Volcano Eruption, What is a Volcano, How Do Volcanoes Erupt? (For CBSE, ICSE, IAS, NET, NRA 2022)

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Volcano Eruption

They are ruptures in the crust of our planet Earth that allow hot gases, molten lava, and some rock fragments to erupt by opening and exposing the magma inside.

What is a Volcano?

Volcano Eruption
  • They are vents where lava and steam erupt on to the Earth՚s surface.
  • Many mountains form by folding, faulting, uplift, and erosion of the Earth՚s crust. Volcanic terrain, however, is built by the slow accumulation of erupted lava.
  • The vent may be visible as a small bowl-shaped depression at the summit of a cone or shield-shaped mountain.
  • Through a series of cracks within and beneath the volcano, the vent connects to one or more linked storage areas of molten or partially molten rock (magma) .
  • This connection to fresh magma allows the volcano to erupt over and over again in the same location.
  • So, the volcano grows ever larger, until it is no longer stable. Pieces of the volcano collapse as rock falls or as landslides.

How Do Volcanoes Erupt?

  • It is So Hot Deep Within the Earth That Some Rocks Slowly Melt and Turn into a Thick Flowing Matter Known as Magma.
  • Though it is lighter than the solid rock around it, magma rises and collects in magma chambers.
  • Some of the magma pushes through vents and fissures to the Earth՚s surface. Magma that has erupted is called lava.
  • Some volcanic eruptions are explosive and others are not.
  • We need to understand the Earth՚s structure to know how volcanoes erupt.
  • The explosivity of an eruption depends on the composition of the magma. If magma is thin and runny, gases can escape easily from it. When this type of magma erupts, it flows out of the volcano.
  • At the top lies the lithosphere, being the outermost layer that consists of the upper crust and mantle. The thickness of the crust ranges from 10 km to 100 km in mountainous locations and mainly consists of silicate rock.
  • A good example is the eruptions at Hawaii՚s volcanoes.
  • Lava flows rarely kill people because they move slowly enough for people to get out of their way. If magma is thick and sticky, gases cannot escape easily. Pressure builds up until the gases escape violently and explode.
  • The Earth՚s mantle within the crust is classified into different sections depending on individual seismology. These include upper mantle, that ranges between 8 – 35 km to 410 km; transition zone ranges from 400 – 660 km; lower mantle lies between 660 – 2891 km.
  • Explosive volcanic eruptions can be dangerous and deadly. They can blast out clouds of hot tephra from the side or top of a volcano.
  • The conditions change dramatically from the crust in the mantle location. The pressures rise drastically and temperatures rise to . This viscous and molten rock gets collected into large chambers within the Earth՚s crust.
  • These fiery clouds race down mountainsides destroying almost everything in their path. Ash erupted into the sky falls back to Earth like powdery snow. If thick enough, blankets of ash can suffocate plants, animals, and humans.
  • When hot volcanic materials mix with water from streams or melted snow and ice, mudflows form. Mudflows have buried entire communities located near erupting volcanoes.

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