Global Geological And Climatic Events

Sundhnuksgigar Volcano erupts in Iceland


From UPSC perspective, the following things are important :

Prelims level: Frequent Volcanic eruptions this year, Sundhnuksgigar and other Volcanoes Why in the News?

Why in the News?

Southwest Iceland witnessed the eruption of the Sundhnuksgigar volcano, triggering evacuations in the nearby areas.

About Sundhnuksgigar Volcano 

  • Sundhnuksgigar is a row of craters just outside the town of Grindavik on the Reykjanes peninsula
  • It is situated on the Mid-Atlantic Ridge, a divergent boundary where the Eurasian and North American tectonic plates are moving apart.

What is a Volcano?

  • A volcano is a fissure or vent in the Earth’s crust through which gases, molten rock materials (lava), ash, steam, sulphur dioxide etc., are expelled during an eruption.
  • These openings occur where the rock layers in the Earth’s crust are relatively weak.
  • Volcanic activity is categorized as an endogenic process, originating from within the Earth.
  • Depending on the explosivity of the volcano, various extrusive and intrusive landforms can be formed.

Different types of volcanoes can be classified based on the frequency of eruption and the nature of the eruption:

1.   Frequency of eruption:

  • Active volcanoes: Frequent eruptions in Pacific Ring of Fire: New Zealand, Southeast Asia, Japan, western Americas. Linked to plate tectonics, like Kilauea and Santa Maria. High seismicity, volcanic activity.
  • Dormant Volcanoes: These are not currently erupting but have the potential to erupt again in the future. An example is Mount Kilimanjaro in Tanzania, the highest mountain in Africa.
  • Extinct or inactive volcanoes: These have not erupted in the distant geological past. Dhinodhar Hill in Gujarat is an example.

2.   Nature of Eruption:

  • Shield Volcanoes: Largest and least explosive volcanoes, formed from basalt lava. Often low in explosivity, except when water interacts. Hawaiian volcanoes exemplify this..
  • Composite Volcanoes: Volcanoes with cooler, thicker lava, built up through explosive eruptions. Layer ash, pyroclastic material, and lava flow. Examples: Mayon, Fuji, Rainier.
  • Calderas: The most explosive volcanoes, prone to collapsing inward during eruptions rather than building upwards. The resulting depressions are called calderas.
  • Flood Basalt Provinces: These volcanoes erupt highly fluid lava that travels long distances, covering vast areas with thick basalt flows.

Reasons for Iceland’s Volcanism

  • Tectonic Activity: Iceland is situated on the Mid-Atlantic Ridge, where the Eurasian and North American plates diverge. This creates volcanic rift zones where magma rises to the surface, leading to eruptions.
  • Hotspots: Additionally, Iceland is positioned over a hotspot, contributing to heightened volcanic activity. Hotspots are areas where magma from the mantle rises towards the surface, fueling eruptions.
  • Subglacial Volcanism: Iceland’s volcanic activity is not limited to the surface; some eruptions occur beneath glaciers, leading to explosive interactions between lava and ice. These subglacial eruptions can produce powerful steam explosions, ash clouds, and catastrophic floods known as jokulhlaup.


[2021] Mention the global occurrence of volcanic eruptions in 2021 and their impact on the regional environment.

[2013] Consider the following:

  1. Electromagnetic radiation
  2. Geothermal energy
  3. Gravitational force
  4. Plate movements
  5. Rotation of the earth
  6. Revolution of the earth

Which of the above are responsible for bringing dynamic changes on the surface of the earth?

(a) 1, 2, 3 and 4 only

(b) 1, 3, 5 and 6 only

(c) 2, 4, 5 and 6 only

(d) 1, 2, 3, 4, 5 and 6

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