Volcanism

1. What is Volcanism?

• Volcanism refers to the process of magma (molten rock) rising from deep within the Earth and erupting onto the surface as lava, ash, and gases.
• It is a natural phenomenon that shapes the Earth’s surface and is closely related to plate tectonics.

2. Causes of Volcanism

• Heat and Pressure Inside Earth: The Earth’s interior is extremely hot, and this heat causes rocks to melt, forming magma.
• Plate Tectonics: Most volcanoes occur at tectonic plate boundaries:
  • Divergent Boundaries: Plates move apart, allowing magma to rise (e.g., Mid-Atlantic Ridge).
  • Convergent Boundaries: Plates collide, and one plate is forced beneath another, melting to form magma (e.g., Ring of Fire).
  • Hotspots: Areas where magma rises from deep within the mantle, unrelated to plate boundaries (e.g., Hawaiian Islands).

3. Types of Volcanoes

• Based on Activity:
  • Active: Erupting or likely to erupt (e.g., Mount Etna, Italy).
  • Dormant: Not currently active but may erupt in the future.
  • Extinct: No longer capable of erupting.
• Based on Shape:
  • Shield Volcanoes: Broad, gently sloping (e.g., Mauna Loa, Hawaii).
  • Composite Volcanoes: Steep, conical (e.g., Mount Fuji, Japan).
  • Cinder Cone Volcanoes: Small, steep-sided (e.g., Paricutin, Mexico).

4. Volcanic Eruptions

• Explosive Eruptions: Violent eruptions with ash, gases, and pyroclastic flows (e.g., Mount St. Helens).
• Effusive Eruptions: Gentle lava flows (e.g., Hawaiian volcanoes).
• Materials Ejected:
  • Lava: Molten rock on the surface.
  • Ash: Fine particles of rock and glass.
  • Gases: Water vapor, carbon dioxide, sulfur dioxide.

5. Volcanic Landforms

• Craters: Bowl-shaped depressions at the top of a volcano.
• Calderas: Large, basin-like depressions formed after a massive eruption.
• Lava Plateaus: Flat, elevated landforms created by successive lava flows (e.g., Deccan Traps, India).
• Volcanic Mountains: Formed by the accumulation of erupted materials.

6. Global Distribution of Volcanoes

• Ring of Fire: A major area in the Pacific Ocean with frequent volcanic activity (e.g., Japan, Indonesia, Philippines).
• Mid-Atlantic Ridge: Underwater volcanic activity where plates diverge.
• Hotspots: Isolated volcanic regions (e.g., Hawaii, Yellowstone).

7. Impact of Volcanism

• Positive Effects:
  • Fertile soil for agriculture (e.g., Java, Indonesia).
  • Geothermal energy production (e.g., Iceland).
  • Formation of new land (e.g., Hawaiian Islands).
• Negative Effects:
  • Destruction of life and property.
  • Climate change due to ash and gases blocking sunlight.
  • Air travel disruptions (e.g., 2010 Eyjafjallajökull eruption in Iceland).

8. Volcanism in India

• Deccan Traps: One of the largest volcanic features in the world, formed by massive lava flows 65 million years ago.
• Barren Island: India’s only active volcano, located in the Andaman and Nicobar Islands.

Details about Types of Volcano

1.Shield Volcanoes

• Description:
  • Broad, gently sloping volcanoes formed by the eruption of low-viscosity (runny) basaltic lava.
  • The lava flows easily and spreads over large areas, creating a shield-like shape.
• Landforms:
  • Wide, flat domes with shallow slopes.
  • Often have a central crater or multiple vents.
• Examples:
  • Mauna Loa, Hawaii: The largest active shield volcano on Earth.
  • Kilauea, Hawaii: Known for its frequent and gentle eruptions.

2. Composite Volcanoes (Stratovolcanoes)

• Description:
  • Tall, steep, conical volcanoes formed by alternating layers of lava, ash, and volcanic debris.
  • Eruptions are explosive due to high-viscosity (thick) magma, which traps gases.
• Landforms:
  • Symmetrical cones with steep slopes.
  • Often have a crater at the summit and secondary vents on the sides.
• Examples:
  • Mount Fuji, Japan: A classic example of a composite volcano.
  • Mount St. Helens, USA: Known for its catastrophic 1980 eruption.

3. Cinder Cone Volcanoes

• Description:
  • Small, steep-sided volcanoes formed by the accumulation of volcanic cinders (small fragments of lava) ejected during explosive eruptions.
  • Usually short-lived and form quickly.
• Landforms:
  • Cone-shaped hills with a bowl-shaped crater at the top.
  • Often found on the flanks of larger volcanoes.
• Examples:
  • Paricutin, Mexico: A famous cinder cone that suddenly formed in a farmer’s field in 1943.
  • Sunset Crater, USA: Located in Arizona, it is a well-preserved cinder cone.

