Discuss the causes of volcanic eruption and describe the land-forms formed by deposition of its lava

Volcanoes are one of the most powerful forces of nature. They have the ability to destroy everything around them when they erupt, but they also help create new land and shape the Earth’s surface. In this article, we will explain why volcanoes erupt, and also describe the different landforms that are created by the lava that comes out during an eruption.

What is a Volcano?

A volcano is an opening or a crack on the Earth’s surface through which hot lava, ash, gases, and rocks come out from deep inside the Earth. Volcanoes can be found on land and also under the oceans. Some volcanoes look like big mountains, while others are flat or hidden.

Where are Volcanoes Found?

Volcanoes are usually found along plate boundaries, where two parts of the Earth’s crust meet. These areas are known as "volcanic belts". The most famous volcanic belt is the Ring of Fire, which is around the edge of the Pacific Ocean. Many active volcanoes are located here.

What Causes a Volcanic Eruption?

A volcanic eruption is caused by the movement of magma from deep inside the Earth. Magma is hot, melted rock that is stored in the Earth’s mantle (a layer below the crust). When pressure builds up inside the Earth, the magma rises toward the surface and eventually comes out. Here are the main causes of volcanic eruptions:

1. Movement of Tectonic Plates

The Earth’s crust is made up of large pieces called tectonic plates. These plates float on the hot mantle. When they move or crash into each other, cracks form. Through these cracks, magma can rise and cause an eruption. There are three main types of plate movements that cause eruptions:

·        Convergent boundaries (plates come together): One plate goes under another, causing melting and magma formation.

·        Divergent boundaries (plates move apart): Magma rises up to fill the gap between the plates.

·        Transform boundaries (plates slide past each other): These sometimes create weak spots that allow magma to escape.

2. Increase in Pressure

As magma rises, it carries with it dissolved gases like water vapor and carbon dioxide. When it gets closer to the surface, the pressure around it becomes less. This causes the gases to expand and push against the rock. If the pressure becomes too high, the magma breaks through the surface and erupts.

3. Presence of Water

Water can seep into the Earth and reach hot rocks underground. When water touches these rocks, it turns into steam and increases pressure. This steam helps magma to rise and can also cause explosions.

4. Weak Spots in the Earth’s Crust

Sometimes, volcanic eruptions occur in places where the crust is thin or weak. These weak spots allow magma to reach the surface more easily. This is often the case in hotspot volcanoes, like those in Hawaii.

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What Comes Out During an Eruption?

When a volcano erupts, it releases many materials:

·        Lava – molten rock that flows on the surface

·        Ash – fine powder that can travel long distances

·        Gases – like sulfur dioxide, water vapor, and carbon dioxide

·        Volcanic bombs – large pieces of rock thrown out during powerful eruptions

What Happens After Lava Comes Out?

When lava comes out of the volcano, it spreads over the land. As it cools down, it hardens into solid rock. This creates many types of landforms. Some of them take thousands of years to form, while others appear quickly after the eruption.

Landforms Created by Lava Deposition

Here are some important landforms that are made when lava is deposited and cooled:

1. Volcanic Cones

These are mountain-shaped structures that form around the opening of a volcano. There are different types:

·        Cinder Cones – made from small pieces of lava that fall around the vent. They are steep and small.

·        Composite Cones (Strato-volcanoes) – made of layers of lava and ash. These are tall and have explosive eruptions. Example: Mount Fuji in Japan.

·        Shield Cones – made from thin lava that flows far before cooling. They are wide and gently sloping. Example: Mauna Loa in Hawaii.

2. Lava Plateaus

When lava flows from cracks (not just one opening), it can cover large areas. Over time, layers of lava build up to form a flat highland called a lava plateau. Example: Deccan Plateau in India.

3. Lava Domes

These are small, dome-shaped hills formed when thick, sticky lava piles up near the vent because it does not flow far. These domes grow slowly and may collapse or explode later.

4. Caldera

Sometimes, after a huge eruption, the top of the volcano collapses into the empty magma chamber below. This forms a large bowl-shaped depression called a caldera. Later, it may fill with water to become a crater lake. Example: Crater Lake in Oregon, USA.

5. Volcanic Islands

When underwater volcanoes erupt and the lava builds up over time, it may rise above the sea level to form an island. Example: The Hawaiian Islands.

6. Lava Tubes and Tunnels

As lava flows, the outer part may cool and harden, but the hot lava inside keeps flowing. When the inner lava flows away, it leaves behind empty tunnels called lava tubes. These can sometimes be explored like caves.

7. Basalt Columns

When thick lava cools slowly, it may crack into hexagonal columns. These beautiful formations are called columnar basalts. Example: Giant’s Causeway in Northern Ireland.

Benefits and Dangers of Volcanic Eruptions

Volcanic eruptions are dangerous but they also have benefits.

Dangers:

·        Destruction of life and property

·        Ash clouds can affect climate and health

·        Lava flows burn everything in their path

·        Gases can be toxic

Benefits:

·        Lava turns into fertile soil, good for farming

·        Volcanoes form new land

·        Hot springs and geothermal energy come from volcanic activity

·        Many minerals and natural resources are found near volcanoes

Volcanoes are a natural part of the Earth’s system. They erupt due to the movement of tectonic plates, rising magma, and pressure build-up. While they can cause destruction, they also help create new landforms such as volcanic cones, lava plateaus, and islands. By studying volcanoes and their effects, we can better prepare for eruptions and also understand how our planet is constantly changing. Volcanoes are not just destructive — they are also creators of beauty and new life.