Volcanic Eruption, Meaning, Causes, Stages, Types & Impacts

Volcanic Eruption

Volcanic Eruption: Deep within the Earth, it is so hot that some rocks slowly melt and become a thick flowing substance called magma. Since magma is lighter than the surrounding solid rock, it rises and gathers in magma chambers. Some of the magma eventually surges through fissures and vents to the Earth’s surface. When this hot lava and gas are released from a volcano, often explosively, this is called a Volcanic Eruption. A “glowing avalanche,” which occurs when recently erupted lava slides down the flanks of a volcano, is the most hazardous type of eruption.

A volcanic eruption on the undersea volcano Hunga Tonga-Hunga Haapai, located in the Tongan archipelago in the southern Pacific Ocean, started on December 20, 2021. On January 15, 2022, approximately four weeks after the eruption’s initial start, it reached its largest and most intense peak.

What is a Volcanic Eruption?

A volcano is a vent or fissure or a rupture in a planet’s crust, such as the one on Earth, that permits hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. Most volcanoes on Earth are found underwater, and they are most frequently found where tectonic plates are diverging or convergent.

Volcanoes are formed due to eruptions of lava and ash. The appearance of volcanoes is mostly cone-shaped mountains or hills. Magma on reaching the Earth’s surface is referred to as lava. On cooling down on lava, it results in the formation of rock. Volcanic Eruption mostly occur at destructive and constructive borders, but not at conservative boundaries. There are a few volcanoes that occur inside water, along the seabed or ocean floor.

Volcanic Eruption Stages

Based on the type of material erupted, the type of eruption, and the type of alteration since these volcanoes occurred, volcanoes can take on a variety of shapes. Volcanoes are mostly categorised into three groups:

Active Volcanoes: Volcanoes that are currently erupting or are likely to do so at some point in the future are considered active volcanoes.

Dormant Volcanoes: Volcanoes that are categorised as being dormant are ones that are not anticipated to erupt anytime soon.

Extinct Volcanoes: Volcanoes that are extinct are ones whose eruption is not anticipated by anyone. Nobody is aware of the frequency of these volcanoes.

Volcanic Eruption Types

Volcanoes are segmented as per the style of eruption and the form which is created on the earth’s surface.

Shield Volcanoes: The size of these volcanoes is greater than that of any currently active volcano on Earth’s surface. These volcanoes are composed of basalt. In the event that water gets inside the vent, it will explode. Other than that, these volcanoes are distinguished by mild explosivity. The lava that is venturing upwards does so in the shape of a fountain and emerges from the top of the cone before changing into a cinder cone.

Composite Volcanoes: The eruptions of lavas that are cooler and more viscous than basalt give rise to composite volcanoes. Explosive eruptions are how these volcanoes typically occur. With lava, a substantial amount of pyroclastic debris and ashes are easily removed. Layers are formed as a result of the material gathering close to the vent apertures. The largest composite volcanoes in the globe that have erupted in the past include the Mayon Volcano in the Philippines, Mount Fuji in Japan, etc.

Caldera: The most explosive volcanoes on the earth are regarded as calderas. Most of these volcanoes are explosive. They’re more likely to collapse in on themselves during an eruption than to build something. Calderas are the name for the ruined depressions.

Flood Basalt Provinces: Volcanoes in the Flood Basalt Province spew fluid lava that can readily travel great distances. Thick basalt lava flows have blanketed many areas of the world. Volcanoes of the Mid-Ocean Ridge:  These volcanoes typically erupt in oceanic regions. There is a network of mid-ocean ridges that span the ocean basins for more than 70000 kilometres. The majority of eruptions routinely occur in the centre of this ridge.

Volcanic Eruption Causes

Depending on each seismology, the Earth’s mantle within the crust is divided into several portions. These range from 8 to 35 km to 410 km for the upper mantle, 400 to 660 km for the transition zone, and 660 to 2891 km for the lower mantle. From the crust to the mantle site, the conditions drastically alter. Temperatures can reach 1000^oC, and pressures increase dramatically. Within the crust of the Earth, these viscous, molten rocks are gathered in large chambers.

