Volcanoes: Facts, Formation, and The Deadliest in History

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1. What are volcanoes?

Volcanoes are, to put it simply, openings on the surface of the Earth, or any planet for that matter, which are capable of allowing magma, ash and gaseous substances to seep or explode from within the planet through the outer crust.

2. Why do volcanoes erupt?

Located beneath the outer crust of the Earth (or other planets), rock is heated to such a hot temperature that it melts and becomes liquid magma, or molten lava. This liquid substance is less dense than the solid rock (different properties with a higher melting point) and so it is pushed upward toward the surface of the Earth. This is the same thing that happens if a solid object is placed in a container with water. Because the water is more malleable than the solid, it is forced to move. The same thing happens below the surface of the Earth. When the magma reaches the surface of the Earth, it takes advantages of weak points in the outer crust, along the fault lines. Often, the magma contains water and gases as well. When these elements reach air above the Earth’s surface, they can react violently, creating a reaction that results in an eruption. However, not all volcanoes erupt violently. Some seep molten lava over long periods of time.

3. How are volcanoes formed?

Volcanoes are formed, usually along tectonic plates. The Earth’s crust is made up of tectonic plates. These separate plates adjoin each other along fault lines, but they are constantly moving. When they move, the cause earthquakes. Sometimes, when tectonic plates cause an earthquake, magma from within the earth escapes. If this takes place, the magma needs to be displaced somewhere. When it reaches the cold air of the Earth’s atmosphere, it changes from a liquid to a gas, and hardens, often creating a mountainous formation over years and years of eruptions. The length of time it takes a volcano to form depends on the frequency at which it erupts.

4. How are underwater volcanoes formed?

Underwater volcanoes are formed in much the same way as volcanoes that are formed above ground. Often, underwater, or submarine volcanoes are not mountainous volcanoes that people are used to seeing above ground. Instead, these volcanoes are simply fizzures or holes within the Earth’s crust that allow gas, liquid or ash to escape from the underlayers of the planet. These volcanoes are located along fault lines in tectonic plates and behave in the same ways as volanoes that are located above ground along fault lines. Because lava is buoyant in water, when a submarine volcano erupts, the lava often floats upward rather than outward (due to gravity above ground) as it does above ground. Because of the upward direction and rapid cooling effect of the water, these volcanoes are often much taller and narrower than above ground volcanoes.

5. Major volcanic eruptions in the last 50 years

What are the ten deadliest volcanoes in history?
Tambora, Indonesia
Year: 1815
Deaths: 92,000

Krakatau, Indonesia
Year: 1883
Deaths: 36,417

Mount Pelee, Martinique
Year: 1902
Deaths: 29,025

Ruiz, Colombia
Year: 1985
Deaths: 25,000

Unzen, Japan
Year: 1792
Deaths: 14,300

Laki, Iceland
Year: 1783
Deaths: 9,350

Kelut, Indonesia
Year: 1919
Deaths: 5,110

Galunggung, Indonesia
Year: 1882
Deaths: 4,011

Vesuvius, Italy
Year: 1631
Deaths: 3,500

Vesuvius, Italy
Year: 79
Deaths: 3,360

6. How often do volcanoes erupt?

All volcanoes are different. There is no way to predict when a volcano will erupt. Some known volcanoes have been continuously erupting for millenia, like the Strombilo volcano in Italy, while other structures haven’t erupted for an equally long amount of time.

Despite their inability to predict when a volcano will erupt, scientists have developed a classification system that labels each volcano as dominant, active and extinct. Dominant volcanoes are those that have erupted in the past but have ceased to erupt in recent times. The exact dates of “in the past” and “recent times” depend on the region and the timeline of records that have been kept for a particular volcano. Active volcanoes erupt regularly. These are still unable to be predicted, but they have a history of showing regular or semi-regular eruptions. An extinct volcano is one for which scientists have no records of eruptions. These are believed to be incapable of erupting in the future.

7. How long are volcanoes active for?

It is not known how long volcanoes are active for because the length of time differs between each volcano. As far as scientists have been able to determine, there is no reasoning behind why certain volcanoes seem to have become extinct while others continue to be active.

8. Where are volcanoes found? Where do volcanoes form?

Volcanoes are formed along fault lines in the Earth’s tectonic plates. These are characteristically weak points that can pull apart, slide against each other or push against each other and cause gaps, openings and holes in the surface of the planet, allowing liquid magma to be displaced above the surface of the Earth.

9. Which country has three out of the five active volcanoes in Europe? Where are the remaining two?

Italy is home to Mount Etna, Mount Vesuvius and Mount Stromboli, all active volcanoes. Mount Hekla is another active volcano that is located in Iceland, and Santorini is an entire stretch of islands created by volcanic eruptions located about 120 miles off the coast of Greece.

10. Which country has the most volcanoes?

The Republic of Indonesia contains 167 known active volcanoes in the world. This is more than any other country.

11. How many volcanoes are in the US?

There are around 100 volcanoes located in the US, 60 of which are within Alaska.

Resources about Volcanoes

Focuses of Nature – Volcanoes National Geographic
Website

USGS – Volcano Hazards Program
Website

Annenberg Media Exhibits – Volcanoes
Website

FEMA For Kids – Volcanoes
Website

Resource by A.Moore

I just moved to Michigan from South Carolina. This is my first winter here and so far it's freezing. I enjoy traveling, drawing, camping, writing, and doing community service in my spare time. I work for a education company and help them with their outreach to teachers and students. Hope everyone enjoys my articles.

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