Landslide

Natural disasters: Landslide - Latest posts

The term landslide or, less frequently, landslip, refers to several forms of mass wasting that include a wide range of ground movements, such as rockfalls, deep-seated slope failures, mudflows and debris flows. Landslides occur in a variety of environments, characterized by either steep or gentle slope gradients: from mountain ranges to coastal cliffs or even underwater, in which case they are called submarine landslides. Gravity is the primary driving force for a landslide to occur, but there are other factors affecting slope stability which 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 rainfall, an earthquake, 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 of the slope material, to an increase in the shear stress borne by the material, or to 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 glaciers melting;

• rising of groundwater or increase of pore water pressure (e.g. due to aquifer 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, and soil structure (e.g. after a wildfire – a fire in forests lasting for 3–4 days);

• erosion of the toe of a slope by rivers or ocean waves;

• physical and chemical weathering (e.g. by repeated freezing and thawing, heating and cooling, salt leaking in the groundwater or mineral dissolution);

• ground shaking caused by earthquakes, which can destabilize the slope directly (e.g. by inducing soil liquefaction), or weaken the material and cause cracks that will eventually produce a landslide;

• volcanic eruptions;

• deforestation, cultivation and construction;

• vibrations from machinery or traffic;

• blasting and mining;

• earthwork (e.g. by altering the shape of a slope, or imposing new loads);

• in shallow soils, the removal of deep-rooted vegetation that binds colluvium to bedrock;

• agricultural or forestry activities (logging), and urbanization, which change the amount of water infiltrating the soil.

Landslides are aggravated by human activities, such as:

• deforestation, cultivation and construction;

• vibrations from machinery or traffic;

• blasting and mining;

• earthwork (e.g. by altering the shape of a slope, or imposing new loads);

• in shallow soils, the removal of deep-rooted vegetation that binds colluvium to bedrock;

• agricultural or forestry activities (logging), and urbanization, which change the amount of water infiltrating the soil.

Types

Debris flow

Slope material that becomes saturated with water may develop into a debris flow or mud flow. The resulting slurry of rock and mud may pick up trees, houses and cars, thus blocking bridges and tributaries causing flooding along its path.

Debris flow is often mistaken for flash flood, but they are entirely different processes.

Muddy-debris flows in alpine 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, resulting in temporary water blockage. As the impoundments fail, a "domino effect" may be created, with a remarkable growth in the volume of the flowing mass, which takes up the debris in the stream channel. The solid–liquid mixture can reach densities of up to 2,000 kg/m3 (120 lb/cu ft) and velocities of up to 14 m/s (46 ft/s) (;). 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 (0.68 sq mi)) affected by a debris flow,[9] estimated a peak discharge of 750 m3/s (26,000 cu ft/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 (670 cu ft/s), a value about 40 times lower than that calculated for the debris flow that occurred.

Earthflow

An earthflow 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 (0.039 in/yr)[4][5] to 20 km/h (12.4 mph). Though these are a lot like mudflows, overall they are more slow moving and are covered with solid material carried along by flow from within. They are different from fluid flows which 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: the higher the 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 which creates the intrusion of water into the earthflows. Water then increases the pore-water pressure and reduces the shearing strength of the material.

Debris slide

Goodell Creek Debris Avalanche, Washington, USA

A debris slide is a type of slide characterized by the chaotic movement of rocks, soil, and debris mixed with water and/or ice. 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. 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.

Steep coastal cliffs can be caused by catastrophic debris avalanches. These have been common on the submerged flanks of ocean island volcanos such as the Hawaiian Islands and the Cape Verde Islands. Another slip of this type was Storegga landslide.

Debris slides generally start with big rocks that start at the top of the slide and begin to break apart as they slide towards the bottom. This is much slower than a debris avalanche. Debris avalanches are very fast and the entire mass seems to liquefy as it slides down the slope. This is caused by a combination of saturated material, and steep slopes. As the debris moves down the slope it generally follows stream channels leaving a v-shaped scar as it moves down the hill. 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.

Rock avalanche

A rock avalanche, sometimes referred to as sturzstrom, is a type of large and fast-moving landslide. It is rarer than other types of landslides and therefore poorly understood. It exhibits typically a long run-out, 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.

Shallow landslide

A landslide in which the sliding surface is located within the soil mantle or weathered bedrock (typically to a depth from few decimeters to some meters) is called a shallow landslide. 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.

Deep-seated landslide

Deep-seated landslides are those in which the sliding surface is mostly deeply located below the maximum rooting depth of trees (typically to depths greater than ten meters). They usually involve deep regolith, weathered rock, and/or bedrock and include large slope failure associated with translational, rotational, or complex movement. This type of landslide potentially occurs in an tectonic active region like Zagros Mountain in Iran. 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.

