TAG: GS 3: ECOLOGY AND ENVIRONMENT
THE CONTEXT: Iceland is one of the most volcanically active regions on the planet. It witnesses an eruption every four to five years. However, since 2021, the frequency has spiked to almost one eruption per year.
Recent Eruptions in Iceland
- The Fagradalsfjall volcano in southwest Iceland erupted in 2021 and subsequently in December 2023.
- This volcano, dormant for over 6,000 years, became active in 2021.
- Intense seismic activities preceding eruptions allowed authorities to anticipate the events and take precautionary measures like evacuations, minimizing potential risks to local communities.
- Volcanoes are natural geologic features characterized by openings or vents through which magma, ash, gases, and rocks are expelled onto the Earth’s surface.
- These formations occur both on land and underwater.
- The molten rock beneath the Earth’s surface is referred to as magma and becomes lava when it erupts onto the surface.
Volcanic Formation Mechanisms
- According to scientific understanding, the ascent of magma to the surface occurs through various mechanisms:
- Divergent Boundaries:
- At these plate boundaries, such as the Mid-Atlantic Ridge, tectonic plates move apart from each other.
- The gap formed allows magma to rise and create new crust. Underwater volcanoes often form along these boundaries.
- Convergent Boundaries:
- When plates move towards each other, one may be forced beneath the other in a process called subduction.
- The melting of the subducted plate creates magma, leading to volcanic activity.
- These are areas within the Earth’s mantle where magma upwelling occurs due to high temperatures.
- As the magma rises, it can create volcanoes on the Earth’s surface.
- Divergent Boundaries:
Types of Volcanoes
- Volcanoes vary in shape, size, and eruption style based on factors like magma viscosity, gas content, and composition.
- The two main types are:
- These volcanoes have steep sides and a cone-shaped appearance due to their explosive eruptions that produce layers of ash, lava, and volcanic rocks like pumice.
- Examples include Mount St. Helens in the United States and Mount Fuji in Japan.
2. Shield Volcanoes:
- They are characterized by a broad, gently sloping profile formed by the flowing of low-viscosity lava during non-explosive eruptions.
- Mauna Loa and Mauna Kea in Hawaii are prominent shield volcanoes.
Iceland’s Volcanic Activity
- Geological Location and Tectonic Activity:
- Iceland is situated on the Mid-Atlantic Ridge, where the Eurasian and North American tectonic plates drift apart.
- This movement results in rift zones, where the Earth’s crust fractures, allowing magma to rise and cause eruptions.
- The constant separation of these tectonic plates leads to the creation of volcanic rift zones, enhancing volcanic activity.
Presence of Hotspots:
- Additionally, Iceland is positioned over a hotspot, a region beneath the Earth’s surface with exceptionally high temperatures that facilitate magma formation and upward movement.
- This hotspot contributes to the heightened volcanic activity on the island.
- Iceland’s geologic positioning on the Mid-Atlantic Ridge, coupled with the presence of a hotspot, creates ideal conditions for frequent volcanic activity.
- Understanding the mechanisms behind volcanic eruptions aids in predicting and preparing for such natural events, crucial for safeguarding lives and minimizing potential damages to infrastructure and the environment.