The Ground Shakes Expectorating Lava And Belching Out Fumes

Dated – 15.04.2010,
Dept. Of British Civil Aviation

The authorities of the British Civil Aviation sent an order to close the country’s airspace. The order was made due to the spewing cloud of ash passing out from the erupting EyjafjallajAi??kull volcano, Iceland. This volcano has erupted for the second time within a time span of less than a month. The results of this volcano include melting ice, rising levels of water leading to flood, shooting out smoke and fumes into the air and forceful fleeing of hundreds of people. Many flights have been cancelled. The air traffic is highly disrupted across the northern Europe.

What Is Volcano ?

Sometimes, an opening is formed at the earth crust (the surface of the earth) allowing hot magma, ashes and toxic fumes escaping through it. Most of these materials oozes out from below the earth’s surface. This opening is called as a Volcano. The name ‘Volcano’ was named according to the name of the ‘Vulcano island’ off Sicily. This island derived its name from the Roman God of Fire, the ‘Vulcan’.

What Causes Volcano ?

Our lithosphere is broken into tectonic plates. Mother Earth contains 7-8 major plates and many minor plates. The rigid outermost shell of a rocky planet is named as the lithosphere. The word ‘Lithosphere’ is also derived from two Greek words; the ‘lithos’ (meaning ‘rocky’) and ‘spaira’ (meaning ‘sphere’). It comprises of the earth crust and a portion of the upper mantle. The relative movement of the tectonic plates to one another at either can be either of three different types of plate boundaries:-

  • Convergent (or collisional) boundaries
  • Divergent boundaries (or spreading centres)
  • Transform boundaries

Volcanic activities, mountain-building, earthquakes or formation of oceanic trench are all results of plate boundaries. The movement is typically about 0-100 mm annually. The heat dissipated from the mantle causes the movement of the tectonic plates. Volcanic eruptions are the result of diverging or converging motion of the tectonic plates. But can also occur due to stretching and thinning of the earth’s crust.

Common Examples Of Volcanic Eruptions –

  • Example of volcano caused due to movement of tectonic plates across divergent plate boundaries is Mid-Atlantic Ridge. The plates are pulled apart resulting in this volcano.
  • Example of volcano caused due to movement of tectonic plates across convergent plat boundaries is Pacific Ring of Fire. This volcano is caused where two plates slide past each other.
  • Examples of volcanoes caused due to stretching and hence, thinning of the crust of the earth is African Rift Valley, the Rio Grande Rift, North America), the wells of Gray-Clearwater volcanis field and the Eifel volcanoes, European Rhine Graben. These volcanoes are named as the ‘non-hotspot intraplate volcanism’.
  • Example of volcanoes caused by the mantle plumes is the one at Hawaii. These are named as hotspots. These occur at a much distance from the plate boundaries.

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