Types of Volcanic Eruptions

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What are Volcanic Eruptions?

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The Volcanic eruptions might be a spectacular event to watch but it is really dangerous to encounter one. The volcanic eruptions explode when the lava and the gas are discharged from the volcanic vent. One of the most common consequences of this eruption is the population movements. A large crowd is often forced to flee as the molten lava from the volcano flows. Volcanic eruptions are often caused temporary food shortages and also leads to volcanic ash landslides known as Lahar.

We will know about six basic types of volcanic eruptions which are sure to amaze us. It has different variants and nature which will be worthy to learn. 

Six Types of Volcanic Eruptions 

In the Volcanic landforms, we have learned the classification of volcanoes by their size and shape. While in this section we will also classify the volcanoes by their eruptive habits. To note, the type of volcanic eruption which occurs plays a prior role in the evolving a volcanic landform, which forms a significant link between the eruptive habit and between the volcanic structure. 

Generally speaking, the eruptions can be categorized as being effusive or being explosive. 

The Effusive eruptions involve outpouring of the basaltic magma which has a lower viscosity and gaseous content. Explosive eruptions are generally involved with magma and have more viscosity with higher gaseous content. This magma is often broken down into pyroclastic fragments which are caused by explosive gas expansion at the time of expansion.

Based on the eruption behaviour of the volcano, volcanic activity is generally divided into six major types. The types are:

  1. Icelandic

  2. Hawaiian

  3. Strombolian

  4. Vulcanian

  5. Pelean

  6. Plinian

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The Icelandic type is characterized by effusions of molten basaltic lava that flow from long and parallel fissures.  After it is cooled down these outpourings get to build into lava plateaus.

The Hawaiian type of volcano eruption is a lot similar to the Icelandic type. In Hawaiian eruption type, however, the fluid lava which flows from the volcano’s summit and the radial fissures to create the shield volcanoes, are very large and have gentle slopes on them.

Strombolian eruptions, yet another type of eruption which involves moderate bursts of the expanding gases, ejects clots of incandescent lava in the cyclical or moreover by continuous small eruptions. These are known as the “lighthouse of the Mediterranean” as they have small frequent outbursts on the Stromboli Island, located on the northeast coast of Italy.

The Vulcanian eruption type is named after the Vulcano Island, located near Stromboli, this eruption generally involves moderate explosions of the gas laden accompanied with volcanic ash. The mixture forms dark, turbulent eruption clouds which rapidly ascend and thus expand in folded shapes.

Next type, Pelean eruption. This type of eruption is associated with explosive outbursts which also release the pyroclastic flows, a dense mixture of the hot volcanic fragments, and the gas that is described as lava, gas, or other hazardous substances. These eruptions are named after the destructive eruption of Mount Pelée which is located on the Caribbean island in the year 1902. The fluids produced by these volcanic eruptions are heavier than air but are of low viscosity and thus pour down from the valleys and sloped with higher velocity. Thus, causing extreme damage. 

Last on the list is the Plinian type of eruption which is an intensely violent kind of volcanic eruption that is illustrated by the outburst of Mount Vesuvius in Italy. In this type of volcanic eruption, the gases boiling out of the gas-rich magma produces an enormous and nearly continuous jetting blast. 

Fun Fact

1. Some volcanic eruptions are quite explosive while others are spectacular and relatively harmless.

  • The reason for this out, there are at least four factors .

  • The number of gaseous constituents dissolved in the magma.

  • The thickness or the viscosity of the magma coming out.

  • Rate of decompression of the magma as it proceeds onto the surface. 

  • The number of nucleation sites on which the gases form bubbles. 

2. A volcanic eruption occurs when?

When the hot materials from the Earth's interior surface are thrown out from a volcano, eruptions take place. Eruptions can explode from the side branches or the top vent of the volcano. Even there are some eruptions that are very terrible and thus throw out huge amounts of rock and volcanic ash which can kill many people.

FAQ (Frequently Asked Questions)

1. What is a Volcanic Vent?

Ans. A volcanic vent is described as an opening that is exposed on the earth's surface, from where the volcanic material is emitted or comes out. The volcano with its cone-shaped structure, or the edifice, is built with the more-or-less symmetrical accumulation of the lava also known as the pyroclastic material on this central vent.

Volcanic vents are the openings in the Earth's crust from where the lava and the pyroclastic flows are ejected out. After the volcanic eruptions, these volcanic vents continue to release steam and gas fumes through the small openings that are the surrounding of a volcano which are known as the fumaroles.

2. What are Pyroclastic Fragments?

Ans. Pyroclastic fragments which are also known as pyroclasts are produced by many processes which are connected with volcanic eruptions. These are the particles from the core of the volcano that is expelled through the volcanic vents.

This pyroclastic flows consists of a high-density mix of hot lava blocks, pumice, ash, and other volcanic gas. This flow moves at a very high speed down the volcanic slopes, generally following from the valleys.

3. What are Fissures?

Ans. On the volcanoes, a fissure gets formed like an elongate fracture or a crack at the surface from where the lava erupts. The fissure eruptions are typically intertwined to a central vent after a certain period of hours or number of days.

Fissure eruptions when the magma from the volcano flows up through the cracks then into the ground leaks out onto the surface.