![Landslide in Cusco, Peru - 2018](https://upload.wikimedia.org/wikipedia/commons/b/b2/Landslide_in_Cusco%2C_Peru_-_2018.jpg)
Landslides, also known as landslips, are several forms of
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 is not entrained in ...
that may include a wide range of ground movements, such as
rockfall
A rockfall or rock-fallWhittow, John (1984). ''Dictionary of Physical Geography''. London: Penguin, 1984. . is a quantity/sheets of rock that has fallen freely from a cliff face. The term is also used for collapse of rock from roof or walls of min ...
s, deep-seated
slope
In mathematics, the slope or gradient of a line is a number that describes both the ''direction'' and the ''steepness'' of the line. Slope is often denoted by the letter ''m''; there is no clear answer to the question why the letter ''m'' is use ...
failures,
mudflow
A mudflow or mud flow is a form of mass wasting involving fast-moving flow of debris 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 significa ...
s, and
debris flow
Debris flows are geological phenomena in which water-laden masses of soil and fragmented rock rush down mountainsides, funnel into stream channels, entrain objects in their paths, and form thick, muddy deposits on valley floors. They generally ...
s.
Landslides occur in a variety of environments, characterized by either steep or gentle slope gradients, from
mountain
A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited Summit (topography), summit area, and ...
ranges to
coast
The coast, also known as the coastline or seashore, is defined as the area where land meets the ocean, or as a line that forms the boundary between the land and the coastline. The Earth has around of coastline. Coasts are important zones in n ...
al
cliff
In geography and geology, a cliff is an area of rock which has a general angle defined by the vertical, or nearly vertical. Cliffs are formed by the processes of weathering and erosion, with the effect of gravity. Cliffs are common on co ...
s or even underwater, in which case they are called
submarine landslide
Submarine landslides are marine landslides that transport sediment across the continental shelf and into the deep ocean. A submarine landslide is initiated when the downwards driving stress (gravity and other factors) exceeds the resisting str ...
s.
Gravity
In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stro ...
is the primary driving force for a landslide to occur, but there are other factors affecting
slope stability
Slope stability analysis is a static or dynamic, analytical or empirical method to evaluate the stability of earth and rock-fill dams, embankments, excavated slopes, and natural slopes in soil and rock. Slope stability refers to the condition of i ...
that produce specific conditions that make a slope prone to failure. In many cases, the landslide is triggered by a specific event (such as a heavy
rain
Rain is water droplets that have condensed from atmospheric water vapor and then fall under gravity. Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the Earth. It provides water f ...
fall, an
earthquake
An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from ...
, a slope cut to build a road, and many others), although this is not always identifiable.
Causes
Landslides occur when the slope (or a portion of it) undergoes some processes that change its condition from stable to unstable. This is essentially due to a decrease in the
shear strength
In engineering, shear strength is the strength of a material or component against the type of yield or structural failure when the material or component fails in shear. A shear load is a force that tends to produce a sliding failure on a materia ...
of the slope material, an increase in the
shear stress
Shear stress, often denoted by (Greek: tau), is the component of stress coplanar with a material cross section. It arises from the shear force, the component of force vector parallel to the material cross section. ''Normal stress'', on the ot ...
borne by the material, or a combination of the two. 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:
* saturation by rain water infiltration, snow melting, or
glacier
A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its Ablation#Glaciology, ablation over many years, often Century, centuries. It acquires dis ...
s melting;
*rising of
groundwater
Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidate ...
or increase of pore water pressure (e.g. due to
aquifer
An aquifer is an underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials (gravel, sand, or silt). Groundwater from aquifers can be extracted using a water well. Aquifers vary greatly in their characterist ...
recharge in rainy seasons, or by rain water infiltration);
*increase of hydrostatic pressure in cracks and fractures;
* loss or absence of vertical vegetative structure,
soil nutrients Seventeen elements or nutrients are essential for plant growth and reproduction. They are carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P), potassium (K), sulfur (S), calcium (Ca), magnesium (Mg), iron (Fe), boron (B), manganese (M ...
, and
soil structure
Soil structure describes the arrangement or the way of soil in the solid parts of the soil and of the pore space located between them. It is determined by how individual soil granules clump, bind together, and aggregate, resulting in the arrangem ...
(e.g. after a wildfire – a fire in forests lasting for 3–4 days);
*
erosion
Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...
of the top of a slope by rivers or sea
wave
In physics, mathematics, and related fields, a wave is a propagating dynamic disturbance (change from equilibrium) of one or more quantities. Waves can be periodic, in which case those quantities oscillate repeatedly about an equilibrium (res ...
s;
*physical and chemical
weathering
Weathering is the deterioration of rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs ''in situ'' (on site, with little or no movement), ...
(e.g. by repeated freezing and thawing, heating and cooling, salt leaking in the groundwater or mineral dissolution);
* ground shaking caused by
earthquake
An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from ...
s, which can destabilize the slope directly (e.g., by inducing
soil liquefaction
Soil liquefaction occurs when a cohesionless saturated or partially saturated soil substantially loses strength and stiffness in response to an applied stress such as shaking during an earthquake or other sudden change in stress condition, in ...
) or weaken the material and cause cracks that will eventually produce a landslide;
*
volcanic eruptions
Several types of volcanic eruptions—during which lava, tephra (ash, lapilli, volcanic bombs and volcanic blocks), and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often ...
;
Landslides are aggravated by human activities, such as:
*
deforestation
Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated d ...
