Where are Santa Clara County's Earthquake Faults and Flood Plains_Earthquake faults and flood plains are of interest to home buyers throughout the Golden State and to their lenders, too. Part of the home sale and home buying process is to provide information on these risk factors so that consumers (and their lenders) can make an informed decision.

Natural Hazard Reports are included in the disclosures when homes are bought and sold here in Silicon Valley. Those reports will indicate whether or not the property is located in areas with known natural hazards, including

  • Flood Plains (100 and 500 year floods from heavy rainfall)
  • Liquefaction Zones
  • Earthquake Fault Zones
  • Unstable Soils Areas (landslide areas)
  • Flooding from dam failure zones

But wouldn’t you like to know where those places are before ever deciding where to target your next home?

Mapping Earthquake Faults and Flood Plains

You can! There are loads of tools online, including the Cal My Hazards Awareness Map, which is my go-to resource for many of the zones. This shows the state mapped fault zones, but NOT the county mapped ones.

The county mapped fault zones, such as the Shannon Fault, will be listed in a Natural Hazard Disclosure link (though they may not always name the fault, only state that one is there).  You can also view a PDF of the county mapped geologic sites from this page on the Santa Clara County website (the map is about 30 MB btw). It’s a bit of a pain – you must download it and then read it using Adobe Acrobat to click-through make the various “layers” of natural hazards visible on each page. Give yourself time, it is a slow process for accessing this information! In addition, the latest update to this map (as of this writing) was in 2012.

Another excellent site from the California Department of Water Resources provides Inundation Maps to let you know where flooding may take place from dam failure.

After doing some research on areas, you may want more information on how to mitigate the danger from seismic threats. There’s a booklet for that which is free: The Homeowner’s Guide to Earthquake Safety & Environmental Hazards. This info is so important that it is required that buyers be given it in escrow or before.

For sellers, it is crucial to understand any local hazards. If your home appears to be in a liquefaction area or flood plain, you need to know that the public may be eliminating your home for that reason. If that is bad info, you need to get the word out so that buyers don’t write off your home or worry about it when there may not be a concern. Or if your home is in a flood plain or fault zone, you need to realize it so that you get your home marketed appropriately, understanding that this could be impacting your market value.

Barclay’s Locaide County Map Books

The tool I miss most for my clients is the Barclay’s Locaide, which is almost impossible to find now and long out of publication.

Many of us Realtors used to utilize it pre-GPS to find our way to homes and neighborhoods, but also to know which zip code it was in, which school district, which MLS area, and of course which natural hazard zones, if any – all in one binder.  On any given page, it shows all of the natural hazard zones, including earthquake faults and flood plains, but not liquefaction zones which are shown on a county wide map at the front of the book. The front of the book also had county view pages showing the county and state mapped earthquake fault zones, unstable soils areas, etc. 

The Barclays Locaide, which I believe was last printed in 2006, is difficult to find now but may be available in Realtor Board stores. As of this writing, it does not appear to be available to buy online, but keep checking just in case. A while back I found a used one that had been printed in 2000 – so they do show up sometimes.


Barclays locaide sample of what is included - displays Earthquake faults and flood plains


The bottom line is that the info is all out there, but it may be piecemeal. The best solution is to have a great Natural Hazards Disclosure report for the property you want to buy or sell. But for buyers before you locate the right house, you may want to target neighborhoods for house-hunting. That’s where those locaide maps, or the many various online tools, are helpful.