Landslides are a major geomorphic process that shape the landscape. Landslides can be classified into two main types, viz. Mass movement and Flows in the Himalayan region. The Himalayan region is prone to both kinds of landslides. In general, the Himalayan region is prone to rock falls and debris movements, whereas the Western Ghats are prone to mass movements. This is primarily due to the differences in lithology, structure and rainfall pattern between these two regions.
The Himalayan region has a higher incidence of landslides caused by earthquake-induced slope failures as well as by recent anthropogenic disturbances such as road construction and deforestation.
Also, in this region, the highest activity has been observed in the wet season due to heavy rainfall and snowmelt whereas the Western Ghats have not undergone any major earthquake-induced slope failures so far, but they are prone to mass movement due to heavy rainfall and soil creep, though there have been some significant instances of mudflow during periods of intense rainfall.
Landslides are a very common occurrence in both regions. They happen due to a variety of reasons.
The Western Ghats often experience landslides during the monsoon season. This is because of the heavy rainfall and high humidity along with the steep topography in this region. When the vegetation is cleared for agricultural activities, there is a higher chance of the top soil being washed away during the rains. This causes landslides especially in these areas where building activity has taken place.
In contrast, the Himalayan region experiences landslides due to earthquakes and high-speed winds. The Himalayas have many faults and when earthquakes occur, they can cause landslides in this area. Due to high velocity wind, snow avalanches are also known to occur in this region causing huge damage to life and property
Causes of landslide in Himalaya
The Himalayas are subjected to various types of land slides which occur due to different causes. These are:
1.Tectonic activities: The movement of land mass along faults is responsible for the occurrence of landslide in this region. Due to the constant tectonic activity the mountains become unstable and landslides occur.
2.Climate change: The irregular rains, earthquakes and other tectonic activities are responsible for climate change which increases the chances of triggering landslide in this region. This problem has increased after global warming as now a days we experience extreme rainfall and extreme temperature conditions as well as rapid melting of glaciers which leads to heavy flood and landslides in this region.
3.Unplanned construction: The unplanned constructions on hill slopes especially near rivers and water bodies increase the chances of landslides in this area.
Landslides are the result of the mass movement of dirt, rocks, or debris down a mountain slope caused by gravity. Geology, morphology, and human activities all contribute to the cause of landslides.
The following factors contribute to landslides in the Himalayan area and Western Ghats:
4.Plate Tectonics: The Himalayan region is tectonically active due to the Indian Plate’s northward movement at a pace of 5 centimetres per year. This movement causes the Indian Plate to collide with the Eurasian Plate, resulting in regular tremors and isostatic imbalances. However, the Western Ghats are more stable tectonically than the Himalaya.
5.Exogenetic forces: The Himalayan region is home to a number of swift-flowing rivers, including the Ganges, the Indus, and the Brahmaputra. These flowing rivers erode the hilly area on a vast scale, resulting in landslides. Perennial rivers are uncommon in the Western Ghats.
6.Human intervention: Development activities such as road and railway building, unplanned urbanisation that ignores the slope elements of the environment, and so on exacerbated the occurrence of landslides. As a Biodiversity Hotspot, the Western Ghats have less human intervention and are less prone to landslides than the Himalayan region.
The Himalayan area is formed of sedimentary rocks that are more susceptible to denudation and erosion than other types of rocks. While the majority of the Western Ghats are made up of basalt rocks that are extremely resistant to erosion and denudation.
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