Expo 11, P.5
16 Mar 2014
Volcanoes’ Eruptions and Shapes
A volcano is an opening in the planet’s surface that allows intensely heated, molten rock, ash and gases to escape from below the surface. The word, “volcano” originated from the mythical Roman god of fire, named Vulcan. Volcanoes exist across the globe, even underwater. These volcanoes are either active (volcano still functions); dormant (very little activity); or extinct (no longer active). Studies show that in the past 10,000 years, there are about 1500 volcanoes on land that are known to have been active, but the number of volcanoes underwater is still a mystery. Only recently has geologists discovered how volcanoes are made and classified them by their eruptions and shapes.
Geologists today realize that the process involved in the creation of a volcano is complex, resulting from the evolution of the planet with its plate tectonics. Prabhakar Pillai, author of the article “How are Volcanoes Formed?” says, “A volcano is formed when magma, present in the Earth's interior, manages to rise up to the surface via a vent or a fissure” (Pillai). It is difficult for heat to escape from large objects, such as volcanoes, by conduction or radiation. Instead, meltdowns and the rise of magma are major contributors to the process of creating heat currents from inside the Earth. Once overwhelmed, this heat will escape the only way possible which is upward and allows magma to rise to the surface. This magma, along with ashes, eventually cools down to form distinctive volcanic landforms (Pillai). All volcanoes on Earth are created through this process.
Even though all volcanoes are created the same way, each have a distinctive eruption that are used to classify them. This classification is organized by a volcano’s explosiveness in its eruption. Type of eruption is also significant in the creation of a volcanic landform, which forms an important link between the eruption and volcanic structure. According to Batul Baxamusa, author of “Types of Volcanic Eruptions”, volcanic eruptions are commonly divided into six types by degrees of explosiveness: Hawaiian, Strombolian, Plinian, Lava domes, Surtseyan and Vulcanian (Baxamusa). Hawaiian eruptions are commonly seen in the volcanoes of Hawaii, hence the name that is given. This eruption creates a flow of steady gas-poor magma fluid that can last for hours, even days. Once erupted, the lava explodes out in the form of jets from the summit of the volcano, which results in the formation of a fire mountain (Baxamusa). Strombolian eruptions are similar to those of Hawaiian eruptions. Batul Baxamusa, author of the article “Types of Volcanic Eruptions” states, “This eruption creates huge explosions, which causes lava to reach hundreds of meters in the air, and has intervals in each explosion” (Baxamusa). Similar to Hawaiian eruptions, they create fluid lava containing very little gas. Although they are considered to be the least dangerous of all explosive eruptions, they can cause a lot of destruction, especially when lava flows into inhabited regions. Plinian eruptions are the most violent and destructive of all the volcanic eruptions. These eruptions cause a huge column of gas and ash, which tend to drift thousands of miles away from the volcano (Baxamusa). This leads to more vulnerable regions, even in farther proximity because of the greater volcanic radius. Also, this type is known for its mushroom-like shape when erupted. Lava domes are eruptions that lead to formation of thick lava that does not explode, but squeezes out of a vent, which could even form spikes (Baxamusa). These lava domes are typically round in shape and can be described as an irregular rock piles. This eruption can last months or years and are repetitive, which means the volcano can erupt multiple times before becoming dormant. Surtseyan eruptions are volcanic eruptions that take place in shallow lakes or the oceans. These are violent eruptions…