Burt M. Polson | Napa Valley and Vallejo's Commercial Real Estate Broker

Guiding you through the real estate part of your life™

Commercial Sales, Leasing and Consulting

Private Equity Syndication

Napa Valley and Vallejo, California

Shaking up real estate values with the new fault maps - part 1


I recall going on a run at Alston Park in Napa after the earthquake to find a six-inch crevice that opened up across several trails. Previously living in Browns Valley in Napa I pinpointed the location of my former home on the new Alquist-Priolo earthquake fault zone map to find the house is now within the yellow block signifying it lies within the earthquake fault zone. I am thankful I sold when I did.

When I purchased the home, I suspected the fault was in the area of Century Oaks Park based on previous maps, so I always had bought earthquake insurance. I sold the home back in 2011 and had never experienced an earthquake in that house.

The California Geologic Survey administered by the State of California Department of Conservation released the final earthquake fault maps for Napa County as part of the Alquist-Priolo Map Act.

The 6.0 magnitude earthquake in Napa on August 24, 2014, revealed more of what geologists knew as the West Napa Fault. Not all of the fault ruptured, but it was found to be much longer and fragmented than initially thought.

It was well known the fault ran through American Canyon based on a study back in 1977. The newly released maps are now able to confirm not only the location of the fault but how far it extends north and south.

The Alquist-Priolo Earthquake Fault Zoning Act was established in 1972 to prevent development within the area of a fault. The Alquist-Priolo Act restricts the placement of structures for human occupancy, such as commercial or residential buildings, near or on active fault traces. Other facilities such as roads, utilities or parking areas are not subject to this restriction.

If you find your home or commercial property is within an earthquake fault zone the first thing you should do is secure the structure to the foundation and install cripple walls. Next, ensure the items within are secure and be prepared for the next earthquake with supplies as well as having emergency measures in place. At the same time purchase earthquake insurance.

Unfortunately, land and building values could be affected depending on the proximity of the property to an earthquake fault zone.

The value could be affected if your home is now found to be within an earthquake fault zone like my previous home. I could have seen a decrease in value if I were to attempt to sell the home after the 2014 earthquake or now after the determination of it being in the fault zone.

Some buyers may be apprehensive to purchase a home which lies in a fault zone when other comparable houses exist on the market not in a fault zone. So, a slight reduction in the price may be warranted to compensate for this potential detriment in the eyes of some buyers.

In part 2 we will examine a case study of a new apartment development in American Canyon that has the fault line running directly through it.

Burt M. Polson, CCIM, is an active commercial real estate broker. Reach him at 707-254-8000, or burt@acresinfo.com. Sign up for his email newsletter at BurtPolson.com.

An ACRES Real Estate Services, Inc. Company