Landslide

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

  • Tropical Storm Megi (also known as Agaton) passed over the Philippines on 10 April, causing landslides and floods in its wake.

    The storm struck the east and south coasts of the archipelago, particularly affecting Western Visayas, Eastern Visayas and Craga regions.

    35,000 people were evacuated before the storm arrived, and it is estimated that as many as 200,000 have had to leave their homes since then to move to safer locations. Estimates suggest almost a million people may be affected by the disaster.

    76 people have been reported killed due to floods and landslides, after rivers burst their banks and debris from hills was washed down, and villages near Baybay City have been badly affected.

    UNOOSA/UN-SPIDER requested the activation of the International Charter Space and Major Disasters on behalf of the Philippine Space Agency (PhilSA) and the Philippine National Disaster Risk Reduction and Management Council (NDRRMC)

    read more
  • This article is a republished news article, created and originally published by the International Centre for Integrated Mountain Development (ICIMOD) under a Creative Commons license. Read the original article here.

    Author: Utsav Maden, Knowledge Management and Communication Officer, ICIMOD

    Nepal faces a double whammy of floods and landslides every year. Often considered a secondary hazard, landslides are usually triggered by incessant rainfall falling upon hilly and unstable slopes in Nepal’s predominantly mountainous terrain. As Nepal lies at the cusp of the Indian and Tibetan tectonic plates, it is more susceptible to earthquakes and resulting landslides. Unplanned road building and construction along unstable mountain slopes on relatively young mountain terrain…

    read more
    24/01/2023
  • The training date is in the past. However, videos and resources of the training can be accessed here.

    Small island nations are highly vulnerable to climate change and natural disasters; among them hurricanes, cyclones, and other violent storms. These disasters can lead to severe flooding, landslides, and, in the worst cases, can result in the loss of life and property. In addition, a rise in the global mean sea level places island nations at a higher risk for permanent submersion of land, coastal erosion, coastal ecosystem loss or change, salinization, and impeded drainage.

    This three-part training series will focus on small island nations while introducing the data, methods, and tools useful for monitoring natural hazards. Case studies will be used to demonstrate methodologies applying satellite and…

    read more
  • Implementing science to save lives: A Decade of the Copernicus Emergency Management Service

    The Copernicus Emergency Management Service (CEMS) celebrates a decade of operation as a world leader in emergency mapping, early warning tools and open-access disaster information.

    For the past ten years, CEMS has provided a global service as a fully operation emergency mapping service at no cost to users and with open access data.

    Some highlights on the contribution of CEMS in global disaster risk management activities:

    • 576 Rapid Mapping Activations with 5,500+ maps delivered
    • Designed and implemented the world’s first Global Flood Monitoring tool
    • Ten years of wildfire forecasts up to ten days into the future
    • Average of 200+ flood and 500+ flash flood notifications to Member States and authorised users each year
    • Offers a current and historical database of 7,000+ drought episodes since 1950

    read more
    22/06/2022
  • Publishing institution:
  • Publishing institution:
  • An Australian research team has developed a data-driven tool in proof-of-concept research for regional scale that can predict landslides up to a year in advance.

    The tool has the potential to be a significant way to safeguard people against fatal natural disasters: around 25-50 people are killed by landslides each year in the United States alone, and the global annual death toll is estimated in thousands.

    This new tool strives for two things: first, it aims for early prediction, meaning more than a couple of days in advance, in the hope to undertake some remediation to avert the landslide.
    And due to this, the most accurate projections of the exact site of an oncoming landslide now occur a year in advance.

    The second critical element of the team's new tool is its ability to forecast landslides a month in advance on a regional scale.

    The innovative aspect of the team'…

    read more
    14/03/2022
  • The Copernicus DEM is a Digital Surface Model (DSM) which represents the surface of the Earth including buildings, infrastructure, and vegetation. The Copernicus DEM is provided in 3 different instances. Two worldwide coverages at 90m (GLO-90) and 30m (GLO-30) resolution are openly available to the public for download via the PANDA Catalogue and FTP. A further European coverage (EEA-10) is provided at 10m resolution, but data is restricted to eligible users who meet required access rights.
  • The Copernicus DEM is a Digital Surface Model (DSM) which represents the surface of the Earth including buildings, infrastructure, and vegetation. The Copernicus DEM is provided in 3 different instances. Two worldwide coverages at 90m (GLO-90) and 30m (GLO-30) resolution are openly available to the public for download via the PANDA Catalogue and FTP. A further European coverage (EEA-10) is provided at 10m resolution, but data is restricted to eligible users who meet required access rights.
  • Small island nations are highly vulnerable to climate change and natural disasters, such as hurricanes, cyclones, and other storms, which can lead to severe flooding, landslides, and result in the loss of life and property. In addition, a rise in the global mean sea level places island nations at a higher risk for permanent submersion of land, coastal erosion, coastal ecosystem loss or change, salinization, and impeded drainage.

    This three-part training series will focus on small island nations while introducing the data, methods, and tools useful for monitoring natural hazards. Case studies will be used to demonstrate methodologies applying satellite and model data and open access tools to analyze storm impacts, sea level rise, and landslides on small island nations.

    Course Format:

    • Three 2-hour parts
    • Each part will be offered at two different times of day, once in English and once in Spanish.
    • Time: 11:00 to 13:00 ET (…
    read more

Term Parents

UN-SPIDER Regional Support Offices with hazard-specific expertise