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UNDERSTANDING LANDSLIDES Dr. Walter Hays, Global Alliance For Disaster Reduction.

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Presentation on theme: "UNDERSTANDING LANDSLIDES Dr. Walter Hays, Global Alliance For Disaster Reduction."— Presentation transcript:

1 UNDERSTANDING LANDSLIDES Dr. Walter Hays, Global Alliance For Disaster Reduction

2 ESSENTIAL KNOWLEDGE FOR SOCIETAL SUSTAINABILITY A FRAMEWORK FOR UNDERSTANDING THE IMPACTS OF LANDSLIDES ON PEOPLE AND THEIR COMMUNITIES

3 LANDSLIDES NATURAL PHENOMENA THAT OCCUR WITH OR WITHOUT HUMAN ACTIVITY

4 FORCASTING FUTURE EVENTS  The goal is recording, processing, and interpreting geologic changes in time frames of seconds to weeks; i.e., “real- time geology.”

5 FORCASTING FUTURE EVENTS  Predicting a large volume landslide is important for society, but it depends on long-term monitoring of individual slides.

6 LANDSLIDES Falls, Topples, Slides, Spreads, Flows

7 LANDSLIDE HAZARD  Landslides encompass all categories of gravity-related slope failures in Earth materials.

8 SLOPES  Slopes are the most common landforms.  Although they appear stable and static, slopes are actually dynamic, evolving systems.

9 SLOPES  Material is constantly moving on slopes at rates varying from imperceptible creep to thundering avalanches and rock falls moving at high velocities.

10 LANDSLIDES  Gravity slope failures are triggered by earthquake ground shaking or excess precipitation  The slope does not need to be very steep for a landslide to occur.

11 FORCASTING FUTURE EVENTS  To predict when an earthquake will occur is important for society, but it is not yet feasible because earthquake prediction isn’t.

12 LAHAR  A lahar is a special “landslide” or mud flow induced by an explosive volcanic eruption.

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14 FORCASTING FUTURE EVENTS  Predicting when a volcano will erupt is important for society, but it depends on knowledge of each volcano’s eruption history.

15 MOUNT RANIER  Mount Ranier has generated more than 60 lahars during the past 10,000 years.  Many of these occurred during periods of volcanic quiescence.

16 MOUNT RANIER  Today, Mount Ranier continues to vent steam and convert its andesitic summit into clay.  A plan to evacuate 50,000 people has been developed.

17 LANDSLIDE HAZARD: ALASKA  THE 1964 PRINCE WILLIAM SOUND EARTHQUAKE TRIGGERED A LARGE VOLUME LANDSLIDE AT TURNAGAIN HEIGHTS.  MILLIONS OF CUBIC METERS OF SOIL AND ROCK MOVED DOWN SLOPE.  THE 1964 PRINCE WILLIAM SOUND EARTHQUAKE TRIGGERED A LARGE VOLUME LANDSLIDE AT TURNAGAIN HEIGHTS.  MILLIONS OF CUBIC METERS OF SOIL AND ROCK MOVED DOWN SLOPE.

18 LANDSLIDE HAZARD: ALASKA  Slope failure was induced by ground shaking of “Quick Clay.”

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22 LANDSLIDE HAZARD: ECUADOR

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25 LANDSLIDE HAZARD: JAPAN

26 LANDSLIDE HAZARD: WASHINGTON STATE

27 LATERAL SPREADING: JAPAN

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29 LATERAL SPREAD: SAN FRANCISCO


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