Saturday, February 12, 2005
Types of Volcanic Eruptions
- A mild eruption is observed when some steam and gases are the only elements coming out in some cases and in others when some lava is quietly descending on the sides of the volcano.
- A violent eruption is observed when a loud and violent explosion blasts rocks, steam, ashes, gases and important quantities of lava. These eruptions are often spectacular and sometimes even famous.
The type of volcanic eruptions is often named after a famous volcano that has similar characteristics. A volcano might display only one type of eruption as another one might display several ones.
- The Plinian eruption is the most powerful type which will eject lava during violent explosions. It sends ashes, and gases miles into the atmosphere. Mount St.Helen displayed this type of eruption on May 18, 1980. Large areas, up to hundreds of miles downwind, can be affected by the deadly pyroclastic flows caused by the mix of ashes and gases that were released during the eruption.
- The Phreatic eruption is caused by the blast of steam that is produced by the cold ground or water on the surface that comes in contact with hot rock or magma. During the type of eruption, only steam and fragments of solid rock are projected into the air. There is no magma that erupts in this case.
- The Strombolian eruption sends strands of lava into the air then descends the sides of the volcano resembling small rivers. A good example of this type of volcanic eruption is the Irazùù Volcano in Costa Rica that erupted in 1965.
- The Hawaiian eruption happens when the lava erupts from either the central vent or linear vents coming out of fissures. The lava then streams down the sloped sides of the volcano. An eruption that happened in a linear vent was the Mauna Loa Volcano in 1950 and a good example of a central vent eruption was in the Kilauea Iki Crater of the Kilauea Volcano, in 1959.
- The Vulcanian eruption is displayed when a thick cloud mixed of ashes and gases explodes from the main vent rising high over the summit as a white cloud surrounding the upper part of the volcano. In 1947, the Parìcutin Volcano was a good example of this type of volcanic eruption.
- The Vesuvian eruption as demonstrated by Mount Vesuvius in Italy, A.D. 79, discharges a thick cauliflower-shaped cloud that contains enormous quantities of ashes and gases that erupts violently high up in the sky.
- The Peléan also known as Nuée ardente (glowing cloud) type of volcanic eruption discharges a great amount of ash, dust, gas and lava fragments that are exploding from the central vent in a tongue-shaped avalanche of glowing elements that move down the sides of the volcano at speeds as high as one hundred miles per hour. This type of eruption was demonstrated by the Mayon Volcano in the Philippines, in 1968.
As you can see, a volcano has its own personality to show the world and it does that in a variety of ways. Beauty, danger and mystery mix together to offer spectacular and sometimes unpredictable, volcanic eruptions.