Landslides are rock, earth, and debris flowing down slopes due to gravity. They are caused by heavy rains, earthquakes, volcanic eruptions, floods, and other factors. Landslides can travel over 260 feet per second and cause damage by burying villages, closing roads, and breaking infrastructure. They commonly occur in areas with steep slopes, such as mountain ranges, river valleys, and coastal areas. On average, landslides cause 25 casualties per year in the U.S. and have resulted in disasters like the 1994 Nevado del Ruiz eruption that killed over 2,000 people in Colombia.

1. Landslides
By: Madeline Sette,
Rachelle Kruzelak,
Keaton Beckes,
and Noah Orner

2. Definition
●Landslides are rock, earth, and/or debris
flowing or sliding down slopes due to
gravity.

3. Causes
●Heavy rains
●Earthquakes
●Volcano eruptions
●Floods
●Grading
●Terrain Cutting
●Droughts

4. Air
●Confined by falling rock debris, air may
act as a cushion to reduce the friction
between the sliding material and the
underlying rock or ground.

5. Gravity
●Gravity provides the energy to displace
the soil and bedrock, but other factors
contribute to an increase in stress and
decrease in strength. A stress tends to
make part of a block material slide block
material slide with respect to an
adjoining part.

6. Vibrations
●Vibrations from blasting, heavy traffic
and earthquakes also can contribute to
shear stress and precipitate slides.

7. Speed
●Landslides travel at least over than 260
feet per second

8. Types
●Rockfalls- large chunks of rock that tumble down a
cliff or steep slopes
●Lahars- ash from a volcano mixes with water, to form a
thick river of mud
●Earthflows- contain less water and flow more slowly;
move shorter distances
●Slope Failure- involve one block or a series of slump
blocks
●Slump- larges masses move downward and outward
due to a gravity pull
●Debris Slides- consist of moving masses of mud, soil,
and rocks mixed with water

9. Hotspots
●Anywhere with steep slopes and
weathering
●High mountain ranges, sheer cliffs, and
steep sided river valleys
●Where volcanoes erupt and along
coasts

10. Damage
●Causes a billion dollars of damage each
year in the U.S.
●Average of twenty-five casualties a
year in the U.S.

11. Effects
●Bury entire villages that are at the
bottom of the mountain range
●Close roads
●Rapidly moving water and debris can
cause trauma
●Broken gas, electric, water, and sewage
lines can break

12. Effects
●Landslides also sweep up trees, cars,
and buildings
http://landslides.usgs.gov/
research/other/
centralamerica.php

13. Traffic Stops
●Landslides can cause a headache for many
travelers on the road
●Landslides occur on hills near roads quite
often causing bad traffic

14. Pictures
http://landslides.usgs.gov/
research/other/
centralamerica.php
http://web.ndmc.gov.za
/images/landslide1.jpg

15. Nevado Del Hulia
●It was on June 6, 1994 at 3:47 p.m.
●Killed up to 2,000 people and only 271
bodies were found
●1,700 were defined missing presumed
dead, and buried under the mud
●20,000 people made homeless

16. Orosi, Costa Rica
●On August 31, 2005
●7 people were killed
●More than 400 people made homeless
●23 homes completely destroyed

17. Panabaj, Guatamala
●On October 5, 2005, around four o'clock
a.m.
●1,000 people were declared missing
and presumed dead
●Fewer than 80 bodies recovered

18. Sarno, Italy
●On May, 1998.
●Killed 118 people, and more than 1,500
people made homeless

19. Peruvian Andes
●In 1977, a debris avalanche moved
some 20 to 45 million cubic yards of earth
materials at speeds of almost 100 miles
per hour. This slide buried an entire city,
killing most of its 19,000 inhabitants.

20. Safe Spots From Landslides
●Stay on hard bedrock that has not been
moved lately or in the past
●Stay on relatively flat-lying areas far from
slopes or river banks
●Stay at the top of ridges, away from the
top of slopes

21. If in Danger
●Call your fire or police departments
●Warn neighbors in danger
●Evacuate the premises
immediately

22. Eyewitnesses to Landslides
●"It sounded like the mountain exploded, and the whole thing
crumbled." -Dario Libatan
●June 7, 1994, Jorge Garcia observed the landslide area and said,
"only the roof of the school can be seen.“ – Jorge Garcia
●"It sounded like an earthquake. But it was not the earth moving. It
was the air." - Febo Carillo
●"When the... landslide hit the landslide hit the hillsides of Orosi, the
town was able to stick together and recover from the natural
disaster." – Amy Chan

23. Questions
1.What is a landslide?
2.Name 3 causes to landslides?
3.How fast can a landslide travel?
4.What should you do if you are in danger of
a landslide?
5.What are the effects of landslides?
6. What are landslide hotspots?
7. What is the average number of casualties
landslides cause each year in the U.S.?

24. Answers
1.Landslides are rock, earth, and/or
debris flowing or sliding down slopes due
to gravity.
2.Heavy rains, Earthquakes, Volcano
eruptions, Floods, Grading, Terrain
Cutting, Droughts
3.260 feet per second

25. Answers
4. Call your fire or police departments,
Warn neighbors in danger, Evacuate the
premises immediately
5. Bury entire villages that are at the
bottom of the mountain range, Close
roads, Rapidly moving water and debris
can cause trauma, Broken gas, electric,
water, and sewage lines can break

26. Answers
6. Anywhere with steep slopes and
weathering, High mountain ranges, sheer
cliffs, and steep sided river valleys, Where
volcanoes erupt and along coasts
7. Average of25 average a year in the
U.S.

27. Sources
●Landslides. N.p., n.d. Web. 21 Jan. 2010.
http://www.ussartf.org/landslides.htm
●Matthews, William H. “Landslides.” Encyclopedia Americana.
Deluxe Library ed. 1990. Print.
●Spilsbury, Louise & Richard. Landslides and Avalanches in Action.
New York, NY: Rosen Central, 2009. Print.
●Landslide (Mudslide) Saftey. Washington D.C.: Centers for
Disease Control and Prevention, 2003. Print.
●http://landslides.usgs.gov/research/other/centralamerica.php
●http://web.ndmc.gov.za/images/landslide1.jpg

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Landslides!