Landslide

In the early hours of August 2, 2014, nearly 2 kilometers of hillside collapsed in rugged northern Nepal. Image: NASA.

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).

Related content

Data Source

Publishing institution: The University of Sheffield
The Global Fatal Landslide Database (GFLD) has been consistently collected and maintained since 2004. Systematic metadata search tools based in the English language are used to identify relevant reports of landslide activity. Reports are corroborated and data updated by source triangulation using government and aid agency reports, academic papers and personal communications as new information becomes available. This version of the dataset contains all non-seismically triggered fatal landslide events from 2004 to 2016. A web platform is currently under development to host the full database openly and provide users with more functionality, including data download and crowd source reporting.
Publishing institution: European Space Agency (ESA)
ESA's Earth Observation Thematic Exploitation Platform (TEP) is a browser for satellite imagery and specific products on an environmental topic. The TEP platforms are divided into 7 categories: Coastal; Forstry; Geohazards; Hydrology; Polar; Urban; and Food Security. Each platform is a collaborative, virtual work environment providing access to EO data and the tools, processors and Information and Communication Technology resources required to work with them. TEP aims to bridge the gap between the users and the data and tools.

Noticias

Air photo of the Mud Creek landslide, taken on May 27, 2017.

While several studies have already highlighted how global warming and its consequences are predicted to increase the frequency and magnitude of geohazards such as landslides, the relation between ongoing climate shifts and landslide behaviour is still difficult to assess, especially due to uncertainties in both models. In a new research paper, researchers at NASA's Jet Propulsion Laboratory and collaborating institutions have now documented the transition of a stable, slow-moving landslide into catastrophic collapse for the first time.

Their  observations lasted eight years and took place on the California Coast Ranges, which, due to their... read more

Publishing date: 20/02/2019
This set of 12 still images show the potential landslide by month averaged over the last 15 years. Image: NASA.

The National Aeronautics and Space Administration (NASA) of the United States is currently building a worldwide database of landslide events. The Cooperative Open Online Landslide Repository (COOLR) includes NASA’s Global Landslide Catalog (GLC) which provides new insights into landslide hazards around the world. 

The COOLR project is an open platform where scientists and citizen scientists around the world can share landslide reports to guide awareness of landslide hazards for improving scientific modelling and emergency... read more

Publishing date: 07/06/2018

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