Why In News?

Mayon Volcano in the Philippines had a nearly six-minute “moderately explosive eruption” that sent an ash column 3,000 metres above its crater.

What Is Mayon Volcano?

  • Location: Mayon is an active volcano in Albay province on Luzon Island, Philippines. 

  • Height: It rises to 2,462 m above the Albay Gulf and is the Philippines’ most active volcano.   

  • Perfect Cone: One of the most symmetrical volcanic cones on Earth, with a base about 130 km in circumference and steep upper slopes.  

  • Summit Crater: A circular crater about 250 m across sits at its peak. 

  • Ecological And Economic Value

  • Protected Area: Mayon is the centre of Mayon Volcano Natural Park, and UNESCO designated the Albay area a Biosphere Reserve in 2016.  

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  • Livelihoods: Large abaca (Manila hemp) plantations grow on its fertile lower slopes.  

  • Tourism: Its striking cone attracts climbers, campers and tourists. 

  • Deadliest Eruption: The 1814 eruption killed more than 1,200 people and destroyed several towns.  

Why Is Mayon So Active?

Tectonic Setting

  • Ring Of Fire: Mayon lies on the Pacific Ring of Fire, a horseshoe-shaped belt of volcanoes and earthquakes around the Pacific Ocean.  

  • Subduction Zone: It stands on Luzon’s eastern side near the Philippine Trench, where the Philippine Sea Plate sinks beneath the Philippine Mobile Belt. 

  • Magma Formation: As the sinking plate descends, water released from it lowers the melting point of the mantle above. This creates magma that rises to feed volcanoes. 

 

Stratovolcano Structure

  • Layered Cone: Mayon is a stratovolcano, built of alternating layers of lava and ash.  

  • Viscous Magma: Stratovolcanoes usually have thick, gas-rich andesitic magma, which leads to explosive eruptions and steep slopes.  

About Stratovolcano

A stratovolcano—also called a composite volcano—is a tall, steep, cone-shaped mountain built up over thousands of years by alternating layers of hardened lava, ash, pumice, and tephra.

Key Characteristics & Structure

  • Shape: Gentle slopes near the base that quickly rise into steep, symmetrical profiles toward the summit.  

  • Magma Type: Typically driven by viscous, gas-rich, intermediate-to-felsic magma (such as andesite, dacite, and rhyolite) with high silica content.  

  • Internal Anatomy: Features a central plumbing system with a primary vent near the peak, occasional side vents, lava domes, and sometimes collapsed summit craters called calderas. 

  • Global Presence: They account for roughly 60% of Earth's individual volcanoes and commonly form along subduction zones and the Pacific Ring of Fire.

Why They Are Dangerous?

Because sticky, viscous magma traps gas under high pressure, stratovolcanoes tend to produce violent, explosive eruptions rather than quiet, flowing lava.  

  • Pyroclastic Flows: Fast-moving avalanches of scorching gas and rock fragments that incinerate everything in their path. 

  • Lahars: Rapid, destructive mudflows created when snow, ice, or heavy rain mixes with loose volcanic ash and debris on steep slopes.  

  • Ash Clouds: Widespread ash fallout that disrupts air travel and poses severe health risks. 

Famous Examples

  • Mount Fuji (Japan)

  • Mount St. Helens (United States)

  • Mount Vesuvius (Italy)

  • Mount Rainier (United States)  

Source: NDTV

PRACTICE QUESTION

Q. Consider the following statements:

1. Mayon Volcano lies close to the Philippine Trench, where the Philippine Sea Plate subducts beneath the Philippine Mobile Belt.

2. Stratovolcanoes are generally fed by low-viscosity basaltic magma, which produces gentle, effusive eruptions.

3. Barren Island volcano in India is associated with the subduction of the Indian Plate beneath the Burma Microplate.

How many of the statements given above are correct?

(a) Only one

(b) Only two

(c) All three

(d) None

Answer: (b)

Explanation:

Statement 1 is correct: Mayon Volcano is an active stratovolcano located on Luzon Island in the Philippines. It is geographically associated with the Philippine Trench, where the Philippine Sea Plate subducts westward beneath the Philippine Mobile Belt.

Statement 2 is incorrect: Stratovolcanoes (or composite volcanoes) are typically characterized by high-viscosity andesitic, dacitic, or rhyolitic magma, which traps gases and builds pressure, resulting in highly explosive eruptions. In contrast, low-viscosity basaltic magma is characteristic of shield volcanoes, which exhibit gentle, effusive eruptions.  

Statement 3 is correct: Barren Island, South Asia's only active volcano located in the Andaman Sea, is formed along a convergent plate boundary where the Indian Plate subducts beneath the Burma Microplate (a part of the Eurasian Plate).