Geography Chapters

1. Continents and Oceans2. Biosphere3. Lithosphere4. Hydrosphere5. Atmosphere6. Latitudes and Longitudes7. Different Heat Zones of the Earth8. Longitudes and Time Zones9. International Date Line10. Motion of the Earth11. Effect of the Tilted Axis on Day and Night12. The Atmosphere (Composition and Layers)13. Weather and Climate14. Atmospheric Pressure15. Internal Structure of the Earth16. Rocks17. Earthquakes and Volcanoes18. Various Landforms (Mountains, Plateaus, Plains, Grasslands)19. Landforms Created by River System20. Landforms Created by Glacier21. Landforms Created by Wind22. Landforms Created by Groundwater23. The Indian Subcontinent Position, Extent, and Physical Features24. Climatic Diversity in the Indian Subcontinent25. Soil Resources of the Indian Subcontinent26. Agriculture in India27. Land Use Pattern of India28. Water Resources and Their Utilization in India29. Multipurpose River Valley Projects30. Transport in India31. Rivers of India

Earthquakes and Volcanoes

“Earthquakes and volcanoes are powerful natural forces that shape the Earth's surface.”

Definitions

  • Earthquake: A sudden shaking of the Earth's surface caused by the movement of tectonic plates.
  • Volcano: An opening in the Earth's crust through which molten rock, ash, and gases are ejected.

Causes of Earthquakes

  • Movement of tectonic plates
  • Volcanic activity
  • Man-made causes (e.g., mining, reservoir-induced seismicity)

Types of Volcanoes

  • Active Volcano: Currently erupting or may erupt soon (e.g., Mount Etna)
  • Dormant Volcano: Not erupted recently but may erupt again (e.g., Mount Fuji)
  • Extinct Volcano: Not expected to erupt again (e.g., Edinburgh Castle hill)

Important Terms

  • Focus: The point inside the Earth where the earthquake originates.
  • Epicenter: The point on the Earth's surface directly above the focus.
  • Seismograph: An instrument used to detect and record earthquakes.
  • Richter Scale: A scale that measures the magnitude (intensity) of an earthquake.
  • Lava: Molten rock that erupts from a volcano.
  • Magma: Molten rock beneath the Earth's surface.

Earthquake vs Volcano

Earthquake

  • Caused by tectonic movement
  • Sudden ground shaking
  • Measured on Richter Scale
  • Epicenter & Focus involved

Volcano

  • Caused by rising magma
  • Eruption of lava and gases
  • May form new landforms
  • Located on weak crust areas

Major Earthquake Zones in India

  • Himalayan Region (Zone 5 – Very high risk)
  • Indo-Gangetic Basin (Zone 4)
  • Gujarat (Kutch region)
  • North-East India

Major Volcano Belts

  • Ring of Fire: Pacific Ocean belt with most of the world’s active volcanoes
  • Mid-Atlantic Ridge: Undersea volcanic belt in the Atlantic Ocean
  • Mediterranean Belt: From Italy to Indonesia

Previous Year Questions

  • SSC CGL 2021: What is the point inside Earth where an earthquake originates?
  • Focus
  • RRB NTPC 2019: Which instrument records earthquakes?
  • Seismograph
  • SSC CHSL 2018: Which scale is used to measure earthquake intensity?
  • Richter Scale
  • HSSC CET 2021: Where is the ‘Ring of Fire’ located?
  • Pacific Ocean
  • RRB ALP 2020: What is lava?
  • Molten rock coming out of a volcano
  • SSC MTS 2017: Dormant volcano is?
  • Inactive now but may erupt again
  • HSSC JE 2018: Which part of India is most prone to earthquakes?
  • Himalayan Region
  • SSC GD 2019: What is magma?
  • Molten rock beneath Earth's surface
  • RRB Group D 2018: Which belt has the most volcanoes?
  • Ring of Fire
  • SSC JE 2017: What is the point on Earth’s surface above the focus?
  • Epicenter
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