Thousands of Earthquakes Rock Iceland | 17 Nov 2023

Source: IE

Why in News?

Iceland has declared a state of emergency following a series of 800 earthquakes that struck the southwestern Reykjanes peninsula in less than 14 hours.

• Approximately 1,400 earthquakes were detected in a day, and the peninsula has experienced over 24,000 seismic events since late October. The strongest of these earthquakes, with a magnitude of 5.2, occurred approximately 40 km from Reykjavík, Iceland's capital.

What is Happening in Iceland?

• About Iceland:
  • Iceland is located on the Mid-Atlantic Ridge, technically the longest mountain range in the world, but on the floor of the Atlantic Ocean. The ridge separates the Eurasian and North American tectonic plates — making it a hotbed of seismic activity.
    • The Mid-Atlantic Ridge is a divergent or constructive plate boundary where tectonic plates move away from each other, leading to the creation of new oceanic crust
  • This geological setting makes the region prone to frequent earthquakes, with an annual average of approximately 26,000, as reported by Perlan, a natural history museum based in Reykjavik.
  • While most of these tremors go unnoticed, the occurrence of earthquake swarms, characterized by numerous small earthquakes without a discernible mainshock, raises concerns about the possibility of an impending volcanic eruption.
    • These earthquake swarms indicate heightened tectonic stress in specific areas.
• Notable Icelandic Volcanoes:
  • Iceland boasts a total of 33 active volcanoes.
  • Eyjafjallajökull, one of Iceland's most famous volcanoes, erupted in 2010, causing a widespread ash cloud.
    • Other notable volcanoes include Hekla, Grímsvötn, Hóluhraun, and Litli-Hrútur, part of the Fagradalsfjall system.

How are Earthquake Swarms a Sign of Volcanic Activity?

• Magma Formation and Movement:
  • Intense heat beneath the Earth's surface melts rocks, giving rise to magma, a flowing substance lighter than solid rock.
  • The buoyancy of magma propels it upwards, with most of it being confined to magma chambers deep underground.
• Volcanic Eruptions:
  • While the majority of magma cools and solidifies over time, a fraction erupts through vents and fissures on the Earth's surface.
  • These eruptions are the visible outcomes of the geological processes occurring beneath the surface.
• Earthquake Swarms as Indicators:
  • The movement of magma near the Earth's surface exerts force on surrounding rock layers.
  • This force often leads to the occurrence of earthquake swarms, clusters of seismic activity in a particular region.
• Proximity to Eruption:
  • Magma movement underground doesn't always culminate in a volcanic eruption.
  • The closer magma gets to the Earth's surface, the higher the likelihood of an eruption, accompanied by more frequent and symptomatic earthquake swarms.