Question

What causes the force that pushes magma from the magma chamber through the pipe and vent of a volcano?

gravity
water flow
expanding gases
convergent boundaries

Answer 1

The primary force that pushes magma from the magma chamber through the pipe and vent of a volcano is **expanding gases**. In the magma chamber, gases dissolved in the magma (such as water vapor, carbon dioxide, and sulfur dioxide) can expand significantly as the pressure decreases when the magma rises toward the surface. This expansion creates pressure that forces the magma upward through the volcanic conduit. While gravity does play a role in the overall movement of magma, it is the pressure from the expanding gases that is the main driving force behind volcanic eruptions.