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.