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SACRAMENTO – The
Department of Conservation (DOC) today
urged residents to watch for potential
landslide warning signs and exercise
safety precautions as California enters
the rainy season. Residents whose homes
are on or below slopes need to check for
the signs of impending landslides and
contact local authorities about any
landslide concerns.
“Most Californians
are aware that we live in earthquake
country, but landslides can be every bit
as dangerous as temblors,” said State
Geologist Dr. John Parrish, head of
DOC’s California Geological Survey.
“Fortunately, unlike earthquakes,
landslides sometimes give warning signs
that residents can identify in order to
protect the safety of their homes and
families.”
A landslide is any
mass of earth and rock that moves
downhill by sliding, flowing or falling.
Large, slow-moving landslides composed
of bedrock can cause extensive property
damage but usually do not result in loss
of life. Debris flows, commonly called
mudslides, are more dangerous types of
landslides because they can move very
quickly before people have a chance to
get out of harm’s way. Mud, rock and
debris caught by these rapid flows can
travel from 10 mph to 100 mph.
“If you live in an
area where there was considerable rain
last year, you’re more susceptible to
landslides this winter,” said Parrish.
“Once the heavy rains begin, and the
rainfall is three-to-four inches a day
or a quarter inch an hour, the soil
becomes waterlogged and may trigger
mudslides. Residents should be on the
lookout for location-specific warnings
from local and state agencies.”
When California
rainfall exceeds normal levels by 150
percent or more, landslides cause, on
average, property damage in excess of
$100 million and as many as five deaths
each year. In January 2005, heavy
rainfall contributed to landslides that
claimed 10 lives in Ventura County and
caused tens of millions of dollars in
damage around the state.
Californians who live
on slopes or in areas that have
experienced landslides in the past can
take some of the following steps to
protect their homes and families from
damage:
♦ On rainy nights,
the single most important precaution is
to avoid sleeping in lower-floor
bedrooms on the sides of houses that
face hazardous slopes. In California,
most of the deaths caused by debris
flows have occurred when people sleeping
in these positions were buried by
debris.
♦ Monitor rainfall
during intense rainstorms, and install a
plastic rain gauge where it can be
checked frequently.
♦ Consider hiring an
engineering geologist to evaluate your
property.
♦ Plant vegetation
and install engineered drainage systems
on slopes, and consider constructing
properly designed diversion walls to
deflect debris flows.
♦ Check for new
cracks in the soil, structural shifts,
holes or bare spots on hills, tilting
trees, bulges at the base of slopes, or
material moving downhill.
♦ Watch for new
springs or seeps and excess surface
erosion around your property. Identify
if any nearby streams appear muddier
than normal.
♦ Listen for unusual
rumbling sounds and noises that may
indicate moving earth and rocks,
breaking vegetation or structures, or
that pipes are being pulled apart.
The California
Geological Survey provides technical
information and advice about landslides,
erosion, sedimentation, and other
geologic hazards to the public, local
governments, agencies and industries
that make land-use decisions in
California. More information about
landslides, including landslide maps and
mitigation steps, can be found
here.
In addition to,
mapping and studying earthquakes and
other geologic phenomena, the Department
of Conservation classifies areas
containing mineral deposits; ensures
reclamation of land used for mining;
regulates oil, gas and geothermal wells;
promotes beverage container recycling;
and administers agricultural and
open-space land conservation programs.
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