Magma seeks to find cracks and areas of weakness in the mantle because it is lighter than the surrounding rock and floats upward towards the surface. The molten rock is known as magma when it is below the surface and explodes as ash when it rises. When the lava flows readily, it spreads far and creates wide shield volcanoes. It takes on the shape of a classic cone volcano when it is too thick. The magma rises to the surface and erupts because its density between the region of its formation and the crust is lower than that of the surrounding rocks. Along with water, dissolved carbon dioxide, sulphur dioxide, and andesitic and rhyolitic minerals make up the magma. Magma and extra water are broken up by the formation of bubbles. The water level drops and the gas/magma rise in the channel as the magma gets closer to the surface. The magma ruptures into pyroclasts and bursts out when the volume of the created bubbles reaches about 75%. These are the top three contributors to volcanic eruptions:

• The magma’s buoyancy
• The magma’s expelled gases are under pressure.
• Pressure on the chamber lid rising

Lava domes are the result of lava building up inside a volcano and exploding if it is very thick. We are aware that the Earth’s mantle is very warm, with temperatures ranging from 1000° to 3000° Celsius. Due to the intense pressure and heat, the inner rocks melt. The melted material weighs little. Due to its high level of flotation, this thin lava rises to the crust.  When it reaches the surface, a volcano’s highest point eventually erupts. With each eruption, the volcanic vent is covered with rocks, lava, and ash. The viscosity of the magma has a significant impact on the eruption’s nature.

Volcanic Eruption Impact

• Rock is formed on the surface of the Earth by volcanic eruptions.
• Climate is impacted by gases and dust particles released into the atmosphere during volcanic eruptions.
• Over millions of years, during periods of extremely high volcanism, volcanoes have also contributed to global warming by releasing greenhouse gases into the atmosphere.
• Volcanoes are located in specific locations on Earth, but as gases, dust, and ash enter the atmosphere, their impacts may be more broadly dispersed.
• This is because eruptions in the tropics can affect the climate in both hemispheres because of the patterns of air circulation.
• Mid- or high-latitude eruptions only affect the hemisphere they are located in.

Volcanic Eruption UPSC

• A volcano is a vent or fissure or a rupture in a planet’s crust, such as the one on Earth, that permits hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.
• The term magma is used for molten rock that is underground and lava for molten rock that breaks through the Earth’s surface.
• Magma has a temperature between 1300 and 2400 degrees.
• Compared to magma, lava has a lower temperature. The temperature spans 1300 to 2200 degrees Fahrenheit.
• The most recent volcanic eruption on the undersea volcano Hunga Tonga-Hunga Haapai, located in the Tongan archipelago in the southern Pacific Ocean, started on December 20, 2021. On January 15, 2022, approximately four weeks after the eruption’s initial start, it reached its largest and most intense peak.

A UPSC aspirant should be well versed with the topic of Volcanic Eruptions from both Prelims and Mains point of View. The details in the article would help candidates preparing for UPSC 2023.

Volcanic Eruption FAQs

Q) Where did the most recent volcano erupt?

Ans. Tonga, an island in the southern Pacific, saw a volcanic eruption that caused tsunami waves to spread throughout the Pacific. The Tonga Islands are situated on the Pacific Ocean’s Ring of Fire, an area of very active volcanoes and earthquakes.

Q) What is a volcano?

Ans. A volcano is a vent or fissure or a rupture in a planet’s crust, such as the one on Earth, that permits hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.

Q) What is Volcanism?

Ans. Volcanism is the release of molten rock to the surface from deep below the Earth. The interior heat of the Earth causes volcanism, which is linked to tectonic movements and a component of the rock cycle. When molten lava reaches the Earth’s surface, volcanic eruptions happen.

Q) Which is an active volcano in India?

Ans. The only active volcano in India is on Barren Island, which is part of the Andaman and Nicobar Islands. As a result, statement 1 is true. It is situated in the southern region of Andaman Island. The Andaman Sea is roughly 140 kilometres from Port Blair.

Q) Is Himalaya an active volcano?

Ans. There is no volcanism in the Himalayas because they are also a tectonic border where plates collide. The Indian Plate [of the Indian Subcontinent] and the Eurasian Plate are smack dab in the middle of this collision. There is no discernible difference in density between the two plates because they are both made of continental lithospheric crust.

Q) Is Mount Everest a volcano?

Ans. A volcano is not Mount Everest. Tens of millions of years ago, the Indian and Eurasian tectonic plates collided, resulting in their creation.

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