What are Volcanoes? Know Some Amazing Facts.

Volcanoes are wonderful gifts of nature and architectural marvels on Earth. Volcanoes not only create curiosity in the minds of nature lovers but create havoc in millions. The word Volcano derives from the name Vulcano, a volcanic Island in the Aeolian Island of Italy, which ultimately derives its name from the Roman God of fire Vulcan.

What are volcanoes?

Volcanoes are wonderful gifts of nature and architectural marvels on Earth. Volcanoes not only create curiosity in the minds of nature lovers but create havoc in millions. The word Volcano derives from the name Vulcano, a volcanic Island in the Aeolian Island of Italy, which ultimately derives its name from the Roman God of fire Vulcan.

A Volcano is an opening or vent through which the magma and the dissolved gases it contains are discharged or erupted. If the magma reaches the surface is called lava. The volcano is formed due to heat and pressure built up deep inside the earth, causing part of the earth’s upper mantle or lower crust melts into magma, and it is collected in the underground magma chamber, from where heat, pressure, and gasses force it erupts to the earth surface.

Volcanoes usually appear at the edges of Earth’s crustal plates. The events may emerge in the middle of the plates at hotspots, where the heat of interior molten rock moves upwards through the crust.

Volcanoes spew not only lava but poisonous gages, ash, cinders, and fragments of rock collectively called pyroclastic flow, which can do more devastation than simply lava flow.

Around 1350 active volcanoes are reported to be in existence around the world. But of the active volcanoes, two more classes of volcanoes are found on the earth. One which has erupted once in history and will not erupt again in the future is called extinct. A volcano that has erupted long back and has apprehension of eruption in the future is called dormant.

Eruption types:

Types of volcanic eruptions play an important role in the evolution of volcanic landforms, which has a significant link between eruptive habits and the formation of volcanic structures.

The way the volcano erupts depends upon the thickness of its magma and how much gas it contains inside. In a huge gas-rich magma, violent expansion of bubbles can shatter the magma and discharge the volcanic ash into the sky with huge force, forming an ash cloud.

In case of a gentle eruption, lava flows slowly down the sides of the volcano. On the basis of the character of volcanic eruption, it may be divided into six types as follows. i.e-Icelandic/fissure, Hawaiian, Strombolian, Vulcanian, Pelean, and Plinian,

Icelandic/Fissure:

Icelandic eruption is the calm and quiet flow of magma without a loud explosion. The effusion of molten basaltic lava flows from long parallel fissures which often built lava plateaus.

Hawaiian:

Hawaiian eruption is usually a mild eruption, that creates fountains and streams of running lava. It is named after the Hawaiian volcano. Here eruption is the calmest type of volcanic event. Further gusher-like lava fountains formed by the eruption are called “curtains of fire. “

Strombolian:

Strombolian is a type of volcanic eruption named after the Stromboli Volcano, which has been erupting in regular intervals for centuries. It is a slow and explosive eruption driven by gas bubbles in the magma, that creates showers of cinders and lava bombs. Strombolian eruptions are louder but no sustainable eruptive columns are formed in the process.

Vulcanian:

This type of eruption is named after Vulcano Volcano, Italy. The Vulcanian eruption is a violent one that begins with a cannon-like explosion ejecting lumps of rock called bombs and blocks. More explosive than Strombolian eruption and sometimes destroy part of the volcanic structure. The ash disperses moderately and its abundance indicates a high degree of fragmentation.

Pelean:

Pelean eruption was named after Mount Pele volcano in Martinique, France. In this type of eruption, a large amount of gas, dust, ash, and lava fragments are blown out of the volcano’s central crater powered by the collapse of rhyolite and dacite (originated from the name of the Roman province of Dacia, the rock first found in Carpathian Mountain). The collapse of the andesite lava dome often creates large eruptive columns.

