Mass WastingMass WastingErosionChapter 23Chapter 23click here for 9/page to printMass WastingMass Wasting The downslope movement of rock, regolith, and soil under the direct influence of gravity gyG it i th t lli fGravity is the controlling forceMass WastingMass WastingImportant triggering factors•SaturationSaturation• Oversteepening• Removal of vegetation •Ground vibrations•Ground vibrationsImportant triggering factorsImportant triggering factorsSaturation of the material with water•Destroys particle cohesionyp• Water adds weightImportant triggering factorsImportant triggering factorsOt dlOversteepened slopes • Unconsolidated granular particles assume a stable slope called the angle of repose •Stable slope angle is different for various Stab e s ope a g e s d e e t o a ousmaterials •Oversteepened slopes are unstable•Oversteepened slopes are unstableImportant triggering factorsImportant triggering factorsOt dlOversteepened slopes • Undercutting by streams• Undercutting by human interference•Addition of material to top of slope•Addition of material to top of slope• Natural—deposition•Humancausedconstruction•Human-caused--constructionImportant triggering factorsImportant triggering factors• Removal of anchoring vegetation• Wildfires•DroughtDrought• Development, logging • Ground vibrations • from earthquakesMass WastingMass Wasting Types of mass wasting processesTypes of mass wasting processes Defined by y• The material involved •How the material moves•How the material movesTypes of mass wasting processesDefined by the material involved • Debris•Mud•Mud• Earth•RockTypes of mass wasting processesDefined by how the material movesThe character of the movement •Fall•Fall • Slide •FlowTypes of mass wasting processesDefined by how the material movesThe rate of the movement •Fast•Fast•SlowForms of mass wastingForms of mass wasting • Slump• Rockslide• Debris flow•Earth flow•Earth flow•Creep• SolifluctionForms of mass wastingForms of mass wastingSlump•Rapid movement along a curved surface•Rapid movement along a curved surface• Occur along oversteepened slopesSlumpSlump• http://www.physicalgeography.net/fundamentals/10x.htmlSlump—diagram pg• Scarp•RotationalRotational blocksCk•Cracks •Hummockyuocytoe•http://geology.about.com/od/naturalhazardsclimate/ig/Landslides/slide-rotat.htmGovernment Hill AKGovernment Hill, AK• 1964• http://walrus.wr.usgs.gov/geotech/radaraapg/fig4.htmlGovernment Hill, AK ,seismic cross section• http://walrus.wr.usgs.gov/geotech/radaraapg/fig5.htmlBlock slide at Vaiont DamBlock slide at Vaiont DamForms of mass wastingForms of mass wastingRockslide •Rapid•Rapid • Blocks of bedrock move down a slopeCousin to RockfallRockslideHowe SoundRockslide—Howe Sound•http://www.flickr.com/photos/7605772@N08/2723218006•http://blog.fligtar.com/tag/travel/Elkton Oregon March 4 2006Elkton, Oregon, March 4, 2006• http://www.kmtr.com/news/local/story.aspx?content_id=010798AE-AF2F-41D5-93F5-120A64493D45Elkton Oregon March 4 2006Elkton, Oregon, March 4, 2006• http://www.kmtr.com/news/local/story.aspx?content_id=010798AE-AF2F-41D5-93F5-120A64493D45Ne adoNevado HuascaránHuascarán•Peru 1970•Peru 1970• Buried two ttowns• 18,000 killed• Geologists warned government of potentialhttp://landslides.usgs.gov/html_files/landslides/slides/slide5.htmGrosVentrerockslidediagramGrosVentrerockslide--diagramGros Ventre• http://www.goldengatephoto.com/WestUS/wyother.html#grosventreGros Ventre landslide—photolandslidephotoSlide Lake WyomingSlide Lake, Wyoming• http://www.uwsp.edu/geo/projects/geoweb/participants/dutch/VTrips/GrosVentre.HTMSherman Glacier Rock Avalanche, March 1964Rock FallRock Fall• July 1996•YosemiteYosemite• http://landslides.usgs.gov/html_files/landslides/slides/slide9.htmRock FallRock Fall• http://sts.gsc.nrcan.gc.ca/geoscape/vancouver/graphics/mountain1.gifForms of mass wastingForms of mass wastingDebris flow (mudflow) •Rapid flow of debris with water•Rapid flow of debris with water• Confined to channels • Dry areas with heavy rains •Lahar composed of volcanic materials•Lahar composed of volcanic materialsDebris FlowDebris Flow•http://geology.about.com/od/naturalhazardsclimate/ig/Landslides/slide-debflow.htmSnohomish County, WAJanuary 2006• http://www.komotv.com/stories/41527.htmUS 50 SierraUS 50, Sierra Nevadas,Nevadas, California1997http://landslides.usgs.gov/monitoring/hwy50/index.phpDebris flow damageDebris flow damageLa Conchita, CaliforniaCaliforniaS i 1995•Spring 1995• No one injured or jkilled• http://landslides.usgs.gov/html_files/landslides/slides/slide21.htmLa Conchita CaliforniaLa Conchita, California•February 2005February 2005Toes of La Conchita covering highway 101• http://www.cnn.com/interactive/weather/0501/gallery.storms/frameset.exclude.htmlLa Conchita 2005La Conchita, 2005• http://www.redcross.org/article/0,1072,0_312_3943,00.htmlSlide Mountain, Nevada, May 1983http://landslides.usgs.gov/html_files/landslides/slides/slide2.htmLahar debris flowLahar debris flow• http://landslides.usgs.gov/html_files/landslides/slides/slide13.htmToutle River Debris Flow• http://pubs.usgs.gov/fs/fs-176-97/fs-176-97.htmlNevado del Ruiz• http://volcanoes.usgs.gov/Hazards/What/Lahars/RuizLahars.htmlEruption of Nevado del Ruiz• http://volcanoes.usgs.gov/Hazards/What/Lahars/RuizLahars.htmlConfluence of lahars, Nevado del Ruiz• http://volcanoes.usgs.gov/Hazards/What/Lahars/RuizLahars.htmlArmero site, Nevado del Ruiz• http://volcanoes.usgs.gov/Hazards/What/Lahars/RuizLahars.htmlPhilippine Landslide 2006Philippine Landslide, 2006• http://www.alertnet.org/thenews/pictures/MAN52D.htmScar of Philippine landslideScar of Philippine landslide• http://news.yahoo.com/news?tmpl=story&u=/060219/481/xbm10202190643Forms of mass wastingForms of mass wastingEarthflowEarthflow • Rapid or slow• Typically occur on hillsides in humid regionsregions • Water saturates the soil • Liquefaction: associated with earthquakes and clay soilsearthquakes and clay soilsHollywood Hills CAHollywood Hills, CA• January 2005• http://www.cnn.com/interactive/weather/0501/gallery.storms/frameset.exclude.htmlNiigata Japan 1964Niigata, Japan, 1964• http://www.ce.washington.edu/~liquefaction/selectpiclique/nigata64/tiltedbuilding.jpgAnchorage AKAnchorage, AK1964•
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