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SACRAMENTO – A new
Seismic Hazard Zone map covering the
City of Ventura and the unincorporated
community of Casitas Springs became
official today. The map, issued by the
Department of Conservation’s California
Geological Survey, impacts planners,
developers, property sellers and real
estate agents.
If property is
located in a Zone of Required
Investigation, where liquefaction or
earthquake-induced landslides could
occur during a large earthquake, the
local building department must require
geologic studies before projects are
issued permits. Also, property sellers
and real estate agents must inform
buyers if property they're selling is in
a Seismic Hazard Zone, as is the case
when property is in a designated flood
zone.
“This map will help
improve public safety by ensuring these
earthquake hazards are taken into
account during new construction,” DOC
Director Darryl Young said.
The liquefaction zone
in the Ventura quadrangle covers the
urbanized lowlands occupied by the City
of Ventura, the Ventura River
floodplain, the beaches, and the bottoms
of some creek canyons. Landslide zones
cover more than half of the land portion
of the quadrangle.
Shaking causes most
of the damage during earthquakes, and in
many cases, it is cost effective to
retrofit houses and buildings to
minimize damage caused by severe
shaking. Local public libraries have a
number of publications by the Governor’s
Office of
Emergency Services,
American Red Cross and the Federal
Emergency Management Agency that can be
used as guides to making homes more
earthquake-ready.
Seismic Hazard Zone
maps show areas at risk from the
secondary earthquake hazards of
landslides and liquefaction. It is
generally not as cost effective to
retrofit an
existing building for
the impacts of liquefaction or
landslides as it is to build in safety
features at the design stage. Therefore,
design changes to better protect life
and property during future earthquakes
are required before new developments are
approved and built. “It’s easier and
less expensive – not to mention better
for public safety -- to institute design
changes as a precaution in the
construction phase than to rebuild after
liquefaction or landslide damage,” Young
said.
With this new map,
the California Geological Survey has
issued 89 official Seismic Hazard Zone
Maps, 72 for Southern California and 17
for the Bay Area. Another 17 maps are in
various stages of public review. Each
map covers about 60 square miles.
DOC/California
Geological Survey geologists use
computer models as well as analyses of
existing geological mapping and hundreds
of engineering borings to produce the
maps, which are drawn on a scale where
one inch equals 2,000 feet.
Color copies of
official maps can be purchased through
DOC's California Geological Survey at
(213) 239-0878, (916) 445-5716, or (415)
904-7707. The maps also can be viewed
and downloaded on the Web at http://gmw.consrv.ca.gov/shmp.
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