A landslide or landslip is a geological phenomenon A geological phenomenon is a phenomenon which is explained by or sheds light on the science of geology which includes a wide range of ground movement, such as rock falls, deep failure of slopes and shallow debris flows, which can occur in offshore, coastal and onshore environments. Although the action of gravity Gravitation, or gravity, is one of the four fundamental interactions of nature , in which objects with mass attract one another. In everyday life, gravitation is most familiar as the agent that gives weight to objects with mass and causes them to fall to the ground when dropped. Gravitation causes dispersed matter to coalesce, thus accounting for is the primary driving force for a landslide to occur, there are other contributing factors affecting the original slope stability The field of slope stability encompasses the analysis of static and dynamic stability of slopes of earth and rock-fill dams, slopes of other types of embankments, excavated slopes, and natural slopes in soil and soft rock. Slope stability investigation, analysis , and design mitigation is typically completed by geologists, engineering geologists,. Typically, pre-conditional factors build up specific sub-surface conditions that make the area/slope prone to failure, whereas the actual landslide often requires a trigger before being released.

Contents 1 Causes of landslides 2 Types of landslide 2.1 Debris flow 2.2 Earth flow 2.3 Debris avalanche 2.4 Sturzstrom 2.5 Shallow landslide 2.6 Deep-seated landslide 3 Causing tsunamis 4 Related phenomena 5 Landslide prediction mapping 6 Prehistoric landslides 7 Prehistoric submarine landslides 8 Historical landslides 8.1 19th Century 8.2 20th Century 8.3 21st Century 9 Extraterrestrial landslides 10 See also 11 References 12 External links

Causes of landslides

Main article: Causes of landslides The causes of landslides are usually related to instabilities in slopes. It is usually possible to identify one or more landslide causes and one landslide trigger. The difference between these two concepts is subtle but important. The landslide causes are the reasons that a landslide occurred in that location and at that time. Landslide causes are The Mameyes Landslide Tropical Storm Isabel was the ninth tropical storm of the 1985 Atlantic hurricane season. The storm's track extended from the Caribbean Sea to the southeastern United States during the second week of October. Prior to developing into a tropical cyclone, it produced torrential rainfall, resulting in great damage and loss of life in Puerto Rico, in barrio Tibes Tibes is one of the 31 barrios in the municipality of Ponce, Puerto Rico. Together with Magueyes, Portugues, Monte Llano, Maragüez, Machuelo Arriba, Sabanetas, and Cerrillos, Tibes is one of the municipality's eight rural interior barrios. Tibes attracted attention recently when, in 1975, what was to become the discovery of the oldest cemetery in, Ponce, Puerto Rico, which buried more than 100 homes, was caused by extensive accumulation of rains and, according to some sources, lightning.

Landslides occur when the stability of a slope The field of slope stability encompasses the analysis of static and dynamic stability of slopes of earth and rock-fill dams, slopes of other types of embankments, excavated slopes, and natural slopes in soil and soft rock. Slope stability investigation, analysis , and design mitigation is typically completed by geologists, engineering geologists, changes from a stable to an unstable condition. A change in the stability of a slope can be caused by a number of factors, acting together or alone. Natural causes of landslides include:

