I moved to the San Francisco Bay Area in 1983 and like most newbies, couldn’t wait to experience my first earthquake. With no idea what to expect, my emotions ranged from apprehension to intense curiosity. I didn’t have long to wait – three months after we arrived, I boarded a plane to fly to a conference in Los Angeles. Within seconds of the wheels leaving the ground, a voice came over the cabin speakers stating, “This is the Captain speaking. The Bay Area just experienced an earthquake – we’ll keep you updated as we get more information.”

In the immortal words of Maxwell Smart, “Missed it by THAT much …”

Since then I’ve weathered many temblors and have grown “accustomed” to the ground moving from time to time. It’s the simple reality for those of us who’ve lived here a while and gone through events such the Loma Prieta Quake. The moving and shaking is an integral part of living in one of the best spots on the globe.

Newcomers, however, have many concerns about buying a home in an earthquake zone.

And rightly so. For many buyers, it’s the great unknown, especially since fault zones crisscross the Bay Area. The recent shaker on the east coast coupled with the devastating quakes in Japan and Haiti have heightened buyer paranoia. As a result, local Realtors are frequently asked about earthquakes and many don’t know where to go to provide accurate information. Consequently, many buyers are afraid to buy a home close to an established fault.

They reason that the closer you get, the higher your chances of losing your home in a major seismic event. I’m not sure that’s true.

In 1989, the Loma Prieta earthquake rocked the Bay Area. The epicenter of the quake was in Forest of Nisene Marks State Park in Santa Cruz County, an unpopulated area in the Santa Cruz Mountains approximately 2–3 miles (3–5 km) north of unincorporated Aptos and approximately 10 mi (16 km) northeast of Santa Cruz.

You’d assume the worst damage would have been at the epicenter. You’d be wrong. While it’s true that nearby San Cruz suffered severe damage, the most notable devastation was over 70 miles away. When the shaking was done, the Marina area of San Francisco had sustained major destruction, the upper section of the I-880 Cypress Freeway Viaduct section in Oakland had collapsed, crushing numerous cars and their occupants on the lower section, and an upper section of the Bay Bridge had fallen to the deck below.

There are numerous faults impacting the Bay Area. Since the San Francisco East Bay sits right on top of the Hayward Fault, running from Fremont northeast up through Richmond and into the bay, I’m frequently asked about earthquake safety in relationship to the Hayward Fault. Although I can’t give a definitive answer, I do have some opinions.

If past earthquakes affecting the Bay Area have taught us anything, it’s that a serious shaker will affect areas far away from the epicenter.

Therefore, if there’s a significant quake on the Hayward Fault, it’s a fair bet that it, like the Loma Prieta event, will affect locales at least 70 miles away. If you draw a 70 mile radius circle on a map using the center of the fault (San Leandro) as the center, it will impact THE ENTIRE BAY AREA, not just the Central County.

Concerned about a specific fault (such as the Hayward Fault) and its impact on your potential purchase?

Here are FIVE critical things to understand:

1.    Understand the Impact Radius.

If you are genuinely concerned about earthquakes and the potential impact on your home, you might consider looking to buy somewhere outside the 70 mile radius of any fault that provides you with concern. And therein lays a significant problem: because this is California, that could easily put you inside the radius of another fault. Thinking you might be safe outside California? The recent quake on the east coast has shown us a simple fact: earthquakes aren’t just limited to the west coast of the United States. They can hit anywhere.

2.    Understand the Building Implications.

Earthquakes typically don’t kill, but man-made structures do. For Bay Area residents, earthquakes are a ‘routine’ part of our day-to-day existence. We understand that our local homes can be affected based upon the type and severity of the temblor. While a short, sharp jolt might rattle your teeth and knock items off walls and shelves, a long rolling quake may not feel as severe but it could literally push homes off their foundations.

Older Bay Area homes have little or no seismic protection as originally built. In reality, some still aren’t anchored to their foundations – I found one just last week – a darling Oakland bungalow built in 1925.  To protect Bay Area residents, upgraded earthquake-resistant building codes have been factored into home designs over the past 30-40 years.

The newer the home, the better the codes and the better the protection from earthquakes.

One of the changes is to build homes on concrete slabs instead of having elevated foundations and cripple walls. When the Loma Prieta quake hit in 1989, I was living in a 1978–era home built on a slab. I felt the entire house move up and down and watched in amazement as every interior door opened and shut, opened and shut until the shaking subsided. I did a quick check after the event was done and discovered that there was no measureable damage of any kind to my home.

