-Appeared on San Diego County Apartment Association (SDCAA)

San Diego is earthquake country.

The region’s mountains and many of its valleys were formed by the San Andreas fault system— the tectonic boundary between the Pacific and North American tectonic plates, which run to the east of the county from the Gulf of California through the Salton Sea and into L.A., according to the California Earthquake Authority.

Do you know the risks you face from earthquake damage?

Photo Credit to The Weather Channel

This fault is known to cause powerful earthquakes as big as magnitude 8, and can also generate strong shaking levels right here in San Diego.

The Rose Canyon fault runs along the coast and beneath downtown San Diego. Geologists say this is the biggest earthquake threat to San Diego, capable of earthquakes of magnitude 6.5 to 6.8. Likewise, the Elsinore and San Jacinto faults cut through East County and can also generate moderately-sized but potentially damaging earthquakes.

What makes your building vulnerable to earthquakes?

Earthquake vulnerabilities are determined by a number of factors.

These factors include your apartment building’s proximity to a local fault; its architecture (soft-story, unreinforced masonry and non ductile concrete are the most vulnerable apartment buildings, depending on the year they were built); the composition of the soil your building was constructed on; and the topography surrounding your building.

Proximity to a fault

The closer your building is to an earthquake fault, (Rose Canyon, Elsinore or San Jacinto), the more likely it is to suffer damage from seismic activity.


Your apartment’s building type is a major factor in determining earthquake risk. Structures most vulnerable to earthquake damage include pre-1978 soft-story or “dingbat” apartments; pre-1975 unreinforced masonry buildings; pre-1994 concrete tilt-up buildings; pre-1977 non-ductile concrete structures; and pre-1996 steel moment frame structures.

Soil composition

The type of soil your structure is built on has a significant impact on how seismic waves impact the building. Soil liquefaction occurs when water-saturated earth loses its strength and stiffness due to ground-shaking of an earthquake. Simply put, the shaking causes the ground to move and slosh like liquid, putting structures above it at great risk.


A landslide zone indicates a higher likelihood of an earthquake-induced landslide that could result in property damage by either compromising the foundation of a structure, or having earth from above slide into an adjacent property.

“When the ground breaks under an existing building, there’s a higher chance that the building will collapse,” Tim McCrink, supervising engineering geologist and program manager for seismic hazards for the California Geological Survey once told the Los Angeles Times.

What are the benefits of a seismic retrofit?

If your apartment building was constructed in the 1970s or earlier, it is probably not up to the latest seismic safety codes. A seismic retrofit can help to:

  1. Protect your building’s equity: Avoid damage that could reduce its value.
  2. Guard against liability: Demonstrate reasonable care to protect your property and your tenants.
  3. Preserve a building’s cash flow: Protecting your building means your tenants will be able to continue living there and paying rent after a major quake.
  4. Avoid demolition costs: Demolition of a building can cost $10 a square foot or even more, particularly if hazardous materials such as lead or asbestos are present.
  5. Qualify a structure for earthquake insurance: Many apartment owners are now opting for earthquake insurance, which can sometimes help to cover costs associated with reconstruction and loss of income following a quake. Most carriers require retrofits of older buildings before they will cover them.

Most apartment owners have worked very hard for their property. It’s what they rely on for their retirement, and it’s definitely in their best interest to protect it.

Keeping yourself informed about the potential risks of earthquakes not only to your building, but to your own financial well-being is something that all California residents should follow. Optimum Seismic will provide free seismic retrofitting consultations to help get you started.