,
cultivation and
construction
Construction is a general term meaning the art and science to form objects, systems, or organizations,"Construction" def. 1.a. 1.b. and 1.c. ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0) Oxford University Press 2009 and com ...
;
*
vibrations
Vibration is a mechanical phenomenon whereby oscillations occur about an equilibrium point. The word comes from Latin ''vibrationem'' ("shaking, brandishing"). The oscillations may be periodic, such as the motion of a pendulum—or random, such ...
from
machinery
A machine is a physical system using power to apply forces and control movement to perform an action. The term is commonly applied to artificial devices, such as those employing engines or motors, but also to natural biological macromolecule ...
or
traffic
Traffic comprises pedestrians, vehicles, ridden or herded animals, trains, and other conveyances that use public ways (roads) for travel and transportation.
Traffic laws govern and regulate traffic, while rules of the road include traffic ...
;
*
blasting and
mining
Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef, or placer deposit. The exploitation of these deposits for raw material is based on the economic via ...
;
*
earthwork (e.g. by altering the shape of a slope, or imposing new loads);
* in shallow
soil
Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ...
s, the removal of deep-
root
In vascular plants, the roots are the organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often below the sur ...
ed
vegetation
Vegetation is an assemblage of plant species and the ground cover they provide. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic character ...
that binds
colluvium
Colluvium (also colluvial material or colluvial soil) is a general name for loose, unconsolidated sediments that have been deposited at the base of hillslopes by either rainwash, sheetwash, slow continuous downslope creep, or a variable combinatio ...
to
bedrock
In geology, bedrock is solid Rock (geology), rock that lies under loose material (regolith) within the crust (geology), crust of Earth or another terrestrial planet.
Definition
Bedrock is the solid rock that underlies looser surface mater ...
;
* agricultural or forestry activities (
logging
Logging is the process of cutting, processing, and moving trees to a location for transport. It may include skidding, on-site processing, and loading of trees or logs onto trucks or skeleton cars.
Logging is the beginning of a supply chain ...
), and
urbanization
Urbanization (or urbanisation) refers to the population shift from rural to urban areas, the corresponding decrease in the proportion of people living in rural areas, and the ways in which societies adapt to this change. It is predominantly t ...
, which change the amount of water infiltrating the soil.
![Landslide in Sweden (Surte) 1950, 2](https://upload.wikimedia.org/wikipedia/commons/7/7f/Landslide_in_Sweden_%28Surte%29_1950%2C_2.jpg)
*temporal variation in
land use
Land use involves the management and modification of natural environment or wilderness into built environment such as settlements and semi-natural habitats such as arable fields, pastures, and managed woods. Land use by humans has a long h ...
and
land cover
Land cover is the physical material at the surface of Earth. Land covers include grass, asphalt, trees, bare ground, water, etc. Earth cover is the expression used by ecologist Frederick Edward Clements that has its closest modern equivalent being ...
(LULC): it includes the human abandonment of farming areas, e.g. due to the economic and social transformations which occurred in Europe after the Second World War.
Land degradation
Land degradation is a process in which the value of the biophysical environment is affected by a combination of human-induced processes acting upon the land.
It is viewed as any change or disturbance to the land perceived to be deleterious ...
and extreme rainfall can increase the frequency of
erosion
Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...
and landslide phenomena.
Types
Hungr-Leroueil-Picarelli classification
In traditional usage, the term landslide has at one time or another been used to cover almost all forms of
mass movement Mass movement may refer to:
* Mass movement (geology), the movement of rock and soil down slopes due to gravity
* Mass movement (politics)
A mass movement denotes a political party or movement which is supported by large segments of a population. P ...
of rocks and
regolith
Regolith () is a blanket of unconsolidated, loose, heterogeneous superficial deposits covering solid rock. It includes dust, broken rocks, and other related materials and is present on Earth, the Moon, Mars, some asteroids, and other terrestria ...
at the Earth's surface. In 1978, geologist David Varnes noted this imprecise usage and proposed a new, much tighter scheme for the classification of mass movements and
subsidence
Subsidence is a general term for downward vertical movement of the Earth's surface, which can be caused by both natural processes and human activities. Subsidence involves little or no horizontal movement, which distinguishes it from slope move ...
processes.
[Varnes D. J., Slope movement types and processes. In: Schuster R. L. & Krizek R. J. Ed., Landslides, analysis and control. Transportation Research Board Sp. Rep. No. 176, Nat. Acad. oi Sciences, pp. 11–33, 1978.] This scheme was later modified by Cruden and Varnes in 1996,
[Cruden, David M., and David J. Varnes. "Landslides: investigation and mitigation. Chapter 3-Landslide types and processes." Transportation research board special report 247 (1996).] and refined by Hutchinson (1988),
[Hutchinson, J. N. "General report: morphological and geotechnical parameters of landslides in relation to geology and hydrogeology." International symposium on landslides. 5. 1988.] Hungr et al. (2001),
[Hungr O, Evans SG, Bovis M, and Hutchinson JN (2001) Review of the classification of landslides of the flow type. Environmental and Engineering Geoscience VII, 221-238.] and finally by Hungr, Leroueil and Picarelli (2014).
The classification resulting from the latest update is provided below.
