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Describe Phreatic Eruptions and their Consequences. | UPSC geography optional paper 1 2019

Describe Phreatic Eruptions and their Consequences.
(UPSC geography optional paper 1 2019, 10 Marks)
अग्नाशय विस्फोटॊ और उसके परिणामों का वर्णन कीजिए।


The phreatic eruption is one type of volcanic eruption when magma heats up groundwater or surface water or both and vapor is released with intense pressure along with ash, and rock. It may reach up to 7 kilometers high. In phreatic eruption, no new lava erupts.

  • In 2018, Approximately 5500-meter peak columns of steam and ashes formed, after the phreatic eruption of Mount Merapi in Java Island.
  • In 2019, Phreatic eruption of White Island in New Zealand.

The following diagram shows the mechanism of the phreatic eruption.

The consequence of Phreatic eruption:
Since eruption comes without warning and people are unprepared for a sudden eruption, consequences are multidimensional.

  • When water vapor, the dust settled down on earth, it creates an extensive landform with depression called Maars. Later, when water accumulated in the depression zone it becomes a crater lake.
  • When it erupts in the ocean near coastal areas, it generates Tsunami waves and destroys coastal towns and villages.
  • It releases carbon dioxide and hydrogen sulfide into the atmosphere and increases the toxicity in the atmosphere.
  • Evacuation of residents needed, if not evacuated timely that may lead to human loss.
  • Shut down of economic activities such as airport and industrial activities in those regions.
For Explanation, please watch the below videos:

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