California is working hard to beat earthquakes. Located in Stockton, California, the Tyrell Gilb Research Lab is actively designing and testing earthquake resistant structures. Opened in July, 2003, it is designed to perform large scale systems testing. Their quake simulator shakes structures up to 3 stories tall and 25 feet long. Shear wall systems can be tested to 5 stories in height and 50 feet in length. Their motto is, “One test is worth a thousand expert opinions.” In July, 2009, they tested a full-scale, seven-story wood-framed condominium tower in a simulated 7.5 magnitude earthquake. It not only survived, but escaped the test with barely a scratch. This unprecedented research highlights the importance of earthquake-resistant construction, and will ultimately improve the construction and safety of wood buildings in the U.S. and around the world.

Everything learned in the Stockton facility goes into the statewide Universal Building Code to ensure that all new homes built in California have the best protection possible.

I recommend that you make yourself aware of the level of seismic protection in your home. If you live in an older home, start with a property inspection by a qualified seismic specialist. Based on their report, you may want to consider upgrades. At the very least, ensuring that your property is bolted to its’ foundation. Cripple walls? Consider reinforcement. Cracked foundations? Have them repaired. Since this is an active seismic zone, there are many contractors here in the Bay Area specializing in seismic upgrading.

Want to make upgrades on your own? There is a tremendous resource provided by the Association of Bay Area Governments (ABAG). They provide a complete Standardized Plan Set designed to help homeowners upgrade the seismic readiness of their homes. Their website states, “This plan set is a standard for strengthening homes to better withstand earthquake shaking. When approved by the local building official, the plan set may be used to strengthen older homes without the need for an engineer to develop costly site-specific plans and design calculations. This plan set provides a low-cost method to help improve an older home’s chances of surviving an earthquake.”

You can even take seminars at the Building Education Center to learn how to seismically upgrade your home (See Seminar #7 – taught by Engineer Tony DeMascole and Retrofitting Contractor Jim Gillett).

3.    Understand Liquefaction

If you’ve ever purchased a home in California, you’ll see a section in the Natural Hazards Disclosure showing the level of liquefaction for your home. It’s defined by the USGS in the following way:

“Liquefaction takes place when loosely packed, water-logged sediments at or near the ground surface lose their strength in response to strong ground shaking. Liquefaction occurring beneath buildings and other structures can cause major damage during earthquakes. For example, the 1964 Niigata earthquake caused widespread liquefaction in Niigata, Japan which destroyed many buildings. Also, during the 1989 Loma Prieta, California earthquake, liquefaction of the soils and debris used to fill in a lagoon caused major subsidence, fracturing, and horizontal sliding of the ground surface in the Marina district in San Francisco.” (Click here for a Liquefaction Flash Animation)

Homes built in areas with higher liquefaction potential are at greater risk for damage during a major seismic event. For this reason, California State law mandates that every real estate transaction for any home (4 units or less) be accompanied by a Natural Hazards Disclosure. These disclosures ensure that potential buyers are informed about seismic hazards and potential liquefaction zones.

4.    Understand Your Insurance Options

And then there’s the matter of insurance. Thinking that your homeowner’s insurance policy covers earthquakes? You’d be wrong. You might also assume that everyone living in an active fault zone would have an earthquake policy. Again, you’d be completely wrong. In reality, it’s estimated that less than 10% of Bay Area owners have quake insurance. While very costly and with a high deductable, if you are concerned about an earthquake’s potential to damage your home, it’s an option you want to consider.

5.    Understand the Truth

Informed buyers are those who take the time to research all the facts before buying. It’s critical you do so – there are many urban legends out there and outright fantasies as well. The USGS (U.S. Geological Survey) has conveniently provided a site designed to differentiate between fact and fiction (Click here to access the site). And read the Natural Hazard Disclosure provided by the seller of any home you are interested in – the information in the report will be the most accurate and up-to-date data available (as long as the report is current – if it’s older than 6 months old, ask for an updated version).

The next quake? It’s truly not a matter of if it will happen, but when. Since no one knows when or where it will hit, we have some practical advice:

Prepare now so that when the shaking is over, you AND your home are left … STANDING.

Important related websites:

USGS Earthquake Site

Bay Area earthquakes within the past week

Latest Earthquakes in the World - Past 7 days

Association of Bay Area Governments (ABAG): Earthquake and Hazards Programs

Association of Bay Area Governments (ABAG): Seismic Upgrade Standardized Plan Sets

Association of Bay Area Governments (ABAG): Liquefaction Maps and Information

Tyrell Gilb Research Laboratory Video Library

List of other Earthquake Websites

California Geological Survey Web Site

California Geological Survey - Alquist-Priolo Earthquake Fault Zones

QuakeInfo.org

California Seismic Safety Commission

CGS: Interactive Seismic Hazards Zone Map

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