Rajya Sabha TV: In Depth – India’s Active volcano

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Rajya Sabha TV: In Depth – India’s Active volcano


(TOPICS COVERED:

PRELIMS:  Indian and World Geography – Physical

MAINS: GENERAL STUDIES I – Important Geophysical phenomena such as volcanic activity, geographical features and their location)

 

India’s live volcano in the Andaman and Nicobar islands is reported to be erupting once again in 2018. The eruptions could be linked to the recent earthquake that rocked Indonesia in Southeast Asia. The active volcano in India is Barren Island and is uninhabited, located about 140 km from Port Blair.

 

Diagram of a volcanic eruption.

VOLCANO

  • It is a rupture in the crust of a planetary-mass object (like Earth), that causes hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.
  • On Earth, volcanoes are generally found where tectonic plates (like Eurasian, Pacific, Somali, etc) diverge or converge. Examples- volcanoes occurring in mid-oceanic ridge and Ring of Fire.
  • Eruption of volcanoes can be hazardous for humans and other lives living in its vicinity and volcanic ash may be a threat to aircrafts. Volcanoes can also cause
  • Large volcanic eruptions inject water vapour (H2O), Carbon Dioxide (CO2), Sulphur Dioxide (SO2), ash, etc into the stratosphere to heights of 16-32 km.
  • A volcano is considered to be “active” if it has erupted in the last 10,000 years. Examples – Kilauea (Hawaiian Islands), Mount Etna (Italy), etc.
  • Extinct volcanoes are unlikely to erupt again as the volcano no longer has a magma supply. Examples – Volcanoes on Hawaiian Emperor seamount chain in the Pacific Ocean, Shiprock in New Mexico, etc.

 

  VOLCANIC EXPLOSIVITY INDEX (VEI)

  • It is a relative measure of the explosiveness of volcanic eruptions.
  • It was devised by Chris Newhall of the United States Geological Survey in
  • Explosivity value is determined by volume of products, eruption cloud height, and qualitative observations.
  • The indices of VEI range from VEI 0 (non-explosive eruptions) to VEI 8 (most explosive eruptions recorded).
  • The 1815 eruption of Mount Tambora (in present day Indonesia) had VEI 7. The ash erupted and dispersed around the world and lowered global temperatures. It was called as “Year without a summer” in 1816 that observed extreme weather events and harvest failures in many areas.

 

   BARREN ISLAND (ANDAMAN ISLANDS)

  • Barren Island is located in Andaman Sea, about 140 km from Port Blair.
  • It is a part of Indian Union Territory of Andaman and Nicobar islands.
  • Barren volcano in the region is the only confirmed active volcano in South Asia (along a chain of volcanoes from Sumatra to Myanmar)
  • The oldest subaerial lava flows of the volcano are calculated to be 1.6 million years old.
  • Recent timeline of volcanic eruptions in Barren island:

1787: First recorded eruption

1789, 1795, 1803, 1852: Further eruptions were recorded.

1991: The eruption occurred after about 150 years of dormancy. It lasted for about 6 months and caused considerable damage, particularly to the island’s fauna.

1995: Eruption reported

2004-05: Eruption recorded and linked to 2004 Indian Ocean earthquake.

2017: Volcano was spotted. They were a continuation of eruption in 2005, as per a study by Indian Space Research Organisation (ISRO).

2018: Volcanic eruptions reported and linked to 28 September 2018 earthquakes in Sulawesi, Indonesia.

 

CONCLUSION

         Volcanoes are phenomenon which can cause a lot of damage if it occurs in the vicinity of populations living in the region. Barren islands are quite far away from human habitations, but can disrupt the paths of flights travelling in the region. Volcanoes, Earthquakes, etc are natural phenomenon but early predictions and preparations can reduce the possible hazards.

 

Question (Prelims 2018)

Consider the following statements:

  1. The Barren Island volcano is an active volcano in the Indian Territory.
  2. Barren Island lies about 140 km East of Great Nicobar.
  3. The last time the Barren Island erupted was in 1991 and has remained inactive since then.

Which of the following statements above is/ are correct?

  1. 1 only
  2. 2 and 3
  3. 3 only
  4. 1 and 3