An extinct volcano is a volcano that hasn't erupted in 10,000 years. The lava supply of the extinct volcano has run out. An extinct volcano is no longer located near a geologic hotspot that is active. It might be difficult to verify whether a volcano is genuinely extinct. The topic “Extinct Volcanoes” is an important concept in the UPSC Exam's Geography syllabus.

What are Extinct Volcanoes?

• Extinct volcanoes, also known as "dead volcanoes," are volcanoes that are no longer active and have not erupted in historical times, nor do they show any signs of future eruption.
• These volcanoes have essentially ceased all volcanic activity and are considered to be permanently dormant.
• It's important to note that while these volcanoes are classified as "extinct," there is always a small possibility that they could become active again in the distant future, though the likelihood is extremely low.
• Extinct volcanoes have undergone geological processes that have led to the sealing of their magma chambers, effectively preventing the buildup of pressure and magma required for an eruption.
• Over time, erosion, weathering, and other geological forces can alter the appearance of extinct volcanoes, making them look quite different from their active or dormant counterparts.
• Extinct volcanoes have not erupted in tens of thousands of years and are unlikely to do so again.
• The Yellowstone Caldera in Yellowstone National Park, for example, hasn't erupted violently in about 640,000 years, but experts believe it is still active.
  • As recently as 10,000 years ago, there was some modest activity and lava flow.
  • The region also experiences mild earthquakes on a regular basis, and the ground in some parts is rising up, indicating that the volcano is still active.
• Volcanoes that were supposed to be extinct erupted once more.
  • Mount Vesuvius, for instance, famously erupted in AD 79, devastating Herculaneum and Pompeii.
  • In 1995, the volcano on the island of Montserrat, the Soufriere Hills, was reactivated.

Extinct Volcanoes – Features

• Erosion: Extinct volcanoes typically show signs of significant erosion due to weathering, water flow, and other natural processes. Their original volcanic shape may be modified or even obliterated over time.
• Filled Craters: The craters of extinct volcanoes might be partially or completely filled with sediments, vegetation, or water, giving them a different appearance than the open craters of active or dormant volcanoes.
• Lack of Recent Activity: The absence of recent eruptions and seismic activity is a key indicator that a volcano is extinct. The geological record and historical accounts are used to determine if a volcano has been inactive for an extended period.
• Surrounding Landscape: Extinct volcanoes can blend into the surrounding landscape and may be covered with vegetation or have taken on a more subdued appearance over time.

Examples of Extinct Volcanoes

Kyushu-Palau Ridge in the Philippine Sea

• The Philippine Sea's Kyushu-Palau Ridge is a feature on the ocean floor.
• It gets its name from the nearby islands.
• The Pacific island nation of Palau is located from the northern end to the southern end of the Japanese island of Kyushu.
• The seafloor ridges start around 900 kilometers east of the Bungo Channel or Bungo Strait, which connects the Japanese islands of Kyushu and Shikoku.
• The ridge produces a line on the ocean floor that runs southeast toward Palau. Along this line, there is a chain of dormant volcanoes.

Huascarán in Peru

• Huascarán is Peru's highest peak and South America's fourth tallest.
• It stands at a height of 6,768 meters and is found in Peru's Ancash Region.
• For mountain climbers, Huascarán has become a tourist destination.
• It's the only relic of a long-dead volcano.
• It has shrunk through time, with the Ancash Earthquake in 1970 causing a large portion of the mountain to disintegrate and slide away.
• It killed over 17,000 people in little communities around the mountain since that part of the mountain was pure rock and ice.

Mount Buninyong in Australia

• Mount Buninyong is an extinct volcano located 15 kilometers south of Ballarat, Victoria, Australia.
• The Western Victorian Volcanic Plains have a 745-meter volcano.
• The volcano's scoria cone rises almost 200 meters above the surrounding terrain, making it one of Victoria's largest scoria volcanoes.
• There is a large crater in the center of the moon.
• The volcano erupted numerous times, and the volcano's west side was breached during one of the eruptions.
• Lava spilled through this rift in the side during subsequent eruptions. Another crater could have caused the rupture.

