Editing Landslide (section)

==Causes==
{{Main|Causes of landslides}}
[[Image:Mameyes.jpg|thumb|[[1985 Puerto Rico floods|The Mameyes Landslide]], in the Mameyes [[neighborhood]] of barrio [[Portugués Urbano]] in [[Ponce, Puerto Rico]], was caused by extensive accumulation of rains and, according to some sources, lightning. It buried more than 100 homes.]]
[[File:Landslide in Sweden (Surte) 1950, 2.jpg|thumb|The landslide at [[Surte]] in Sweden, 1950. It was a [[quick clay]] slide that killed one person.]]

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 (soil)|shear strength]] of the slope material, an increase in the [[shear stress]] 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:
* increase in water content (loss of suction) or saturation by rain water infiltration, snow melting, or [[glacier]]s melting;<ref>{{Cite journal|last1=Subramanian|first1=S. Siva|last2=Fan|first2=X.|last3=Yunus|first3=A. P.|last4=Asch|first4=T. van|last5=Scaringi|first5=G.|last6=Xu|first6=Q.|last7=Dai|first7=L.|last8=Ishikawa|first8=T.|last9=Huang|first9=R.|year=2020|title=A Sequentially Coupled Catchment-Scale Numerical Model for Snowmelt-Induced Soil Slope Instabilities|url=https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019JF005468|journal=Journal of Geophysical Research: Earth Surface|language=en|volume=125|issue=5|pages=e2019JF005468|doi=10.1029/2019JF005468|bibcode=2020JGRF..12505468S|s2cid=218825257|issn=2169-9011|access-date=2021-02-23|archive-date=2022-03-06|archive-url=https://web.archive.org/web/20220306044629/https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019JF005468|url-status=live}}</ref>
*rising of [[groundwater]] or increase of pore water pressure (e.g. due to [[aquifer]] recharge in rainy seasons, or by rain water infiltration);<ref name=":2">{{Cite journal|last1=Hu|first1=Wei|last2=Scaringi|first2=Gianvito|last3=Xu|first3=Qiang|last4=Van Asch|first4=Theo W. J.|date=2018-04-10|title=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|journal=Engineering Geology|language=en|volume=237|pages=1–11|doi=10.1016/j.enggeo.2018.02.005|bibcode=2018EngGe.237....1H |issn=0013-7952}}</ref>
*increase of hydrostatic pressure in cracks and fractures;<ref name=":2" /><ref name=":3">{{Cite journal|last1=Fan|first1=Xuanmei|last2=Xu|first2=Qiang|last3=Scaringi|first3=Gianvito|date=2017-12-01|title=Failure mechanism and kinematics of the deadly June 24th 2017 Xinmo landslide, Maoxian, Sichuan, China|journal=Landslides|language=en|volume=14|issue=6|pages=2129–2146|doi=10.1007/s10346-017-0907-7|bibcode=2017Lands..14.2129F |s2cid=133681894|issn=1612-5118}}</ref>
* loss or absence of vertical vegetative structure, [[soil nutrients]], and [[soil structure]] (e.g. after a wildfire);<ref>{{Cite journal|last1=Rengers|first1=Francis K.|last2=McGuire|first2=Luke A.|last3=Oakley|first3=Nina S.|last4=Kean|first4=Jason W.|last5=Staley|first5=Dennis M.|last6=Tang|first6=Hui|date=2020-11-01|title=Landslides after wildfire: initiation, magnitude, and mobility|journal=Landslides|language=en|volume=17|issue=11|pages=2631–2641|doi=10.1007/s10346-020-01506-3|s2cid=221110680|issn=1612-5118|doi-access=free|bibcode=2020Lands..17.2631R }}</ref>
*[[erosion]] of the top of a slope by rivers or sea [[wave]]s;<ref>{{Cite journal|last1=Edil|first1=T. B.|last2=Vallejo|first2=L. E.|date=1980-07-01|title=Mechanics of coastal landslides and the influence of slope parameters|url=https://dx.doi.org/10.1016/0013-7952%2880%2990009-5|journal=Engineering Geology|series=Special Issue Mechanics of Landslides and Slope Stability|language=en|volume=16|issue=1|pages=83–96|doi=10.1016/0013-7952(80)90009-5|bibcode=1980EngGe..16...83E |issn=0013-7952}}</ref>
*physical and chemical [[weathering]] (e.g. by repeated freezing and thawing, heating and cooling, salt leaking in the groundwater or mineral dissolution);<ref name=":0" /><ref name=":1" /><ref>{{Cite journal|last1=Fan|first1=Xuanmei|last2=Xu|first2=Qiang|last3=Scaringi|first3=Gianvito|last4=Li|first4=Shu|last5=Peng|first5=Dalei|date=2017-10-13|title=A chemo-mechanical insight into the failure mechanism of frequently occurred landslides in the Loess Plateau, Gansu Province, China|url=https://www.sciencedirect.com/science/article/pii/S001379521730889X|journal=Engineering Geology|language=en|volume=228|pages=337–345|doi=10.1016/j.enggeo.2017.09.003|bibcode=2017EngGe.228..337F |issn=0013-7952}}</ref>
* ground shaking caused by [[earthquake]]s, 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;<ref name=":3" /><ref>{{Cite journal|last1=Fan|first1=Xuanmei|last2=Scaringi|first2=Gianvito|last3=Domènech|first3=Guillem|last4=Yang|first4=Fan|last5=Guo|first5=Xiaojun|last6=Dai|first6=Lanxin|last7=He|first7=Chaoyang|last8=Xu|first8=Qiang|last9=Huang|first9=Runqiu|date=2019-01-09|title=Two multi-temporal datasets that track the enhanced landsliding after the 2008 Wenchuan earthquake |bibcode-access=free |url=https://www.earth-syst-sci-data.net/11/35/2019/essd-11-35-2019.html|journal=Earth System Science Data|language=en|volume=11|issue=1|pages=35–55|doi=10.5194/essd-11-35-2019|issn=1866-3508|bibcode=2019ESSD...11...35F|doi-access=free|access-date=2019-01-09|archive-date=2020-03-04|archive-url=https://web.archive.org/web/20200304105948/https://www.earth-syst-sci-data.net/11/35/2019/essd-11-35-2019.html|url-status=live}}</ref><ref>{{Cite journal|last1=Fan|first1=Xuanmei|last2=Xu|first2=Qiang|last3=Scaringi|first3=Gianvito|date=2018-01-26|title=Brief communication: Post-seismic landslides, the tough lesson of a catastrophe |bibcode-access=free |journal=Natural Hazards and Earth System Sciences|language=en|volume=18|issue=1|pages=397–403|doi=10.5194/nhess-18-397-2018|issn=1561-8633|bibcode=2018NHESS..18..397F|doi-access=free}}</ref>
* [[volcano|volcanic eruptions]];<ref>{{Cite journal|last1=Watt |first1=Sebastian F.L.|last2=Talling |first2=Peter J.|last3=Hunt |first3=James E. |s2cid-access=free |year=2014|title=New Insights into the Emplacement Dynamics of Volcanic Island Landslides|journal=Oceanography|volume=27|issue=2|pages=46–57|doi=10.5670/oceanog.2014.39|jstor=24862154|s2cid=55516702|issn=1042-8275|doi-access=free|bibcode=2014Ocgpy..27b..46W }}</ref>
* changes in pore fluid composition;<ref>{{Cite journal |last1=Di Maio |first1=C. |last2=Scaringi |first2=G. |date=2016-01-18 |title=Shear displacements induced by decrease in pore solution concentration on a pre-existing slip surface |url=https://www.sciencedirect.com/science/article/pii/S0013795215300922 |journal=Engineering Geology |language=en |volume=200 |pages=1–9 |doi=10.1016/j.enggeo.2015.11.007 |bibcode=2016EngGe.200....1D |issn=0013-7952}}</ref>
* changes in temperature (seasonal or induced by climate change).<ref>{{Cite journal |last1=Scaringi |first1=Gianvito |last2=Loche |first2=Marco |date=2022-03-15 |title=A thermo-hydro-mechanical approach to soil slope stability under climate change |journal=Geomorphology |language=en |volume=401 |pages=108108 |doi=10.1016/j.geomorph.2022.108108 |bibcode=2022Geomo.40108108S |s2cid=245941223 |issn=0169-555X|doi-access=free }}</ref><ref>{{Cite journal |last1=Shibasaki |first1=Tatsuya |last2=Matsuura |first2=Sumio |last3=Okamoto |first3=Takashi |date=2016-07-16 |title=Experimental evidence for shallow, slow-moving landslides activated by a decrease in ground temperature: Landslides Affected by Ground Temperature |url=http://doi.wiley.com/10.1002/2016GL069604 |journal=Geophysical Research Letters |language=en |volume=43 |issue=13 |pages=6975–6984 |doi=10.1002/2016GL069604|s2cid=132940118 }}</ref>