4. Calderas

• Description:
  • Large, basin-shaped depressions formed when a volcano collapses into its magma chamber after a massive eruption.
  • Often associated with explosive eruptions that empty the magma chamber.
• Landforms:
  • Circular or oval-shaped depressions, sometimes filled with water to form lakes.
  • Can be several kilometers wide.
• Examples:
  • Yellowstone Caldera, USA: A supervolcano with a massive caldera.
  • Crater Lake, USA: Formed by the collapse of Mount Mazama.

5. Lava Plateaus

• Description:
  • Extensive, flat landforms created by successive eruptions of highly fluid lava that spreads over large areas.
  • The lava cools and solidifies to form thick, horizontal layers.
• Landforms:
  • Flat or gently rolling terrain.
  • Often dissected by rivers and erosion over time.
• Examples:
  • Deccan Traps, India: One of the largest volcanic features in the world, formed by massive lava flows 65 million years ago.
  • Columbia River Plateau, USA: Formed by ancient lava flows.

6. Fissure Volcanoes

• Description:
  • Volcanoes that erupt from long cracks or fissures in the Earth’s crust, rather than a central vent.
  • Typically produce large volumes of lava that spread over wide areas.
• Landforms:
  • Flat, extensive lava plains.
  • Lack a prominent central cone.
• Examples:
  • Laki Fissure, Iceland: Erupted in 1783, producing one of the largest lava flows in history.
  • Deccan Traps, India: Also formed by fissure eruptions.

7. Submarine Volcanoes

• Description:
  • Volcanoes located underwater, often along mid-ocean ridges or hotspots.
  • Eruptions can create new islands or seamounts.
• Landforms:
  • Seamounts (underwater mountains) and volcanic islands.
  • Pillow lava formations (rounded lava shapes formed underwater).
• Examples:
  • Loihi Seamount, Hawaii: An active submarine volcano that may become an island in the future.
  • Surtsey, Iceland: An island formed by a submarine eruption in 1963.

8. Hotspot Volcanoes

• Description:
  • Volcanoes formed by plumes of hot magma rising from deep within the mantle, independent of plate boundaries.
  • As the tectonic plate moves over the hotspot, a chain of volcanoes forms.
• Landforms:
  • Volcanic islands or mountain chains.
  • Often have shield volcano characteristics.
• Examples:
  • Hawaiian Islands: Formed by the Pacific Plate moving over a hotspot.
  • Yellowstone, USA: A hotspot beneath the North American Plate.

Interesting Trivia about Volcano

1. the Pacific Ring of Fire

 Location: Surrounds the Pacific Ocean, covering countries like the U.S. (Alaska, California), Japan, Indonesia, Philippines, Chile, etc.
Length: Approximately 40,000 km (largest tectonic activity zone).
Volcanoes: Home to 75% of the world’s active volcanoes (~450 volcanoes)

Major Volcanoes in the Ring of Fire

Mount St. Helens (USA) – 1980 eruption was one of the most powerful in recent history.
Mount Fuji (Japan) – An iconic stratovolcano.
Krakatoa (Indonesia) – 1883 eruption caused global climatic effects.
Mount Pinatubo (Philippines) – 1991 eruption caused significant global cooling.
Mauna Loa & Kilauea (Hawaii, USA) – Active shield volcanoes.

UPSC Prelims Previous Year Questions (PYQs) Related to Ring of Fire

Q1 (2018): Which of the following is NOT a part of the Pacific Ring of Fire?
a) Japan
b) Indonesia
c) Brazil
d) Chile
Answer: c) Brazil (not on the Pacific Plate).

Q2 (2015): The Ring of Fire is associated with which geological feature?
a) Tropical cyclones
b) Volcanic eruptions and earthquakes
c) Desertification
d) Glacial movements
Answer: b) Volcanic eruptions and earthquakes.

Q3 (2022): The 2004 Indian Ocean Tsunami was caused by an earthquake along which tectonic boundary?
a) San Andreas Fault
b) Sunda Megathrust
c) Mid-Atlantic Ridge
d) East African Rift
Answer: b) Sunda Megathrust (part of the Ring of Fire).

Current affairs related to UPSC CSE

1. Kīlauea Volcano, Hawaii, USA

• Eruption Period: December 2024 – January 2025
• Details: Kīlauea, one of the world’s most active volcanoes, began erupting on December 23, 2024, within Halemaʻumaʻu crater. The eruption featured lava fountains reaching up to 295 feet and extensive lava flows covering parts of the crater floor. Activity continued into January 2025, with both the north and south vents actively emitting lava.