Causing tsunamis

See also: Tsunami § Tsunami generated by landslides

Landslides that occur undersea, or have impact into water e.g. significant rockfall or volcanic collapse into the sea, can generate tsunamis. Massive landslides can also generate megatsunamis, which are usually hundreds of meters 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.

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. 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, geology, land use/land cover, and hydrogeology. Since many factors are considered for landslide hazard mapping, GIS 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 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, 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 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 and development is also an essential key to reducing the negative impacts felt by landslides.

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.

Prehistoric landslides

• Storegga Slide, some 8,000 years ago off the western coast of Norway. Caused massive tsunamis in Doggerland and other countries connected to the North Sea. A total volume of 3,500 km³ (840 cu mi) debris was involved; comparable to a 34 m (112 ft) 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. 12 km³ (2.9 cu mi), Switzerland, some 10000 years ago in post-glacial Pleistocene/Holocene, 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 on the North Island 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 256 metres (840 ft) deep.

• Cheekye Fan, British Columbia, Canada, ca. 25 km² (9.7 sq mi), Late Pleistocene in age.

• The Manang-Braga rock avalanche/debris flow may have formed Marsyangdi Valley in the Annapurna Region, Nepal, during an interstadial period belonging to the last glacial period. Over 15 km³ of material are estimated to have been moved in the single event, making it one of the largest continental landslides.

• A massive slope failure 60 km north of Kathmandu Nepal, involving an estimated 10–15 km³. Prior to this landslide the mountain may have been the world's 15th mountain above 8000m.

Historical landslides

The 1806 Goldau landslide on September 2, 1806

The Cap Diamant Québec rockslide on September 19, 1889

Frank Slide, Turtle Mountain, Alberta, Canada, on 29 April 1903

Khait landslide, Khait, Tajikistan, Soviet Union, on July 10, 1949

Monte Toc landslide (260 million cubic metres, 9.2 billion cubic feet) falling into the Vajont Dam basin in Italy, causing a megatsunami and about 2000 deaths, on October 9, 1963

Hope Slide landslide (46 million cubic metres, 1.6 billion cubic feet) near Hope, British Columbia on January 9, 1965.

The 1966 Aberfan disaster

Tuve landslide in Gothenburg, Sweden on November 30, 1977.

The 1979 Abbotsford landslip, Dunedin, New Zealand on August 8, 1979.

Val Pola landslide during Valtellina disaster (1987) Italy

Thredbo landslide, Australia on 30 July 1997, destroyed hostel.

Vargas mudslides, due to heavy rains in Vargas State, Venezuela, in December, 1999, causing tens of thousands of deaths.

2005 La Conchita landslide in Ventura, California causing 10 deaths.

2007 Chittagong mudslide, in Chittagong, Bangladesh, on June 11, 2007.

2008 Cairo landslide on September 6, 2008.

The 2009 Peloritani Mountains disaster caused 37 deaths, on October 1.

The 2010 Uganda landslide caused over 100 deaths following heavy rain in Bududa region.

Zhouqu county mudslide in Gansu, China on August 8, 2010.[36]

Devil's Slide, an ongoing landslide in San Mateo County, California

2011 Rio de Janeiro landslide in Rio de Janeiro, Brazil on January 11, 2011, causing 610 deaths.

2014 Pune landslide, in Pune, India.

2014 Oso mudslide, in Oso, Washington

2017 Mocoa landslide, in Mocoa, Colombia

Prehistoric landslides

Date	Place	Name	Lat.	Long.	Volume	Comments	Sources
21–22 Ma	Southwest Utah, USA	Markaguntgravity slide	37.7N	112.83W	~1700–2000 km3		[1][2]
48 Ma	Heart Mountain, Wyoming	Heart Mountain slide			~2000 km3	Mostly eroded now	[2][3]
Late Pleistocene	British Columbia	Cheekye Fan			~0.15 km3	Collapse of the western flank of Mount Garibaldi	[4]
≈ 10,000 BCE	Saidmarreh, Iran	Saidmarreh landslide	33N	47.65E	20 km3		[5]
8,000 BCE	Switzerland	Flims Rockslide			9 km3		[6]
~2800 BCE	Zion Canyon, Utah, United States				0.286 km3	Landslide created the currently level floor of Zion Canyon inside Zion National Park.	[7]
~1920 BCE	Jishi Gorge, QinghaiProvince, China				0.040–0.080 km3	Landslide dammed the Yellow River, breach of dam may have caused the Great Flood of Gun-Yu	[8]
≈ 200 BCE	North Island, New Zealand				2.2 km3	Dammed Lake Waikaremoana	[9][10]

Submarine landslides

Date	Place	Name/article	Lat.	Long.	Volume	Comments	Sources
ca. 1.0 Ma	off northeastern Oahu	Nu'uanu Slide			7,500 km3	Massive debris field: 25,000 km2	[11]
Less than 2.6 Ma	off South Africa	Agulhas Slide			20,000 km3	The largest so far described	[12]
ca. 170,000 BP	off North Island, New Zealand	Ruatoria debris avalanche			3,000 km3		[13]
ca. 8,000 BP	Norwegian Sea	Storegga Slide	64.87	1.3	3,500 km3	Triggered a large tsunami that swept over the Shetland and Orkney Islands	[14]
18 Nov 1929	Grand Banks of Newfoundland	1929 Grand Banks earthquake	44.54	−56.01	200 km3	Broke 12 submarine communications cables; the tsunami killed 28 people on the Burin Peninsula.

