Why Do Volcanoes Erupt?


A volcano is a landform present on the surface of the earth that consists of an opening from which molten lava, gases, and volcanic ash escape. When the hot molten material present underground tend to escape from the cracks in the earth’s crust, it is known as a volcanic eruption. The eruption can be either explosive, which means the material is released up in the air forcefully or it can be gentle, which means the material comes out slowly. A volcano is usually a mountain-like structure that can be dormant, active, or extinct in nature. When a volcano erupts, it releases a high amount of steam, sulfur dioxide, ash, and other gases in the open environment.

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Causes of Volcanic Eruption

The main cause of a volcanic eruption is the magma escaping from the underground. Magma is formed when the ocean water comes in contact with the earth’s mantle and tends to decrease its melting point. When the rock layer present above the magma gets loose and breaks down the lava slides out. Hence, the increase in magmatic force is one main reason that causes a volcano to explode. Another reason for volcanic activity to occur is the internal energy of the earth. The internal energy of the earth is generally channelized by three main factors including the action of the radioactive material present beneath the earth’s crust, conversion of earth’s gravitational energy into heat energy, and primeval solar energy trapped inside the earth. The magma consists of a number of dissolvable compounds. At high concentrations, the water and sulfur compounds contained by the lava resist to dissolve and tend to form gas bubbles. These gas bubbles possess high pressure. They tend to move in the upward direction and burst out with great force, leading to a volcanic eruption.

Causes of Volcanic Eruption

Types of Volcanic Eruption

Active Volcanoes

The volcanoes that experience frequent volcanic eruptions are known as active volcanoes. There are approximately 500 active volcanoes present on the earth, a majority of which are located in the Pacific Ring of Fire. In other words, active volcanoes are those that have recently experienced or are expected to have eruptions in the near future.

Dormant Volcanoes

Dormant volcanoes are the volcanoes that no longer produce eruptions; however, there are chances that they might begin to erupt again sometime in the future. Mount Kilimanjaro located in Tanzania and Mount Fuji in Japan are some of the examples of dormant volcanoes.

Extinct Volcanoes

The volcanoes that lack the lava supply and do not have any chances to erupt again in the future are known as extinct volcanoes. An extinct volcano is also known as a dead volcano. Some examples of extinct volcanoes include Mount Kilimanjaro in Tanzania, Mount Buninyong in Victoria Australia, the Nut in Tasmania Australia, Tamu Massif in the Northwest Pacific Ocean, etc.

Types of Volcanic Eruption

Positive Effects of Volcanoes

1. Volcanoes help the earth to remove excessive heat trapped inside it.

2. They help to build new islands. Hence, they are a prominent example of the constructive forces of nature.

3. The volcanic deposits are often used as building materials because of their massive tensile strength.

4. Volcanoes help to generate geothermal energy that can be further used for a number of applications.

5. The ash released during a volcanic eruption can be used as a fertilizer.

6. Volcanoes contribute to form a tourist site, thereby generating economic benefits.

Positive Effects of Volcanoes

Islands formed by a volcano

Negative Effects of Volcanoes

1. Volcanoes lead to a number of infectious and respiratory diseases.

2. Toxic gases are released prior to and during a volcanic eruption that contaminates the environment and deteriorates the air quality index.

3. Sulphur dioxide released by a volcano causes acid rain.

4. Volcanoes cause a lot of tragic accidents.

5. The cities and other habitats located around a volcano are much likely to suffer discomfort.

6. Volcanoes are responsible for the loss of many human and animal lives.

Negative Effects of Volcanoes

Lava from a volcano damaging the nearby agricultural land

8 Countries with the Most Volcanoes

Following is the list of the countries, with the number of volcanoes listed against them:

1. Indonesia – 139.

2. Iceland – 130.

3. Japan – 112.

4. Chile – 104.

5. Ethiopia – 57.

6. Papua New Guinea – 53.

7. Philippines – 50.

8. Mexico – 43.

Region Where most Volcanoes are Located

Most of the volcanoes present on the earth are located around the pacific ocean. These volcanoes are roughly arranged in the form of a ring known as the ring of fire. Indonesia is the country that is considered to be the hub for most of the volcanoes. A total of 139 volcanoes currently persist in the nation, out of which 76 volcanoes have erupted approximately 1,171 times. The subduction of the Indian Ocean crust beneath the Asian plate tends to form a volcanic arc known as the Sunda Volcanic Arc. The Sunda Volcanic Arc stretches for approximately 3,000 km and is home to approximately 76% of volcanoes existing in Indonesia.

Pacific Ring of Fire

Pacific Ring of Fire; where most volcanoes are located

The Country with no volcanic activity

Australia is a country with no volcanic activities; however, it is home to over 150 volcanoes. None of the volcanoes has been erupted for over four to five thousand years. Hence, it is considered to be a no-volcano region. The reason is that Australia is located in the middle of the Indo-Australian plate; therefore, the region rarely experiences any geological faults. In the absence of the geological faults in the plates, the molten rock does not receive sufficient energy to get away and hence, it does not cause the volcano to explode.

Australia as a No-Volcano Region

Volcanoes in Australia and their location in the centre of the Indo-Australian Plate

World’s Most Dangerous Volcano

Vesuvius volcano is considered to be the most dangerous volcano present on the earth. It is located in the Gulf of Naples, Italy. The eruption of lava and gases from this volcano is highly explosive and violent in nature. The areas located near the volcano are densely populated, which increases the risk to the lives of around 3 million people. Vesuvius has been inactive since the year 1944; however, there are chances for it to revive and explode in the future. As per the observation of the previous outbursts, Vesuvius has been highly devastating and has caused harm to more than thousands of people in the past.


Vesuvius Volcano located in Italy

World’s Largest Volcano

Mauna Loa is the largest volcano present on our planet. It is located in Hawaii about 4 km above sea level. It is an active volcano. The top of the volcano is situated at a height of approximately 17 km from the base. Mauna Loa has had a total number of 33 massive eruptions to date. It is quite heavy and has a bulky structure, which has caused a bend in the oceanic crust present under the volcano.

Mauna Loa

Mauna Loa Volcano located in Hawaii

World’s Smallest Volcano

The Cuexcomate is the smallest volcano in the world. It is located in central Mexico. It is about 950 years old volcano. It is 13 meters tall and has a diameter equal to 23 meters. Located in the suburb of the city of Puebla, Cuexcomate is a very popular tourist destination. It has been inactive for several years, and there are no possible chances for the volcano to erupt in the near future.


Cuexcomate Volcano located in Central Mexico

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