Mass wasting , also known as mass movement , is a general term for the movement of rock or soil down slopes under the force of gravity . It differs from other processes of erosion in that the debris transported by mass wasting is not entrained in a moving medium, such as water, wind, or ice. Types of mass wasting include creep , solifluction , rockfalls , debris flows , and landslides , each with its own characteristic features, and taking place over timescales from seconds to hundreds of years. Mass wasting occurs on both terrestrial and submarine slopes, and has been observed on Earth , Mars , Venus , Jupiter's moon Io , and on many other bodies in the Solar System .
42-482: A mudflow , also known as mudslide or mud flow , is a form of mass wasting involving fast-moving flow of debris and dirt that has become liquified by the addition of water. Such flows can move at speeds ranging from 3 meters/minute to 5 meters/second. Mudflows contain a significant proportion of clay, which makes them more fluid than debris flows , allowing them to travel farther and across lower slope angles. Both types of flow are generally mixtures of particles with
84-569: A form of mass wasting. A distinction is then made between mass wasting by subsidence, which involves little horizontal movement, and mass wasting by slope movement. Soil creep is a slow and long term mass movement. The combination of small movements of soil or rock in different directions over time is directed by gravity gradually downslope. The steeper the slope, the faster the creep. The creep makes trees and shrubs curve to maintain their perpendicularity, and they can trigger landslides if they lose their root footing. The surface soil can migrate under
126-569: A form of mass wasting. A distinction is then made between mass wasting by subsidence, which involves little horizontal movement, and mass wasting by slope movement. Soil creep is a slow and long term mass movement. The combination of small movements of soil or rock in different directions over time is directed by gravity gradually downslope. The steeper the slope, the faster the creep. The creep makes trees and shrubs curve to maintain their perpendicularity, and they can trigger landslides if they lose their root footing. The surface soil can migrate under
168-443: A large mass of earth and rocks down a hill or a mountainside. Landslides can be further classified by the importance of water in the mass wasting process. In a narrow sense, landslides are rapid movement of large amounts of relatively dry debris down moderate to steep slopes. With increasing water content, the mass wasting takes the form of debris avalanches , then earthflows , then mudflows . Further increase in water content produces
210-443: A large mass of earth and rocks down a hill or a mountainside. Landslides can be further classified by the importance of water in the mass wasting process. In a narrow sense, landslides are rapid movement of large amounts of relatively dry debris down moderate to steep slopes. With increasing water content, the mass wasting takes the form of debris avalanches , then earthflows , then mudflows . Further increase in water content produces
252-428: A mudflow. Mudflows can be caused by unusually heavy rains or a sudden thaw. They consist mainly of mud and water plus fragments of rock and other debris, so they often behave like floods. They can move houses off their foundations or bury a place within minutes because of incredibly strong currents. When a mudflow occurs it is given four named areas, the 'main scarp', in bigger mudflows the 'upper and lower shelves' and
294-425: A sheetflood, which is a form of sheet erosion rather than mass wasting. On Earth , mass wasting occurs on both terrestrial and submarine slopes. Submarine mass wasting is particularly common along glaciated coastlines where glaciers are retreating and great quantities of sediments are being released. Submarine slides can transport huge volumes of sediments for hundreds of kilometers in a few hours. Mass wasting
336-425: A sheetflood, which is a form of sheet erosion rather than mass wasting. On Earth , mass wasting occurs on both terrestrial and submarine slopes. Submarine mass wasting is particularly common along glaciated coastlines where glaciers are retreating and great quantities of sediments are being released. Submarine slides can transport huge volumes of sediments for hundreds of kilometers in a few hours. Mass wasting
378-573: A significant amount of sediment, mudflows have higher flow heights than a clear water flood for the same water discharge. Also, sediment within the mudflow increases granular friction within the flow structure of the flow relative to clear water floods, which raises the flow depth for the same water discharge. Difficulty predicting the amount and type of sediment that will be included in a mudflow makes it much more challenging to forecast and engineer structures to protect against mudflow hazards compared to clear water flood hazards. Mudflows are common even in
420-417: A very muddy stream (stream erosion), without a sharp dividing line. Many forms of mass wasting are recognized, each with its own characteristic features, and taking place over timescales from seconds to hundreds of years. Based on how the soil, regolith or rock moves downslope as a whole, mass movements can be broadly classified as either creeps or landslides . Subsidence is sometimes also regarded as
