Inside a Volcano Beneath the surface of a volcano is a magma reservoir where rock that is exposed to heat and pressure changes into magma. A long tube through the crust called a pipe connects the reservoir to the surface. pipe vent crater crust magma reservoir lava side vent Vents and Craters Lava flows out onto the surface through an opening called a vent. Some volcanoes form smaller side vents where lava and gases escape. A cone- shaped depression called a crater often forms during explosive eruptions. magma pressure from surrounding rock pressure from expanding gases Why Does a Volcano Erupt? When magma rises toward the surface, gas bubbles expand and increase in pressure. The force of the gas pushes the magma out of the vent and causes an eruption. Inside a Volcano © Copyright NewPath Learning. All Rights Reserved. 94-4536 Visit www.newpathlearning.com for Online Learning Resources. Photos courtesy of USGS. magma reservoir
Pause and Review Label the volcano. Describe what happens inside a volcano that causes it to erupt. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ Inside a Volcano © Copyright NewPath Learning. All Rights Reserved. 94-4536 Visit www.newpathlearning.com for Online Learning Resources.