Volcanoes tell us that the Earth's mantle consist of molten rock called magma. As tectonic plates move, the pressure of magma in the Earth's mantle increases. The pressurized magma erupts through a thin spot in the Earth's crust. The molten magma that erupts to the surface of the Earth is called lava.

Volcanoes, like earthquakes, are the most common near the border zones of tectonic plates. Volcanoes can also exist under water.

Volcanic eruptions tell us that a volcano is active, but predicting the time of a volcanic eruption is impossible. Some volcanoes are monitored with different measurement devices, which are used to gain information about the volcano's activity and hopefully warn neighboring areas of an impending eruption. 

Volcanic eruptions disturb human activity. During a volcanic eruption, volcanic matter such as ash is released to the atmosphere. This volcanic matter can create problems for agriculture and air traffic. 

Pictures and videos on a map  Real-time information on volcanic activity  Animation on the Galapagos islands

THE LARGEST RECORDED VOLCANIC ERUPTIONS IN HUMAN HISTORY

Area	Volcano	Year	Damages
Greece	Santorini	1650	An extremely powerful eruption and tsunami. No clear information on the damages.
Italy	Vesuvius	79	Approximately 3 400 fatalities, including the Roman city of Pompeii.
Hawaii	Kilauea	1983	Lava covered over 80 km2 of the island.
Columbia	Nevado del Ruiz	1984	Over 20 000 fatalities.

VOLCANOES WORTH FOLLOWING

Area	Volcano	Why is it worth following?
Italy, Napoli region	Campi Flegrei	A supervolcano. A large caldera with 24 craters. It has risen over 30 cm during the 2000s. It has increased its volcanic activity during recent years.

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A volcano.​