Plinian:

Plinian type of volcanic eruption named after the Mountain Vesuvius volcano, which caused the destruction of the sophisticated Roman town of Pompeii, Herculaneum in 79 AD. It is the most explosive and devastating violent type of eruption.

In the process, a steady and most powerful stream of gas and magma is blasted into the air. The massive eruptive columns are the distinctive feature of a Plinian eruption and the columns may reach the atmosphere up to 2 to 50 KM.

Ash columns:

A violent volcanic eruption can create tall columns of ash. The height of the columns varies depending on the amount of energy it has in the eruption and how much magma is thrown out into the air. The most energetic phase of eruption may last for hours together causing mass devastation. The ash columns may reach 5KM (3.1 miles) to 50 KM ( 31 miles).

Volcanic crater lake:

A lake formed in the crater rim of a volcano due to high explosive activities or collapse ( of the volcano ) during the volcanic eruption. Lakes are generally formed in the case of calderas and are filled with water. The water may come from anywhere like precipitation, ground seepage, or melting of ice.

Types of Volcanoes:

Volcanoes take different shapes depending upon the types of magma involved and the structure of the chamber and vents through which they erupt. Further, the way the eruption laid down materials on the earth’s surface was also taken into account.

Sometimes a volcano can be classified from the ground or air but underground composition and forms are also the right keys to identification. The volcanoes are classified into five categories on the above parameters i.e Strato Volcano, Shield Volcano, Calderas Volcano, Somma Volcano, and Complex Volcan

Strato Volcanoes:

Strato volcanoes are large volcanoes, built by a series of eruptions, and are also called composite volcanoes. Strato Volcanoes are steep and cone-shaped structures built of ash, rock and lava spewed out during eruptions and deposited in layers.

The lava spewing from Strato Volcanoes becomes cool and hard before spreading far away, due to high viscosity. They are the most common types of volcanoes. Mayon Volcano, Malinao town, Philippines falls in this category of volcano.

Shield Volcanoes:

Shield Volcanoes are large dome-shaped mountains, built of lava flows of basalt (a dark fine-grained volcanic rock). Shield volcanoes are found where ever fluid low-silica lava reaches the surface of a rocky planet. Here thin lava travels a long way before it hardens.

Shield volcanic eruptions are nonexplosive, 0-1 reading recorded on Volcanic Explosivity Index (VEI). Mount Mouna Loa, Hawaii, Kilauea, Hawaii US, State of Hawaii in the Pacific Ocean are bright examples of Shield Volcanoes.

Calderas Volcano:

Calderas volcano is a large bowl-shaped depression with in-facing rims. When a large volume of magma erupted within a short time, structural support for the rock above the magma chamber got lost. This type of Volcano is rare. Kilauea Volcano, Hawaii, Nemrut Caldera, Van Lake, Eastern Turkey, Summit Calderas, and Fernandina Island are a few examples of this type of volcano.

Somma Volcano:

Somma Volcano is also Calderas that has now partly been filled with newly formed central cones. Many of the Somma Volcanoes are found on Russia’s Kamchatka Peninsula and the Kuril Islands. Fogo Island, Cape Verde, and Mount Vesuvius, Italy are Somma Volcanoes.

Complex Volcanoes:

A complex Volcano is also called Compound Volcano. A volcanic complex consists of two or more vents or a volcano with an associated Volcanic dome, either in its crater or flanks.

They are formed due to changes in eruption patterns/habits or in the location of the principal vent area on a particular Volcano. Homa Mountain, Kenya is an example of a Complex Volcano.

Volcanology is a vast area of study, and observations of volcanoes, for which many Universities have opened departments of Volcanology. New research will definitely focus on unexploited areas of Volcanoes which will in turn empower inquisitively.

N.B.

Magma: Molten rocks are called magma. Lava: When magma reaches the surface called lava. Magma chamber: A reservoir of magma within the earth’s crust beneath a volcano, Crater: mouth of a volcano, Vent: A opening or crack in the earth’s surface through which lava and gas escape,