Movements in the earth's crust can cause both volcanic eruptions and earthquakes. To help you understand the processes involved, we have collected a range of volcano terms with their definitions, volcano diagrams, volcano images and more to help with your learning about the geography topic of volcanoes. Scroll down to find out more.
WHAT IS A VOLCANO?
Label a volcano
What is a volcano?
A volcano is an opening in the earth's crust through which magma, ash and gas erupt. Volcanoes can be different shapes although they are commonly cone shaped
mountains as seen in this picture. These cone shaped volcanoes are made up of layers of ash and lava. Most volcanoes are found at plate boundaries.
Mount Fuji, Japan
Mount Fuji in Japan. This famous volcano sits close to
the point where three tectonic plates meet.
An active volcano is one that is known to have erupted in recent times, or which is likely to erupt again. For example, Mount Etna in Italy.
What is an active volcano?
Mount Etna in Italy is an active volcano.
It has erupted nine times since the year 2000.
What is a dormant volcano?
A volcano that has erupted in the last 2000 years but not recently. It is inactive but not extinct. It is difficult to decide whether a volcano is dormant or extinct.
What is an extinct volcano?
A volcano that is not expected to erupt again. For example, Mount Kenya is an extinct volcano.
Mount Etna, Italy
Inside a volcano
This diagram has all the parts of a volcano clearly labelled. Most volcanoes are cone shaped mountains like this one in the diagram. Volcanoes can erupt from the crater on their peak or from asecondary vent on their side. The side of a volcano
is called the flank.
The layers of ash and lava are built up over successive eruptions. The more eruptions there are, the more layers of ash and lava there will be.
What is a shield volcano? What is a cone volcano?
Cone volcanoes are usually steep sided. They are formed from layers of ash and lava. Shield volcanoes are made from
fast flowing, lava which flows easily over the surface, forming larger volcanoes with gentle sides.
The top 10 volcanoes according to Time magazine are:
Mount St. Helens
Nevado del Ruiz
Read more: Time Magazine
Mount Vesuvius, Italy
The city of Naples with Mount Vesuvius in the background.
Where are volcanoes located?
Volcanoes are most commonly found along plate boundaries.
The earth's crust is cracked and the pieces of the Earth's crust formed by the cracks are called tectonic plates.
These tectonic plates can be seen in this map.
The plates are continually moving (albeit very slowly, a few millimetres a year) and this movement helps to form volcanoes.
What does the inside of a volcano look like and how close can someone get to a live volcano? Both these questions are answered here in this short clip lasting 1 minute.
Up close to the molten hot lava, what would it look like? Have a look in this three minute clip.
This excellent animation shows what is happening inside the earth to make the tectonic plates move around.