Under this classification, six types of movement are recognized. Each type can be seen both in rock and in soil. A fall is a movement of isolated blocks or chunks of soil in free-fall. The term topple refers to blocks coming away by rotation from a vertical face. A slide is the movement of a body of material that generally remains intact while moving over one or several inclined surfaces or thin layers of material (also called shear zones) in which large deformations are concentrated. Slides are also sub-classified by the form of the surface(s) or shear zone(s) on which movement happens. The planes may be broadly parallel to the surface ("planar slides") or spoon-shaped ("rotational slides"). Slides can occur catastrophically, but movement on the surface can also be gradual and progressive. Spreads are a form of subsidence, in which a layer of material cracks, opens up, and expands laterally. Flows are the movement of fluidised material, which can be both dry or rich in water (such as in mud flows). Flows can move imperceptibly for years, or accelerate rapidly and cause disasters. Slope deformations are slow, distributed movements that can affect entire mountain slopes or portions of it. Some landslides are complex in the sense that they feature different movement types in different portions of the moving body, or they evolve from one movement type to another over time. For example, a landslide can initiate as a rock fall or topple and then, as the blocks disintegrate upon the impact, transform into a debris slide or flow. An avalanching effect can also be present, in which the moving mass entrains additional material along its path.
Flows
Slope material that becomes
saturated
Saturation, saturated, unsaturation or unsaturated may refer to:
Chemistry
* Saturation, a property of organic compounds referring to carbon-carbon bonds
** Saturated and unsaturated compounds
**Degree of unsaturation
** Saturated fat or fatty ac ...
with water may produce a
debris flow
Debris flows are geological phenomena in which water-laden masses of soil and fragmented rock rush down mountainsides, funnel into stream channels, entrain objects in their paths, and form thick, muddy deposits on valley floors. They generally ...
or
mud flow
A mudflow or mud flow is a form of mass wasting involving fast-moving flow of debris 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 significa ...
. However, also dry debris can exhibit flow-like movement. Flowing debris or mud may pick up trees, houses and cars, and block bridges and rivers causing
flooding
A flood is an overflow of water ( or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are an area of study of the discipline hydrolog ...
along its path. This phenomenon is particularly hazardous in
alpine
Alpine may refer to any mountainous region. It may also refer to:
Places Europe
* Alps, a European mountain range
** Alpine states, which overlap with the European range
Australia
* Alpine, New South Wales, a Northern Village
* Alpine National Pa ...
areas, where narrow gorges and steep valleys are conducive of faster flows. Debris and mud flows may initiate on the slopes or result from the fluidization of landslide material as it gains speed or incorporates further debris and water along its path. River blockages as the flow reaches a main stream can generate temporary dams. As the impoundments fail, a domino effect may be created, with a remarkable growth in the volume of the flowing mass, and in its destructive power.
![The Costa della Gaveta earthflow](https://upload.wikimedia.org/wikipedia/commons/8/86/The_Costa_della_Gaveta_earthflow.jpg)
An
earthflow
An earthflow (earth flow) is a downslope viscous flow of fine-grained materials that have been saturated with water and moves under the pull of gravity. It is an intermediate type of mass wasting that is between downhill creep and mudflow. The ty ...
is the downslope movement of mostly fine-grained material. Earthflows can move at speeds within a very wide range, from as low as 1 mm/yr
to many km/h. Though these are a lot like
mudflow
A mudflow or mud flow is a form of mass wasting involving fast-moving flow of debris 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 significa ...
s, overall they are more slow-moving and are covered with solid material carried along by the flow from within. Clay, fine sand and silt, and fine-grained, pyroclastic material are all susceptible to earthflows. These flows are usually controlled by the pore water pressures within the mass, which should be high enough to produce a low shearing resistance. On the slopes, some earthflow may be recognized by their elongated shape, with one or more lobes at their toes. As these lobes spread out, drainage of the mass increases and the margins dry out, lowering the overall velocity of the flow. This process also causes the flow to thicken. Earthflows occur more often during periods of high precipitation, which saturates the ground and builds up water pressures. However, earthflows that keep advancing also during dry seasons are not uncommon. Fissures may develop during the movement of clayey materials, which facilitate the intrusion of water into the moving mass and produce faster responses to precipitation.
A rock avalanche, sometimes referred to as
sturzstrom
A Sturzstrom (from the German '' Sturz'' (fall) and ''Strom'' (stream, flow)) or ''rock avalanche'' is a large landslide consisting of soil and rock (geology), rock which travels a great horizontal distance (as much as 20 or 30 times) compared to ...
, is a large and fast-moving landslide of the flow type. It is rarer than other types of landslides but it is often very destructive. It exhibits typically a long runout, flowing very far over a low-angle, flat, or even slightly uphill terrain. The mechanisms favoring the long runout can be different, but they typically result in the weakening of the sliding mass as the speed increases.
The causes of this weakening are not completely understood. Especially for the largest landslides, it may involve the very quick heating of the shear zone due to friction, which may even cause the water that is present to vaporize and build up a large pressure, producing a sort of hovercraft effect. In some cases, the very high temperature may even cause some of the minerals to melt. During the movement, the rock in the shear zone may also be finely ground, producing a nanometer-size mineral powder that may act as a lubricant, reducing the resistance to motion and promoting larger speeds and longer runouts. The weakening mechanisms in large rock avalanches are similar to those occurring in seismic faults.
Slides
Slides can occur in any rock or soil material and are characterized by the movement of a mass over a planar or curvilinear surface or shear zone.
A debris slide is a type of slide characterized by the chaotic movement of material mixed with water and/or ice. It is usually triggered by the saturation of thickly vegetated slopes which results in an incoherent mixture of broken timber, smaller vegetation and other debris.
Debris flows and avalanches differ from debris slides because their movement is fluid-like and generally much more rapid. This is usually a result of lower shear resistances and steeper slopes. Debris slides generally begin with the detachment of rock chunks high on the slopes, which break apart as they slide towards the bottom.