UPSC prelims PYQ

1. UPSC CSE Prelims 2018

Consider the following statements:

1. The Barren Island volcano is an active volcano located in the Indian Territory.
2. Barren Island lies about 140 km east of Great Nicobar.
3. The last time the Barren Island volcano erupted was in 1991 and it has remained inactive since then.

Which of the statements given above is/are correct?

a) 1 only

b) 2 and 3 only

c) 3 only

d) 1 and 3 only

Answer: a) 1 only

Explanation:

• Statement 1: Correct. The Barren Island volcano is the only active volcano in Indian territory, located in the Andaman Sea.
• Statement 2: Incorrect. Barren Island is located about 140 km northeast of Port Blair, not east of Great Nicobar.
• Statement 3: Incorrect. The Barren Island volcano has had multiple eruptions since 1991, with notable activity in 1994-95, 2005-06, and as recently as 2017.

Therefore, only statement 1 is correct.

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2. UPSC CSE Prelims 2013

Consider the following:

1. Electromagnetic radiation
2. Geothermal energy
3. Gravitational force
4. Plate movements
5. Rotation of the earth
6. Revolution of the earth

Which of the above are responsible for bringing dynamic changes on the surface of the earth?

a) 1, 2, 3, and 4 only

b) 1, 3, 5, and 6 only

c) 2, 4, 5, and 6 only

d) 1, 2, 3, 4, 5, and 6

Answer: d) 1, 2, 3, 4, 5, and 6

Explanation:

• Electromagnetic radiation: Drives weather and climate patterns, influencing erosion and sedimentation.
• Geothermal energy: Causes volcanic activity and geothermal phenomena, altering the Earth’s surface.
• Gravitational force: Influences tides and mass movements like landslides.
• Plate movements: Lead to earthquakes, mountain building, and volcanism.
• Rotation of the earth: Affects atmospheric and oceanic circulation patterns, impacting erosion and deposition.
• Revolution of the earth: Contributes to seasonal changes, affecting weathering and erosion processes.

All these factors contribute to dynamic changes on the Earth’s surface.

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3. UPSC CSE Prelims 2013

Which of the following adds/add carbon dioxide to the carbon cycle on the planet Earth?

1. Volcanic action
2. Respiration
3. Photosynthesis
4. Decay of organic matter

Select the correct answer using the code given below:

a) 1 and 3 only

b) 2 only

c) 1, 2, and 4 only

d) 1, 2, 3, and 4

Answer: c) 1, 2, and 4 only

Explanation:

• Volcanic action: Releases carbon dioxide (CO₂) into the atmosphere during eruptions.
• Respiration: Organisms release CO₂ as a byproduct of metabolic processes.
• Photosynthesis: Plants absorb CO₂ to produce oxygen and glucose; thus, it removes CO₂ from the atmosphere.
• Decay of organic matter: Decomposition processes release CO₂ back into the atmosphere.

Therefore, statements 1, 2, and 4 add CO₂ to the carbon cycle, while statement 3 removes it.

1. UPSC CSE Mains 2021 (GS Paper 1)

Q: Discuss about the vulnerability of India to earthquake-related hazards. Give examples including the salient features of major disaster-prone regions.

2. UPSC CSE Mains 2013 (GS Paper 1)

Q: Bring out the causes for more frequent landslides in the Himalayas than in the Western Ghats.

3. UPSC CSE Mains 2011 (GS Paper 1)

Q: What do you understand by the theory of “Plate Tectonics”? Discuss the prominent geological processes which are caused by plate movements.

4. UPSC CSE Mains 2010 (GS Paper 1)

Q: What are the important types of landforms created by volcanism? Discuss with examples.

MCQ on Volcanism

1. Consider the following statements regarding volcanic eruptions:

1. Explosive eruptions are usually associated with low-viscosity magma.
2. Effusive eruptions produce gentle lava flows and are common in shield volcanoes.
3. Pyroclastic flows are associated with effusive eruptions.

Which of the statements given above is/are correct?
(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 2 and 3 only

Explanation: Statement 1 is incorrect—explosive eruptions are associated with high-viscosity magma. Statement 2 is correct—shield volcanoes typically have effusive eruptions. Statement 3 is incorrect—pyroclastic flows occur in explosive eruptions.

2. With reference to the Ring of Fire, consider the following statements:

1. It is the world’s largest zone of tectonic activity.
2. It is associated with both volcanic eruptions and earthquakes.
3. It is formed due to hotspot volcanism.

