🌋 How Volcanoes Work
Volcanoes are openings in the Earth’s crust where molten rock, ash and gases escape from deep underground. They form at the edges of the massive tectonic plates that make up the Earth’s surface — where plates crash together or pull apart, the pressure forces magma upward. Volcanoes have shaped our planet for billions of years — and continue to do so today!
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How Volcanoes Form
- Volcanoes form where tectonic plates meet or pull apart
- Magma (molten rock) pushes up through cracks in the Earth's crust
- The world has about 1,500 potentially active volcanoes
- Around 50–70 volcanoes erupt every year
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Types of Eruption
- Effusive eruptions produce slow, flowing lava rivers
- Explosive eruptions blast ash and rock kilometres into the sky
- Some eruptions create pyroclastic flows — clouds of hot gas and rock reaching 700°C
- A supervolcano eruption could affect the entire planet
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Famous Volcanoes
- Mount Everest is tall — but Mauna Kea in Hawaii is taller measured from the ocean floor
- Vesuvius buried Pompeii in 79 AD under metres of ash in hours
- Krakatoa's 1883 eruption was heard 5,000 km away
- Mount Etna in Sicily is Europe's most active volcano
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Lava Facts
- Lava can reach temperatures of 1,200°C — hot enough to melt steel
- It flows at speeds from walking pace to 60 km/h depending on type
- Pahoehoe lava is smooth and rope-like; A'a lava is rough and jagged
- New land is created as lava cools and solidifies — Hawaii grows a little each year
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Life Around Volcanoes
- Volcanic soil is extremely fertile — great for growing crops
- Hot springs and geysers near volcanoes are home to unique heat-loving bacteria
- The deep ocean floor near underwater volcanoes hosts hydrothermal vent ecosystems
- Despite the danger, 800 million people live near active volcanoes
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Volcanoes in Space
- Olympus Mons on Mars is the largest volcano in the solar system — 21 km tall
- Jupiter's moon Io is the most volcanically active body in our solar system
- Venus has more volcanoes than any other planet — over 1,600
- Volcanic activity on Enceladus (Saturn's moon) sprays ice into space
✨ Amazing Volcano Facts
🌋 The word ‘volcano’ comes from Vulcan — the Roman god of fire and metalworking.
🔥 Pompeii was buried so quickly in 79 AD that archaeologists found preserved loaves of bread in bakery ovens.
🌎 About 80% of the Earth’s surface was shaped by volcanic activity over millions of years.
⛰️ Iceland sits on a volcanic hotspot — it has 130 volcanic mountains and gets 25% of its electricity from geothermal energy.
👀 Underwater volcanoes (called seamounts) outnumber land volcanoes — there may be over 1 million on the ocean floor.
🌿 After the 1980 eruption of Mount St Helens in the USA, forests grew back within just a few years thanks to fertile volcanic ash.
🤔 Volcano Quiz
Click each answer to check it instantly!
Question 1 of 6
What is magma called once it reaches the surface?
Question 2 of 6
What is the largest volcano in our solar system?
- Mauna Kea
- Olympus Mons
- Mount Etna
- Mount Vesuvius
Question 3 of 6
What is a pyroclastic flow?
- A slow river of cooling lava
- A type of ash cloud that rises straight up
- The underground chamber where magma collects
- A cloud of superheated gas and rock racing down a volcano
Question 4 of 6
Why is volcanic soil so good for farming?
- It is always perfectly moist from underground water
- It is rich in minerals released from deep inside the Earth
- It is warmer than other soils year round
- It contains no rocks that would block plant roots
Question 5 of 6
What temperature can lava reach?
- About 1,200°C
- About 3,000°C
- About 700°C
- About 400°C
Question 6 of 6
What connects tectonic plates to volcanic activity?
- Tectonic plates have no connection to where volcanoes form
- Volcanoes form randomly with no geological pattern
- Volcanoes only form at the exact centre of tectonic plates
- Most volcanoes form where tectonic plates meet, separate or one slides under another
📚 Key Words
magma
Molten (liquid) rock found underground. Once it erupts from a volcano it is called lava.
lava
Magma that has reached the Earth's surface through a volcanic eruption.
tectonic plates
The massive sections of the Earth's outer layer that slowly move, carrying the continents with them.
pyroclastic flow
A fast-moving cloud of hot gas, ash and volcanic rock — one of the most dangerous volcanic hazards.
active volcano
A volcano that has erupted recently or is likely to erupt again. There are about 1,500 potentially active volcanoes on Earth.
supervolcano
An exceptionally large volcano capable of an eruption that would affect the entire planet's climate.
eruption
When a volcano expels lava, ash, gas or rock — either explosively or as a slow lava flow.
geothermal
Relating to heat from inside the Earth. Geothermal energy uses this heat to generate electricity.
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