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In the following part of the article, the definition of volcanoes with key facts, different stages, types and major volcanoes in India is provided with the detailed latest information.

What are Volcanoes?

Volcanoes are explained as landforms, or mountains, where molten rocks appear from the surface of the planet. The volcano mountain opens under the pool of molten rocks inside the earth’s surface.

• A volcano is referred to as a vent or fissure in the crust of the earth from where lava, ash, rocks, and gases come out.
• Active volcanoes are those categories of a volcano that appear in the recent past.
• Mantle volcanoes include a weaker zone which is being referred to as the asthenosphere.

• Magma is the material present in the asthenosphere.
• Material that flows to or reaches the ground includes different materials like lava flows, pyroclastic debris, dust, ash, volcanic bombs, among other gases. Sulfur compounds, nitrogen compounds, and some traces of argon, hydrogen, and chlorine are the kind of gases present in these volcanoes.

Volcanoes: Key Facts

• Volcanoes are formed due to eruptions of lava and ash.
• The appearance of volcanoes is mostly cone-shaped mountains or hills.
• Magma on reaching the Earth's surface is referred to as lava. On cooling down on lava, it results in the formation of rock.
• Volcanic eruptions mostly occur at destructive and constructive borders, but not at conservative boundaries.
• There are a few volcanoes that occur inside water, along the seabed or ocean floor.

Different Stages of Volcanoes

• Volcanoes appear in a variety of forms, based upon the nature of the material erupted, the kind of eruption, the kind of change since these volcanoes occurred.
• Mainly volcanoes are divided into three main categories including:
• Active Volcanoes: A volcano will be categorized as an active volcano if at a particular time it is likely to erupt or is erupting already.
• Dormant Volcanoes: The classification of volcanoes that is being referred to as dormant are those volcanoes that are not likely to erupt soon.
• Extinct Volcanoes: Extinct volcanoes are those volcanoes whose eruption is not expected by anyone. No one has any idea about the occurrence of these volcanoes

Reasons for Volcano Formation

The occurrence of a volcano is mainly due to the formation of magma in the lower section of the earth’s crust. The earth’s crust includes massive slabs named as plates that all fit together like a jigsaw puzzle.

The friction that happens due to the movement of plates results in earthquakes and volcanic eruptions. The tremendous pressure results in putting much force on these solid rocks and other materials, resulting in creating a new passage to the surface of the Earth. When the magma reaches the air, it’s being referred to as lava.

Types of Volcanoes

Volcanoes are segmented as per the style of eruption and the form which is created on the earth’s surface.

Shield Volcanoes

• These kinds of volcanoes are the largest of other volcanoes that are presently active on the surface of the Earth.
• These kinds of volcanoes are made up of basalt.
• They will become explosive in case water goes inside the vent. Else these volcanoes are being characterized by low explosivity.
• The lava that moves upside down does so in a fountain form and emanates the cone at the vent’s top before developing into a cinder cone.

Composite Volcanoes

• Composite Volcanoes occur due to the outbreaks of cooler and more viscous lavas than basalt.
• The occurrence of these volcanoes is mainly explosive eruptions.
• A huge amount of pyroclastic material and ashes easily gets wiped away with lava.
• The material is collected near the vent openings which in turn results in the creation of layers.
• Mayon Volcano, Philippines; Mount Fuji, Japan, etc. are the major composite volcanoes in the world that erupted in the past.

Caldera

• Calderas are considered as the most explosive volcanoes that exist on this planet.
• These volcanoes are mostly explosive.
• On eruption, they are likely to collapse on themselves instead of creating a structure.
• The collapsed depressions are known as calderas.

Flood Basalt Provinces

• Flood Basalt Province volcanoes discharge fluid lava that easily travels long distances.
• Many regions across the globe are covered by thick basalt lava flows.

Mid-Ocean Ridge Volcanoes

• These kinds of volcanoes mostly erupt in the oceanic areas.
• There exists a system of mid-ocean ridges that stretches to more than 70000 kilometres across the ocean basins.
• The central region of this ridge registers the maximum eruptions regularly.

Major Volcanoes in India

So we can say that an opening in the earth’s crust allowing hot molten lava, ash, and gases to escape from under the surface, is being referred to as a volcano. Lava is the molten rock or magma that appears out from the magma chamber via a vent that is present in the middle of a volcanic mountain.

FAQs

MCQs

1. Which type of volcano is known for having broad, gentle slopes?

A) Stratovolcano
B) Shield Volcano
C) Cinder Cone
D) Lava Dome

2. The "Ring of Fire" is associated with:

A) Tornadoes
B) Earthquakes
C) Volcanic activity
D) Hurricanes

3. Which type of lava is associated with explosive volcanic eruptions?

A) Basaltic
B) Andesitic
C) Rhyolitic
D) Ultrabasic

4. The main cause of volcano formation is:

A) Atmospheric pressure
B) Ocean currents
C) Magma movement
D) Wind direction

5. Which of the following is NOT a type of volcano?

A) Shield
B) Stratovolcano
C) Lava Dome
D) Rift Valley

GS Mains Questions and Model Answers

Q1: Explain the process of volcanic eruption and describe the main types of volcanoes.

Answer: Volcanic eruptions occur when magma rises through Earth’s crust due to pressure buildup. Types include shield (broad, low profile), stratovolcano (steep and explosive), cinder cone (small and cone-shaped), and lava dome (viscous lava piles). Eruptions are influenced by magma composition and tectonic setting, creating diverse landforms and volcanic activity patterns.

Q2: Discuss the environmental impacts of volcanic eruptions. How do they affect climate and human life?

Answer: Volcanic eruptions release ash and gases, influencing air quality and contributing to climate cooling by injecting aerosols. Large eruptions, like Tambora in 1815, have caused global temperature drops. Locally, eruptions affect agriculture, health, and infrastructure, with fertile soils benefiting farming over time. Environmental impacts vary with eruption size and location.

Q3: Describe the distribution of major volcanoes worldwide and the tectonic settings associated with their formation.

Answer: Volcanoes are often located along tectonic plate boundaries, especially in the Pacific Ring of Fire. Divergent boundaries, like the Mid-Atlantic Ridge, and convergent boundaries, like the Andes, also host active volcanoes. Hotspot volcanism, seen in Hawaii, forms within tectonic plates due to mantle plumes, demonstrating diverse tectonic origins.

Previous Year Questions on Volcanoes

1. UPSC CSE Prelims 2021:

Question: Which of the following regions is known as the “Ring of Fire”?

A) Atlantic Ocean
B) Indian Ocean
C) Pacific Ocean
D) Arctic Ocean

Answer: (C)

Explanation: The Pacific Ring of Fire is a zone of active volcanoes and seismic activity along the Pacific Ocean’s tectonic boundaries.

2. UPSC CSE Mains 2019 (GS Paper 1):

Question: "Analyze the environmental and economic impacts of volcanic eruptions with examples."

Answer: Volcanic eruptions impact the environment by emitting ash and gases that affect climate. Economically, eruptions damage infrastructure but provide fertile soils for agriculture, as seen around Mount Vesuvius. The economic and environmental effects vary based on eruption magnitude and proximity to populated areas.

It is connected to a pool of lava under the surface of the earth. With time, the lava and ash come out of the magma chamber, cool down, harden and later collect in layers to form a Volcano.