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 Landslides
and mudslides
are a serious problem among those people who live in areas with many
large hills and mountains, and have affected almost every state in
the United States. On the average, 25-50 people in the U.S lose their
lives due to mudslide and landslides. Across the world, they have
caused billions of dollars in damage and taken thousands of lives.
Safety and preparedness are big issues when speaking of mudslides
and landslides. But before this very subject can be breeched, an understanding
of the cause of mudslides and landslides needs to be acquired. A landslide,
by general definition, is the sudden process of a piece of land, usually
from an elevated area, breaking away from the whole, and through gravity,
is carried down to lower elevations. Landslides are typically associated
with periods of heavy rain or large amounts of melting snow. Areas
that have been burned by fire have an increased risk of landslides,
due to increased soil exposure. Flooding, which is a major concern
during heavy rain and snow melt in the first place, can become increasingly
worse with the occurance of a landslide.
 A
mudslide or debris flow, is a type of fast moving landslide. They
usually start on steep hillsides as shallow landslides that liquefy
and accelerate to speeds that are typically about 10 miles per hour,
but can exceed 35 miles per hour. Gravity is the force driving landslide
movement. Factors that allow the force of gravity to overcome the
resistance of earth material to landslide movement include: saturation
by water, steepening of slopes by erosion or construction, alternate
freezing or thawing, earthquake shaking, and volcanic eruptions.The
consistency of debris flows ranges from watery mud to thick, rocky
mud that can carry large items such as boulders, trees, and cars.
Debris flows from many different sources can combine in channels,
and their destructive power may be greatly increased. They continue
flowing down hills and through channels, growing in volume with the
addition of water, sand, mud, boulders, trees, and other materials.
When the flows reach flatter ground, the debris spreads over a broad
area, sometimes accumulating in thick deposits that can wreak havoc
in developed areas.
Any area composed of very weak or fractured
materials resting on a steep slope can and will likely experience
landslides.
These areas include but are not limited
to existing old landslides; the bases of steep slopes; the bases of
drainage channels; and developed hillsides where leach-field septic
systems are used. Look for various warning
signs that would indicate that a land slide is possible, if
not probable. Should you find any of these signs, please take the
proper precautions (see "Landslide Safety Tips" link below)
to insure your safety, and the safety of your loved ones. Although
the physical cause of many landslides cannot be removed, geologic
investigations, good engineering practices, and effective enforcement
of land-use management regulations can reduce landslide hazards.
All
information obtained from USGS.gov,
Disaster Relief.org, and the American
Red Cross
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