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Land Slides


A landslide is a geological phenomenon. It includes a wide range of ground movement.

  • Rock Falls.
  • Deep Failure Of Slopes.
  • Shallow Debris Flows … are all considered as land slides.

Land slides can occur in offshore, coastal and onshore environments.

Landslides are caused when the stability of a slope changes from a stable to an unstable condition.

The change in the stability of a slope is caused by a number of factors. It can be a combination of factors or a single factor that precipitate a landslide.


Causes of Ladslide

Natural Causes
  • Groundwater Pressure Acting on the Slope.
  • Loss of Vegetative Structure.
  • Erosion by Rivers or Ocean Waves.
  • Weakening of a Slope due to Melting of Glaciers or Heavy Rains.
  • Earthquakes.
  • Volcanic Eruptions.

Human Causes

  • Vibrations from Machinery.
  • Blasting of Mines.
  • Earthwork which alters the Slope.
  • Construction, Agricultural, or Forestry Activities which change the amount of water that enters the Soil.


Classification of Landslide

Landslides can be broadly classified into:
  • Debris Flow - excess water on the slopes cause debris flow.
  • Earth Flow - fine-grained materials covering the slopes cause earth flow.
  • Shallow Landslide - the upper layer detaches from the slope and slides down.
  • Deep-seated Landslide - the sliding surface is very deep.

A Report on a recent landslide in Himachal Pradesh

A Massive Landslide at Pangi Village in Himachal Pradesh


A massive landslide hit the Pangi village in August 2007, near Reckong Peo in Kinnaur district of Himachal Pradesh and damaged a 200-meter stretch of old Hindustan-Tibet road, commonly known as the mule track, and blocked the new Hindustan-Tibet road for many hours. The landslide was the result of intense blasting at Pangi village. Due to the blasting the weak zone of the slopes collapsed and caused great damage to the road and nearby villages. The Pangi village was completely vacated to avoid any possible loss of life.


Methods to Lessen the Occurrence of Landslides

  • Hazard mapping can locate areas prone to landslides. These areas can be avoided for building settlements and hence avoid loss of life and property in the event of a Landslide.
  • Construction of a retention wall to stop land from slipping.
  • Increase in the vegetation cover will be an effective way to arrest landslide.
  • Effective surface drainage system will control landslides during rainy season and Spring flows.

Landslides and protection methods:

Causes of Landslides


Landslides are a major natural disaster all over the world. In India landslides are common in the hilly regions of the south and in the Himalayan regions of the north. These landslides cause a lot of damage to life and property.


Land Slides

Landslides occur due to heavy rainfall, steep slopes, seismic activity and poor drainage.

Landslides are also caused due to deforestation and soil erosions. Unrestricted excavation, mining and quarrying also cause landslides.

The site most suited to build houses in landslide prone areas are where the land has not moved in the past. Flat surfaces away from sudden slopes and areas at the top or along the ridges are also suited for building houses.

Houses that are most affected by landslides are the ones that are constructed in the existing landslide areas. House that are built on the steep mountain slopes, near the valley or on the foot hills of the mountains are also most affected during a landslide.

Warning signs before a landslide

  • Landslides usually occur in the same place again and again.
  • Doors and windows jam for the first time.
  • New cracks appear on the walls and floors.
  • Gaps form between the pavement and the building outside the house.
  • Fences and compound walls tend to tilt.
  • Underground water and electricity lines break.
  • When these warning signs occur people have to take precautions.

    To prevent damage to life and property sound construction techniques have to be followed. Seasonal inspection and regular maintenance of the drainage system by the authorities is essential.

    A safe drainage system can prevent landslides to a large extent.


    Surface drainage system should be kept away from steep slopes, loose soil and non-vegetated land.

    Water that drains from the roof and other areas like the portico should not be allowed to flow down the slopes. This water should be drained through the drain pipes.

    Drainage System on the Slopes


    Trees and other vegetation prevent landslides to a large extent.

    Thick Vegetation Prevents Landslides


    Straw, woodchips or bark applied to a depth of one inch is effective in holding the soil from sliding.

    Barriers can be erected to avoid minor landslides.

    Wall to stop landslides in Hubei


    Advancement in scientific techniques has empowered us to understand what factors cause landslides and how to manage them.

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