What is Landslide?
[[File:Landslide 2.jpg|thumb|right|350px| {{center|1=Landslide in [[Pakistan]]}}]] A '''landslide''' includes a wide range of ground movements, such as [[Rock (geology)|rock]] falls, deep failure of slopes and shallow [[debris]] flows. The biggest reason for a landslide is that there is a [[slope]] and material goes down the slope because of [[gravity]]. But other things also contribute to landslides: * [[erosion]] by [[river]]s, [[glacier]]s, or ocean [[wave]]s makes slopes too steep * rock and soil slopes made weak through [[saturation]] by [[snow]]melt or heavy [[rain]]s * [[earthquake]]s that make weak slopes fail or crack the rocks that will eventually fall down * [[volcano|volcanic eruptions]] produce loose ash deposits, heavy rain, and debris flows * [[oscillation|vibrations]] from [[machine]]ry, [[traffic]], [[Explosive material|blasting]] and even [[thunder]] may trigger failure of weak slopes * weight from much rain or snow, stockpiling of rock or ore, from waste piles, or from buildings may stress weak slopes to failure and other structures * [[groundwater]] pressure making the slope unstable * in shallow [[soil]]s, the removal of deep-[[root]]ed [[plant]]s that bind the [[Soil|colluvium]] to [[bedrock]] An underlying reason is the nature of the material. For example, a [[thixotropic]] material such as mud or sand and water, can change from a [[gel]] to a [[Sol (colloid)|sol]] by adding water or pressure, or shaking. It goes from being stable one minute to fluid the next minute. The greatest disasters, like [[lahar]]s or [[mudslide]]s, happen suddenly. It is possible for much of a volcano to just slide down suddenly, as with [[Toba]], [[Krakatoa]] and [[Mount St Helens]]. ==Other websites== {{commonscat|Landslides}} * [http://landslides.usgs.gov/ United States Geological Survey site] * [http://www.em.gov.bc.ca/Mining/Geolsurv/Surficial/landslid/ British Columbia government landslide information] {{Webarchive|url=https://web.archive.org/web/20080612172240/http://www.em.gov.bc.ca/Mining/Geolsurv/