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

Source: U.S. Geological Survey, http://pubs.usgs.gov/fs/2004/3072/pdf/fs2004-3072.pdf

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

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

Source: R.L. Schuster, U.S. Geological Survey, http://pubs.usgs.gov/of/2001/ofr-01-0276/

• 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

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)

• March 1982 Source: Tom Casadevall, U.S. Geological Survey, http://vulcan.wr.usgs.gov/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/