Conclusion

While extinct volcanoes do not pose an immediate threat of eruption, studying their geology and history can provide valuable insights into Earth's geological processes, volcanic activity, and the long-term evolution of landscapes.

FAQs

MCQs

1. Which of the following describes an extinct volcano?

A) A volcano that has erupted recently
B) A volcano that is currently erupting
C) A volcano that is unlikely to erupt again
D) A volcano with continuous geothermal activity

2. Which of these is an example of an extinct volcano?

A) Mount Vesuvius
B) Mount Kilimanjaro
C) Mauna Loa
D) Mount Etna

3. What term describes a volcano that may erupt again but is currently inactive?

A) Extinct
B) Dormant
C) Active
D) Caldera

4. Which of the following methods is used to determine if a volcano is extinct?

A) Radiometric dating
B) Temperature measurement
C) Air quality analysis
D) Seismic monitoring

5. Extinct volcanoes are commonly found in which of these regions?

A) Oceanic ridges
B) Mountain ranges
C) Coastal plains
D) Volcanic arcs

GS Mains Questions and Model Answers

Q1: Define the term ‘extinct volcano’ and discuss its significance in understanding Earth’s geological history.

Answer: An extinct volcano is one that has not erupted for thousands of years and shows no signs of future eruption due to a lack of geothermal activity. These volcanoes are significant in understanding Earth’s geological history, as they provide evidence of past tectonic and volcanic activity. Studying extinct volcanoes helps scientists reconstruct ancient landscapes, identify historical tectonic movements, and understand volcanic evolution. By examining rock compositions and volcanic structures, geologists gain insights into the planet’s changing climate, atmosphere, and even past life conditions.

Q2: Explain the process of identifying whether a volcano is extinct, dormant, or active. What tools and techniques are used?

Answer: Identifying whether a volcano is extinct, dormant, or active involves analyzing its eruption history, geothermal activity, and geological context. Radiometric dating determines the age of rock layers from past eruptions, helping establish if a volcano is extinct. Dormant volcanoes are identified by their inactivity but with retained potential to erupt, while active volcanoes show recent eruptions or current seismic activity. Tools like radiometric dating, geothermal monitoring, and seismic equipment help scientists classify volcanoes accurately, assisting in hazard assessment and volcanic research.

Q3: Discuss the environmental impact of extinct volcanoes on the surrounding landscape. How do they contribute to biodiversity and ecosystem development?

Answer: Extinct volcanoes contribute significantly to the environment by influencing soil composition, hydrology, and habitat diversity. Over time, volcanic rocks weather into mineral-rich soils, promoting plant growth and supporting diverse ecosystems. These areas often become rich habitats for flora and fauna, as volcanic soils are fertile. Additionally, extinct volcanic craters can form lakes or wetlands, creating unique ecosystems that support various species. The landscapes around extinct volcanoes thus play a role in enhancing biodiversity and providing niche habitats, contributing to environmental stability and ecosystem services.

Previous Year Questions on Extinct Volcanoes

1. UPSC CSE Prelims 2021:

Question: Which of the following is an example of an extinct volcano?

A) Mount Fuji
B) Mount Vesuvius
C) Mount Kilimanjaro
D) Mount St. Helens

Answer: (C)

Explanation: Mount Kilimanjaro is considered an extinct volcano due to its long period of inactivity and lack of geothermal activity, indicating it is unlikely to erupt again.

2. UPSC CSE Mains 2020 (GS Paper 1):

Question: "Examine the role of extinct volcanoes in shaping geographical features and supporting biodiversity. How do they contribute to ecosystem stability?"

Answer: Extinct volcanoes play a vital role in shaping geographical features by forming unique landscapes, including mountains, craters, and ridges. These formations, over time, develop fertile soils from volcanic rocks, supporting vegetation and biodiversity. Crater lakes in extinct volcanoes create isolated ecosystems that support diverse species, enhancing regional biodiversity. The mineral-rich soils also enable varied plant growth, promoting ecosystem stability. Studying extinct volcanoes provides insights into past geological processes, and their physical presence continues to support environmental resilience and biodiversity.