Pre-20th-century historic landslides

Date	Place	Name/article	Lat.	Long.	Volume	Casualties	Comments	Sources
563	Lake Geneva, Switzerland and France	Tauredunum event	46.35	6.86		many	Destroyed villages and struck Geneva town.
25 Nov 1248	Mont Granier, France		45.46	5.93		1000+	Destroyed five villages.
1425 - 1450	North Bonneville, Washington	Bridge of the Gods (land bridge)	45.66	-121.94	14 km3		Possibly linked to the 1458 Cascadia Earthquake	[15][16][17]
About 1560	Ozette, Washington	Ozette Indian Village Archeological Site	48.17	-124.73			Partially buried the village at Ozette	[18][19]
2 Sep 1806	Canton of Schwyz, Switzerland	Goldau Rockslide	47.05	8.55	40 MCM	457	Destroyed four villages and caused a tsunami in Lake Lauerz	[20]
24 Dec 1839	Lyme Regis, Dorset	The Undercliff					One of a series of slumps
1855–1856	British Columbia	Collapse of The Barrier			30 MCM			[21]
1881	Qiaojia County, Yunnan, China	Shigaodi Landslide			530 MCM		Formed dam on Jinsha River	[22]
19 Sep 1889	Cap Diamant, Quebec	Québec rockslide	46.485	−71.21		>40		[23]

20th-century landslides

1901–1950

Date	Place	Name/article	Lat.	Long.	Volume	Casualties	Comments	Sources
29 Apr 1903	Turtle Mountain, Alberta, Canada	Frank Slide	49.59	−114.39	30 MCM	~70		[24]
18 Feb 1911	Usoy, Tajikistan	Usoi Dam			2 km3	54	Triggered by M 7.4 earthquake. The rockslide dammed the Murgab River, impounding 65-km- long Lake Sarez, which presently still exists.	[25]
1914	Neuquén and Mendoza, Argentina	Rio Barrancas & Rio Colorado debris flow			2 MCM	190–300	Two small towns were devastated, and numerous ranches and farms destroyed along a 60-km- long valley. Length of flow: 300 km	[25]
19 May 1919	Kelud, East Java, Indonesia	Kelut Lahars				5110	Lahars caused 5,110 deaths, and destroyed or damaged 104 villages. Length 185 km.	[25]
16 Dec 1920	Haiyuan County, Ningxia, China	1920 Haiyuan earthquake				>100,000	Loess flows and landslides over an area of 50,000 km². Failures in loess caused extreme fissuring, landslide dams, and buried villages.	[25]
1920	Veracruz, Mexico	Rio Huitzilapan debris flows				est. 600–870	Debris flows destroyed village of Barranca Grande, and were 40 to 65 m deep. Debris flows extended >40 km. Triggered by M~6.5 earthquake.	[25]
1921	Almaty, Kazakhstan	Alma-Ata Debris Flows				~500	A debris flow in the Valley of Alma-Atinka River destroyed the town of Alma-Ata.	[25]
26 Mar 1924	Amalfi Coast, Italy					~100	A series of major landslides after 18 hours of heavy rain	[26]
23 Jun 1925	Gros Ventre Wilderness, Wyoming	Gros Ventre landslide	43.62	110.55	38 MCM	6 (when the dam failed in 1927)	Blocked the Gros Ventre River, forming a 70-metre-high (230 ft) dam	[27]
9 Mar 1929	Arthur's Pass, South Island	The Falling Mountain landslide	−42.89	171.68	66 MCM		Very rapid rock avalanche triggered by the 1929 Arthur's Pass earthquake	[28]
25 Aug 1933	Diexi, Mao County, Sichuan, China	1933 Diexi earthquake			150 MCM	~3100	The largest landslide formed a 255-metre-high (837 ft) landslide dam on the Min River. This landslide killed all but one of the 577 people in the town of Deixi. The dam then overtopped, causing a flood and 2,500 deaths.	[25]
5 Jul 1938	Kwansai, Hyogo Prefecture, Japan					~1000	Many landslides occurred on the slopes of Mount Rokko, 130,000 homes damaged or destroyed by landslides and floods.	[25][29]
13 Dec 1941	Huaraz, Ancash, Peru	Huaraz debris flow			>10 MCM	4,000–6,000	Caused by rupture of a moraine dam impounding a lake, temporarily dammed the Santa River, after 2 days that failed and the flood swept down the valley to the coast.	[25][30]
16 Aug 1945	Mantaro Valley, Peru	Kuntur Sinqarockslide			5.5 MCM	none from landslide	The rockslide formed a 100-metre-high (330 ft) dam at Rio Mantaro, which failed after 73 days, causing a flood.	[25]
19 Dec 1945	Alcalá del Júcar, Albacete, Spain					16	Worst rockfall to hit the municipality in the 20th century	[31]
18 Sep 1948	Assam, India	Guwahati landslide				~500	Triggered by heavy rain	[32]
10 Jul 1949	Gharm Oblast, Tajikistan	Khait landslide, Yasman valley flowslide	39.17	70.90	75 MCM 245 MCM	~800 ~4,000(7,200 for all the landslides)	Triggered by the 1949 Khait earthquake, largest of several landslides	[33]

