Volcanoes – simply explained for grades 5 to 7

A volcano is an opening in the Earth's crust. There, magma, gases, ash, and rocks can rise up from inside the Earth. As soon as magma reaches the Earth's surface, it is called lava.

Volcanoes do not form by chance. They develop mainly where the Earth's plates are moving. Some volcanoes are high and steep, others are flat and broad.

A volcano can be active, dormant, or extinct. Active means: It has erupted or can erupt again. Dormant means: It is, in a way, sleeping. Extinct means: An eruption is very unlikely.

Remember: Volcanoes are parts of the Earth through which material from deep inside escapes.

A volcano consists of several important parts. You should know these terms:

There are often also side channels through which lava can escape from the sides. After many eruptions, the volcanic cone gradually forms.

The magma chamber supplies the material. It rises through the vent. Lava, ash, and gases come out at the crater.

Remember: Magma chamber, vent, and crater are the three most important parts of a volcano.

An eruption begins deep beneath the Earth. In the magma chamber, magma collects. Many gases are dissolved in it. As the pressure gets greater and greater, the magma pushes upward.

As it rises in the vent, the gases can expand. This makes the pressure increase even more. If it becomes too strong, an eruption occurs.

Then different materials can escape:

Some eruptions are calm and slow. Others are explosive and very dangerous. That depends on how viscous the magma is and how much gas it contains.

Remember: A volcanic eruption is caused by rising magma and high gas pressure.

There are different types of volcanoes. Stratovolcanoes and shield volcanoes are especially important.

Stratovolcanoes are high and steep. They form from many layers of lava, ash, and loose rock. Their eruptions are often violent.

Shield volcanoes are flat and very broad. Their lava is more fluid and flows far. That is why they build broad mountains rather than steep cones.

Stratovolcanoes often look like classic "storybook volcanoes." Shield volcanoes look more like huge, flat bulges.

Remember: Stratovolcanoes are usually steeper and more explosive, shield volcanoes broader and often calmer.

Many volcanoes are located at the boundaries of the Earth's plates. There, large rock plates move against each other. When plates collide, drift apart, or slide past each other, magma can rise.

One especially important area is the Pacific Ring of Fire. It runs around the Pacific Ocean. There are very many active volcanoes there, and earthquakes also happen frequently.

For example, volcanoes are found in:

But there are also volcanoes in the middle of a plate. They form above especially hot areas in the Earth's mantle.

Remember: Most volcanoes are located at plate boundaries, especially around the Pacific Ring of Fire.

Some volcanoes are especially famous:

Vesuvius in Italy is well known because in the year AD 79 it buried the city of Pompeii under ash and rock. It is still considered dangerous today.

Etna is located on Sicily. It is one of the most active volcanoes in Europe. Again and again, eruptions with lava and ash happen there.

Mauna Loa in Hawaii is a shield volcano. It is one of the largest volcanoes on Earth. Its lava is usually fluid and can flow far.

These three volcanoes clearly show how different volcanoes can be.

Remember: Vesuvius, Etna, and Mauna Loa are well-known examples of different types of volcanoes.

Volcanoes can be very dangerous. Lava is not the only problem. Other consequences are often even more threatening.

Dangers include, for example:

Ash can damage houses, cover fields, and disrupt air traffic. Gases can make people and animals sick. Fast, glowing hot clouds of gas and ash are especially dangerous.

That is why active volcanoes are constantly monitored. Researchers measure earthquakes, gases, and ground movements in order to warn people in time.

Remember: Volcanoes are fascinating, but during an eruption they are often life-threatening.

Volcanoes bring not only dangers, but also benefits. Volcanic ash often makes soils very fertile. That is why many people farm in volcanic regions.

In addition, volcanic areas provide valuable raw materials and building materials. In some countries, geothermal energy from underground is used to heat houses or generate electricity.

Volcanoes also attract many visitors. They are exciting natural wonders and important for tourism.

Benefits at a glance:

Remember: Volcanoes can destroy, but they can also benefit people.

Here are five short facts about volcanoes:

Volcanoes are therefore dangerous, useful, and scientifically very exciting at the same time. They show that our Earth is still active inside.

Take-away: If you understand volcanoes, you understand an important part of the structure and forces of the Earth.