Clay and silt slides are usually slow but can experience episodic acceleration in response to heavy rainfall or rapid snowmelt. They are often seen on gentle slopes and move over planar surfaces, such as over the underlying bedrock. Failure surfaces can also form within the clay or silt layer itself, and they usually have concave shapes, resulting in rotational slides
Shallow and deep-seated landslides
![Limone sul Garda Hotel 001](https://upload.wikimedia.org/wikipedia/commons/6/65/Limone_sul_Garda_Hotel_001.JPG)
A landslide in which the sliding surface is located within the
soil
Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ...
mantle or
weathered
''Weathered'' is the third studio album by American rock band Creed, released on November 20, 2001. It was the last Creed album to be released until '' Full Circle'' came out in October 2009, with Creed disbanding in June 2004. It is the only Cr ...
bedrock
In geology, bedrock is solid Rock (geology), rock that lies under loose material (regolith) within the crust (geology), crust of Earth or another terrestrial planet.
Definition
Bedrock is the solid rock that underlies looser surface mater ...
(typically to a depth from few decimeters to some meters) is called a shallow landslide. Debris slides and
debris flows
Debris flows are geological phenomena in which water-laden masses of soil and fragmented rock rush down mountainsides, funnel into stream channels, entrain objects in their paths, and form thick, muddy deposits on valley floors. They generall ...
are usually shallow. Shallow landslides can often happen in areas that have slopes with high permeable soils on top of low permeable soils. The low permeable soil traps the water in the shallower soil generating high water pressures. As the top soil is filled with water, it can become unstable and slide downslope.
![Kihotown Sehara Miepref No,3](https://upload.wikimedia.org/wikipedia/commons/5/57/Kihotown_Sehara_Miepref_No%2C3.jpg)
Deep-seated landslides are those in which the sliding surface is mostly deeply located, for instance well below the maximum rooting depth of trees. They usually involve deep
regolith
Regolith () is a blanket of unconsolidated, loose, heterogeneous superficial deposits covering solid rock. It includes dust, broken rocks, and other related materials and is present on Earth, the Moon, Mars, some asteroids, and other terrestria ...
, weathered rock, and/or
bedrock
In geology, bedrock is solid Rock (geology), rock that lies under loose material (regolith) within the crust (geology), crust of Earth or another terrestrial planet.
Definition
Bedrock is the solid rock that underlies looser surface mater ...
and include large slope failures associated with translational, rotational, or complex movements. They tend to form along a plane of weakness such as a
fault or
bedding plane
In geology, a bed is a layer of sediment, sedimentary rock, or pyroclastic material "bounded above and below by more or less well-defined bedding surfaces".Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, eds., 2005. ''Glossary of Geology'' ...
. They can be visually identified by concave
scarps at the top and steep areas at the toe. Deep-seated landslides also shape
landscapes
A landscape is the visible features of an area of Terrestrial ecoregion, land, its landforms, and how they integrate with Nature, natural or man-made features, often considered in terms of their aesthetic appeal.''New Oxford American Dictionar ...
over geological timescales and produce sediment that strongly alters the course of
fluvial streams.
Causing tsunamis
Landslides that occur undersea, or have impact into water e.g. significant rockfall or volcanic collapse into the sea, can generate
tsunami
A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater explo ...
s. Massive landslides can also generate
megatsunami
A megatsunami is a very large wave created by a large, sudden displacement of material into a body of water.
Megatsunamis have quite different features from ordinary tsunamis. Ordinary tsunamis are caused by underwater tectonic activity (movemen ...
s, which are usually hundreds of meters high. In 1958, one such
tsunami
A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater explo ...
occurred in
Lituya Bay
Lituya Bay (; Tlingit: ''Ltu.aa'',. Spelled L'tua in translation of Tebenkov's log. meaning 'lake within the point')
is a fjord located on the coast of the south-east part of the U.S. state of Alaska. It is long and wide at its widest point. ...
in Alaska.
Related phenomena
* An
avalanche
An avalanche is a rapid flow of snow down a slope, such as a hill or mountain.
Avalanches can be set off spontaneously, by such factors as increased precipitation or snowpack weakening, or by external means such as humans, animals, and earth ...
, 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
A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at average speeds of bu ...
is caused by a collapsing cloud of hot
ash
Ash or ashes are the solid remnants of fires. Specifically, ''ash'' refers to all non-aqueous, non- gaseous residues that remain after something burns. In analytical chemistry, to analyse the mineral and metal content of chemical samples, ash ...
, gas and rocks from a volcanic explosion that moves rapidly down an erupting
volcano
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.
On Earth, volcanoes are most often found where tectonic plates are ...
.
Landslide prediction mapping
Landslide hazard analysis and mapping can provide useful information for catastrophic loss reduction, and assist in the development of guidelines for sustainable
land-use planning
Land use planning is the process of regulating the use of land by a central authority. Usually, this is done to promote more desirable social and environmental outcomes as well as a more efficient use of resources. More specifically, the goals ...
. The analysis is used to identify the factors that are related to landslides, estimate the relative contribution of factors causing slope failures, establish a relation between the factors and landslides, and to predict the landslide hazard in the future based on such a relationship. The factors that have been used for landslide hazard analysis can usually be grouped into
geomorphology
Geomorphology (from Ancient Greek: , ', "earth"; , ', "form"; and , ', "study") is the scientific study of the origin and evolution of topographic and bathymetric features created by physical, chemical or biological processes operating at or n ...
,
geology
Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ear ...