1951–1975

Date	Place	Name/article	Lat.	Long.	Volume	Casualties	Comments	Sources
1953	Wakayama Prefecture, Japan	Arida River landslides				1,046	Multiple slides due to typhoon. Many landslide dams were formed and subsequently failed in the Arid-Kawa valley.	[25]
1953	Minamiyamashiro, Sōraku District, Kyoto, Japan	Minamiyamashiro landslides				336 dead or missing	5,122 homes were destroyed or badly damaged by landslides and floods.	[25]
12 Jul 1954	Media Luna, Colombia	Santa Elena landslide				>100	Mudflow triggered by heavy rain	[34]
26 Oct 1954	Salerno, Amalfi Coast					≈ 300	504 mm rain fell in 16 hours, causing soil slides & debris flows	[35]
1958	Shizuoka Prefecture, Japan	Kanogawalandslides				1,094	19,754 homes were destroyed or badly damaged.	[25]
8 Jul 1958	Lituya Bay, Alaska, United States	1958 Lituya Bay megatsunami			30 MCM	2	Caused by M 7.5 earthquake, the landslide caused a 524m-high megatsunami in Lituya Bay.	[36]
22 May 1960	Riñihue Lake, Chile	Riñihuazo	−39.84	−72.29	≈ 40 MCM		A series of landslides triggered by the 1960 Valdivia earthquake, blocked outflow of Riñihue Lake, causing it to rise more than 20 metres, actions taken to lower the water level prevented repeat of a disastrous flood after the great 1575 earthquake.	[30]
10 Jan 1962	Ranrahirca, Peru	1962 Nevado Huascarán debris avalanche	−9.12	−77.6	13 MCM	4,000 – 5,000	An avalanche of ice and rock triggered by collapse of part of a hanging glacier	[30]
9 Oct 1963	Longarone, Italy	Vajont landslide	46.27	12.33	270 MCM	≈ 2,000	Landslide caused by heavy rains and drawdown of the Vajont Dam reservoir. Casualties and damage caused by tsunamigenerated by landslide into reservoir.	[37]
27 Mar 1964	Seward, Alaska, United States	1964 Alaska earthquake			211 MCM at Seward, 9.6 MCM at Turnagain Heights	106 from tsunami caused by Seward landslide	M 9.2 earthquake caused submarine landslide at Seward, and large landslides in Anchorage	[25]
9 Jan 1965	British Columbia	Hope Slide	49.40	121.26	48 MCM	4	Triggered by a small earthquake	[38]
28 Mar 1965	El Cobre, Chile	El Cobre landslide				>200	Shaking from a magnitude 7.1 earthquake caused failure of two tailings dams at the El Soldado copper mine, the resulting flow destroyed the town of El Cobre.	[39]
1965	Luquan Yi and Miao Autonomous County, Yunnan, China	Pufu Landslide			450 MCM		Created a dam on the Pufuguo Stream, which later failed	[22]
21 Oct 1966	Aberfan, Wales	Aberfan disaster	51.69	3.35		144	Collapse of an unstable colliery spoil-tip built over a series of springs, was triggered by heavy rain, killing nearly half the children at the village school.
18 Feb 1967	Laranjeiras, Rio de Janeiro		−22.97	−43.20		110	Worst single event in a series of landslides caused by very heavy rain in the area around Rio de Janeiro in the summers of 1966 and 1967. A high-velocity debris avalanche struck three buildings, two of them apartment buildings. The preceding rainfall fell at up to 100 mm per hour.	[30]
18 Mar 1967	Caraguatatuba, Brazil		−23.85	−46.63	7.6 MCM	120	Followed heavy rain, 420 mm /24 h	[40]
9 Jul 1967	Kure, Hiroshima Prefecture, Japan		34.25	132.57		159	Heavy rain from Typhoon Billie caused flooding and many landslides, destroying 352 buildings and damaging 551 roads	[41]
18 Aug 1968	Hida River, Gero, Japan		35.45	137.05	740 MCM (official estimated)	104	Triggered by a rainstorm, this debris flow swept two buses off the road, where they were stopped because of an earlier landslide	[42]
3–5 Oct 1968	Darjeeling, India					'thousands'	Floods caused by rainfall of 500–1,000 mm, triggered many landslides, a 60-kilometre-long (37 mi) highway was cut in 92 places	[43][44]
19–20 Aug 1969	Nelson County, Virginia, United States					150 (includes deaths from flooding)	Remnants of Hurricane Camille gave at least 710 mm of rain in about 8 hours, triggering numerous debris flows	[45]
31 May 1970	Yungay, Peru	1970 Nevado Huascarán debris avalanche	−9.12	−77.6	50–100 MCM	>22,000	Triggered by the 1970 Ancash earthquake, the mass travelled 14.5 km at an average velocity of about 300 km/h and buried Yungay	[30][46]
18 Mar 1971	Chungar, Peru	Chungar avalanche and tsunami	−11.12	−76.53	0.1 MCM	400–600	A rock avalanche from a limestone outcrop fell into Yanawayin Lake causing a wave that devastated a mining camp	[30][47]
4 May 1971	Saint-Jean-Vianney, Quebec, Canada	Saint-Jean-Vianney landslide	48.47	−71.22	6.9 MCM	31	This slide occurred in quick clay following heavy rain, destroying 41 homes	[48][49]
6 Jul 1972	Amakusa, Japan	Amakusa disaster				115	Multiple slope failures caused by heavy rainfall	[50]
12–13 Jul 1972	Obara, Shikoku, Japan	Obara landslides				64	218 mm of rain in 5 hours triggered many landslides	[51][52]
Apr 1974	Junín Region, Peru	Mayunmarca Landslide			1.0 to 1.6 km3	450	Rockslide dammed Río Mantaro. Slide velocity estimated at 120–140 km/hr	[53]
22 Jul 1975	Mount Meager massif, British Columbia, Canada	Devastation Glacier landslide			0.013 km3	4	Triggered by the collapse of a glacially debuttressed slope, descended Devastation Creek.	[54][55]

