Glissement de terrain

Definition

The term “landslide” refers to a variety of processes that result in the downward and outward movement of slope-forming materials, including rock, soil, artificial fill, or a combination of these. The materials may move by falling, toppling, sliding, spreading, or flowing (UNDRR).

A landslide is a downslope movement of rock or soil, or both, occurring on the surface of rupture, either curved (rotational slide) or planar (translational slide) rupture, in which much of the material often moves as a coherent or semi coherent mass with little internal deformation (USGS).

Facts and figures

According to the International Disaster Database of the Centre for Research on the Epidemiology of Disasters, in the period from 2000 to 2014, 26,000 persons have lost their lives because of landslides and flash floods while the economic losses amounted to over US$ 40 billion (OFDA/CRED).

Landslides can be classified into different types on the basis of the type of movement and the type of material involved. In brief, material in a landslide mass is either rock or soil (or both); the latter is described as earth if mainly composed of sand-sized or finer particles and debris if composed of coarse fragments. The type of movement describes the actual internal mechanics of how the landslide mass is displaced: fall, topple, slide, spread, or flow. Thus, landslides are described using two terms that refer respectively to material and movement, that is rockfall, debris flow, and so forth. Landslides may also form a complex failure encompassing more than one type of movement that is, rock slide and debris flow (USGS).

The primary driving factor of landslides is gravity acting on a portion of a slope that is out of equilibrium. The following are some of the major landslide triggering mechanisms:

  • River erosions, glaciers, or ocean waves
  • Weakening of rock and soil slope properties through water saturation by snowmelt or heavy rains
  • Stresses, strains and excess of pore pressures induced by the inertial forces during an earthquake (earthquakes of magnitude greater than or equal to 4.0 can trigger landslides)
  • Volcanic eruptions with the production of loose ash deposits that may become debris flows (known as lahars) during heavy rains
  • Stockpiling of rock or ore, from waste piles, or from man-made structures
  • Changes of the natural topography caused by human activity (UNDRR).

UN-SPIDER Regional Support Offices with hazard-specific expertise

Related content on the Knowledge Portal

  • Publishing institution:
  • Facebook Connectivity Lab in collaboration with the Center for International Earth Science Information Network (CIESIN) at Colombia University combines machine vision AI with satellite imagery and census information to create population density maps. With the integration of demographic information, specifically related to age and gender, these maps collectively provide information on both the location and the demographic of a population in a certain country. The population density maps cover the majority of countries around the world.
  • Facebook Connectivity Lab in collaboration with the Center for International Earth Science Information Network (CIESIN) at Colombia University combines machine vision AI with satellite imagery and census information to create population density maps. With the integration of demographic information, specifically related to age and gender, these maps collectively provide information on both the location and the demographic of a population in a certain country. The population density maps cover the majority of countries around the world.
  • Having reliable and timely population distribution data can make a life or death difference for individuals facing crises or living in conflict-ridden regions. These data are also essential for development decision-making and planning and for monitoring progress towards the UN Sustainable Development Goals (SDGs) established by the international community. We need to know where people are located, what conditions they are facing, what infrastructure is available, and what basic services they can access. We also need to ensure that no one is left off the map in pursuit of meeting the SDGs. 

    Gridded population data, which often use remote sensing inputs to improve the spatial allocation of population within a country, are vital for all these purposes. Together with the  growing variety of applications that require spatial population data, there is now a bewildering array of population grids, and users need to know which ones are most suitable for their applications…

    read more
  • The European Space Agency is organising the 11th International Workshop on “Advances in the Science and Applications of SAR Interferometry and Sentinel-1 InSAR”, Fringe 2021.

    Format

    Fringe 2021 is organised around:

    • Papers and e-posters selected by the Scientific Committee;
    • Invited papers on ESA-funded studies and Sentinel-1 and future ESA SAR mission status reports;
    • Round-table discussions with seed questions prepared by the session chairpersons and ESA.

    The event will take place from 31 May - June 4 2021. No participation fees will be charged.

    Objectives

    • To bring together the global InSAR research and development communities and facilitate international exchange between researchers and research groups; 
    • To present the Sentinel-1 mission status, algorithms and products;
    • To review and assess the progress according to the…
    read more
  • Seasonal cold fronts have brought more rain to several municipalities of Chiapas, in Mexico, which are suffering from the aftermath of Hurricane's Eta and Iota. This has caused flooding and landslides in Ixhuatan, Matzam, Tacuba and Juan de Grijalva. The extent of the landslides are not yet known, as access to some rural communities by road has been cut off.

    To support disaster management authorities in Mexico in responding to the floods, UNOOSA, through its UN-SPIDER programme has requested the activation of the International Charter Space and Major Disasters on behalf of the National Disaster Prevention Centre of Mexico (CENAPRED).

    The project management for this activation is provided by the Autonomous University of Mexico State (UAEMEX).

    read more
  • The United Nations Office for Outer Space Affairs (UNOOSA) and the National Aeronautics and Space Administration of the United States Government (NASA) signed a landmark Memorandum of Understanding (MoU) on 17 December 2020 pledging cooperation in areas of science and technology to support the peaceful uses of outer space.

    The MoU brings together NASA's wealth of open-source spacecraft data, tools, and expertise and UNOOSA's unique position as the only UN entity dedicated to outer space affairs, to expand global opportunities to leverage the benefits of space. The partners will design capacity-building programmes, particularly for institutions in countries that do not yet have or that are developing space capabilities, to help them access space.

    Together, UNOOSA and NASA will develop ways to leverage the Artemis programme as part of UNOOSA's Access to Space 4 All Initiative, which offers opportunities for international researchers and institutions, especially in…

    read more
    11/01/2021
  • A new report by the world’s largest humanitarian aid network highlights global disasters, populations most vulnerable to them and the efforts of local institutions in preventing, preparing for and responding to them. The 2020 edition of the World Disasters Report, “Come Heat or High Water”, was launched virtually from the offices of the International Federation of Red Cross and Red Crescent Societies (IFRC) in Vienna on November 16. This year’s report discusses climate- and weather-related disasters and their humanitarian impact. It argues for the usefulness of smart financing and space-based information in disaster management support.

    The report warns that the global effort to address climate change is leaving behind countries…

    read more
    19/11/2020
  • The European Commission plans to rapidly expand its environmental monitoring programme Copernicus. For this purpose, the European Space Agency (ESA) recently pledged 2.55 billion Euros towards contracts to advance the production of six new Copernicus satellite missions. The final of the six contracts was signed last Thursday between ESA and Thales Alenia Space for a mission that will provide new and important information to climate research and disaster management.

    The high-priority Copernicus Radar Observation System for Europe in L-band (ROSE-L) mission is planned to launch in 2028 for a period of 7.5 years. The ROSE-L mission will orbit Earth every few days at an altitude of 690km and will carry a L-Band synthetic aperture radar (SAR). With a wavelength of approximately 23cm, an…

    read more
    18/12/2020

Term Parents

UN-SPIDER Regional Support Offices with hazard-specific expertise