Formation of Himalaya
The Himalayas are a vast mountain
range located in South Asia, which includes some of the highest peaks in the
world, such as Mount Everest. The formation of the Himalayas is the result of
the collision of the Indian and Eurasian tectonic plates. Around 50 million
years ago, India was a separate continent that began moving northward towards
Asia, eventually colliding with the Eurasian plate around 40 to 50 million
years ago. As the two plates collided, the Indian plate was forced beneath the
Eurasian plate, causing the crust to thicken and rise. This process, called
subduction, resulted in the formation of the Himalayas. Over millions of years,
the Himalayas continued to rise as the Indian plate pushed against the Eurasian
plate, resulting in the creation of the highest mountain range in the world.
The ongoing collision between the two plates also caused the formation of many
other mountain ranges, including the Karakoram, Hindu Kush, and the Pamir
Mountains. Today, the Himalayas are still rising at a rate of approximately 5
millimeters per year, and the ongoing collision between the two tectonic plates
continues to shape the landscape of South Asia.
Division of Himalaya
The entire Himalayan arc is about
2500 km long. It has been divided into the Punjab Himalaya, Kumaon Himalaya, Nepal Himalaya, Sikkim-Bhutan
Himalaya, and NEFA Himalaya, respectively, from South-West to East (Gansser,
1964). Each section of the Himalayan arc can be subdivided into five
tectonic zones (Gangetic Plain, Siwalik, Lesser Himalaya, Higher Himalaya, and
Tibetan Tethys Himalaya), from South to North, respectively.
Tectonic Division of Himalaya (After Upreti and Le Fort, 1999, Heim and Gansser (1939), and Gansser (1964))
Major Geological Problems in
Higher Himalaya
The higher Himalayan region faces
several geological problems that pose significant risks to human settlements,
infrastructure, and ecosystems. Snow avalanches are a common occurrence in the
region and can cause widespread damage and loss of life. Glacier lake outburst
floods (GLOFs) are another significant problem in the higher Himalayas, as
warming temperatures and melting glaciers have led to the formation of unstable
glacial lakes that can burst and cause flooding downstream. Rockfall is also a
major concern in the region, as Steep Mountain slopes are prone to erosion and
can result in large rocks falling onto roads, buildings, and people. Landslides
are also a frequent occurrence in the higher Himalayas, particularly during the
monsoon season, and can result in significant damage to infrastructure and
human settlements. These geological problems in the higher Himalayas are exacerbated
by climate change, which is leading to more extreme weather events and
increasing the risk of natural disasters.
Major Geological Problems in
Lesser Himalaya
The Lesser Himalaya region also
faces several geological problems that pose significant risks to human
settlements, infrastructure, and ecosystems. Landslides are a common occurrence
in the region, particularly during the monsoon season when heavy rainfall can
destabilize slopes and cause them to fail. Rockfall is also a significant problem,
as the region is characterized by steep mountain slopes that are prone to
erosion and rock falls. Debris flow, which is a mixture of soil, rock, and
water that moves down slopes, is another major concern in the Lesser Himalaya
region. Debris avalanche, a rapid and destructive mass movement of rock and
debris down a slope, is also a risk in the region. Deep gully erosion, caused
by the concentrated flow of water, is another geological problem that can
result in significant damage to infrastructure and human settlements. Flash
floods are also a frequent occurrence in the region, particularly during the
monsoon season, and can cause widespread damage and loss of life. These
geological problems in the Lesser Himalayas are compounded by human activities
such as deforestation and land-use changes, which can increase the risk of
natural disasters
Major Geological Problems in
Siwalik (Sub Himalaya)
The Siwalik region, also known as
the Sub Himalaya, faces several geological problems that pose significant risks
to human settlements, infrastructure, and ecosystems. Landslides and debris
flow are common occurrences in the region, particularly during the monsoon
season when heavy rainfall can destabilize slopes and cause them to fail.
Erosion is also a significant problem in the Siwalik region, as the region is
characterized by soft sedimentary rocks that are easily weathered by wind and
water. Weathering, which is the process of breaking down rocks into smaller
pieces, is another geological problem that can result in significant damage to
infrastructure and human settlements. Rockfall is also a concern in the
Siwalik region, particularly in areas where steep mountain slopes have been
exposed due to erosion and weathering. These geological problems in the Siwalik
region are compounded by human activities such as deforestation and land-use
changes, which can increase the risk of natural disasters.
Major Geological Problems in
Tarai
The Tarai region, which lies at
the foothills of the Himalayas, faces several geological problems that pose
significant risks to human settlements, infrastructure, and ecosystems. Floods
are a common occurrence in the Tarai region, particularly during the monsoon
season when heavy rainfall can cause rivers to overflow and inundate low-lying
areas. Liquefaction, the transformation of soil from a solid to a
liquid state, is another significant problem in the Tarai region, particularly
in areas with loose and saturated soils. Stream bank cutting, which is the
erosion of riverbanks due to the force of water, is also a concern in the
region, as it can lead to the loss of land and damage to infrastructure.
Subsidence, which is the sinking or settling of the ground surface, is another
geological problem that can result in damage to buildings and infrastructure.
These geological problems in the Tarai region are compounded by human
activities such as deforestation and land-use changes, which can increase the
risk of natural disasters.
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