1976–2000

Date	Place	Name/article	Lat.	Long.	Volume	Casualties	Comments	Sources
30 Nov 1977	Tuve, Gothenburg, Sweden	Tuve landslide	57.75	11.94	3–4 MCM	9	The most severe landslide in the modern history of Sweden, triggered by heavy rain	[56]
29 Apr 1978	Rissa, Norway	Rissa landslide	63.55	9.94	5–6 MCM	1	Quick clay flowed suddenly into Botn lake, causing a small tsunami on the opposite shore	[57]
8 Aug 1979	Abbotsford, Dunedin, South Island, New Zealand	1979 Abbotsford landslip	−45.897	170.435	5 MCM	0	Heavy rain triggered a landslide on an unstable slope, made worse by sand quarrying at the base of the slope, destroying 69 houses	[58]
18 May 1980	Mount St. Helens, Washington, United States	1980 eruption of Mount St. Helens	46.200278	−122.186667	2.9 km3	57	The largest landslide in recorded history. Unplugged the volcanic vent, triggering the eruption. Deaths were from both the landslide and the eruption.	[2]
Apr 1983	Thistle, Utah, United States	Thistle, Utah landslide	40.00	-111.50	~15 MCM	0	Costliest landslide in United States history; damage estimated at $200–400 million (1983 dollars). Landslide formed lake over 160 feet (49 m) deep before draining.	[59]
5 Oct 1985	Portugués Urbano district, Ponce, Puerto Rico	Mameyes landslide				129	120 houses destroyed, greatest death toll in North American history from a single landslide.	[60][61]
13 Nov 1985	Armero, Tolima Department, Colombia	Armero tragedy	−5.03	−74.88		23,000	A minor eruption of the Nevado del Ruiz volcano caused melting of its ice cap. This released a series of lahars, volcanic mudflows, that traveled at speeds of up to 50 km/h down the slopes of the volcano. These lahars swiftly moved into valleys, merging to form larger flows, one of which destroyed the town of Armero.	[30]
28 Jul 1987	Valtellina, Lombardy, Italian Alps	Val Pola landslide			34 MCM	29	Triggered by rapid erosion at the base of a mountain slope, created a wave that travelled 2.7 km upstream	[62]
3–5 Jun 1993	Scarborough, North Yorkshire, England	Holbeck Hall Hotel landslide			~0.5 MCM	0	Classic rotational failure along sea cliffs, resulting court case set important precedent in English law	[63][64]
21 Oct 1993	Pantai Remis, Perak, Malaysia	Pantai Remis landslide				0	Slope failure of an open pit tin mine near the sea resulted in forming a new cove measuring approximately 0.5 by 0.5 km.
4 Mar 1995	La Conchita, California, United States	La Conchita Landslide of 1995			1.3 MCM	0		[65]
30 Jul 1997	Thredbo, New South Wales, Australia	1997 Thredbo landslide				18	A leaking water pipe caused a slope failure that destroyed a ski lodge	[66]
1998–1999	Kelso, Washington, United States	Aldercrest-Banyon Landslide				0	Slow-moving landslide which resulted in the condemnation of 137 houses, and $40 million in damage.	[67]
14–16 Dec 1999	Vargas, Venezuela	Vargas tragedy				30,000	Caused by a heavy storm that deposited 911 mm of rain in a few days	[68]
12 Jul 2000	Mumbai, India	2000 Mumbai landslide	19.09	72.90		78	Caused by land erosion following heavy rains and flooding	[69]

