Los Gatos Weekly-Times
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The Real Deal
Seismic hazard maps are online
Anyone can go online to the website of the California Geological Survey to view and download seismic hazard maps that show areas in the Bay Area that are prone to liquefaction or landslides during an earthquake. Maps of Los Gatos, Palo Alto, Mountain View, Cupertino, San Jose and their surrounding areas are now available.
A seismic hazard map shows hazards from earthquakes that geologists and seismologists agree could occur in California. The analysis takes into consideration the uncertainties in the size and location of earthquakes and the resulting ground motions that can affect a particular site.
The maps are valuable for homeowners and Realtors since homeowners need to disclose whether their neighborhood is considered hazardous in an earthquake. Candace Hill, associate planner with the California Geological Survey, said the maps, which were released by the Seismic Hazards Zonation Program, are also important to developers. She said developers who plan to build in those zones must show how they can mitigate the earthquake hazards.
The Seismic Hazard Mapping Act was enacted by the California legislature in 1997, primarily as a result of the Northridge earthquake of 1994. The act requires the creation and publication of maps showing areas where earthquake-induced liquefaction or landslides could occur. It also requires a Standardized Natural Hazards Disclosure Statement form be completed by real estate sellers and agents at the time of sale of a property. This form must disclose if a property is within one of the designated natural hazards areas.
"The maps are valuable in terms of determining hazards existing for site specific projects for new developments, so developers can mitigate any seismic hazards in order to minimize loss of life and property," said Hill.
Hill recalled the devastating 1989 Loma Prieta earthquake, which hit parts of the Bay Area hard. She said the magnitude 6.7 quake that hit Hawaii recently and caused a lot of damage but no deaths, "serves as a wake-up call that earthquakes can and do happen. Everyone who lives in the Bay Area knows this is earthquake country. It's a fact of life for residents. The maps are there not to alarm, but simply to inform the public about specific areas that are prone to liquefaction and landslides due to earthquakes."
Areas shaded in the color green are at risk for liquefaction. This means the saturated soils in these areas, when shaken, may be unable to support buildings. Areas shaded in blue are prone to earthquake-induced landslides.
Hill said there are 112 maps being developed. Maps of other parts of California, including San Jose, Los Angeles, San Francisco and Oakland have been completed. Recent Seismic Hazard Zone Maps of Palo Alto, Mt. Sizer and revised Mountain View quadrangles covering parts of the South San Francisco Bay Area were just completed recently. Visit www.conservation.ca.gov/cgs/shzp/ and click the "Quickview/Download PDF Maps icon to view the Bay Area maps.
Information provided in this column is presented by the Realtor members of the Silicon Valley Association of Realtors at www.silvar.org. Send questions on any topic to rmeily@silvar.org.
