How Do Volcanoes Erupt?
An eruption happens when the pressure on the magma in the magma chamber forces the magma up through the main vent and out of the volcano. When a volcano erupts, it spews out lava (magma that reaches the surface) and ash clouds but also volcanic bombs and pyroclastic flows.
Types Of Eruptions
Different volcanoes erupt differently, depending on the kind of magma, the amount of silica (Silica determines the viscosity of the magma - how sticky it is) in the magma and how much water there is (water determines the amount of steam) (“Volcanoes
Online”, N.d). Most of the eruptions happen underwater. These eruptions are called submarine eruptions.
Here are the most known and most common types of land eruptions:
Here are the most known and most common types of land eruptions:
- Hawaiian eruption – Hawaiian eruptions are when the volcanoes erupt lava, which usually then gives way to lava flow (“Volcanoes
Online”, 2013). Usually, these volcanoes have a vast, curved shape. This type of volcano is called a shield volcano.
- Strombolian eruption – Strombolian eruptions happen when the magma is viscous. Gas will escape the volcano in an irregular pattern. This type of eruption will often create volcanic bombs and lava flows (“Volcanoes
Online”, 2013).
- Vulcanian eruptions – Vulcanian eruptions suddenly happen after years of the volcano laying dormant. It begins with a violent and loud explosion. Then, pieces of magma are expelled from the volcano with loud bangs. These eruptions also give off a lot of gas, ash, cinders and pumice (“Volcanoes
Online”, 2013).
- Pelean eruptions – Pealean eruptions happen when the magma has a relatively high degree of silica (“Volcanoes
Online”,2013). These volcanic eruptions are a combination of pyroclastic flows, blast eruptions (a very explosive eruption that produces clouds of hot ash and other volcanic material) and dome-formation, which is when the rock spewed from the vent is to vicious to go very far (“Volcanoes
Online”, 2013). A few weeks before one of these eruptions, the volcanoes start emitting ash.
- Plinian eruptions – Plinian eruptions are the most explosive and powerful eruptions. They, like the vulcanian eruptions, start suddenly after many years laying dormant. This sort of eruptions happen when very vicious magma that contains a lot of gas explodes in the volcano (“Volcanoes
Online”, 2013). In that case, the vents act like the barrel of a shotgun: an huge cloud of gas and ash shoots upwards at a very high speed where it creates a giant ash cloud (“Volcanoes
Online”, 2013). Near the end of the eruption, lava flows are sometimes emitted by the volcano.