• groundwater Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock become completely saturated with water is called the (porewater) pressure acting to destabilize the slope
• Loss or absence of vertical vegetative structure, soil nutrients, and soil structure Soil structure is determined by how individual soil granules clump or bind together and aggregate, and therefore, the arrangement of soil pores between them. Soil structure has a major influence on water and air movement, biological activity, root growth and seedling emergence (e.g. after a wildfire A wildfire is any uncontrolled fire in combustible vegetation that occurs in the countryside or a wilderness area. Other names such as brush fire, bushfire, forest fire, grass fire, hill fire, peat fire, vegetation fire, veldfire and wildland fire may be used to describe the same phenomenon depending on the type of vegetation being burned. A)
• erosion Erosion is the process of weathering and transport of solids in the natural environment or their source and deposits them elsewhere. It usually occurs due to transport by wind, water, or ice; by down-slope creep of soil and other material under the force of gravity; or by living organisms, such as burrowing animals, in the case of bioerosion of the toe of a slope by rivers or ocean waves In mathematics and science, a wave is a disturbance that travels through space and time, usually by the transfer of energy. Waves are described by a wave equation that can take on many forms depending on the type of wave. A mechanical wave is a wave that propagates through a medium owing to restoring forces resulting from its deformation. For
• weakening of a slope through saturation by snowmelt, glaciers A glacier is a perennial mass of ice which moves over land. A glacier forms in locations where the mass accumulation of snow and ice exceeds ablation over many years. The word glacier comes from French via the Vulgar Latin glacia, and ultimately from Latin glacies meaning ice. The corresponding area of study is called glaciology melting, or heavy rains
• earthquakes An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time. Earthquakes are measured with a seismometer; a device which also records is known as a seismograph. The adding loads to barely-stable slope
• earthquake-caused liquefaction Soil liquefaction describes the behavior of soils that, when loaded, suddenly suffer a transition from a solid state to a liquefied state, or having the consistency of a heavy liquid. Liquefaction is more likely to occur in loose to moderately saturated granular soils with poor drainage, such as silty sands or sands and gravels capped or destabilizing slopes The Hope Slide was the largest landslide ever recorded in Canada. It occurred in the morning hours of January 9, 1965 in the Nicolum Valley near Hope, British Columbia, and killed four people
• volcanic eruptions A volcano is an opening, or rupture, in a planet's surface or crust, which allows hot magma, ash and gases to escape from below the surface

landslides are aggravated by human activities, Human causes include:deforestation, cultivation and construction, which destabilize the already fragile slopes

• vibrations Oscillation is the repetitive variation, typically in time, of some measure about a central value or between two or more different states. Familiar examples include a swinging pendulum and AC power. The term vibration is sometimes used more narrowly to mean a mechanical oscillation but sometimes is used to be synonymous with "oscillation.& from machinery A machine is a device that uses energy to perform some activity. In common usage, the meaning is that of a device having parts that perform or assist in performing any type of work. A simple machine is a device that transforms the direction or magnitude of a force without consuming any energy. The word "machine" is derived from the Latin or traffic Traffic on roads may consist of pedestrians, ridden or herded animals, vehicles, streetcars and other conveyances, either singly or together, while using the public way for purposes of travel. Traffic laws are the laws which govern traffic and regulate vehicles, while rules of the road are both the laws and the informal rules that may have
• blasting An explosive material, also called an explosive, is a substance that contains a great amount of stored energy that can produce an explosion, a sudden expansion of the material after initiation, usually accompanied by the production of light, heat, and pressure. An explosive charge is a measured quantity of explosive material
• earthwork Earthworks are engineering works created through the moving of massive quantities of soil or unformed rock. Engineers need to concern themselves with issues of geotechnical engineering and with quantity estimation to ensure that soil volumes in the cuts match those of the fills, while minimizing the distance of movement. In the past, these which alters the shape of a slope, or which imposes new loads on an existing slope
• in shallow soils Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics. It is composed of particles of broken rock that have been altered by chemical and environmental processes that include weathering and, the removal of deep-rooted In vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial or aerating (growing up above the ground or especially above water). Furthermore, a stem normally occurring below ground is not exceptional either (see rhizome). So, it is vegetation Vegetation is a general term for the plant life of a region; it refers to the ground cover provided by plants. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic characteristics. It is broader than the term flora which refers exclusively to that binds colluvium Colluvium is the name for loose bodies of sediment that have been deposited or built up at the bottom of a low-grade slope or against a barrier on that slope, transported by gravity. The deposits that collect at the foot of a steep slope or cliff are also known by the same name. Colluvium often outerfingers with alluvium . Coarse deposits due to to bedrock In stratigraphy, bedrock is the native consolidated rock underlying the surface of a terrestrial planet, usually the Earth. Above the bedrock is usually an area of broken and weathered unconsolidated rock in the basal subsoil. The top of the bedrock is known as rockhead and identifying this, via excavations, drilling or geophysical methods, is an
• Construction, agricultural or forestry activities (logging) which change the amount of water which infiltrates the soil.

The landslide at Surte Surte is a locality situated in Ale Municipality, Västra Götaland County, Sweden. It had 5,740 inhabitants in 2005 in Sweden, 1950. It was a quick clay Quick clay, also known as Leda clay and Champlain Sea clay in Canada, is a unique form of highly sensitive marine clay, with the tendency to change from a relatively stiff condition to a liquid mass when it is disturbed slide killing one person.