21st century landslides

Date	Place	Name/article	Lat.	Long.	Volume	Casualties	Comments	Sources
9 Nov 2001	Amboori, Kerala, India					40	Supposedly worst landslide in Kerala state's history.	[70][71]
26 Mar 2004	Mount Bawakaraeng, South Sulawesi, Indonesia				200–300 MCM	32	Landslide caused by collapse of caldera wall	[72][73][74]
10 Jan 2005	La Conchita, California, United States	2005 La Conchita landslide			200,000 m3	10	Remobilization of colluvium from 1995 slide into a debris flow.	[65]
17 Feb 2006	Southern Leyte, Philippines	2006 Southern Leyte mudslide			15 MCM	1,126	Rock-debris avalanche triggered by ten-day period of heavy rain	[75]
11 Jun 2007	Chittagong, Bangladesh	2007 Chittagong mudslides				123	Series of landslides caused by illegal hillside cutting and monsoon rains	[76][77]
6 Sep 2008	Cairo, Egypt	2008 Cairo landslide				119	Rockfall from cliffs, individual boulders up to 70 tonnes	[78]
9 Aug 2009	Siaolin Village, Kaohsiung, Taiwan	Siaolinmudslide			30–45 MCM	439–600	Resulted from Typhoon Morakot.	[79][80][81]
4 Jan 2010	Attabad, Gilgit-Baltistan, Pakistan	Hunza Valleylandslide			30 MCM	20	Formed Attabad Lake by damming Hunza River, blocked Karakoram Highway	[82][83]
20 Feb 2010	Madeira Island, Portugal	2010 Madeira floods and mudslides				42		[84]
1 Mar 2010	Bududa District, Uganda	2010 Ugandan landslide				100–300		[85]
10 May 2010	Saint-Jude, Quebec					4		[86]
23 May 2010	Jiang Zhidong Jiangxi, China	2010 Jiangxi derailment				0	The landslide was caused by previous days of heavy rain and flooding in the region.	[87][88][89]
6 Aug 2010	Mount Meager, British Columbia, Canada	Meager landslide			48.5 MCM	0	Comparable in volume to the 1965 Hope Slide	[90]
8 Aug 2010	Gansu, China	2010 Gansu mudslide				1,287		[91]
8 Oct 2011	Iron County, Utah, United States		37.63°N	112.94°W	4 MCY	0	Covered 1,300 feet of Utah State Route 14.	[92]
10 Apr 2013	Salt Lake City, Utah, United States	Bingham Canyon Minelandslide	40.523°N	112.151°W	55 MCM	0	Possibly the largest historic, non-volcanic, terrestrial landslide in North America.	[93][94][95]
16 Jun 2013	Kedarnath, Uttarakhand, India	2013 North India floods				5,700
13 Dec 2013	Rockville, Utah, United States				Several hundred tons	2	Single boulder crushed a two-storey home with residents inside.	[96]
22 Mar 2014	Oso, Washington, United States	2014 Oso mudslide	48.283°N	121.847°W	10 MCM (early estimate)	43	49 structures destroyed or affected	[97][98]
2 May 2014	Argo District, Badakhshan Province, Afghanistan	2014 Badakhshan mudslides				350–500 reported	4,000 people displaced	[99] As of 4 May 2014
25 May 2014	Mesa County, Colorado, United States	2014 West Salt Creek landslide	39°10′07″N	107°50′54″W		3
30 Jul 2014	Malin, Ambegaon taluka, Pune district, Maharashtra, India	2014 Malin landslide	19°9′40″N	73°41′18″E		136	100+ missing	[100]
2 Aug 2014	Sunkoshi, Sindhupalchok District, Nepal	2014 Sunkoshi blockage			5.5 MCM	156+		[101]
20 Aug 2014	Hiroshima Prefecture, Japan	2014 Hiroshima landslides				74	Deadliest landslides in Japan in 42 years	[102][103]
29 Oct 2014	Badulla District, Sri Lanka	2014 Badulla landslide				16+	192 missing and presumed dead	[104][105]
13 Dec 2014	Jemblung village, Java, Indonesia	2014 Indonesia landslide				93	23 missing	[106][107]
23 Apr 2015	Badakhshan Province, Afghanistan	2015 Badakhshan landslides				52
28 Apr 2015	Salvador, Bahia, Brazil	2015 Bahia landslide				14
18 May 2015	Salgar, Antioquia Department Colombia	2015 Colombian landslide				83	30+ missing	[108] As of 20 May 2015
1 October 2015	El Cambray Dos, Guatemala Department, Guatemala	2015 Guatemala landslide				280	70 missing.
13 November 2015	Lidong Village, Zhejiang, China					38		[109]
2 April 2017	Mocoa, Colombia	2017 Mocoa landslide	1°9′00″N	76°38′51″W		329+	70 missing, third-deadliest weather-related disaster in Colombian history.	[110]
12 June 2017	Rangamati, Chittagongand Bandarban, Bangladesh	2017 Bangladesh landslides	22°38′00″N	92°12′00″E		152	Worst landslides in Bangladesh's history.	[111][112][113][114][115]
24 June 2017	Xinmo village, Mao County, Sichuan Province, southwestern China	2017 Xinmo landslide	32º4'N	103º39'W	Depletion volume: 4.26 MCM Accumulation volume: 13.25 MCM	10 people killed and 73 missing	Probably triggered by the failure of a rock mass previously weakened by the Mw 7.3 Diexi earthquake in 1933 and weathered, after a rainy season.	[116]
14 August 2017	Freetown, Sierra Leone	2017 Sierra Leone mudslides	8°29′N,	13°14′W		1,141+	Triggered by a particularly wet rainy season	[117]
9 January 2018	California, United States	2018 South California landslides				20	Occurred several months after a series of major wildfiresdevastated nearby areas, causing deforestation and increasing the risk of a landslide.	[118][119]

