1. Global Plate Tectonics
The theory of Plate Tectonics explains how the Earth's lithosphere (the rigid outer shell) is broken into large pieces called plates.
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Plates: These plates float over the softer, semi-molten layer beneath, called the asthenosphere.
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Movement: Driven by heat from Earth's interior (mantle convection, ridge push, slab pull), plates move a few centimetres per year — about the speed your fingernails grow.
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Boundaries: Where plates meet, we get different interactions:
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Divergent boundaries – plates move apart (mid-ocean ridges, new crust formation).
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Convergent boundaries – plates collide (mountains, subduction zones).
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Transform boundaries – plates slide past each other (earthquakes).
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Why it matters: This movement shapes continents, mountains, volcanoes, ocean basins, and earthquakes.
2. India's Place in Global Plate Tectonics
India's geologic story is one of the most dramatic and fast-moving continental journeys in Earth's history.
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Past position: Around 150 million years ago (Mesozoic Era), India was part of the southern supercontinent Gondwanaland, along with Africa, Antarctica, Australia, and South America.
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Breakup: About 120 million years ago, the Indian plate broke away and started moving northwards across the Tethys Ocean.
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Fast motion: India moved unusually quickly — about 15–20 cm/year at times (triple the average speed of plates).
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Collision: Around 50 million years ago, the Indian plate collided with the Eurasian plate.
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Result: The Himalayas and the Tibetan Plateau began to rise — and they are still rising today.
3. Current Tectonic Setting of India
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Plate boundaries around India:
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North: Convergent boundary with the Eurasian Plate → Himalayan orogeny (mountain building) and seismic activity in the Himalayan belt.
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West: Transform and convergent interactions with the Arabian Plate along the Owen Fracture Zone and Makran Subduction Zone (earthquake risks in Gujarat, Arabian Sea).
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East: Convergent boundary with the Burma Plate and Sunda Plate → Andaman–Nicobar volcanic arc and earthquakes.
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South: Surrounded by the Indian Ocean spreading ridges (divergent boundaries) in the southwest and southeast.
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Seismic zones: India has four main seismic zones (II–V), with Zone V being the most active (NE India, Kashmir, Andaman–Nicobar).
4. Key Effects on India
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Himalayan growth: Still rising ~5 mm/year; ongoing earthquakes.
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Peninsular stability: Generally stable, but intraplate quakes occur (e.g., Latur, Koyna) due to ancient fault reactivation.
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Volcanism: Andaman–Nicobar volcanic activity (Barren Island volcano).
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Tsunamis: Risk from undersea earthquakes (2004 Indian Ocean tsunami).
Time Period | Event | Impact |
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~150 Ma | India part of Gondwanaland | Connected to Antarctica, Africa, Australia |
~120 Ma | Broke away from Gondwanaland | Started moving north |
~50 Ma | Collision with Eurasia | Formation of Himalayas, Tibetan Plateau |
Present | Active convergence & seismicity | Earthquakes, mountain building, volcanism |
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