Southern California’s mountain ranges are a regional treasure, providing a spectacular backdrop to the communities that make Greater Los Angeles their home.
These natural beauties are the result of a complex web of earthquake faults – ranging in length from less than a mile to hundreds of miles long – crisscrossing our region with the ability to shake the ground with reverse fault, thrust fault, strike-slip, and normal forces that can shatter lives and communities without warning.
An untold number of these lurking threats lie dormant underground. Undetected, until disaster strikes.
New faults are marked in purple. The red areas indicate active deformation zones. (Credit: Temblor.com)
A series of these “sleeping giant” faults was recently discovered in the Long Beach/Seal Beach region – thankfully without having unleashed their destructive force.
Scientists at 3D Seismic Solutions, working with researchers at Caltech, discovered a particularly active fault and other smaller faults in the Southern Cities region, according to Temblor, a catastrophe modeling company. (Visit https://temblor.net/earthquake-insights/newly-identified-fault-in-seal-beach-ca-quietly-rattles-beneath-the-city-13477/ to read the report.)
The faults form a ladder-like grid over the Harbor area and inland to Cal State Long Beach, with a series of rungs crossing at the Los Alamitos Channel and north up to Pacific Coast Highway.
Microsensors were used to measure ground movement and detect 3,000 micro-earthquakes within an eight-week period, suggesting that the primary fault discovered was active.
Understanding the complex structure of the subsurface and the location of these faults is critical to assessing potential earthquake risks, Temblor reported. To date, the only identified fault in the Seal Beach area had been the Alquist-Priolo zone along the Newport-Inglewood fault.
These new seismic findings show there are additional near-surface faults, some of which are active.
Liquefaction presents a second threat to this region of newly identified faults.
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 the extent of work that should be done – so you can start planning to protect yourself in the future.
What types of buildings are most vulnerable?
- Pre-1978 soft-story structures (featuring parking on the ground floor with units built above)
- Pre-1933 unreinforced masonry buildings
- Pre-1980 concrete tilt-up buildings
- Pre-1977 non-ductile concrete structures
- Pre-1996 steel moment frame buildings
If you think your apartment building may be at risk of damage in an earthquake, call Optimum Seismic at 833-978-7664 to arrange a complimentary evaluation of your building.