, land use/land cover, and
hydrogeology
Hydrogeology (''hydro-'' meaning water, and ''-geology'' meaning the study of the Earth) is the area of geology that deals with the distribution and movement of groundwater in the soil and rocks of the Earth's crust (commonly in aquif ...
. Since many factors are considered for landslide hazard mapping,
GIS
A geographic information system (GIS) is a type of database containing Geographic data and information, geographic data (that is, descriptions of phenomena for which location is relevant), combined with Geographic information system software, sof ...
is an appropriate tool because it has functions of collection, storage, manipulation, display, and analysis of large amounts of spatially referenced data which can be handled fast and effectively. Cardenas reported evidence on the exhaustive use of GIS in conjunction of uncertainty modelling tools for landslide mapping.
Remote sensing
Remote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object, in contrast to in situ or on-site observation. The term is applied especially to acquiring information about Earth ...
techniques are also highly employed for landslide hazard assessment and analysis. Before and after aerial photographs and satellite imagery are used to gather landslide characteristics, like distribution and classification, and factors like slope,
lithology
The lithology of a rock unit is a description of its physical characteristics visible at outcrop, in hand or core samples, or with low magnification microscopy. Physical characteristics include colour, texture, grain size, and composition. Lit ...
, and land use/land cover to be used to help predict future events. Before and after imagery also helps to reveal how the landscape changed after an event, what may have triggered the landslide, and shows the process of regeneration and recovery.
Using satellite imagery in combination with GIS and on-the-ground studies, it is possible to generate maps of likely occurrences of future landslides. Such maps should show the locations of previous events as well as clearly indicate the probable locations of future events. In general, to predict landslides, one must assume that their occurrence is determined by certain geologic factors, and that future landslides will occur under the same conditions as past events. Therefore, it is necessary to establish a relationship between the geomorphologic conditions in which the past events took place and the expected future conditions.
Natural disasters
A natural disaster is "the negative impact following an actual occurrence of natural hazard in the event that it significantly harms a community". A natural disaster can cause loss of life or damage property, and typically leaves some econo ...
are a dramatic example of people living in conflict with the environment. Early predictions and warnings are essential for the reduction of property damage and loss of life. Because landslides occur frequently and can represent some of the most destructive forces on earth, it is imperative to have a good understanding as to what causes them and how people can either help prevent them from occurring or simply avoid them when they do occur.
Sustainable land management Sustainable land management (SLM) refers to practices and technologies that aim to integrate the management of land, water, and other environmental resources to meet human needs while ensuring long-term sustainability, ecosystem services, biodiv ...
and development is also an essential key to reducing the negative impacts felt by landslides.
![SlideMinder Extensometer](https://upload.wikimedia.org/wikipedia/commons/b/ba/SlideMinder_Extensometer.png)
GIS offers a superior method for landslide analysis because it allows one to capture, store, manipulate, analyze, and display large amounts of data quickly and effectively. Because so many variables are involved, it is important to be able to overlay the many layers of data to develop a full and accurate portrayal of what is taking place on the Earth's surface. Researchers need to know which variables are the most important factors that trigger landslides in any given location. Using GIS, extremely detailed maps can be generated to show past events and likely future events which have the potential to save lives, property, and money.
Since the ‘90s, GIS have been also successfully used in conjunction to
decision support systems
A decision support system (DSS) is an information system that supports business or organizational decision-making activities. DSSs serve the management, operations and planning levels of an organization (usually mid and higher management) and h ...
, to show on a map real-time risk evaluations based on monitoring data gathered in the area of the
Val Pola disaster (Italy).
Image:Global Landslide Risks.jpg, Global landslide risks
File:Ferguson-slide.jpg, Ferguson Slide on California State Route 140
State Route 140 (SR 140) is a state highway in the U.S. state of California, 102 miles (164 km) in length. It begins in the San Joaquin Valley at Interstate 5 near Gustine, and runs east into Sierra Nevada, terminating in Yosemite National ...
in June 2006
File:Rock_slide_detector_UPRR_Sierra_grade_at_"Cape_Horn",_Colfax,_CA.jpg, Trackside rock slide detector on the UPRR
The Union Pacific Railroad , legally Union Pacific Railroad Company and often called simply Union Pacific, is a freight-hauling railroad that operates 8,300 locomotives over routes in 23 U.S. states west of Chicago and New Orleans. Union Paci ...
Sierra grade near Colfax, CA
Prehistoric landslides
*
Storegga Slide
The three Storegga Slides ( no, Storeggaraset) are amongst the largest known submarine landslides. They occurred at the edge of Norway's continental shelf in the Norwegian Sea, approximately 6225–6170 BCE. The collapse involved an estimated ...
, some 8,000 years ago off the western coast of
Norway
Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and t ...
. Caused massive
tsunamis
A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater expl ...
in
Doggerland
Doggerland was an area of land, now submerged beneath the North Sea, that connected Britain to continental Europe. It was flooded by rising sea levels around 6500–6200 BCE. The flooded land is known as the Dogger Littoral. Geological sur ...
and other areas connected to the
North Sea
The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian S ...
. A total volume of debris was involved; comparable to a thick area the size of Iceland. The landslide is thought to be among the largest in history.
* Landslide which moved
Heart Mountain to its current location, the largest continental landslide discovered so far. In the 48 million years since the slide occurred, erosion has removed most of the portion of the slide.
*
Flims Rockslide, ca. , Switzerland, some 10,000 years ago in post-glacial
Pleistocene
The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...
/
Holocene
The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...
, the largest so far described in the alps and on dry land that can be easily identified in a modestly eroded state.
