Iceland Volcano Eruption: What Are Volcanoes And Why Is The Island So Volcanically Active?

Relevance: GS1 - Important Geophysical phenomena such as earthquakes, Tsunami, Volcanic activity, cyclone etc.

(Source: Indian Express, 12/22/2023)

Click here for Daily Current Affairs

Why in the news?

Recently, the Fagradalsfjall volcano located on the Reykjanes peninsula in southwest Iceland erupted on 18th December 2023 following weeks of tremors and earthquakes.

What are volcanoes?

• The US Geological Survey has described volcanoes as openings or vents where lava, tephra (small rocks), and steam erupt onto the Earth’s surface.
• Formation: The eruption of material significantly hotter than its surroundings onto the surface of the earth results in volcanoes.
  • The erupted material may be liquid rock, which is known as magma when underground, and lava following its eruption, ash, or gases.

Magma rises in three different ways:

1. When tectonic plates move away from each other, the magma rises to fill in the space. This can lead to the formation of underwater volcanoes.
2. Tectonic plates are massive, irregularly shaped slabs of solid rock that are constantly in motion.
3. When tectonic plates move towards each other, a part of the earth’s crust is pushed into the interior of the earth where it is subjected to high heat and pressure leading to it rising as magma.
4. When magma becomes warmer, it becomes less dense allowing it to rise at hotspots which are areas where magma heats up.
5. Volcanic activity is an endogenic process that can lead to the formation of various landforms such as plateaus and mountains.

What are the different kinds of volcanoes?

• The British Geological Survey classifies volcanoes based on:
  • Viscosity of the magma i.e. its resistance to flow
  • Amount of gas in the magma
  • Composition of the magma
  • Way magma reaches the surface

Stratovolcano

• They have steep sides and a more conical shape.
• It is formed from viscous lava which does not flow easily, allowing it to build up around the vent forming a volcano with steep sides.
  • Large quantities of pyroclastic materials and ashes are released alongside the lava.
• They are more likely to be explosive due to the build-up of gases in the magma.
• They are also known as composite volcanoes.
• Examples: Mount Vesuvius, Mount Tambora, Krakatoa, Mount Pinatubo

Shield volcano

• They are the largest kind of volcanoes since the lava flows to a far distance.
• They are less steep and are similar to a shield lying on the ground.
• They consist almost entirely of frozen lavas and are mostly made up of basalt.
  • Since basalt is less viscous, these volcanoes are less steep and extend to a great height and distance.
• They are generally less explosive but can be explosive if water enters the vent.
• The upcoming lava moves in the form of a fountain throws out the cone at the top of the vent and develops into a cinder cone
• Example: Hawaiian volcanoes like Mauna Loa

Caldera

• When a very large, explosive eruption occurs that empties the magma chamber beneath a volcano, the roof of the chamber can collapse to form a depression or bowl with very steep walls on the surface, called caldera.
• They are also formed following eruptions that remove the summit of a single stratovolcano.
• The caldera can be transformed into a caldera lake when filled with rainwater or snow melt.

Other volcanic features include those that can form from the erupted magma such as cinder cones or lava domes.

Cinder cones

• Cinders are extrusive igneous rocks, also known as Scoria.
• They are small volcanoes that consist almost entirely of loose pyroclastic fragments, such as volcanic clinkers, grainy cinders, and almost no lava.
• They have extremely steep sides and possess a small crater on the top.
• Example: Paricutin, Mexico

Lava domes

• A lava dome is a mound-shaped protrusion that is the result of the slow extrusion of viscous lava from a volcano.
• The viscous magma piles up around the vent since it cannot flow away.
• It does not have enough gas or pressure to escape but may erupt explosively later following sufficient pressure build-up.
• Example: Soufrière Hills volcano, on the Caribbean island of Montserrat

Recent volcanic eruption in Iceland

• Fagradalsfjall, a volcano on the Reykjanes peninsula in southwest Iceland, erupted on December 18th, 2023.
• This is the third time that the Fagradalsfjall volcano has erupted in the past two years after being dormant for over 6,000 years before this.
• Fagradalsfjall is a tuya volcano located in a zone of active rifting at the divergent boundary between the Eurasian and North American plates.
• A tuya is a flat-topped, steep-sided volcano that forms when lava erupts through a thick glacier or ice sheet.
• They are generally found in regions covered by glaciers and were volcanically active at the same time.
• Other famous volcanoes in Iceland include Eyjafjallajökull, Hekla, Grímsvötn, Hóluhraun, and Litli-Hrútur (part of the Fagradalsfjall system).

Why is Iceland so volcanically active?

• Iceland is one of the most volcanically active regions on the planet with an eruption taking place every four to five years.
  • However, since 2021 the frequency has risen to around one eruption every year.
• Iceland has 33 active volcanoes which have erupted over 180 times in the past 1,000 years.
• Active volcanos are those that have erupted within the Holocene epoch or those that have the potential to erupt again in the future.
• There are two major reasons for Iceland being volcanically active.

1. Iceland is located on the Mid-Atlantic Ridge, a divergent or constructive plate boundary in the North Atlantic Ocean.

• The Eurasian and North American plates are moving apart a few centimeters every year.
• This results in volcanic rift zones where the Earth’s crust is pulled and fractured and magma rises to the surface and erupts as lava and/or ash.
• The region is thus prone to frequent earthquakes, with an annual average of approximately 26,000.

2. Iceland is located over a hotspot or hot zone where volcanic activity is higher.

• Hotspots are enigmatic geothermal anomalies that are stationary, persistent sources of heat that give rise to volcanoes.
• Magma is hotter in this area than the surrounding regions which causes melting and thinning of the crust.
• Hotspots are not linked to plate boundaries and are fed by underlying mantle plumes that rise from the core-mantle boundary.

(*Click this link to read prelims specific weekly current affairs articles)

FAQs

MCQs

Question: In which of the following countries is the Fagradalsfjall volcano which was recently in the news, located in?

(a) Iceland

(b) Finland

(c) Mexico

(d) Russia

Question: Consider the following statements: (UPSC 2018)

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

Which of the statements given above is/are correct?

(a) 1 only

(b) 2 and 3

(c) 3 only

(d) 1 and 3

Question: Consider the following activities:

1. Spraying pesticides on a crop field
2. Inspecting the craters of active volcanoes
3. Collecting breath samples from spouting whales for DNA analysis

At the present level of technology, which of the above activities can be successfully carried out by using drones? (UPSC 2020)

(a) 1 and 2 only

(b) 2 and 4 only

(c) 1 and 3 only

(d) 1, 2, and 3