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PC: BBC

Context:

Japan's Sakurajima volcano recently erupted, spewing a gigantic ash plume 3,000 meters above the crater.

About Sakurajima Volcano

What is a Volcano?

A volcano is an opening or rupture in Earth's surface that releases hot liquid and semi-liquid rocks, ash, and gases as magma.

Cause of Magma Rise

• Magma is ejected when Earth's tectonic plates converge. The void fills with magma. When this happens, volcanic production can occur underwater.
• Magma rises when tectonic plates move toward each other because high temperatures and pressure melt the crust and generate magma.
• Magma finally rises above the hotspot. Earth has hot places. These areas heat up the magma. This magma rises when less dense. 
• Magma uplift can generate volcanoes for various reasons.

What is a StratoVolcano?

A stratovolcano, also known as a composite volcano, is a tall, conical volcano built up by many layers (strata) of hardened lava, tephra, pumice, and volcanic ash. These volcanoes typically have steep profiles and periodic, explosive eruptions.

Key features of a stratovolcano:

• Shape: Steep, symmetrical cone
  
  
• Composition: Alternating layers of lava flows, volcanic ash, and other volcanic debris
  
  
• Eruption style: Often explosive, producing pyroclastic flows and ash clouds

Source: ndtv.com