Throughout history, the world has witnessed numerous volcanic activities and eruptions. This natural disaster has helped shaped the world as it is today. Furthermore, it has caused devastating results to human society including destroyed homes, livestock and even lost possessions. On the other hand, it also had numerous benefits to the environment, particularly to plants and animals. Although there are only a few volcanic eruptions in modern times, it is still quite helpful to understand the basic nature of this massive landform as well as why do volcanoes erupt.
Major Reasons Behind Volcanic Eruptions
Why do volcanoes erupt? Volcanoes, especially the active ones, have cracks beneath them. Because of this, the melted rocks underneath the tectonic plates start to go out through these cracks. Little by little the super hot magma inside slowly builds up pressure. Once the landform cannot contain the pressure anymore, it releases hot materials continuously until the pressure wears down. The result is a massive eruption that releases lava all over the surrounding areas.
There are three major classes of eruptions. The first one is called magmatic eruption, which is basically a result of released decompressed gas. Under this particular class, the volcanic event can be further subdivided into different kinds including surtseyan, Hawaiian and pelean. The other three kinds under this class are vulcanian, strombolian and plinian, which is the most powerful of all.
The second class of volcanic eruption is called phreatomagmatic eruption. Under this class, the volcanic activity is caused by thermal contraction because of chilling, particularly when water comes into direct contact with the hot materials. Under this class, the eruption can be subdivided into three different kinds, namely Antarctica, subglacial and submarine.
The third class of this aggressive volcanic activity is referred to as phreatic eruption. It is also called steam-blast eruptions. Unlike the previous two classes, this one results from expanding steam that explodes when magma comes into direct contact with surface water. Under this class, the volcano never releases new magma. Instead, it blows out fragments of solid rocks that are found inside.
Additional Information and Other Important Details
One of the best examples of a magmatic eruption is the one that took place in the Philippines in 1968. When Mayon Volcano erupted, lava fragments, dust and gas were blown out of the crater. When these materials fell back into the crater, they created destructive avalanches. Under the phreatomagmatic eruption, the best-known record of such event happened approximately 2,200 years ago when an eruption took place under the ice sheet in Antarctica. Finally, a clear example of phreatic eruption happened in the Philippines when Taal Volcano erupted in 1965.