San Diego’s earthquake risk is significantly higher than previously thought, according to recent maps prepared by the California Geological Survey.

Recent information reveals the region’s fault zones are significantly larger and far-reaching than previously assumed – stretching along the Rose Canyon fault, an extension of the Los Angeles Newport-Inglewood fault, which runs from La Jolla down along the coast through the airport, beneath downtown San Diego and into Seaport Village.  The fault straddles the 5 freeway and branching out into other areas.

San Diego faces both the predictable – and unpredictable – potential natural disasters related to the Rose Canyon fault.. In a recent report, earthquake geologists and engineers say this fault is the biggest earthquake threat to San Diego, capable of earthquakes of magnitude 6.9

The recent EERI San Diego Earthquake Scenario study estimated that the region would experience $5.2 billion lost income, and 36,000 households would be displaced. The earthquake would ruin San Diego’s aging apartments and houses, adding to the crisis in affordable housing. Water, sewer lines and gas line services could be out for months. The I-5 transportation corridor as well as airport and rail services would be seriously affected by the rupture.

One of these new discoveries is a “blind-thrust” fault – the same type that triggered the 6.7-magnitude Northridge quake in 1994.

Blind-thrust earthquakes lie undetected beneath the surface of the earth, and while they are not necessarily the most energetic of faults – they are among the most destructive. Some local examples include the 1994 Northridge and 1987 Whittier Narrows earthquakes.

Seismic waves of blind-thrust faults are highly directed, and soil conditions can frequently lead to liquefaction, which increases ground motion significantly – thereby multiplying the potential for destruction.

And because of their invisibility – undetected until they strike, in most instances – they frequently lurk under densely populated areas making the risk to life, limb, and property significantly higher.

Are the odds in your favor?

There is a 99.1 chance that a killer quake – larger than anything we have known – will happen in our lifetimes, somewhere in California.  Could it strike here?

Seismologists believe that the Rose Canyon Fault has the capacity for a 7.0-magnitude quake.  And when it does strike, the damage caused is projected to be colossal: between $124 million and $13 billion.

In fact, the California Geological Survey ranks San Diego as one of the state’s top 10 areas for projected loss from an earthquake.

That threat, coupled with the region’s older housing inventory, puts San Diego at high risk – particularly for the following building types, which are proven to be more vulnerable to serious damage in major earthquakes:

  • Soft-story apartments built before 1978: These structures, with parking on the ground floor and units built above, are prone to collapse during major earthquakes.
  • Unreinforced Masonry built before 1975: The facades of these buildings can collapse in a quake.
  • Concrete Tilt-up built before 1994: Weak connections can fail and cause walls to pull apart from the roof resulting in collapse.
  • Non-ductile Concrete built before 1978: Limited lateral resisting capacity makes these structures brittle and subject to failure.
  • Steel Moment Frame built before 1996: These buildings can sustain brittle fracturing of the steel frames at welded joints between beams and columns.

San Diego apartment owners are urged to make sure their apartment buildings are ready for the major quakes experts say are coming. The Optimum Seismic team has the technical knowledge and professional experience necessary to do your earthquake retrofit right.  Visit optimumseismic.com or call 833 978-7664 to arrange a complimentary assessment of your building.