* The landslide around 200 BC which formed
Lake Waikaremoana
Lake Waikaremoana is located in Te Urewera in the North Island of New Zealand, 60 kilometres northwest of Wairoa and 80 kilometres west-southwest of Gisborne. It covers an area of . From the Maori Waikaremoana translates as 'sea of rippling wat ...
on the
North Island
The North Island, also officially named Te Ika-a-Māui, is one of the two main islands of New Zealand, separated from the larger but much less populous South Island by the Cook Strait. The island's area is , making it the world's 14th-largest ...
of New Zealand, where a large block of the Ngamoko Range slid and dammed a gorge of Waikaretaheke River, forming a natural reservoir up to deep.
*
Cheekye Fan The Cheekye Fan is a large landslide feature in southwestern British Columbia, Canada, at the head of Howe Sound. It formed by collapse on the west flank of the volcano Mount Garibaldi, which was constructed over a glacier during the Late Pleistocen ...
,
British Columbia
British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...
, Canada, ca. ,
Late Pleistocene
The Late Pleistocene is an unofficial Age (geology), age in the international geologic timescale in chronostratigraphy, also known as Upper Pleistocene from a Stratigraphy, stratigraphic perspective. It is intended to be the fourth division of ...
in age.
* The Manang-Braga rock avalanche/debris flow may have formed Marsyangdi Valley in the Annapurna Region,
Nepal
Nepal (; ne, नेपाल ), formerly the Federal Democratic Republic of Nepal ( ne,
सङ्घीय लोकतान्त्रिक गणतन्त्र नेपाल ), is a landlocked country in South Asia. It is mai ...
, during an interstadial period belonging to the last glacial period. Over 15 km
3 of material are estimated to have been moved in the single event, making it one of the largest continental landslides.
*
Tsergo Ri landslide, a massive slope failure 60 km north of Kathmandu, Nepal, involving an estimated 10–15 km
3. Prior to this landslide the mountain may have been the world's 15th mountain above 8000m.
Historical landslides
* The
1806 Goldau landslide
Goldau is a town in the community of Arth, canton of Schwyz, Switzerland. It lies between the Rigi and Rossberg mountains, and between lakes Zug and Lauerz.
Well known attractions include the Natur- und Tierpark Goldau and the Arth-Goldau valle ...
on September 2, 1806
* The Cap Diamant
Québec rockslide
The Quebec rockslide occurred on September 19, 1889, after a day of heavy rain in Quebec City, Canada. An overhanging piece of slate rock broke off from Cap Diamant and fell 90 metres (300 feet) onto the houses below. The homes of 28 families on C ...
on September 19, 1889
*
Frank Slide
The Frank Slide was a massive rockslide that buried part of the mining town of Frank in the District of Alberta of the North-West Territories,The province of Alberta was not created until September 1905, more than two years after the slide. ...
, Turtle Mountain,
Alberta
Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...
, Canada, on 29 April 1903
*
Khait landslide
The Khait or Hoit landslide occurred on July 10, 1949 in the Hoit district in the Gharm Oblast in the Tajik Soviet Socialist Republic, then part of the Soviet Union. 'Khait' is a transliteration from russian: Хаит; the local modern spelling is ...
, Khait,
Tajikistan
Tajikistan (, ; tg, Тоҷикистон, Tojikiston; russian: Таджикистан, Tadzhikistan), officially the Republic of Tajikistan ( tg, Ҷумҳурии Тоҷикистон, Jumhurii Tojikiston), is a landlocked country in Centr ...
, Soviet Union, on July 10, 1949
* A
magnitude 7.5 earthquake in Yellowstone Park (August 17, 1959) caused a landslide that blocked the Madison River, and created Quake Lake.
*
Monte Toc
Monte Toc, nicknamed the walking mountain by locals due to its tendency to experience landslides, is a mountain on the border between Veneto and Friuli-Venezia Giulia in Northern Italy best known for the Vajont Dam, which was built at the mountai ...
landslide () falling into the
Vajont Dam
The Vajont Dam (or Vaiont Dam) is a disused dam in northern Italy. It is one of the tallest dams in the world, with a height of . It is in the valley of the Vajont River under Monte Toc, in the municipality of Erto e Casso, north of Venice.
...
basin in Italy, causing a
megatsunami
A megatsunami is a very large wave created by a large, sudden displacement of material into a body of water.
Megatsunamis have quite different features from ordinary tsunamis. Ordinary tsunamis are caused by underwater tectonic activity (movemen ...
and about 2000 deaths, on October 9, 1963
*
Hope Slide
The Hope Slide was a landslide that occurred in the morning hours of January 9, 1965 in the Nicolum Valley () in the Cascade Mountains near Hope, British Columbia and killed four people. The volume of rock involved in the landslide has been est ...
landslide () near
Hope, British Columbia
Hope is a district municipality at the confluence of the Fraser and Coquihalla rivers in the province of British Columbia, Canada. Hope is at the eastern end of both the Fraser Valley and the Lower Mainland region, and is at the southern end ...
on January 9, 1965.
* The 1966
Aberfan disaster
The Aberfan disaster was the catastrophic collapse of a colliery spoil tip on 21 October 1966. The tip had been created on a mountain slope above the Welsh village of Aberfan, near Merthyr Tydfil, and overlaid a natural spring. Heavy rain led t ...
