Presentation on theme: "UNDERSTANDING LANDSLIDES Dr. Walter Hays, Global Alliance For Disaster Reduction."— Presentation transcript:
UNDERSTANDING LANDSLIDES Dr. Walter Hays, Global Alliance For Disaster Reduction
ESSENTIAL KNOWLEDGE FOR SOCIETAL SUSTAINABILITY A FRAMEWORK FOR UNDERSTANDING THE IMPACTS OF LANDSLIDES ON PEOPLE AND THEIR COMMUNITIES
LANDSLIDES NATURAL PHENOMENA THAT OCCUR WITH OR WITHOUT HUMAN ACTIVITY
FORCASTING FUTURE EVENTS The goal is recording, processing, and interpreting geologic changes in time frames of seconds to weeks; i.e., “real- time geology.”
FORCASTING FUTURE EVENTS Predicting a large volume landslide is important for society, but it depends on long-term monitoring of individual slides.
LANDSLIDES Falls, Topples, Slides, Spreads, Flows
LANDSLIDE HAZARD Landslides encompass all categories of gravity-related slope failures in Earth materials.
SLOPES Slopes are the most common landforms. Although they appear stable and static, slopes are actually dynamic, evolving systems.
SLOPES Material is constantly moving on slopes at rates varying from imperceptible creep to thundering avalanches and rock falls moving at high velocities.
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.
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.
LAHAR A lahar is a special “landslide” or mud flow induced by an explosive volcanic eruption.
FORCASTING FUTURE EVENTS Predicting when a volcano will erupt is important for society, but it depends on knowledge of each volcano’s eruption history.
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.
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.
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.
LANDSLIDE HAZARD: ALASKA Slope failure was induced by ground shaking of “Quick Clay.”