Which of the statements given above is/are correct?
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2, and 3

Explanation: Statement 1 and 2 are correct—Ring of Fire is the largest tectonic activity zone and experiences volcanic eruptions and earthquakes. Statement 3 is incorrect—it is formed by subduction zones, not hotspots.

3. Consider the following volcanic landforms:

1. Columbia River Plateau
2. Yellowstone Caldera
3. Hawaiian Islands
4. Deccan Traps

Which of the above were formed due to fissure eruptions?
(a) 1 and 4 only
(b) 2 and 3 only
(c) 1, 2, and 3 only
(d) 1, 3, and 4 only

Explanation: Fissure eruptions produce lava plateaus, such as the Columbia River Plateau and Deccan Traps. Yellowstone is a caldera formed by a supervolcano, and Hawaiian Islands were formed by hotspot volcanism.

4. Which of the following statements is/are correct regarding shield volcanoes?

1. They are formed by highly viscous lava that cools quickly.
2. They have broad, gently sloping sides.
3. Mauna Loa and Kilauea are examples of shield volcanoes.

Select the correct answer using the codes given below:
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2, and 3

Explanation: Statement 1 is incorrect—shield volcanoes have low-viscosity lava that spreads widely. Statements 2 and 3 are correct—they have broad, gentle slopes and Mauna Loa & Kilauea are examples.

5. Consider the following statements regarding hotspot volcanoes:

1. They are found only in oceanic regions.
2. They are formed due to mantle plumes and are not associated with plate boundaries.
3. The Hawaiian Islands are an example of hotspot volcanism.

Which of the statements given above is/are correct?
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2, and 3

Explanation: Statement 1 is incorrect—hotspot volcanoes can form in both oceanic and continental regions (e.g., Hawaii and Yellowstone). Statements 2 and 3 are correct.

6. Consider the following statements about cinder cone volcanoes:

1. They are the largest type of volcanoes by size.
2. They have steep sides and a bowl-shaped crater at the summit.
3. Paricutin in Mexico is an example of a cinder cone volcano.

Which of the statements given above is/are correct?
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2, and 3

Explanation: Statement 1 is incorrect—cinder cone volcanoes are the smallest type. Statements 2 and 3 are correct.

7. Which of the following is/are correctly matched?

Type of Volcano	Example
1. Composite Volcano	Mount Fuji
2. Shield Volcano	Deccan Traps
3. Calderas	Yellowstone

Select the correct answer using the codes given below:
(a) 1 and 2 only
(b) 1 and 3 only
(c) 2 and 3 only
(d) 1, 2, and 3

Explanation: Statement 2 is incorrect—Deccan Traps were formed by fissure eruptions, not a shield volcano. Statements 1 and 3 are correct.

8. Which of the following volcanic materials can have a significant impact on global climate?

1. Lava
2. Ash
3. Sulfur dioxide gas

Select the correct answer using the codes given below:
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2, and 3

Explanation: Lava has little effect on climate, while ash and sulfur dioxide can cause global cooling by blocking sunlight.

9. Consider the following statements regarding Deccan Traps:

1. It was formed due to massive volcanic eruptions during the Mesozoic Era.
2. It is one of the largest volcanic features in the world.
3. It is an example of a lava plateau.

Which of the statements given above is/are correct?
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2, and 3

Explanation: Statement 1 is incorrect—Deccan Traps formed during the Cretaceous-Paleogene (end of Mesozoic Era, around 65 million years ago). Statements 2 and 3 are correct.

10. Consider the following pairs:

Volcano	Type
1. Krakatoa	Shield Volcano
2. Mount St. Helens	Composite Volcano
3. Mauna Loa	Shield Volcano

Which of the pairs given above is/are correctly matched?
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2, and 3

Explanation: Pair 1 is incorrect—Krakatoa is a composite volcano, not a shield volcano. Pairs 2 and 3 are correct.

11. Consider the following statements regarding submarine volcanoes:

1. They are found only at mid-ocean ridges.
2. They can lead to the formation of volcanic islands.
3. Pillow lava formations are characteristic of submarine volcanoes.

Which of the statements given above is/are correct?
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2, and 3

Explanation: Statement 1 is incorrect—submarine volcanoes can also occur at hotspots, not just at mid-ocean ridges. Statements 2 and 3 are correct.

12. Which of the following volcanoes is NOT located in the Pacific Ring of Fire?

(a) Mount Fuji
(b) Mount St. Helens
(c) Mauna Loa
(d) Mount Kilimanjaro

Explanation: Mount Kilimanjaro (Africa) is not in the Ring of Fire, while the other three are.