Landslide Changes

Landslide Images
What is a landslide?
The downward sliding of a relatively
dry mass of earth and rock
What is a mudslide?
The downward sliding of
soft wet earth and debris,
made fluid by rain or melted snow
Types of
Landslides
•  ç Major types of
landslide movements
•  Landslides occur at
different speeds —
very slow to very quick
•  All landslides are the
result of gravity, friction
and their materials
•  Both natural and
human-made factors
contribute to landslides
Source: U.S. Geological Survey, http://
pubs.usgs.gov/fs/2004/3072/pdf/
fs2004-3072.pdf
Wow!
Landslides & mudslides
can move:
•  Soil
•  Gravel
•  Rocks
•  Plants
•  Trees
•  Houses
•  Cars
•  Roads
•  …and you
Source: U.S. Geological Survey, http://pr.water.usgs.gov/public/venezuela
La Conchita, CA
•  A typical type of landslide
•  Landslide and earthflow at
a southern California
coastal area
•  People were evacuated
•  The houses nearest the
slide were completely
destroyed
•  Spring 1995
Source: R.L. Schuster, U.S. Geological Survey,
http://pubs.usgs.gov/of/2001/ofr-01-0276/
La Conchita, California
•  Debris flow that
came from a large
landslide above the
town
•  What happened to
the road and
houses?
•  March 2005
Source: U.S. Geological Survey, http://
landslides.usgs.gov/recent/
socal_reconn/photo2.php
Laguna Beach, California
•  A large landslide
occurred in the
Bluebird Canyon area,
near Laguna Beach
•  What happened to the
road and houses?
•  2005
Source: Jim Bowers, U.S. Geological Survey, http://
landslides.usgs.gov/recent/.
Carabelleda, Venezuela
•  An aerial view shows newly opened channels of debris flow
(in foreground and center right)
•  Huge amounts of freshly deposited sediment was spread across
the community by floods and debris flows
•  December 1999
Source: U.S. Geological Survey, http://pr.water.usgs.gov/public/
venezuela/image_14.html
Mount St. Helens, WA
•  An eruption sent pumice and ash 14 km (9 mi) into the air, resulting in a
lahar (the dark deposit on the snow) flowing from the crater
•  Some of the lahar flowed to a lake (lower left corner), but most the debris
went down the river, as far as 80 km (50 mi)
Source: Tom Casadevall, U.S. Geological Survey, http://vulcan.wr.usgs.gov/
•  March 1982
Volcanoes/MSH/Images/mudflow_images.html
Experiment
to Learn
•  A debris-flow flume in Oregon
provides a laboratory to study
landslides
•  A concrete chute up a hillside
(see stairs and windows)
• 
• 
• 
• 
Drop wet or dry soil and rocks
See what happens
Measure what happens
Try different materials and
conditions
Source: U.S. Geological Survey, http://vulcan.wr.usgs.gov/Projects/MassMovement/Publications/
OFR92-483/OFR92-483_inlined.html
Howe Sound, British Columbia, Canada
•  To prevent future
landslide destruction,
a retention structure
was created
•  The stream bed was
cleared, straightened
and deepened above
and below the
structure
•  Note the highway
crossing at the bottom
Source: Copyright © Geology Department, Malaspina University-College, British Columbia, Canada
http://www.mala.bc.ca/~earles/howesound/