Mass Wasting The downslope movement of rock and soil due to gravity

From A Homeowners Policy (Why this is so important)

What triggers mass wasting? 1. Gravity 2. Water  Diminishes particle cohesion  Water adds weight

3. Oversteepening of slopes  Stable slope angle (angle of repose) is different for various materials

4. Removal of anchoring vegetation, such as by fire

5. Ground vibrations from earthquakes  May cause expensive property damage  Can cause liquefaction – water saturated surface materials behave as fluid- like masses that flow Landslide triggered by 1994 North earthquake in S. California

Forms of mass wasting 1. Slump Movement along a curved surface

2. Rockfall Blocks of bedrock slide down a slope Generally very fast and destructive

Rockfall Debris

Rockfall in action

3. Mudflow Consists of soil with a large amount of water Dry areas after heavy rain A lahar from the 1980 Mt. St. Helens eruption

Box f2a

Box f2b

4. Landslide Rock and soil suddenly fall Steep slopes

Landslide photo

5. Creep  Very slow movement downhill

Creeping Headstones

6. Solifluction  Slow, downslope flow of water saturated soil over frozen layers

Curved trees Stuck windows Stuck doors Leaning walls Plaster cracks Foundation cracks Damaged chimneys Leaning poles Scarps Toes Seeps Pavement damage Curved trees Stuck windows Stuck doors Leaning walls Plaster cracks Foundation cracks Damaged chimneys Leaning poles Scarps Toes Seeps Pavement damage Recognizing Problem Areas

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 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:

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 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 "B"

Landslide Diagnosis "C"

Landslide Diagnosis "D"