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.

Landslide mitigation

Landslide mitigation refers to several man-made activities on slopes with the goal of lessening the effect of landslides. Landslides can be triggered by many, sometimes concomitant causes. In addition to shallow erosion or reduction of shear strength caused by seasonal rainfall, landslides may be triggered by anthropic activities, such as adding excessive weight above the slope, digging at mid-slope or at the foot of the slope. Often, individual phenomenon join together to generate instability over time, which often does not allow a reconstruction of the evolution of a particular landslide. Therefore, landslide hazard mitigation measures are not generally classified according to the phenomenon that might cause a landslide. Instead, they are classified by the sort of slope stabilization method used:

• Geometric methods, in which the geometry of the hillside is changed (in general the slope);

• Hydrogeological methods, in which an attempt is made to lower the groundwater level or to reduce the water content of the material

• Chemical and mechanical methods, in which attempts are made to increase the shear strength of the unstable mass or to introduce active external forces (e.g. anchors, rock or ground nailing) or passive (e.g. structural wells, piles or reinforced ground) to counteract the destabilizing forces.

Each of these methods varies somewhat with the type of material that makes up the slope.

Source:

wikipedia commons

1.  www.thesaurus.com. Roget's 21st Century Thesaurus. 2013. Retrieved 16 March 2018.
2. ^ Jump up to:^a b Hu, Wei; Scaringi, Gianvito; Xu, Qiang; Van Asch, Theo W. J. (2018-04-10). "Suction and rate-dependent behaviour of a shear-zone soil from a landslide in a gently-inclined mudstone-sandstone sequence in the Sichuan basin, China". Engineering Geology. 237: 1–11.
3. ^ Jump up to:^a b Fan, Xuanmei; Xu, Qiang; Scaringi, Gianvito (2017-12-01). "Failure mechanism and kinematics of the deadly June 24th 2017 Xinmo landslide, Maoxian, Sichuan, China". Landslides. 14 (6): 2129–2146.
4. ^ Jump up to:^a b c Di Maio, Caterina; Vassallo, Roberto; Scaringi, Gianvito; De Rosa, Jacopo; Pontolillo, Dario Michele; Maria Grimaldi, Giuseppe (2017-11-01). .
5. ^ Jump up to:^a b Di Maio, Caterina; Scaringi, Gianvito; Vassallo, R (2014-01-01). 
6. ^ Fan, Xuanmei; Scaringi, Gianvito; Domènech, Guillem; Yang, Fan; Guo, Xiaojun; Dai, Lanxin; He, Chaoyang; Xu, Qiang; Huang, Runqiu (2019-01-09).
7. ^ Fan, Xuanmei; Xu, Qiang; Scaringi, Gianvito (2018-01-26). .
8. ^ Fan, Xuanmei; Xu, Qiang; Scaringi, Gianvito (2018-10-24). "The "long" runout rock avalanche in Pusa, China, on August 28, 2017: a preliminary report". Landslides. 16: 139–154. 
9. ^ Jump up to:^a b Chiarle, Marta; Luino, Fabio (1998). "Colate detritiche torrentizie sul Monte Mottarone innescate dal nubifragio dell'8 luglio 1996". La prevenzione delle catastrofi idrogeologiche. Il contributo della ricerca scientifica (conference book). pp. 231–245.
10. ^ Arattano, Massimo (2003). "Monitoring the presence of the debris flow front and its velocity through ground vibration detectors". Third International Conference on Debris-flow Hazards Mitigation: Mechanics, Prediction, and Assessment (debris flow): 719–730.
11. ^ Jump up to:^a b Easterbrook, Don J. (1999). Surface Processes and Landforms. Upper Saddle River: Prentice-Hall. ISBN 978-0-13-860958-0.