Types of landslide

The following text needs to be harmonized with text in Landslide classification For example, the McGraw-Hill Encyclopedia of Science and Technology distinguishes the following types of landslides:.

Main article: Landslide classification For example, the McGraw-Hill Encyclopedia of Science and Technology distinguishes the following types of landslides:

Debris flow

Amboori Amboori or Amboory is a village in the south east of Thiruvananthapuram district in the state of Kerala in India. Amboori is long inhabited by kanikar tribe. Amboori is a grama Panchayat with a population of 9,839. Demography is dominated by Nadars, who form around 40% total population, rest include ,Pulayas, Ezhavas, Nairs etc. Another important debris flow, occurred on 9 November 2001 in Kerala, India. The event killed 39 people.^[1]

Slope material that becomes saturated An aquifer is an underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology. Related terms include aquitard, which is a bed of low permeability along an aquifer, and with water may develop into a debris flow A debris flow is a fast moving, liquified landslide of unconsolidated, saturated debris that looks like flowing concrete. It is differentiated from a mudflow in terms of the viscosity and textural properties of the flow. Flows can carry material ranging in size from clay to boulders, and may contain a large amount of woody debris such as logs and or mud flow A mudslide is the most rapid and fluid type of downhill mass wasting. It is a rapid movement of a large mass of mud formed from loose soil and water. Similar terms are mudflow, mud stream, debris flow (e.g. in high mountains), jökulhlaup, and lahar (from volcanoes, see also pyroclastic flow). The resulting slurry of rock In geology, rock is a naturally occurring solid aggregate of minerals and/or mineraloids and mud may pick up trees, houses and cars, thus blocking bridges and tributaries A tributary or affluent is a stream or river which flows into a main stem river. A tributary does not flow directly into a sea, ocean, or lake. Tributaries and the mainstem river serve to drain the surrounding drainage basin of its surface water and groundwater by leading the water out into an ocean or some other large body of water causing flooding A flood is an overflow of an expanse of water that submerges land. The EU Floods directive defines a flood as a temporary covering by water of land not normally covered by water. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Flooding may result from the volume of water within a body of water, along its path.

Debris flow is often mistaken for flash flood A flash flood is a rapid flooding of geomorphic low-lying areas - washes, rivers, dry lakes and basins. It may be caused by heavy rain associated with a storm, hurricane, or tropical storm or meltwater from ice or snow flowing over icesheets or snowfields. Flash floods can also occur after the collapse of natural ice or debris dam, or a human, but they are entirely different processes.

Muddy-debris flows in alpine Alpine climate is the average weather for a region above the tree line. The climate becomes colder at high elevations—this characteristic is described by the lapse rate of air: air tends to get colder as it rises, since it expands. The dry adiabatic lapse rate is 10 °C per km of elevation or altitude. Therefore, moving up 100 meters on a areas cause severe damage to structures and infrastructure and often claim human lives. Muddy-debris flows can start as a result of slope-related factors and shallow landslides can dam stream beds A stream bed is the channel bottom of a stream, river or creek; the physical confine of the normal water flow. The lateral confines or channel margins, during all but flood stage, are known as the stream banks or river banks. In fact, a flood occurs when a stream overflows its banks and flows onto its flood plain. As a general rule, the bed is, resulting in temporary water blockage. As the impoundments fail, a "domino Dominoes generally refers to the collective gaming pieces making up a domino set (sometimes called a deck or pack) or to the subcategory of tile games played with domino pieces. In the area of mathematical tilings and polyominoes, the word domino often refers to any rectangle formed from joining two congruent squares edge to edge. The traditional effect" may be created, with a remarkable growth in the volume of the flowing mass, which takes up the debris Debris is rubble, wreckage, ruins, litter and discarded garbage/refuse/trash, scattered remains of something destroyed, or, in geology, large rock fragments left by a melting glacier etc. The singular form of debris is debris. Depending on context, debris can refer to a number of different things in the stream channel. The solid-liquid mixture can reach densities of up to 2 tons/m³ and velocities of up to 14 m/s (Chiarle and Luino, 1998; Arattano, 2003). These processes normally cause the first severe road interruptions, due not only to deposits accumulated on the road (from several cubic metres to hundreds of cubic metres), but in some cases to the complete removal of bridges or roadways or railways crossing the stream channel. Damage usually derives from a common underestimation of mud-debris flows: in the alpine valleys, for example, bridges are frequently destroyed by the impact force of the flow because their span is usually calculated only for a water discharge. For a small basin in the Italian Alps (area = 1.76 km²) affected by a debris flow, Chiarle and Luino (1998)^{[citation needed]} estimated a peak discharge of 750 m³/s for a section located in the middle stretch of the main channel. At the same cross section, the maximum foreseeable water discharge (by HEC-1), was 19 m³/s, a value about 40 times lower than that calculated for the debris flow that occurred.

