Volcanic Eruptions

Volcanic Eruptions
The word volcano generates a familiar image in our minds. It is the image of a large land mass or mountain that has a wide opening at the top and spews out red hot molten lava and huge clouds of smoke whenever it erupts. A volcano is the symbol of the awesome power of nature, and people who live near one are fearful of an eruption. A volcanic eruption is a natural phenomenon that most of us have become familiar with through the television, or from reading books. Most of us have not personally experienced the sight of a volcano, much less the fury of a sudden eruption from one. Furthermore, the average person is not aware of the many factors that go into describing and classifying this natural phenomenon. Taking a closer look at this phenomenon reveals a detailed variety of ways to describe volcanoes and their eruptions. These descriptions identify the sizeand shape of volcanoes, and the wide nature of volcanic eruptions ranging from the quiet oozing of molten lava to violent eruptions. Volcanoes are a complex phenomena that are classified by activity levels, types of volcanic eruptions, and the basic underlying physical science of volcanic activity that is common to each of them.

The main types of volcanoes according to activity levels are known as Active, Intermittent, Dormant, and Extinct volcanoes (Volcanic Eruptions). An Active volcano is one in which there is a constant state of eruption taking place. An Intermittent volcano is one in which eruptions occur on a somewhat regular basis, with periods of inactivity in between. A Dormant volcano is one that is inactive, meaning that there is no observable eruptive activity present. However, Dormant volcanoes have not been inactive over a long enough period of time to safely and accurately designate them as ones that definitely will not erupt again. An Extinct volcano is one in which there are no recorded eruptions as far back as records have been kept (Volcanic Eruptions). The activity levels of volcanoes are important to determine, so that people can determine which volcanoes are safe to visit or live near, and which ones are dangerous and unpredictable.

Volcanic eruptions are not typically viewed as occurring as many types of eruptions, but rather as a standard phenomenon of lava and smoke being ejected from the mouth of the volcano. However, there are several specific volcanic eruption characteristics which lead to them being designated as specific types of volcanic eruptions. They are commonly classified as Hawaiian, Pelean, Vulcanian, Strombolian, or Vesuvian. A Hawaiian eruption is characterized by lava flows which are generated by the escape of molten hot lava through fissures along the slopes or sides of volcanoes, or vents which have the lava shoot high into the air before returning to form lava lakes. As a result, they produce a wide series of lava streams and some lakes which feed these streams. Many tourists visit such volcanoes in Hawaii each year, probably without ever realizing the exact type of volcano that they are viewing. A Pelean eruption is characterized by a great blast of molten lava, ash, lava, and dust which rises above the volcano, then falls back and rapidly flows down the slopes of the volcano. The powerful explosion and massive amount of volcanic debris and gas can cause great destruction to the surrounding land and people. The blast and its lava are very bright and sometimes referred to as glowing. This is obviously a type of volcano that nobody would want to visit. A Vulcanian eruption is described as one in which a sudden violent and noisy eruption takes place as the gases force a cloud of ash, which is dense and steaming hot, high into the air above the rim of the volcano. Again, it is probably not known to a person who views this volcano as to the type that it is classified, other than the fact that it is scary and dangerous. Strombolian eruptions are intermittent because the magma is thicker and this prohibits the gases from freely escaping. Instead, the intermittent release of gas causes clumps or bombs of thick molten lava to be discharged from the volcano. The lava flows down the sides of the volcano in distinct streams of hot lava towards the base of the volcano. A Vesuvian eruption is characterized by a violent eruption of large amounts of gases that contain ash and result in the formation of a large wide cloud that hovers around and extends into the sky above the volcano (Watson). These vlassifications of types of volcanoes are important to scientists, and mech less familiar or important to the average person.

The basic underlying physical science of the mechanism of a typical volcanic eruption involves a process that displays some or all of the following common components. These include Magma, Lava, Gas, Ash, and Volcanic ash. Magma is very hot molten rock which is formed of the earth’s crust. It is ejected from the depths of the volcano during an eruption as the result of pressure changes. Lava is magma which has been erupted from the volcano and has now come in contact with the atmosphere or the surrounding Earth. Moving lava is termed a lava flow. Gases such as carbon dioxide and steam are emitted from the rising magma and they saturate the immediate atmosphere. These can be poisonous gases and they can occur at a density great enough to cause death through suffocation. Volcanic ash is very tiny pieces of volcanic rock that is released during the eruption, and is either a solid or in the form of a liquid or molten state. These basic terms and concepts are present within all eruptions (Watson). As a result, volcanic activity is a summation of a common and predictable underlying physical science that leads to a phenomena that is present in each type of volcano and each classification of volcanic eruption.

In conclusion, society benefits from the work of scientisit who develop a deeper understanding of volcanoes and classify them according to activity levels and types of eruptions. This allows people and nations the opportunity to make decisions regarding which volcanoes are safe to visit and live near, and which are unstable and dangerous. There are several types of volcanoes that produce various types of eruptions. However, even though there is this variety with classifying volcanoes, the basic mechanism and components of the physical science characteristic of each are similar. As a result, we think of all volcanoes as being large elevated land masses or mountains with a large opening at the top, and all volcanic eruptions as violent events that result in large explosions and smoke and hot molten lava being shot up into the air and flowing down the sides of the mountains to the flat lands below. It is true that a volcanic eruption is arguably the most powerful natural phenomena on Earth. Fortunately most of us have never experienced this devastating force of nature, and we never will. Interestingly though, volcanoes and their eruptions are much more complex events. There is much more to learn regarding all of nature, and scientists will continue to study volcanoes and their eruptions in an effort to make the earth safer from natural disasters and to discover unknown facts about the world in which we live.

Works Cited

1. Watson, John." Types of Volcanic Eruptions." Unites States Geological Survey. 5 Feb. 1997 <http://pubs.usgs.gov/gip/volc/eruptions.html>.
2. " Volcanic Eruptions." Think Quest. 8 Oct. 2008 < http://library.thinkquest.org/17457/volcanoes/erupts.php>.