Landslides are aggravated by human activities, such as:
* [[deforestation]], [[Tillage|cultivation]] and [[construction]];
* [[oscillation|vibrations]] from [[machinery]] or [[traffic]];<ref>{{Cite journal|last=Laimer|first=Hans Jörg|date=2017-05-18|title=Anthropogenically induced landslides – A challenge for railway infrastructure in mountainous regions|url=https://www.sciencedirect.com/science/article/pii/S0013795216307335|journal=Engineering Geology|language=en|volume=222|pages=92–101|doi=10.1016/j.enggeo.2017.03.015|bibcode=2017EngGe.222...92L |issn=0013-7952}}</ref>
* [[Explosive material|blasting]] and [[mining]];<ref>{{Cite journal|last1=Fan|first1=Xuanmei|last2=Xu|first2=Qiang|last3=Scaringi|first3=Gianvito|date=2018-10-24|title=The "long" runout rock avalanche in Pusa, China, on 28 August 2017: a preliminary report|journal=Landslides|language=en|volume=16|pages=139–154|doi=10.1007/s10346-018-1084-z|s2cid=133852769|issn=1612-5118}}</ref>
* [[Earthworks (engineering)|earthwork]] (e.g. by altering the shape of a slope, or imposing new loads);
* in shallow [[soil]]s, the removal of deep-[[root]]ed [[vegetation]] that binds [[colluvium]] to [[bedrock]];
* agricultural or forestry activities ([[logging]]), and [[urbanization]], which change the amount of water infiltrating the soil.
*temporal variation in [[land use]] and [[land cover]] (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]] and extreme rainfall can increase the frequency of [[soil erosion|erosion]] and landslide phenomena.<ref name=":6">{{cite journal | title = Investigation on Farmland Abandonment of Terraced Slopes Using Multitemporal Data Sources Comparison and Its Implication on Hydro-Geomorphological Processes | author = Giacomo Pepe | author2 = Andrea Mandarino | author3 = Emanuele Raso | author4 = Patrizio Scarpellini | author5 = Pierluigi Brandolini | author6 = Andrea Cevasco | journal = [[Water (journal)|Water]] | year = 2019 | oclc = 	8206777258 | issue = 11 | volume = 8 | page = 1552 | doi = 10.3390/w11081552 | publisher = [[MDPI]] | issn = 2073-4441 | doi-access = free | bibcode = 2019Water..11.1552P | hdl = 11567/968956 | hdl-access = free }}, at the introductory section.</ref>