D.R.R.R. Mass Movement PDF

D.R.R.R Avalanche. A rapid flow of Mass movement can be: surface materials down a hill or a downslope movement such as mountainside. landslides a vertical movement such as Debris - Loose na...

D.R.R.R Avalanche. A rapid flow of Mass movement can be: surface materials down a hill or a downslope movement such as mountainside. landslides a vertical movement such as Debris - Loose natural material ground subsidence or collapse. consisting especially of broken pieces of rock. Landslides also have several types according to its composition and Fragment - A broken part of manner of movement. These types are: something. Rockfalls Landslide - It is defined as Flows the movement of a mass of Debris avalanche rock, debris, or earth down Slumps a slope. Creep Limestone - A sedimentary rock Rockfall composed primarily of calcium -occurs when carbonate (CaCO3) fragment of large masses of rocks break Mass movement - A geological process and fall from a steep by which soil, sand, and rock move slope. downslope typically as a solid continuous or discontinuous mass, largely under the Flows force of gravity. This type of landslide involves the Rock - An aggregate of one or more movement of material mineral. in a liquid form. In communities near GEOMORPHOLOGY volcanoes, this is known as a lahar Science that studies the nature flow. and history of landforms and the processes of weathering, erosion Debris avalanches are and deposition that created them. an extremely rapid movement of rocks and Mass movement of surface soil. They are very materials is a geological hazard dangerous because which is caused by different factors they flow at a speed of such as: 100 to 300 km/hr and heavy rainfall may contain boulders or earthquakes with the presence of large rocks. gravity.  D.R.R.R Creep is relatively Collapse is a fast opening of the land less dangerous surface and movement of surface mass movement materials. which involves the slow When the underlying ground downslope collapses, the result is a sinkhole. movement of soil and weak rocks Dissolution on the surface. -happens when the soil cover is thin and highly permeable so that acidic GROUND groundwater can seep easily SUBSIDENCE DUE through it and dissolve the TO KARST underlying limestone bedrock. lowering of the land surface with Cover Subsidence little or no horizontal motion due -form when sandy, permeable to sinkhole collapse sediment sits on the top of a limestone bedrock. Sinkhole collapse could be due to: Cover Collapse -occurs suddenly and Gravity without warning. This is Lowering of groundwater table the deadliest among the Heavy rains three. Ground shaking due to earthquakes Ponding of sub-terranean river WHY ARE WE PRONE TO LANDSLIDES Weak and incompetent rocks Aside from a landslide, ground Thick and weak soil cover subsidence and collapse are also Fractured and jointed rocks examples of geological or mass Adversely oriented fractures movement hazard. Very steep slopes River mouths that emanate from land- Unlike the downslope movement of a slide-prone hills and mountains landslide, subsidence and collapse move High amounts of rainfall vertically. Anthropo-genic factors Subsidence is a slow lowering of a land surface.