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Edit Comment Close Premium member Presentation Transcript Landslides / Mass Wasting : Landslides / Mass Wasting From My Homeowners Policy(Why this is so important) : From My Homeowners Policy(Why this is so important) Mass Wasting : Mass Wasting Any downslope movement of rock and soil under the influence of gravity. "Landslide" "Rockslide" "Creep" "Rock Fall" Landslide Anatomy : Landslide sketch from the West Virginia Geological Survey Landslide Anatomy Important Landslide Facts : Most are very slow (inches per year) Most occur naturally Homeowners insurance does not pay. Important Landslide Facts Landslide Geography : Landslide Geography Steep Slopes Slide-Prone Soils High Precipitation National Landslide Overview Map (connect) Slide-Prone Area Map : Slide-Prone Area Map Slide-prone area map by Peter Lessing, West Virginia Geological Survey Angle of Repose : Angle of Repose The maximum slope at which loose, cohesionless material is stable Angle of Repose Determined By : Angle of Repose Determined By Particle size (higher for large particles) Particle shape (higher for angular shapes) Shear strength (higher for high shear strength) Upsetting Stability : Increase the slope Decrease the shear strength Increase the effect of gravity Upsetting Stability Landslide Triggers(A Few Examples) : Landslide Triggers(A Few Examples) Removal of Support Addition of Moisture Removal of Vegetation Addition of Weight Oversteepening Vibrations Erosion Excavation Forest fires Timbering Rainfall, Snowmelt Water disposal, Improper grading Volcanic ash, Landslides, Snow Placement of fill (Used like "removal of support") Grading fill steeper than its repose angle Earthquakes, Thunder Blasting, Heavy equipment Landslide Considerations: : Landslide Considerations: Gradient Risk starts at only 15o Soil / Bedrock Clay soils / shale bedrock are the worst Moisture Pore pressure, Lubrication, Weight Vegetation Roots anchor soil, remove water Support Must be maintained Weight Drives the slide, compression of substrate Vibrations Result in a loss of friction Oversteepening Exceeding the angle of repose What was the trigger?Who is to blame? : What was the trigger?Who is to blame? #1 What was the trigger?Who is to blame? : What was the trigger?Who is to blame? #2 What was the trigger?Who is to blame? : What was the trigger?Who is to blame? #3 What was the trigger?Who is to blame? : What was the trigger?Who is to blame? #4 What was the trigger?Who is to blame? : What was the trigger?Who is to blame? #5 What was the trigger?Who is to blame? : What was the trigger?Who is to blame? #6 Types of Landslides : Types of Landslides Slump Rotational Slide Rock and soil moving as a unit over a curved failure surface. Complex Landslide Earthflow Mudflow Debris Flow / Avalanche Rock Slide Block Glide Creep Similar to a slump, but the material breaks-up and flows. Much higher moisture content than an earthflow - the material makes a "batter" with water. A block of bedrock sliding down dip. Gradual downslope movement of rock and soil. A combination of two different slide types. Recognizing Problem Areas : Curved trees Stuck windows Stuck doors Leaning walls Plaster cracks Foundation cracks Damaged chimneys Leaning poles Scarps Toes Seeps Pavement damage Recognizing Problem Areas Before buying on a hillside: : Be suspicious! Check target and adjacent properties Some problems can be fixed Fixes are temporary and expensive Get expert advice Soil Conservation Service / Geological Survey Before buying on a hillside: Landslide Stabilization : Get expert advice Your efforts will probably give temporary relief Support the base Anchor through slip plane Lower water table Runoff control Plant vegetation Excavate slide mass Landslide Stabilization Landslide Diagnosis "A" : Landslide Diagnosis "A" Landslide Diagnosis "B" : Landslide Diagnosis "B" Landslide Diagnosis "C" : Landslide Diagnosis "C" Landslide Diagnosis "D" : Landslide Diagnosis "D" You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.