Special Topic – UPSC Geography Synopsis
UPSC Prelims Geography Revision | Page 2
Earthquakes and Volcanoes
Earthquakes and volcanoes are important internal forces that continuously shape the Earth’s surface. These topics are highly important for UPSC and other competitive exams.
Earthquakes
An earthquake is the sudden shaking of the Earth’s crust caused by the release of energy inside the Earth.
Important Terms
- Focus – Point inside the Earth where earthquake originates
- Epicenter – Point on the Earth’s surface directly above the focus
- Seismic Waves – Energy waves produced during earthquakes
Types of Seismic Waves
- P-Waves (Primary Waves)
- S-Waves (Secondary Waves)
- Surface Waves
P-Waves
P-Waves travel fastest and can move through solids, liquids and gases.
S-Waves
S-Waves travel only through solids. They are more destructive than P-Waves.
Causes of Earthquakes
- Tectonic plate movements
- Volcanic activity
- Landslides
- Human activities
Most earthquakes occur near tectonic plate boundaries.
Earthquake Measurement
- Richter Scale – Measures magnitude
- Mercalli Scale – Measures intensity
- Seismograph – Instrument used to record earthquakes
Volcanoes
A volcano is an opening in the Earth’s crust through which lava, ash and gases erupt.
Important Components
- Magma Chamber
- Vent
- Crater
- Lava
Types of Volcanoes
- Active Volcanoes
- Dormant Volcanoes
- Extinct Volcanoes
Active Volcanoes
These volcanoes erupt frequently. Example: Mount Etna.
Dormant Volcanoes
Dormant volcanoes remain inactive for long periods but may erupt again.
Extinct Volcanoes
These volcanoes are not expected to erupt again.
Major Volcanoes of the World
- Mount Fuji – Japan
- Mount Etna – Italy
- Krakatoa – Indonesia
- Mauna Loa – Hawaii
Rocks
Rocks are naturally occurring solid masses that form the Earth’s crust.
Types of Rocks
- Igneous Rocks
- Sedimentary Rocks
- Metamorphic Rocks
Igneous Rocks
Formed from cooling and solidification of magma. Example: Granite.
Sedimentary Rocks
Formed by deposition of sediments. Example: Sandstone.
Metamorphic Rocks
Formed due to heat and pressure. Example: Marble.
Soils
Soil is the uppermost layer of the Earth that supports plant growth.
Major Soil Types in India
- Alluvial Soil
- Black Soil
- Red Soil
- Laterite Soil
- Mountain Soil
Black Soil
Black soil is ideal for cotton cultivation. It is also known as Regur soil.
Monsoon System
Monsoon refers to seasonal reversal of winds. India receives most of its rainfall from monsoon winds.
Types of Monsoon
- Southwest Monsoon
- Northeast Monsoon
The Southwest Monsoon is the main rainy season in India.
Important UPSC Facts
- P-Waves travel through liquids and solids
- S-Waves cannot travel through liquids
- Ring of Fire is a volcanic belt around the Pacific Ocean
- Black soil is suitable for cotton
- Monsoon is vital for Indian agriculture
Quick Revision Box
- Focus → Origin point of earthquake
- Epicenter → Surface point above focus
- Volcano → Opening in Earth’s crust
- Igneous Rocks → Formed from magma
- Black Soil → Cotton cultivation
- Southwest Monsoon → Main rainy season
Mind Map – Earth Processes
-
Earth Processes
- Earthquakes
- Volcanoes
- Rocks
- Soils
- Monsoon
Shaktimatha Learning
UPSC Geography Synopsis – English Version
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