Physiography of India

Plate tectonics has played a
Gondwana, began drifting northward around 100 million years ago. This tectonic movement and its interaction with other tectonic plates, particularly the Eurasian Plate, have given rise to the Himalayas, the Indo-Gangetic Plains, the Deccan Plateau, and the coastal regions. These movements are also responsible for seismic activities, volcanic formations, and various natural disasters like earthquakes, landslides, and tsunamis.

1. Formation of the Himalayas and Northern Plains

The Himalayas, one of the youngest and highest mountain ranges in the world, owe their existence to the collision of the Indian Plate with the Eurasian Plate.

Role of Plate Tectonics:

• Continental Collision: Around 50 million years ago, the Indian Plate collided with the Eurasian Plate. This convergence continues today, leading to the uplifting of the Himalayas and the creation of the Tibetan Plateau. The Indian Plate continues to move at a rate of about 5 cm per year, causing the mountains to rise.
• Indo-Gangetic Plain: The Indo-Gangetic Plain was formed as a result of the sedimentation that occurred at the foothills of the Himalayas. The immense erosion of the rising Himalayas has deposited thick layers of alluvial soil in this region, making it one of the most fertile plains in the world.

Implications for Natural Disasters:

• Earthquakes: The collision between the Indian and Eurasian plates generates immense stress, leading to frequent seismic activity along the Himalayan belt. Major earthquakes, such as the 2005 Kashmir earthquake and the 2015 Nepal earthquake, have caused widespread devastation.
• Landslides: The steep and geologically young Himalayan slopes, combined with heavy monsoon rains, lead to frequent landslides. These are common in states like Uttarakhand, Himachal Pradesh, and parts of Sikkim, especially during the rainy season.
• Glacial Lake Outburst Floods (GLOFs): The Himalayas are home to many glaciers, and as the climate warms, the risk of glacial lake outburst floods increases. These events can result in flash floods, which are a growing concern in regions like Ladakh and Nepal.

2. Peninsular India and the Deccan Plateau

The Deccan Plateau and the southern part of the Indian subcontinent have a different tectonic history compared to the north. The plateau is composed of ancient igneous and metamorphic rocks, formed before the Indian Plate drifted northward.

Role of Plate Tectonics:

• Volcanic Activity: The Deccan Plateau was shaped by massive volcanic eruptions around 65 million years ago, known as the Deccan Traps, as India passed over a hot spot. This volcanic activity left behind thick basalt layers that now form the bedrock of much of the plateau.
• Stable Craton: Unlike the northern regions, the southern part of India sits on a stable geological platform (the Peninsular Craton), which has not experienced significant tectonic activity in recent times. This stability means fewer earthquakes in this region.

Implications for Natural Disasters:

• Earthquakes: Although the Deccan Plateau is tectonically stable compared to the north, intra-plate seismic activity can still occur. For instance, the Latur earthquake in 1993 in Maharashtra, which occurred within the Indian Plate, was unexpected and caused considerable damage.
• Droughts: The Deccan Plateau has a semi-arid climate and relies on the monsoon for water. The region is highly susceptible to droughts, which are exacerbated by irregular rainfall patterns due to its physiography. This has major implications for agriculture and water availability in states like Karnataka, Maharashtra, and Telangana.

3. Western and Eastern Ghats

The Western and Eastern Ghats are mountain ranges running along India’s western and eastern coasts, respectively. These ranges were formed by the movement of the Indian Plate and the rifting that separated India from Africa and Madagascar during its northward journey.

Role of Plate Tectonics:

• Faulting and Uplifting: The Western Ghats are older than the Himalayas and were formed due to the tectonic processes that uplifted the region. The Eastern Ghats, though lower in elevation, were also shaped by tectonic forces, though they have eroded over time.
• Rift Zones: The Narmada and Tapti valleys, located between the Western and Eastern Ghats, are examples of rift valleys formed by faulting due to tectonic forces.

Implications for Natural Disasters:

• Landslides: The steep slopes of the Western Ghats are prone to landslides, especially during the monsoon season. States like Kerala and Karnataka frequently experience landslides that disrupt local communities and infrastructure.
• Floods: The proximity of the Western Ghats to the Arabian Sea means that regions on the windward side receive heavy monsoonal rainfall, leading to floods. The Kerala floods of 2018 were exacerbated by the geography of the Western Ghats, where steep terrain funnels rainwater into narrow valleys, causing rivers to overflow.

4. Thar Desert

The Thar Desert in northwestern India is a dry and arid region, shaped by climatic and tectonic forces.

Role of Plate Tectonics:

• Tectonic Uplift and Rain Shadow Effect: The desert lies in the rain shadow of the Aravalli Range, an ancient mountain range formed due to tectonic forces. This rain shadow, combined with the prevailing winds from the west, has contributed to the desertification of the region.
• Seismic Activity: The region is close to the Indian Plate’s boundary with the Arabian Plate, which has caused earthquakes in the past. The 2001 Bhuj earthquake in Gujarat, near the Thar Desert, is an example of tectonic activity in this region.

Implications for Natural Disasters:

• Droughts: The Thar Desert is highly prone to droughts due to low and erratic rainfall. The harsh environmental conditions make the region vulnerable to water scarcity, affecting agriculture and local livelihoods.
• Desertification: Ongoing desertification, driven by both climatic changes and human activities such as deforestation and overgrazing, is a growing challenge in the Thar Desert.

5. Coastal Regions and Tsunamis

India’s extensive coastline, stretching over 7,500 kilometers along the Arabian Sea, Bay of Bengal, and Indian Ocean, has been shaped by tectonic forces over millions of years.

Role of Plate Tectonics:

• Indian Ocean Ridge: The Indian Plate’s interaction with the Indian Ocean Ridge has contributed to the formation of islands like the Andaman and Nicobar Islands, which are part of an active tectonic zone.
• Subduction Zones: The eastern coast of India is influenced by the subduction zone near the Sunda Trench, where the Indo-Australian Plate is being subducted beneath the Eurasian Plate.

Implications for Natural Disasters:

• Tsunamis: The 2004 Indian Ocean tsunami was triggered by an undersea earthquake off the coast of Sumatra. It devastated coastal areas in southern India, particularly Tamil Nadu and the Andaman and Nicobar Islands. The subduction zone in this region remains a source of potential future tsunamis.
• Cyclones and Storm Surges: Coastal regions, especially along the eastern seaboard, are prone to tropical cyclones, which cause storm surges and flooding. The physiography of the Bay of Bengal allows cyclones to gain intensity, making states like Odisha, West Bengal, and Andhra Pradesh vulnerable.

Conclusion:

Plate tectonics has been the driving force behind India’s diverse physiography, from the soaring Himalayas to the Deccan Plateau and the coastal plains. This tectonic activity, however, also comes with the risk of natural disasters such as earthquakes, landslides, tsunamis, and droughts. Understanding the relationship between tectonic movements and India’s geography is crucial for disaster management, sustainable development, and mitigating the impacts of these natural calamities on human populations and infrastructure.