462-417: A very muddy stream (stream erosion), without a sharp dividing line. Many forms of mass wasting are recognized, each with its own characteristic features, and taking place over timescales from seconds to hundreds of years. Based on how the soil, regolith or rock moves downslope as a whole, mass movements can be broadly classified as either creeps or landslides . Subsidence is sometimes also regarded as
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#1732855569462504-432: A wide range of sizes, which typically become sorted by size upon deposition. Mudflows are often called mudslips , a term applied indiscriminately by the mass media to a variety of mass wasting events. Mudflows often start as slides, becoming flows as water is entrained along the flow path; such events are often called mud failures . Other types of mudflows include lahars (involving fine-grained pyroclastic deposits on
546-431: Is rock glaciers , which form from rockfall from cliffs oversteepened by glaciers. Landslides can produce scarps and step-like small terraces. Landslide deposits are poorly sorted . Those rich in clay may show stretched clay lumps (a phenomenon called boudinage ) and zones of concentrated shear. Debris flow deposits take the form of long, narrow tracks of very poorly sorted material. These may have natural levees at
588-431: Is rock glaciers , which form from rockfall from cliffs oversteepened by glaciers. Landslides can produce scarps and step-like small terraces. Landslide deposits are poorly sorted . Those rich in clay may show stretched clay lumps (a phenomenon called boudinage ) and zones of concentrated shear. Debris flow deposits take the form of long, narrow tracks of very poorly sorted material. These may have natural levees at
630-678: Is a common phenomenon throughout the Solar System, occurring where volatile materials are lost from a regolith . Such mass wasting has been observed on Mars , Io , Triton , and possibly Europa and Ganymede . Mass wasting also occurs in the equatorial regions of Mars, where stopes of soft sulfate -rich sediments are steepened by wind erosion. Mass wasting on Venus is associated with the rugged terrain of tesserae . Io shows extensive mass wasting of its volcanic mountains. Mass wasting affects geomorphology , most often in subtle, small-scale ways, but occasionally more spectacularly. Soil creep
672-623: Is a common phenomenon throughout the Solar System, occurring where volatile materials are lost from a regolith . Such mass wasting has been observed on Mars , Io , Triton , and possibly Europa and Ganymede . Mass wasting also occurs in the equatorial regions of Mars, where stopes of soft sulfate -rich sediments are steepened by wind erosion. Mass wasting on Venus is associated with the rugged terrain of tesserae . Io shows extensive mass wasting of its volcanic mountains. Mass wasting affects geomorphology , most often in subtle, small-scale ways, but occasionally more spectacularly. Soil creep
714-419: Is a general term for any process of erosion that is driven by gravity and in which the transported soil and rock is not entrained in a moving medium, such as water, wind, or ice. The presence of water usually aids mass wasting, but the water is not abundant enough to be regarded as a transporting medium. Thus, the distinction between mass wasting and stream erosion lies between a mudflow (mass wasting) and
756-419: Is a general term for any process of erosion that is driven by gravity and in which the transported soil and rock is not entrained in a moving medium, such as water, wind, or ice. The presence of water usually aids mass wasting, but the water is not abundant enough to be regarded as a transporting medium. Thus, the distinction between mass wasting and stream erosion lies between a mudflow (mass wasting) and
798-432: Is located in steep mountain channels. The 2006 Sidoarjo mud flow may have been caused by rogue drilling. The point where a muddy material begins to flow depends on its grain size, the water content, and the slope of the topography. Fine grained material like mud or sand can be mobilized by shallower flows than a coarse sediment or a debris flow. Higher water content (higher precipitation/overland flow) also increases
840-442: Is not entrained in a moving medium, such as water, wind, or ice. Types of mass wasting include creep , solifluction , rockfalls , debris flows , and landslides , each with its own characteristic features, and taking place over timescales from seconds to hundreds of years. Mass wasting occurs on both terrestrial and submarine slopes, and has been observed on Earth , Mars , Venus , Jupiter's moon Io , and on many other bodies in
882-456: Is rarely apparent but can produce such subtle effects as curved forest growth and tilted fences and telephone poles. It occasionally produces low scarps and shallow depressions. Solifluction produced lobed or sheetlike deposits, with fairly definite edges, in which clasts (rock fragments) are oriented perpendicular to the contours of the deposit. Rockfall can produce talus slopes at the feet of cliffs. A more dramatic manifestation of rockfall
