Volcanoes are some of the most fearsome things in nature.

They're responsible for the largest explosions ever known.

They have created entire land masses,

and they've shaped the Earth climate

and may have been responsible for mass extinction events during our planet's history.

Today, as you are listening to this, somewhere on Earth, there are over 40 of them erupting

right this second.

Learn more about volcanoes, how they work, and how they're different from each other,

on this episode of Everything Everywhere Daily. What a volcano is is actually pretty easy to define.

A volcano is an opening in the earth's crust that allows for magma from below the earth's surface to come to the surface,

expelling gas, ash, and lava.

The difference between magma and lava is that magma refers to molten or semi-molten rock below

the surface of the earth, and lava refers to molten rock on the surface of the earth.

Defining what a volcano is is much easier than understanding how they work.

Every point on the surface of the earth has magma below it. Why don't we have volcanoes shooting up everywhere,

or at least at random points all over the planet?

The crust of the Earth is made up of a lighter rock

than the rock inside the mantle.

The average density of continental crust is approximately 2.7 grams per cubic centimeter.

And the crust on the ocean floor is approximately 3 grams per cubic centimeter.

The magma from inside the Earth is usually only going to be able to break through the crust where there is some sort of event or condition that allows it to break through.

Most volcanoes on Earth exist at the boundary of

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