12. ^ Jump up to:^a b Le Bas, T.P. (2007), "Slope Failures on the Flanks of Southern Cape Verde Islands", in Lykousis, Vasilios (ed.), Submarine mass movements and their consequences: 3rd international symposium, Springer, ISBN 978-1-4020-6511-8
13. ^ Schuster, R.L. & Krizek, R.J. (1978). Landslides: Analysis and Control. Washington, D.C.: National Academy of Sciences.
14. ^ Hu, Wei; Scaringi, Gianvito; Xu, Qiang; Huang, Runqiu (2018-06-05). 5518. 
15. ^ Hu, Wei; Xu, Qiang; Wang, Gonghui; Scaringi, Gianvito; McSaveney, Mauri; Hicher, Pierre-Yves (2017-10-31). 
16. ^ Scaringi, Gianvito; Hu, Wei; Xu, Qiang; Huang, Runqiu (2017-12-20). 
17. ^ Renwick, W.; Brumbaugh, R.; Loeher, L (1982). "Landslide Morphology and Processes on Santa Cruz Island California". Geografiska Annaler. Series B, Physical Geography. 64 (3/4): 149–159. 
18. ^ Johnson, B.F. (June 2010).. Earth magazine. pp. 48–55.
19. ^ Popular Science. Retrieved 2017-10-20.
20. ^ Mitchell, N (2003). "Susceptibility of mid-ocean ridge volcanic islands and seamounts to large scale landsliding". Journal of Geophysical Research. 108 (B8): 1–23.
21. ^ Chen, Zhaohua; Wang, Jinfei (2007). "Landslide hazard mapping using logistic regression model in Mackenzie Valley, Canada". Natural Hazards. 42: 75–89.
22. ^ Clerici, A; Perego, S; Tellini, C; Vescovi, P (2002). "A procedure for landslide susceptibility zonation by the conditional analysis method1". Geomorphology. 48 (4): 349–364. 
23. ^ Cardenas, IC (2008).  Ingenieria e Investigación. 28 (1).
24. ^ Cardenas, IC (2008).  Ingenieria e Investigación. 28 (2).
25. ^ Metternicht, G; Hurni, L; Gogu, R (2005). "Remote sensing of landslides: An analysis of the potential contribution to geo-spatial systems for hazard assessment in mountainous environments". Remote Sensing of Environment. 98 (2–3): 284–303. .
26. ^ De La Ville, Noemi; Chumaceiro Diaz, Alejandro; Ramirez, Denisse (2002). "Remote Sensing and GIS Technologies as Tools to Support Sustainable Management of Areas Devastated by Landsli
27. PDF). Environment, Development and Sustainability. 4 (2): 221–229.
28. ^ Fabbri, Andrea G.; Chung, Chang-Jo F.; Cendrero, Antonio; Remondo, Juan (2003). "Is Prediction of Future Landslides Possible with a GIS?". Natural Hazards. 30 (3): 487–503.
29. ^ Lee, S; Talib, Jasmi Abdul (2005). "Probabilistic landslide susceptibility and factor effect analysis". Environmental Geology. 47(7): 982–990.
30. ^ Ohlmacher, G (2003). "Using multiple logistic regression and GIS technology to predict landslide hazard in northeast Kansas, USA". Engineering Geology. 69 (3–4): 331–343. 
31. ^ Rose & Hunger, "Forecasting potential slope failure in open pit mines", Journal of Rock Mechanics & Mining Sciences, February 17, 2006. August 20, 2015.
32. ^ 2011-07-06 at the Wayback Machine A.v. Poschinger, Angewandte Geologie, Vol. 11/2, 2006
33. ^ Fort, Monique (2011). . Geografia Fisica e Dinamica Quaternaria. 34: 5–16.
34. ^ Weidinger, Johannes T.; Schramm, Josef-Michael; Nuschej, Friedrich (2002-12-30). "Ore mineralization causing slope failure in a high-altitude mountain crest—on the collapse of an 8000 m peak in Nepal". Journal of Asian Earth Sciences. 21 (3): 295–306. 
35. ^ BC Geographical Names.
36. ^ Peres, D. J.; Cancelliere, A. (2016-10-01). "Estimating return period of landslide triggering by Monte Carlo simulation". Journal of Hydrology. Flash floods, hydro-geomorphic response and risk management. 541: 256–271.
37. ^ Easyseosolution.com. August 19, 201
38. ^ Cbc.ca. January 13, 2011. Retrieved January 13, 2011.