Earth flow

A rock slide in Guerrero The State of Guerrero is a state in the southern meridional region of Mexico. The state capital is Chilpancingo de los Bravo. Other important cities include Acapulco, Petatlan, Taxco, Iguala, and Zihuatanejo. The modern entity did not exist until 1849, when it was carved out of territories from the states of Mexico, Puebla and Michoacán. The, Mexico

Earthflows An earthflow is a downslope viscous flow of fine grained materials that have been saturated with water, and moves under the pull of gravity. They are an intermediate type of mass wasting that is between downhill creep and mudflow. The types of materials that are susceptible to earthflows are clay, fine sand and silt, and fine-grained pyroclastic are downslope, viscous flows of saturated, fine-grained materials, which move at any speed from slow to fast. Typically, they can move at speeds from 0.17 to 20 km/h. Though these are a lot like mudflows A mudslide is the most rapid and fluid type of downhill mass wasting. It is a rapid movement of a large mass of mud formed from loose soil and water. Similar terms are mudflow, mud stream, debris flow (e.g. in high mountains), jökulhlaup, and lahar (from volcanoes, see also pyroclastic flow), overall they are slower moving and are covered with solid material carried along by flow from within. They are different from fluid flows in that they are more rapid. Clay, fine sand and silt, and fine-grained, pyroclastic material are all susceptible to earthflows. The velocity of the earthflow is all dependent on how much water content is in the flow itself: if there is more water content in the flow, the higher the velocity will be.

These flows usually begin when the pore pressures in a fine-grained mass increase until enough of the weight of the material is supported by pore water to significantly decrease the internal shearing strength of the material. This thereby creates a bulging lobe which advances with a slow, rolling motion. As these lobes spread out, drainage of the mass increases and the margins dry out, thereby lowering the overall velocity of the flow. This process causes the flow to thicken. The bulbous variety of earthflows are not that spectacular, but they are much more common than their rapid counterparts. They develop a sag at their heads and are usually derived from the slumping at the source.

Earthflows occur much more during periods of high precipitation, which saturates the ground and adds water to the slope content. Fissures develop during the movement of clay-like material creates the intrusion of water into the earthflows. Water then increases the pore-water pressure and reduces the shearing strength of the material.^[2]

Debris avalanche

Goodell Creek Debris Avalanche, Washington

A debris avalanche is a type of slide characterized by the chaotic movement of rocks soil and debris mixed with water or ice (or both). They are usually triggered by the saturation of thickly vegetated slopes which results in an incoherent mixture of broken timber, smaller vegetation and other debris.^[3] Debris avalanches differ from debris slides because their movement is much more rapid. This is usually a result of lower cohesion or higher water content and commonly steeper slopes.

Movement

Debris slides generally begin with large blocks that slump at the head of the slide and then break apart as they move towards the toe. This process is much slower than that of a debris avalanche. In a debris avalanche this progressive failure is very rapid and the entire mass seems to somewhat liquefy as it moves down the slope. This is caused by the combination of the excessive saturation of the material, and very steep slopes. As the mass moves down the slope it generally follows stream channels leaving behind a V-shaped scar that spreads out downhill. This differs from the more U-shaped scar of a slump. Debris avalanches can also travel well past the foot of the slope due to their tremendous speed.^[4]

Blockade of Hunza river

Sturzstrom

A sturzstrom A sturzstrom is a rare, unique type of landslide consisting of soil and rock which is characterized by having a great horizontal movement when compared to its initial vertical drop - as much as 20 or 30 times the vertical distance. Sturzstroms are similar to glaciers, mudslides, and lava flows. Sturzstroms flow across land fairly easily, and their is a rare, poorly understood type of landslide, typically with a long run-out. Often very large, these slides are unusually mobile, flowing very far over a low angle, flat, or even slightly uphill terrain.

