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SACRAMENTO – A new
Seismic Hazard Zone map covering part of
unincorporated Los Angeles County and
part of the city of Palmdale 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 Ritter Ridge
Quadrangle covered in this map includes
the rapidly growing Palmdale area –
Rancho Vista, Ritter Ranch, City Ranch,
most of the land along the California
Aqueduct and the crest of the Sierra
Pelona.
The liquefaction zone
includes the areas around Amargosa
Creek, stream channels on the south side
of Sierra Pelona, and the Leona and
Anaverde valleys. The earthquake-induced
landslide zone covers about 13 percent
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 91 official Seismic Hazard Zone
Maps, 73 for Southern California and 18
for the Bay Area. Another 15 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
here.
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