|
SACRAMENTO – A
Seismic Hazard Zone map for a 51 square
mile area of Orange County, including
parts of the communities of San Juan
Capistrano and Rancho Santa Margarita,
became official today. The map, issued
by the California Department of
Conservation, impacts local planners,
developers, property sellers and real
estate agents.
If property is
located in a “zone of required
investigation,” where liquefaction or
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 potential buyers if
property they're selling is in a Seismic
Hazard Zone, as is the case when
property is in a designated flood or
wildfire zone.
DOC’s California
Geological Survey released the Cañada
Gobernadora quadrangle map in
preliminary form in March. It is now
official after public review and
comment. The map is on file with local
government offices, including the
planning department, building department
and county recorder's office.
A portion of Rancho
Santa Margarita is in the northwest
corner of the map while San Juan
Capistrano is in the southwest corner.
The Cleveland National Forest extends
into the eastern and northeastern parts.
Caspers Regional Park spreads across the
central part. The remainder of the land
in Orange County is unincorporated. The
area lies on the western slope of the
Santa Ana Mountains, which is
characterized by rugged, mountainous
terrain, dissected by several large
canyons, such as Cañada Gobernadora.
Residential development is underway in
the unincorporated community of Coto de
Caza at the northern end of Cañada
Gobernadora and to the west in Cañada
Chiquita.
Liquefaction hazard
zones are restricted to the bottoms of
canyons, especially San Juan Creek,
Cañada Chiquita, Cañada Gobernadora and
shorter segments of tributary canyons. A
zone along Cañada Gobernadora Creek
affects the community around Coto De
Caza Golf Course, west of Line Ridge
Road. The earthquake-induced landslide
zone covers about 25 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, which also
can be dangerous. 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
constructed.
Seventeen maps
affecting Orange County are now
official. The effort to identify and map
seismic hazards is ongoing. A
preliminary Seismic Hazard Zone maps for
the Santiago Peak quadrangle, just north
of Cañada Gobernadora, will become
official in December. Several areas of
Los Angeles and Ventura counties are
also being mapped.
Color copies of
official maps can be purchased through
DOC's California Geological Survey (213)
239-0878 or (916) 445-5716. The maps
also can be found on the Web
here.
In addition to
studying and mapping earthquakes and
other geologic phenomena, the Department
of Conservation maps and classifies
areas containing mineral deposits;
ensures reclamation of land used for
mining; regulates oil, gas and
geothermal wells; administers
agricultural and open-space land
conservation programs; and promotes
beverage container recycling.
###
|