Features that may Indicate Catastrophic Landslide Movement
"Landslides have a maximum speed of about
17 miles per hour," stated the lead geologist
for the City of Anaheim, Mark McLarty with Eberhart and Stone, Inc., to
a group of landslide victims -- as if we all could somehow easily drive
away from our impending doom at 60 miles per hour. But what if the
unsuspecting homeowner doesn't sleep in his car, with his family at his
What to do and look for during
and immediately after heavy rains
Areas that are generally prone to landslide hazards:
On existing old landslides.
On or at the base of slopes.
In or at the base of minor drainage hollows.
At the base or top of an old fill slope.
At the base or top of a steep cut slope.
Developed hillsides where leach field septic systems are
Areas that are typically considered safe from landslides:
On hard, non-jointed bedrock that has not moved in the past.
On relatively flat-lying areas away from sudden changes in
At the top or along the nose of ridges, set back from the
tops of slopes.
Features that might be noticed prior to major landsliding:
Springs, seeps, or saturated ground in areas that have not
typically been wet before.
New cracks or unusual bulges in the ground, street pavements
Soil moving away from foundations.
Ancillary structures such as decks and patios tilting and/or
moving relative to the main house.
Tilting or cracking of concrete floors and foundations.
Broken water lines and other underground utilities.
Leaning telephone poles, trees, retaining walls or fences
Offset fence lines.
Sunken or down-dropped road beds.
Rapid increase in creek water levels, possibly accompanied
by increased turbidity (soil content).
Sudden decrease in creek water levels though rain is still
falling or just recently stopped.
Sticking doors and windows, and visible open spaces indicating
jambs and frames out of plumb.
What to do if you suspect imminent landslide danger:
Contact your local fire, police or public works department.
Inform affected neighbors
For further information on landslides in your area:
Contact your County Geologist--Some cities also staff geologists.
Contact your State Geologist or Engineer
If a very detailed site analysis is desired, contract with
a private consulting company specializing in earth movement Such companies
would likely be those specializing in geotechnical engineering, structural
engineering, or civil engineering. Your, Local, state, or county geologist
could possibly advise you as to the best kind of professional to contact.
Information from :
State of California Department of Conservation, Sacramento,
and National Landslide Information Center, U.S. Geological
Survey, Denver, CO