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Parts of a Volcano

Volcanoes are one of the most powerful forces of nature on Earth. There are many parts of a volcano and they all do different things. Let’s take a closer look! An image of a volcano erupting.

Magma Chamber

Most of the parts of a volcano we can’t actually see. They are deep underground, inside the volcano. The magma chamber is at the bottom of the volcano. These are pools of molten rock underneath the Earth’s crust. The molten rock is under intense pressure in the chamber.

Over time this pressure leads to the surrounding rock cracking. This creates places for the magma to seep out and onto the surface. When it reaches the surface this is an eruption. When magma is inside the volcano it’s magma but once it is outside it’s lava. 

An illustration showing parts of a volcano.

Pictured are the parts of volcanoes.


Lava is what comes out of the volcano during an eruption, it is silicate rock that is hot enough to be in liquid form. When lava erupts from a volcano it is between 700 to 1,200 °C. What makes lava so hot? Geothermal energy! That’s heat created within the Earth that is leftover from its formation. It’s also from the decay of radioactive elements in the Earth.
After lava leaves the volcano it moves downhill in a lava flow. As it makes contact with the air and flows, it begins to cool and harden. This creates new igneous rock, which often forms around the volcano. This may eventually result in a cinder-cone volcano.   


The throat of a volcano is the uppermost part of the volcano, the entrance where ash and lava spew out of. 

An illustration of a volcano cross-section.

The throat of a volcano is the tube through which lava flows.


A volcano conduit is like the plumbing for the volcano. It is a pipe or vent at the heart of a volcano where material wells up from beneath the crust. This pipe then carries the magma from the chamber to the surface. Large volcanoes may have an entire network of conduits. After an eruption, the lava may cool over the conduit. This creates a plug.


A volcanic crater is a pit, generally circular. It can be large and sometimes very deep. We often find lava vents at the bottom. Craters form when the lava chamber empties enough for the crust above to collapse. This can happen slowly over time with the chamber emptying. Or it can happen quickly when the volcano erupts. 

Pyroclastic Flow/Currents

A pyroclastic flow is the fast-moving current of hot gas and rock. It is moving away from the volcano after it erupts. Pyroclastic means fire-broken rock. It refers to rocks that form from lava erupted as molten shreds. These currents can move up to 450 mph, with the gas getting as hot as 1,830 °F degrees.

An image of a pyroclastic flow..

this is a pyroclastic flow.

These currents often stay close to the ground and move downhill from the eruption. The currents speed depends on its density, the gradient of the slope and the volcano’s output rate. These currents are one of the greatest dangers associated with volcanic eruptions. They are one of the major causes of damage to the surrounding areas of the volcano.

Ash Cloud

Ash from volcanos is just small pieces of pulverized rock, minerals, and volcanic glass. These particles get created during a volcanic eruption.
This ash is made in two ways. One way is when lava comes into contact with water. This causes the water to evaporate into steam and for the magma to shatter. Another way is when dissolved gases in the magma expand. They expand until the magma shatters and propels into the air. As the magma cools in the air it solidifies into volcanic rock and glass. 

These fragments are so small the ash often gets picked up by the wind and spread out over a wide area. Because of this, ash can cause damage to the environment. Humans and animals may breathe this ash into their lungs and the ash may get into water systems. 

An image of lava in Hawaii dripping into water.

Lava rising to the surface and falling into the water.

Volcanic Bombs

Volcanoes make a huge mess when they erupt. They eject lava, ash and volcanic bombs! Volcanic bombs are larger projectiles soaring through the air. They form when the volcano erupts. We define volcanic bombs as measuring more the 2.5 inches. They cool before they hit the ground, many miles from the eruption site.

Volcanic bombs can sometimes be quite large, some even several feet in diameter. These volcanic bombs can be extremely dangerous, causing structural damage and fatalities. Luckily, such explosions don’t happen often.  

An image of lava solidifying into black rock.

Lava solidifying.

Other Great Resources:

Homework Help – What are the Different Parts of a Volcano: http://www.primaryhomeworkhelp.co.uk/mountains/volcanoparts.html

(Video) National Geographic’s Amazing Planet: Volcanos & Earthquakes: https://www.youtube.com/watch?v=_FsjrFv2l40

(Video) National Geographic Volcanos 101: https://www.youtube.com/watch?v=uZp1dNybgfc


 Written by: Monica Siegenthaler