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#1732855569462924-456: Is rarely apparent but can produce such subtle effects as curved forest growth and tilted fences and telephone poles. It occasionally produces low scarps and shallow depressions. Solifluction produced lobed or sheetlike deposits, with fairly definite edges, in which clasts (rock fragments) are oriented perpendicular to the contours of the deposit. Rockfall can produce talus slopes at the feet of cliffs. A more dramatic manifestation of rockfall
966-614: The Gaillard Cut of the Panama Canal accounted for 55,860,400 cubic meters (73,062,600 cu yd) of the 128,648,530 cubic meters (168,265,924 cu yd) of material removed while excavating the cut. Rockslides or landslides can have disastrous consequences, both immediate and delayed. The Oso disaster of March 2014 was a landslide that caused 43 fatalities in Oso, Washington , US. Delayed consequences of landslides can arise from
1008-461: The Gaillard Cut of the Panama Canal accounted for 55,860,400 cubic meters (73,062,600 cu yd) of the 128,648,530 cubic meters (168,265,924 cu yd) of material removed while excavating the cut. Rockslides or landslides can have disastrous consequences, both immediate and delayed. The Oso disaster of March 2014 was a landslide that caused 43 fatalities in Oso, Washington , US. Delayed consequences of landslides can arise from
1050-730: The Solar System . Subsidence is sometimes regarded as a form of mass wasting. A distinction is then made between mass wasting by subsidence, which involves little horizontal movement, and mass wasting by slope movement . Rapid mass wasting events, such as landslides, can be deadly and destructive. More gradual mass wasting, such as soil creep, poses challenges to civil engineering , as creep can deform roadways and structures and break pipelines. Mitigation methods include slope stabilization , construction of walls, catchment dams, or other structures to contain rockfall or debris flows, afforestation , or improved drainage of source areas. Mass wasting
1092-577: The hills around Los Angeles , California, where they have destroyed many homes built on hillsides without sufficient support after fires destroy vegetation holding the land. On 14 December 1999 in Vargas , Venezuela , a mudflow known as The Vargas tragedy significantly altered more than 60 kilometers (37 mi) of the coastline. It was triggered by heavy rainfall and caused estimated damages of US$ 1.79 to US$ 3.5 billion, killed between 10,000 and 30,000 people, forced 85,000 people to evacuate , and led to
1134-488: The 'toe'. The main scarp will be the original area of incidence, the toe is the last affected area(s). The upper and lower shelves are located wherever there is a large dip (due to mountain or natural drop) in the mudflow's path. A mudflow can have many shelves. The world's largest historic subareal (on land) landslide occurred during the 1980 eruption of Mount St. Helens , a volcano in the Cascade Mountain Range in
1176-485: The State of Washington , US The volume of material displaced was 2.8 km (0.67 cu mi). Directly in the path of the huge mudflow was Spirit Lake . Normally a chilly 5 °C (41 °F), the lahar instantly raised the temperature to near 38 °C (100 °F). Today the bottom of Spirit Lake is 100 ft (30 m) above the original surface, and it has two and a half times more surface area than it did before
1218-407: The complete collapse of the state's infrastructure. Landslide is a more general term than mudflow. It refers to the gravity-driven failure and subsequent movement downslope of any types of surface movement of soil, rock, or other debris. The term incorporates earth slides, rock falls, flows, and mudslides, amongst other categories of hillslope mass movements . They do not have to be as fluid as
1260-509: The eruption. The largest known of all prehistoric landslides was an enormous submarine landslide that disintegrated 60,000 years ago and produced the longest flow of sand and mud yet documented on Earth. The massive submarine flow travelled 1,500 km (930 mi) – the distance from London to Rome. By volume, the largest submarine landslide (the Agulhas slide off South Africa) occurred approximately 2.6 million years ago. The volume of
1302-655: The flanks of volcanoes) and jökulhlaups (outbursts from under glaciers or icecaps). A statutory definition of "flood-related mudslide" appears in the United States' National Flood Insurance Act of 1968, as amended, codified at 42 USC Sections 4001 and following. Heavy rainfall, snowmelt , or high levels of groundwater flowing through cracked bedrock may trigger a movement of soil or sediments in landslides that continue as mudflows. Floods and debris flows may also occur when strong rains on hill or mountain slopes cause extensive erosion and/or mobilize loose sediment that
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1344-690: The formation of landslide dams , as at Thistle, Utah , in April 1983. Volcano flanks can become over-steep resulting in instability and mass wasting. This is now a recognised part of the growth of all active volcanoes. It is seen on submarine volcanoes as well as surface volcanoes: Kamaʻehuakanaloa (formerly Loihi) in the Hawaiian–Emperor seamount chain and Kick 'em Jenny in the Lesser Antilles Volcanic Arc are two submarine volcanoes that are known to undergo mass wasting. The failure of
