Mass Wasting Mass Wasting The downslope movement of rock regolith and soil under the direct influence of gravity Gravity is the controlling force Mass Wasting Important triggering factors Saturation Oversteepening Removal of vegetation Ground vibrations Important triggering factors Saturation of the material with water Destroys particle cohesion Water adds weight Important triggering factors Oversteepened slopes Unconsolidated granular particles assume a stable slope called the angle of repose Stable slope angle is different for various materials Oversteepened slopes are unstable Important triggering factors Oversteepened slopes Undercutting by streams Undercutting by human interference Addition of material to top of slope Natural deposition Human caused construction Important triggering factors Removal of anchoring vegetation Wildfires Drought Development logging Ground vibrations from earthquakes Mass Wasting Types of mass wasting processes Defined by The material involved The movement of the material Types of mass wasting processes Defined by the material involved Debris Mud Earth Rock Types of mass wasting processes Defined by the movement of the material The character of the movement Fall Slide Flow Types of mass wasting processes Defined by the movement of the material The rate of the movement Fast Slow Forms of mass wasting Slump Rockslide Debris flow Earth flow Creep Solifluction Types of mass wasting USGS Landslide Types http pubs usgs gov fs 2004 3072 fs 2004 3072 html Forms of mass wasting Slump Rapid movement along a curved surface Occur along oversteepened slopes Slump diagram Slump http www physicalgeography net fundamentals 10x html Government Hill AK 1964 http walrus wr usgs gov geotech radaraapg fig4 html Government Hill AK seismic cross section http walrus wr usgs gov geotech radaraapg fig5 html Forms of mass wasting Rockslide Rapid Blocks of bedrock move down a slope Cousin to Rockfall Rockslide diagram http www kmtr com mediacenter default aspx videoId 4191 video kmtr com 4199 video kmtr com 4200 video kmtr com 4195 video kmtr com 4189 video kmtr com navCatId 5 2 2 Elkton Oregon March 4 2006 http www kmtr com news local story aspx content id 010798AE AF2F 41D5 93F5 120A64493D45 Elkton Oregon March 4 2006 http www kmtr com news local story aspx content id 010798AE AF2F 41D5 93F5 120A64493D45 Nevado Huascar n Peru 1970 Buried two towns 18 000 killed Geologists warned government of potential http landslides usgs gov html files landslides slides slide5 htm Gros Ventre rockslide diagram http www goldengatephoto com WestUS wyother html grosventre Gros Ventre landslide photo Slide Lake Wyoming http www uwsp edu geo projects geoweb participants dutch VTrips GrosVentre HTM Sherman Glacier Rock Avalanche March 1964 Rock Fall July 1996 Yosemite http landslides usgs gov html files landslides slides slide9 htm Rock Fall http sts gsc nrcan gc ca geoscape vancouver graphics mountain1 gif Forms of mass wasting Debris flow mudflow Rapid flow of debris with water Confined to channels Dry areas with heavy rains Lahar composed of volcanic materials Snohomish County WA January 2006 http www komotv com stories 41527 htm US 50 Sierra Nevadas California 1997 http landslides usgs gov monitoring hwy50 index php La Conchita California Spring 1995 No one injured or killed http landslides usgs gov html files landslides slides slide21 htm La Conchita California February 2005 La Conchita 2005 http www redcross org article 0 1072 0 312 3943 00 html Slide Mountain Nevada 1983 http landslides usgs gov html files landslides slides slide2 htm Debris flow damage Lahar debris flow http landslides usgs gov html files landslides slides slide13 htm Toutle River Debris Flow http pubs usgs gov fs fs 176 97 fs 176 97 html Nevado del Ruiz http volcanoes usgs gov Hazards What Lahars RuizLahars html Eruption of Nevado del Ruiz http volcanoes usgs gov Hazards What Lahars RuizLahars html Confluence of lahars Nevado del Ruiz http volcanoes usgs gov Hazards What Lahars RuizLahars html Armero site Nevado del Ruiz http volcanoes usgs gov Hazards What Lahars RuizLahars html Philippine Landslide 2006 http www alertnet org thenews pictures MAN52D htm Scar of Philippine landslide http news yahoo com news tmpl story u 060219 481 xbm10202190643 Forms of mass wasting Earthflow Rapid or slow Typically occur on hillsides in humid regions Water saturates the soil Liquefaction associated with earthquakes and clay soils Earthflow diagram Hollywood Hills CA January 2005 http www cnn com interactive weather 0501 gallery storms frameset exclude html Niigata Japan 1964 http www ce washington edu liquefaction selectpiclique nigata64 tiltedbuilding jpg Anchorage AK 1964 http www owlnet rice edu sehh AlaskaEQ Alaska Sci EQScience 1964 liquefaction damage http walrus wr usgs gov geotech radaraapg fig5 html Alaska 1964 http www ce washington edu liquefaction selectpiclique alaska64 landslideintowater jpg Hyperlink to sand boil liquefaction http walrus wr usgs gov geotech images TIsandboils mov Sheffield Dam 1925 Santa Barbara County Earth quake caused flow http www ce washington edu liquefaction selectpiclique dams sheffielddam1 jpg Forms of mass wasting Creep Slow movement of soil and regolith downhill Causes fences and utility poles to tilt Cause of creep frost heave Some visible effects of creep Creep Bedrock curled due to creep mass wasting http www ngdc noaa gov seg hazard slideset 6 6 140 slide shtml Creep Curved trunks due to soil creep http classes colgate edu dkeller geol101 massw images creep1 jpg Forms of mass wasting Solifluction Slow movement in areas underlain by permafrost Upper active soil layer becomes saturated and slowly flows over a frozen surface below Solifluction Lobes http piru alexandria ucsb edu collections geography3b misc solifluction lobes jpg 5b1 5d jpg Ground subsidence in Alaska due to solifluction Measuring ground movement Mass Wasting Potential EXPLANATION LANDSLIDE INCIDENCE Low less than 1 5 of area involved Moderate 1 5 15 of area involved High greater than 15 of area involved LANDSLIDE SUSCEPTIBILITY INCIDENCE Moderate susceptibility low incidence High susceptibility low incidence High susceptibility moderate incidence Mass Wasting Potential EXPLANATION LANDSLIDE INCIDENCE Low less than 1 5 of area involved Moderate 1 5 15 of area involved High greater than 15 of area involved LANDSLIDE SUSCEPTIBILITY INCIDENCE Moderate susceptibility low incidence High susceptibility low incidence High
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