WHAT ARE VOLCANOES - AND WHY DO THEY KEEP ERUPTING IN ICELAND?

The Background

• This marks the third eruption of the Fagradalsfjall volcano in the past two years.
• However, it had been dormant for over 6,000 years before becoming active in March 2021.
• Iceland, known for its high volcanic activity, experiences eruptions every four to five years.
• The frequency has increased to almost one eruption per year since 2021.

Volcanoes

• According to the US Geological Survey “Volcanoes are openings, or vents where lava, tephra and steam erupt onto the Earth’s surface.”
• They can be on land or in the ocean, formed by the eruption of material hotter than its surroundings.
• The material could be liquid rock (known as “magma”, when it’s underground and “lava” when it breaks through the surface), ash, and/or gases.

Volcanic Processes

• According to NASA, the rise of magma can take place in three different ways

1. When tectonic plates move away from each other.

• The magma rises up to fill in the space.
• When this happens underwater volcanoes can form.

2. When the plates move towards each other.

• When this happens, part of Earth’s crust can be forced deep into its interior.
• The high heat and pressure cause the crust to melt and rise as magma.

3. The way magma rises at the hotspots - hot areas inside of the Earth, where magma gets heated up.

• As magma gets warmer, it becomes less dense, leading to its rise.

Volcanic Features

• The type of volcano depends on factors such as magma viscosity, gas content, composition and the way magma reaches the surface.
• There are two broad types of volcanoes
  • Stratovolcanoes: with steep sides
  • Shield volcanoes: with a low profile resembling a shield lying on the ground
• Various volcanic features, like cinder cones or lava domes, can form from erupted magma, along with processes that shape volcanoes.

Reasons for Iceland's Volcanic Activity

• Iceland's high volcanic activity is attributed to two main reasons.

1. It sits on the Mid-Atlantic Ridge, where the Eurasian and North American plates are moving apart, causing volcanic rift zones.
   • These zones result from the Earth's crust being pulled apart, allowing magma to rise and erupt.
2. Iceland is located over a hotspot, leading to enhanced volcanic activity in the region.