1386-514: The formation of landslide dams , as at Thistle, Utah , in April 1983. Volcano flanks can become over-steep resulting in instability and mass wasting. This is now a recognised part of the growth of all active volcanoes. It is seen on submarine volcanoes as well as surface volcanoes: Kamaʻehuakanaloa (formerly Loihi) in the Hawaiian–Emperor seamount chain and Kick 'em Jenny in the Lesser Antilles Volcanic Arc are two submarine volcanoes that are known to undergo mass wasting. The failure of
1428-455: The influence of cycles of freezing and thawing, or hot and cold temperatures, inching its way towards the bottom of the slope forming terracettes . Landslides are often preceded by soil creep accompanied with soil sloughing —loose soil that falls and accumulates at the base of the steepest creep sections. Solifluction is a form of creep characteristics of arctic or alpine climates. It takes place in soil saturated with moisture that thaws during
1470-455: The influence of cycles of freezing and thawing, or hot and cold temperatures, inching its way towards the bottom of the slope forming terracettes . Landslides are often preceded by soil creep accompanied with soil sloughing —loose soil that falls and accumulates at the base of the steepest creep sections. Solifluction is a form of creep characteristics of arctic or alpine climates. It takes place in soil saturated with moisture that thaws during
1512-423: The northern flank of Mount St. Helens in 1980 showed how rapidly volcanic flanks can deform and fail. Methods of mitigation of mass wasting hazards include: Mass wasting Mass wasting , also known as mass movement , is a general term for the movement of rock or soil down slopes under the force of gravity . It differs from other processes of erosion in that the debris transported by mass wasting
1554-750: The potential to initiate a mudflow. After a mudflow forms, coarser sediment may be picked up by the flow. Coarser sediment picked up by the flow often forms the front of a mudflow surge and is pushed by finer sediment and water that pools up behind the coarse-grained moving mudflow-front. Mudflows may contain multiple surges of material as the flow scours channels and destabilizes adjacent hillslopes (potentially nucleating new mudflows). Mudflows have mobilized boulders 1–10 m across in mountain settings. Some broad mudflows are rather viscous and therefore slow; others begin very quickly and continue like an avalanche . They are composed of at least 50% silt and clay-sized materials and up to 30% water. Because mudflows mobilize
1596-573: The sides of the tracks, and sometimes consist of lenses of rock fragments alternating with lenses of fine-grained earthy material. Debris flows often form much of the upper slopes of alluvial fans . Triggers for mass wasting can be divided into passive and activating (initiating) causes. Passive causes include: Activating causes include: Mass wasting causes problems for civil engineering , particularly highway construction . It can displace roads, buildings, and other construction and can break pipelines. Historically, mitigation of landslide hazards on
1638-573: The sides of the tracks, and sometimes consist of lenses of rock fragments alternating with lenses of fine-grained earthy material. Debris flows often form much of the upper slopes of alluvial fans . Triggers for mass wasting can be divided into passive and activating (initiating) causes. Passive causes include: Activating causes include: Mass wasting causes problems for civil engineering , particularly highway construction . It can displace roads, buildings, and other construction and can break pipelines. Historically, mitigation of landslide hazards on
1680-816: The slide was 20,000 km (4,800 cu mi). The areas most generally recognized as being at risk of a dangerous mudflow are: Mass wasting Subsidence is sometimes regarded as a form of mass wasting. A distinction is then made between mass wasting by subsidence, which involves little horizontal movement, and mass wasting by slope movement . Rapid mass wasting events, such as landslides, can be deadly and destructive. More gradual mass wasting, such as soil creep, poses challenges to civil engineering , as creep can deform roadways and structures and break pipelines. Mitigation methods include slope stabilization , construction of walls, catchment dams, or other structures to contain rockfall or debris flows, afforestation , or improved drainage of source areas. Mass wasting
1722-409: The summer months to creep downhill. It takes place on moderate slopes, relatively free of vegetation, that are underlain by permafrost and receive a constant supply of new debris by weathering . Solifluction affects the entire slope rather than being confined to channels and can produce terrace-like landforms or stone rivers . A landslide, also called a landslip, is a relatively rapid movement of
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1764-409: The summer months to creep downhill. It takes place on moderate slopes, relatively free of vegetation, that are underlain by permafrost and receive a constant supply of new debris by weathering . Solifluction affects the entire slope rather than being confined to channels and can produce terrace-like landforms or stone rivers . A landslide, also called a landslip, is a relatively rapid movement of
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