Skip to main content

Global Plate Tectonics and India Subcontinent


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.

  • Plates: These plates float over the softer, semi-molten layer beneath, called the asthenosphere.

  • 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.

  • Boundaries: Where plates meet, we get different interactions:

    1. Divergent boundaries – plates move apart (mid-ocean ridges, new crust formation).

    2. Convergent boundaries – plates collide (mountains, subduction zones).

    3. Transform boundaries – plates slide past each other (earthquakes).

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.

  • 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.

  • Breakup: About 120 million years ago, the Indian plate broke away and started moving northwards across the Tethys Ocean.

  • Fast motion: India moved unusually quickly — about 15–20 cm/year at times (triple the average speed of plates).

  • Collision: Around 50 million years ago, the Indian plate collided with the Eurasian plate.

  • Result: The Himalayas and the Tibetan Plateau began to rise — and they are still rising today.

3. Current Tectonic Setting of India

  • Plate boundaries around India:

    • North: Convergent boundary with the Eurasian Plate → Himalayan orogeny (mountain building) and seismic activity in the Himalayan belt.

    • West: Transform and convergent interactions with the Arabian Plate along the Owen Fracture Zone and Makran Subduction Zone (earthquake risks in Gujarat, Arabian Sea).

    • East: Convergent boundary with the Burma Plate and Sunda Plate → Andaman–Nicobar volcanic arc and earthquakes.

    • South: Surrounded by the Indian Ocean spreading ridges (divergent boundaries) in the southwest and southeast.

  • 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

  • Himalayan growth: Still rising ~5 mm/year; ongoing earthquakes.

  • Peninsular stability: Generally stable, but intraplate quakes occur (e.g., Latur, Koyna) due to ancient fault reactivation.

  • Volcanism: Andaman–Nicobar volcanic activity (Barren Island volcano).

  • Tsunamis: Risk from undersea earthquakes (2004 Indian Ocean tsunami).


Time PeriodEventImpact
~150 MaIndia part of GondwanalandConnected to Antarctica, Africa, Australia
~120 MaBroke away from GondwanalandStarted moving north
~50 MaCollision with EurasiaFormation of Himalayas, Tibetan Plateau
PresentActive convergence & seismicityEarthquakes, mountain building, volcanism


Comments

Post a Comment

Popular posts from this blog

REMOTE SENSING INDICES

Remote sensing indices are band ratios designed to highlight specific surface features (vegetation, soil, water, urban areas, snow, burned areas, etc.) using the spectral reflectance properties of the Earth's surface. They improve classification accuracy and environmental monitoring. 1. Vegetation Indices NDVI – Normalized Difference Vegetation Index Formula: (NIR – RED) / (NIR + RED) Concept: Vegetation reflects strongly in NIR and absorbs in RED due to chlorophyll. Measures: Vegetation greenness & health Uses: Agriculture, drought monitoring, biomass estimation EVI – Enhanced Vegetation Index Formula: G × (NIR – RED) / (NIR + C1×RED – C2×BLUE + L) Concept: Corrects for soil and atmospheric noise. Measures: Vegetation vigor in dense canopies Uses: Tropical rainforest mapping, high biomass regions GNDVI – Green Normalized Difference Vegetation Index Formula: (NIR – GREEN) / (NIR + GREEN) Concept: Uses Green instead of Red ...
Post a Comment
Read more

Energy Interaction with Atmosphere and Earth Surface

In Remote Sensing , satellites record electromagnetic radiation (EMR) that is reflected or emitted from the Earth. Before reaching the sensor, radiation interacts with: The Atmosphere The Earth's Surface These interactions control how satellite images look and how we interpret them. I. Interaction of EMR with the Atmosphere When solar radiation travels from the Sun to the Earth, four main processes occur: 1. Absorption Definition: Absorption occurs when atmospheric gases absorb radiation at specific wavelengths and convert it into heat. Main absorbing gases: Ozone (O₃) → absorbs Ultraviolet (UV) Carbon dioxide (CO₂) → absorbs Thermal Infrared Water vapour (H₂O) → absorbs Infrared Concept: Atmospheric Windows These are wavelength regions where absorption is very low, allowing radiation to pass through the atmosphere. Remote sensing depends on these windows. For example, satellites like Landsat 8 use visible, near-infrared, and thermal bands located in atmospheric windows. 2. Trans...
Post a Comment
Read more

Landsat band composition

Short-Wave Infrared (7, 6 4) The short-wave infrared band combination uses SWIR-2 (7), SWIR-1 (6), and red (4). This composite displays vegetation in shades of green. While darker shades of green indicate denser vegetation, sparse vegetation has lighter shades. Urban areas are blue and soils have various shades of brown. Agriculture (6, 5, 2) This band combination uses SWIR-1 (6), near-infrared (5), and blue (2). It's commonly used for crop monitoring because of the use of short-wave and near-infrared. Healthy vegetation appears dark green. But bare earth has a magenta hue. Geology (7, 6, 2) The geology band combination uses SWIR-2 (7), SWIR-1 (6), and blue (2). This band combination is particularly useful for identifying geological formations, lithology features, and faults. Bathymetric (4, 3, 1) The bathymetric band combination (4,3,1) uses the red (4), green (3), and coastal bands to peak into water. The coastal band is useful in coastal, bathymetric, and aerosol studies because...
Post a Comment
Read more

Atmospheric Window

The atmospheric window in remote sensing refers to specific wavelength ranges within the electromagnetic spectrum that can pass through the Earth's atmosphere relatively unimpeded. These windows are crucial for remote sensing applications because they allow us to observe the Earth's surface and atmosphere without significant interference from the atmosphere's constituents. Key facts and concepts about atmospheric windows: Visible and Near-Infrared (VNIR) window: This window encompasses wavelengths from approximately 0. 4 to 1. 0 micrometers. It is ideal for observing vegetation, water bodies, and land cover types. Shortwave Infrared (SWIR) window: This window covers wavelengths from approximately 1. 0 to 3. 0 micrometers. It is particularly useful for detecting minerals, water content, and vegetation health. Mid-Infrared (MIR) window: This window spans wavelengths from approximately 3. 0 to 8. 0 micrometers. It is valuable for identifying various materials, incl...
Post a Comment
Read more

Landsat 8 Band designation and Band Combination.

Landsat 8 Band designation and Band Combination.  Landsat 8-9 Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) Bands Wavelength (micrometers) Resolution (meters) Band 1 - Coastal aerosol 0.43-0.45 30 Band 2 - Blue 0.45-0.51 30 Band 3 - Green 0.53-0.59 30 Band 4 - Red 0.64-0.67 30 Band 5 - Near Infrared (NIR) 0.85-0.88 30 Band 6 - SWIR 1 1.57-1.65 30 Band 7 - SWIR 2 2.11-2.29 30 Band 8 - Panchromatic 0.50-0.68 15 Band 9 - Cirrus 1.36-1.38 30 Band 10 - Thermal Infrared (TIRS) 1 10.6-11.19 100 Band 11 - Thermal Infrared (TIRS) 2 11.50-12.51 100 Vineesh V Assistant Professor of Geography, Directorate of Education, Government of Kerala. https://www.facebook.com/Applied.Geography http://geogisgeo.blogspot.com
1 comment
Read more