1. Landslide Images

2. The downward sliding of a relatively dry mass of earth and rock
What is a landslide?
The downward sliding of a relatively dry mass of earth and rock

3. What is a mudslide?
The downward sliding of soft wet earth and debris, made fluid by rain or melted snow

4. Types of Landslides  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,

5. Wow! Landslides & mudslides can move: Soil Gravel Rocks Plants Trees
Houses
Cars
Roads
…and you
Source: U.S. Geological Survey,

6. 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,

7. 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,

8. 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,

9. 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,

10. 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,

11. 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,

12. 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