ABSTRACT

Volcanoes also emit hot gases when they erupt. Magma contains dissolved gases, mostly water vapor (steam), carbon dioxide, and sulfur dioxide. As magma rises toward the surface and the confining pressure of the overlying rocks decreases, dissolved gases bubble out of solution, like the fizz in a bottle

What volcanoes are, where they occur, and why they form

The different types of volcanoes and the hazards associated with each type

How scientists study volcanoes and come to understand and predict their eruptions

How people can lower the risks posed by volcanoes

I N T H I S C H A P T E R Y O U W I L L L E A R N :

see, the amount of dissolved gases in magmas helps determine how explosive an eruption will be. The more dissolved gas, the more dangerous the magma.