*
Tuve landslide
The Tuve landslide was a large landslide in Tuve, Gothenburg, Sweden on November 30, 1977. Some 67 houses were destroyed, killing 9, injuring about 60 and making around 600 people homeless. The slide began at 16.05 and lasted 5–6 minutes. The ...
in
Gothenburg
Gothenburg (; abbreviated Gbg; sv, Göteborg ) is the second-largest city in Sweden, fifth-largest in the Nordic countries, and capital of the Västra Götaland County. It is situated by the Kattegat, on the west coast of Sweden, and has ...
, Sweden on November 30, 1977.
* The
1979 Abbotsford landslip
On 8 August 1979, a major landslip occurred in the Dunedin, New Zealand suburb of Abbotsford. It was the largest landslide in a built-up area in New Zealand's history, resulting in the destruction of 69 houses – around one sixth of the suburb ...
,
Dunedin
Dunedin ( ; mi, Ōtepoti) is the second-largest city in the South Island of New Zealand (after Christchurch), and the principal city of the Otago region. Its name comes from , the Scottish Gaelic name for Edinburgh, the capital of Scotland. Th ...
, New Zealand on August 8, 1979.
* The
eruption of Mount St. Helens
On March 27, 1980, a series of volcanic explosions and pyroclastic flows began at Mount St. Helens in Skamania County, Washington, United States. A series of phreatic blasts occurred from the summit and escalated until a major explosive eru ...
(May 18, 1980) caused an enormous landslide when the top 1300 feet of the volcano suddenly gave way.
*
Val Pola landslide
The Val Pola landslide (Val Pola rock avalanche) happened in Valtellina, Lombardy, Northern Italian Alps, on July 28, 1987 and resulted in the Valtellina disaster (destruction of villages, road closure, and flooding threat) with a total cost of 4 ...
during
Valtellina disaster
The Val Pola landslide (Val Pola rock avalanche) happened in Valtellina, Lombardy, Northern Italian Alps, on July 28, 1987 and resulted in the Valtellina disaster (destruction of villages, road closure, and flooding threat) with a total cost of 4 ...
(1987) Italy
*
Thredbo landslide
The Thredbo landslide was a catastrophic landslide that occurred at the village and ski resort of Thredbo, New South Wales, Thredbo, New South Wales, Australia, on 30 July 1997. Two ski lodges were destroyed and 18 people died. Stuart Diver was ...
, Australia on 30 July 1997, destroyed hostel.
*
Vargas mudslides, due to heavy rains in
Vargas State )
, anthem = '' Carmañola Americana''
, image_map = Vargas in Venezuela.svg
, map_alt =
, map_caption = Location within Venezuela
, pushpin_map =
, pushpin_map_alt ...
,
Venezuela
Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...
, in December, 1999, causing tens of thousands of deaths.
*
2005 La Conchita landslide
The town of La Conchita, California, experienced major landslides in 1995 and 2005. The latter landslide killed 10 people, and destroyed or damaged dozens of houses. The 2005 landslide occurred on part of a previous landslide that occurred in 19 ...
in Ventura,
California
California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...
causing 10 deaths.
*
2007 Chittagong mudslide
The 2007 Chittagong mudslides ( bn, ২০০৭ চট্টগ্রাম ভূমিধস) occurred in the port city of Chittagong in south-eastern Bangladesh. On 11 June 2007, heavy monsoon rainfall caused mudslides that engulfed slums ...
, in
Chittagong
Chittagong ( /ˈtʃɪt əˌɡɒŋ/ ''chit-uh-gong''; ctg, চিটাং; bn, চিটাগং), officially Chattogram ( bn, চট্টগ্রাম), is the second-largest city in Bangladesh after Dhaka and third largest city in B ...
,
Bangladesh
Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mos ...
, on June 11, 2007.
*
2008 Cairo landslide
The 2008 Duweika Rockslide happened on September 6, 2008 at a crowded self-built settlement in the Manshiyat Naser district of Cairo, Egypt, resulting in the first major urban disaster to hit the city in the 21st Century, where over 100 were kille ...
on September 6, 2008.
*
The 2009 Peloritani Mountains disaster caused 37 deaths, on October 1.
* The
2010 Uganda landslide
The 2010 Ugandan landslide occurred in the Bududa District in eastern Uganda on 1 March 2010. The landslide was triggered by heavy rain between 12 pm and 7 pm that day. At least 100 people were believed to have been killed, and 94 bod ...
caused over 100 deaths following heavy rain in
Bududa
Bududa is a town in the Eastern Region of Uganda. It is the main municipal, administrative, and commercial center of Bududa District.
Location
Bududa is located on the south-western slopes of Mount Elgon, approximately , by road, south-east of M ...
region.
*
Zhouqu county mudslide in
Gansu
Gansu (, ; alternately romanized as Kansu) is a province in Northwest China. Its capital and largest city is Lanzhou, in the southeast part of the province.
The seventh-largest administrative district by area at , Gansu lies between the Tibet ...
, China on August 8, 2010.
*
Devil's Slide, an ongoing landslide in
San Mateo County, California
San Mateo County ( ), officially the County of San Mateo, is a county (United States), county located in the U.S. state of California. As of the 2020 United States Census, 2020 census, the population was 764,442. Redwood City, California, Redwoo ...
*
2011 Rio de Janeiro landslide in
Rio de Janeiro
Rio de Janeiro ( , , ; literally 'River of January'), or simply Rio, is the capital of the state of the same name, Brazil's third-most populous state, and the second-most populous city in Brazil, after São Paulo. Listed by the GaWC as a b ...
, Brazil on January 11, 2011, causing 610 deaths.
