Chapter 18 Volcanoes Section Two Volcanic Activity Vocabulary

Chapter 18 Volcanoes Section Two Volcanic Activity

Vocabulary § Magma Chamber: § The pocket beneath a volcano where magma collects. § Pipe: § A long tube through which magma moves from the magma chamber to Earth’s surface. § Vent: § The opening through which molten rock and gas leave a volcano.

Vocabulary § Lava Flow: § The area covered by lava as it pours out of a volcano’s vent. § Crater: § A bowl-shaped area that forms around a volcano’s central opening. § Silica: § A material that is formed from the elements oxygen and silicon; silica is found in magma.

How Magma Reaches Earth’s Surface § True or False: Magma forms in the lithosphere. § False § What happens during a volcanic eruption? § During a volcanic eruption gasses that have been dissolved in the magma rush out, carrying the magma with them.

Inside a Volcano § Circle the letter of each feature that all volcanoes share. § A. pocket of magma beneath the surface. § B. crack to the surface. § C. side vents. § D. crater.

Inside a Volcano § What is a lava flow? § A lava flow is the area covered by lava as it pours out of a vent. § Where does a crater form? § A crater forms at the top of a volcano around the central vent. § True or False: The pipe of a volcano is a horizontal crack in the crust. § False

Characteristics of Magma § What factors determine the force of a volcanic eruption. § Factors that determine the force of a volcanic eruption include the amount of gas dissolved in the magma, how thick or thin the magma is, its temperature, and its silica content.

Types of Volcanic Eruptions § § § Hot, fast-moving lava is called ____. pahoehoe Cool, slow-moving lava is called _____. aa What is a pyroclastic flow? § A pyroclastic flow is an explosive eruption of ash, cinders, bombs, and gases.