at https://maps. conservation.ca.gov/cgs/EQZApp/app/.

If your apartment building is the type proven to be vulnerable to earthquake damage, you should consider having an engineering study done to determine whether any retrofitting work should be done.

What types of buildings are most vulnerable?

• Pre-1978 soft-story structures (represented with parking on the ground floor and units built above) • Pre-1975 unreinforced masonry buildings • Pre-1980 concrete tilt-up buildings • Pre-1978 non-ductile concrete structures

• Pre-1996 steel moment frame buildings

Learn more about the impacts of earthquakes on community resilience by watching “The Resilience Advantage” — an ongoing webinar series featuring experts addressing risks, building safety, social concerns, and business and economic impacts associated with seismic resilience of buildings.

There is no cost to attend.

Optimum Seismic has teamed up with a coalition of leading business organizations and government officials to present information valuable to making informed decisions. We hope you can join us.

The next webinar highlighting the topic Sustainability and Resilience — A Natural Connection is from 11 a.m. to 12:30 p.m. Wednesday, April 21 — with others planned throughout the year. For more information, visit optimumseismic.com/the-resilience-advantage. Past webinars are also posted there for those who missed any of the series. For more information, visit optimumseismic.com or 323-978-7664.

Interactive USGS map lets you zoom in to see for yourself.

Credit: California Department of Conservation

About the Author: 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.