*
2014 Pune landslide
On 30 July 2014, a landslide occurred in the village of Malin in the Ambegaon taluka of the Pune district in Maharashtra, India. The landslide, which hit early in the morning while residents were asleep, was believed to have been caused by a b ...
, in
Pune
Pune (; ; also known as Poona, (List of renamed Indian cities and states#Maharashtra, the official name from 1818 until 1978) is one of the most important industrial and educational hubs of India, with an estimated population of 7.4 million ...
,
India
India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
.
*
2014 Oso mudslide
A major landslide occurred east of Oso, Washington, United States, on March 22, 2014, at 10:37 a.m. local time. A portion of an unstable hill collapsed, sending mud and debris to the south across the North Fork of the Stillaguamish River, ...
, in
Oso, Washington
Oso is a census-designated place (CDP) in Snohomish County, Washington, United States. It is located to the west of Darrington, south of the North Fork of the Stillaguamish River and approximately 50 air miles (80 km) from Seattle. The popu ...
*
2017 Mocoa landslide
The Mocoa landslide was a natural disaster that took place in 2017. During the pre-dawn hours of 1 April 2017, locally heavy rain triggered flash flooding and landslides in the city of Mocoa, Putumayo, Colombia, killing at least 336 p ...
, in
Mocoa
Mocoa () (Kamsá: Shatjok) is a municipality and capital city of the department of Putumayo in Colombia.
The city is located in the northwest of the Putumayo department
Putumayo () is a department of Southern Colombia. It is in the south-w ...
,
Colombia
Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...
*
2022 Ischia landslide
Heavy rain hit the island of Ischia, located in the Tyrrhenian Sea, causing damage to the ''comune'' of Casamicciola Terme. Twelve people were killed and five others were injured.
Background
This was the second natural disaster in Italy in the ...
Extraterrestrial landslides
Evidence of past landslides has been detected on many bodies in the solar system, but since most observations are made by probes that only observe for a limited time and most bodies in the solar system appear to be geologically inactive not many landslides are known to have happened in recent times. Both Venus and Mars have been subject to long-term mapping by orbiting satellites, and examples of landslides have been observed on both planets.
Image:Venus-Landslide.jpg, Before and after radar images of a landslide on Venus. In the center of the image on the right, the new landslide, a bright, flow-like area, can be seen extending to the left of a bright fracture. 1990 image.
Image:Avalanche on Mars February 19th 2008 01.jpg, Landslide in progress on Mars, 2008-02-19
Landslide mitigation
See also
*
Avalanche
An avalanche is a rapid flow of snow down a slope, such as a hill or mountain.
Avalanches can be set off spontaneously, by such factors as increased precipitation or snowpack weakening, or by external means such as humans, animals, and earth ...
*
California landslides Landslides in California occur mainly due to intense rainfall but occasionally are triggered by earthquakes. Landslides are common in Southern California, the San Francisco Bay Area and other parts of Northern California, and the Sierra Nevada. Al ...
*
Deformation monitoring
Deformation monitoring (also referred to as deformation survey) is the systematic measurement and tracking of the alteration in the shape or dimensions of an object as a result of stresses induced by applied loads. Deformation monitoring is a major ...
*
Earthquake engineering
Earthquake engineering is an interdisciplinary branch of engineering that designs and analyzes structures, such as buildings and bridges, with earthquakes in mind. Its overall goal is to make such structures more resistant to earthquakes. An earth ...
*
Geotechnical engineering
Geotechnical engineering is the branch of civil engineering concerned with the engineering behavior of earth materials. It uses the principles of soil mechanics and rock mechanics for the solution of its respective engineering problems. It als ...
*
Huayco
A huaico or huayco (from the Quechua ''wayqu'', meaning "depth, valley") is an Andean term for the mudslide and flash flood caused by torrential rains occurring high in the mountains, especially during the weather phenomenon known as ''El Niño''. ...
*
Landslide dam
A landslide dam or barrier lake is the natural damming of a river by some kind of landslide, such as a debris flow, rock avalanche or volcanic eruption. If the damming landslide is caused by an earthquake, it may also be called a quake lake. Some ...
*
Natural disaster
A natural disaster is "the negative impact following an actual occurrence of natural hazard in the event that it significantly harms a community". A natural disaster can cause loss of life or damage property, and typically leaves some econ ...
*
Railway slide fence Part of a railway signaling system, a slide fence is a fence whose purpose is to prevent trains from being derailed by rockslides in mountainous areas where rockslides may occur without warning. The fence is designed to be displaced by a rock slide, ...
*
Rockslide
A rockslide is a type of landslide caused by rock failure in which part of the bedding plane of failure passes through compacted rock and material collapses ''en masse'' and not in individual blocks. Note that a rockslide is similar to an avalanc ...
*
Slump (geology)
A slump is a form of mass wasting that occurs when a coherent mass of loosely consolidated materials or a rock layer moves a short distance down a Grade_(slope), slope. Movement is characterized by sliding along a concave-upward or planar surface ...
*
Washaway
A washaway is a particular kind of landslide that can affect man-made structures such as cuttings, embankments and bridges. They are thus a hazard to railways and road traffic.
Overview
The biggest danger with washaways is that they may be d ...
*
Urban search and rescue
Urban search and rescue (abbreviated as USAR or US&R) is a type of technical rescue operation that involves the location, extrication, and initial medical stabilization of victims trapped in an urban area, namely structural collapse due to natu ...
References
External links
United States Geological Survey siteBritish Geological Survey landslides siteInternational Consortium on Landslides
{{Authority control
Environmental soil science
Hazards of outdoor recreation
Natural disasters
no:Skred