Mass Wasting Mass Wasting Erosion Chapter 23 Important triggering factors Saturation of the material with water Destroys particle cohesion Water adds weight Important triggering factors The downslope movement of rock regolith and soil under the direct g y influence of gravity Gravity is the controlling force Mass Wasting Important triggering factors Saturation Oversteepening Removal of vegetation Ground vibrations Important triggering factors Important triggering factors Oversteepened slopes Oversteepened slopes Unconsolidated granular particles assume a stable slope called the angle of repose p angle g is different for various Stable slope materials Oversteepened slopes are unstable Mass Wasting Undercutting by streams Undercutting by human interference Addition of material to top of slope Natural deposition Human caused construction Types of mass wasting processes Types of mass wasting processes Removal of anchoring vegetation Wildfires Drought Development logging Ground vibrations Defined by The material involved How the material moves Defined by the material involved Debris Mud Earth Rock from earthquakes 1 Types of mass wasting processes Defined by how the material moves The character of the movement Fall Slide Flow Types of mass wasting processes Defined by how the material moves The rate of the movement Fast Slow Forms of mass wasting Slump Forms of mass wasting Slump Rockslide Debris flow Earth flow Creep Solifluction Slump diagram Scarp Rotational blocks Cracks C k Hummocky toe Slump Rapid movement along a curved surface Occur along oversteepened slopes http www physicalgeography net fundamentals 10x html http geology about com od naturalhazardsclimate ig Landslides slide rotat htm Government Hill AK 1964 Government Hill AK seismic cross section Block slide at Vaiont Dam http walrus wr usgs gov geotech radaraapg fig4 html http walrus wr usgs gov geotech radaraapg fig5 html 2 Forms of mass wasting Rockslide Howe Sound Elkton Oregon March 4 2006 Rockslide Rapid Blocks of bedrock move down a slope Cousin to Rockfall http blog fligtar com tag travel http www flickr com photos 7605772 N08 2723218006 Elkton Oregon March 4 2006 Nevado Huascar n http www kmtr com news local story aspx content id 010798AE AF2F 41D5 93F5 120A64493D45 Gros Ventre rockslide diagram Peru 1970 Buried two towns 18 000 killed Geologists warned government of potential http www kmtr com news local story aspx content id 010798AE AF2F 41D5 93F5 120A64493D45 http landslides usgs gov html files landslides slides slide5 htm http www goldengatephoto com WestUS wyother html grosventre Slide Lake Wyoming Gros Ventre landslide photo Sherman Glacier Rock Avalanche March 1964 http www uwsp edu geo projects geoweb participants dutch VTrips GrosVentre HTM 3 Rock Fall July 1996 Yosemite Forms of mass wasting Rock Fall Debris flow mudflow Rapid flow of debris with water Confined to channels Dry areas with heavy rains Lahar composed of volcanic materials http landslides usgs gov html files landslides slides slide9 htm http sts gsc nrcan gc ca geoscape vancouver graphics mountain1 gif Snohomish County WA January 2006 Debris Flow US 50 Sierra Nevadas California 1997 http www komotv com stories 41527 htm http landslides usgs gov monitoring hwy50 index php http geology about com od naturalhazardsclimate ig Landslides slide debflow htm Debris flow damage La Conchita California La Conchita California Spring 1995 No one injured j or killed February 2005 http landslides usgs gov html files landslides slides slide21 htm 4 Toes of La Conchita covering highway 101 http www cnn com interactive weather 0501 gallery storms frameset exclude html http landslides usgs gov html files landslides slides slide2 htm Lahar debris flow http www redcross org article 0 1072 0 312 3943 00 html Nevado del Ruiz Toutle River Debris Flow http landslides usgs gov html files landslides slides slide13 htm Eruption of Nevado del Ruiz Slide Mountain Nevada May 1983 La Conchita 2005 http volcanoes usgs gov Hazards What Lahars RuizLahars html http pubs usgs gov fs fs 176 97 fs 176 97 html Confluence of lahars Nevado del Ruiz http volcanoes usgs gov Hazards What Lahars RuizLahars html http volcanoes usgs gov Hazards What Lahars RuizLahars html Armero site Nevado del Ruiz http volcanoes usgs gov Hazards What Lahars RuizLahars html 5 Philippine Landslide 2006 Scar of Philippine landslide 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 http news yahoo com news tmpl story u 060219 481 xbm10202190643 http www alertnet org thenews pictures MAN52D htm Hollywood Hills CA Niigata Japan 1964 January 2005 Anchorage AK 1964 http www cnn com interactive weather 0501 gallery storms frameset exclude html 1964 liquefaction damage http www owlnet rice edu sehh AlaskaEQ Alaska Sci EQScience http www ce washington edu liquefaction selectpiclique nigata64 tiltedbuilding jpg Alaska 1964 Sheffield Dam 1925 Santa Barbara County CA Earth quake E th k caused earthflow http www ce washington edu liquefaction selectpiclique alaska64 landslideintowater jpg http www ce washington edu liquefaction selectpiclique dams sheffielddam1 jpg http walrus wr usgs gov geotech radaraapg fig5 html Hyperlink to sand boil liquefaction http walrus wr usgs gov geotech images TIsandboils mov 6 Forms of mass wasting Cause of creep frost heave Some visible effects of creep Creep Slow movement of soil and regolith downhill Causes fences and utility poles to tilt Creep Bedrock curled due to creep mass wasting Creep Forms of mass wasting Curved trunks due to soil creep Solifluction Slow movement in areas underlain by permafrost Upper active soil layer becomes saturated and slowly flows over a frozen surface below http www gpc edu janderso physical massw htm Solifluction Lobes http classes colgate edu dkeller geol101 massw images creep1 jpg Ground subsidence in Alaska due to solifluction Measuring ground movement http piru alexandria ucsb edu collections geography3b misc solifluction lobes jpg 5b1 5d jpg 7 Mass Wasting Potential Mass Wasting Potential Mass Wasting EXPLANATION 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 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
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