See also: Slump (geology)

Shallow landslide

Hotel Limone at the Garda Lake. Part of a hill of Devonian The Devonian is a geologic period and system of the Paleozoic Era spanning from 416 to 359.2 million years ago (ICS, 2004,. It is named after Devon, England, where rocks from this period were first studied shale Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering or bedding less than one centimeter in thickness, was removed to make the road, forming a dip-slope. The upper block detached along a bedding plane and is sliding down the hill, forming a jumbled pile of rock at the toe of the slide.

Landslide in which the sliding surface is located within the soil Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics. It is composed of particles of broken rock that have been altered by chemical and environmental processes that include weathering and mantle or weathered bedrock (typically to a depth from few decimetres to some metres). They usually include debris slides, debris flow, and failures of road cut-slopes. Landslides occurring as single large blocks of rock moving slowly down slope are sometimes called block glides.

Shallow landslides can often happen in areas that have slopes with high permeable soils on top of low permeable bottom soils. The low permeable, bottom soils trap the water in the shallower, high permeable soils creating high water pressure in the top soils. As the top soils are filled with water and become heavy, slopes can become very unstable and slide over the low permeable bottom soils. Say there is a slope with silt and sand as its top soil and bedrock as its bottom soil. During an intense rainstorm, the bedrock will keep the rain trapped in the top soils of silt and sand. As the topsoil becomes saturated and heavy, it can start to slide over the bedrock and become a shallow landslide. R. H. Campbell did a study on shallow landslides on Santa Cruz Island California. He notes that if permeability decreases with depth, a perched water table may develop in soils at intense precipitation. When pore water pressures are sufficient to reduce effective normal stress to a critical level, failure occurs.^[5]

Deep-seated landslide

Landslide of soil and regolith in Pakistan

Landslides in which the sliding surface is mostly deeply located below the maximum rooting depth of trees (typically to depths greater than ten meters). Deep-seated landslides usually involve deep regolith, weathered rock, and/or bedrock and include large slope failure associated with translational, rotational, or complex movement. These typically move slowly, only several meters per year, but occasionally move faster. They tend to be larger than shallow landslides and form along a plane of weakness such as a fault or bedding plane. They can be visually identified by concave scarps at the top and steep areas at the toe. ^[6]

Causing tsunamis

Landslides that occur undersea, or have impact into water, can generate tsunamis. Massive landslides can also generate megatsunamis, which are usually hundreds of metres high. In 1958, one such tsunami occurred in Lituya Bay in Alaska.

Related phenomena

• An avalanche, similar in mechanism to a landslide, involves a large amount of ice, snow and rock falling quickly down the side of a mountain.
• A pyroclastic flow is caused by a collapsing cloud of hot ash, gas and rocks from a volcanic explosion that moves rapidly down an erupting volcano.

Show All>>

 

 

 

What Links Here:

 

Recently Viewed Pages:

• Home
• Hazard: News
• Search Terms
• About Us
• Blogs
• Hazard: Encyclopedia
• Incident: Answers
• CPR and First Aid
• Volcano: Answers
• Biohazard: Images

 

Most Popular Pages:

• Biohazard: Images
• Volcano: Answers
• Biosafety Level: Images
• IMDG Code: Images
• CPR and First Aid
• Pseudocertainty Effect: Blogs
• Muster Drill: Blogs
• Landslide
• Fail-safe: Blogs
• International Identity Federation: Blogs

Related 'Landslide' Searches:

related terms:	Debris	Landslide	Water	Slope
	Flow	Movement	Landslides	Flows
	Slopes	Shallow	Factors	Occur

---

top user searches:	►

---

or search for "Landslide" in:		Web:		The Entire Web	Related Sites	Web Directories
		This Site:		Page Titles	Karr Network Sites*
		News:		Headlines	Weather	Events	Blogs
		Reference:		Encyclopedia	Dictionary	eTexts	Quotes
				Local Map	Answers
		Multimedia:		Images	Videos
		People:		Discussion Groups	Social Networking
		Shopping:		General Merch.	Consumer Opinion	Auctions	Classifieds

 

---

The Entire Web Web Directories Related* Sites Karr Network Sites* Page Titles Headlines Weather Events Blogs Encyclopedia Dictionary eTexts Quotes Answers Local Map Videos Images Social Networking Discussion Groups General Items Auctions Classifieds Consumer Opinion

Sitemap News Dictionary Encyclopedia Blogs Answers Videos Images Shopping Directory More…