Warm-up What is your favorite holiday tradition?

Volcanoes

What are volcanoes? A volcano is an opening in Earth that erupts gases, ash, and lava.

How do volcanoes form? Magma is less dense than the rock around it, so it is forced toward the surface Vent: Opening that magma flows through Crater: The steep-walled depression around a volcano’s vent

Where do volcanoes occur? Divergent Plate Boundaries – Plates move apart as magma comes up forming a volcano Convergent Plate Boundaries – Oceanic Plates subduct under Continental Plates and melt into magma that will sometime rise to form a volcano

Where do volcanoes occur?

Hot Spots – Areas between Earth’s mantle and core that are unusually hot. Example: – Hawaiian Islands Pacific Plate moving over a stationary hot spot.

Hot Spot Occurrence

What controls eruptions? The more trapped gases, silica and water vapor the more explosive the eruption.

What controls eruptions? – quiet eruption -> Basaltic Magma, silica poor – Silica Rich: explosive eruption Granitic Magma, Mount St. Helens, WA – Intermediate Silica: Quiet / explosive eruption. Andesitic Magma, Convergent Plate Boundaries, Krakatau, South America

Forms of Volcanoes Shield Volcano – Quiet eruptions – Silica poor – Basaltic lava – Layers buildup and form a broad volcano with gently sloping sides – Example: Hawaiian Islands

Forms of Volcanoes Cinder Cone Volcanoes – Explosive eruptions – Silica rich – Granitic lava – Steep sides of loosely packed tephra (ash) – Paricutín, Mexico

Forms of Volcanoes Composite Volcano/ Stratovolcano – Varying explosions depend on amount of silica and trapped gases. – Andesitic lava – Dome shaped – Mount Saint Helens, WA

Violent Eruptions 1883: Krakatau, Indonesia 1906: Vesuvius, Italy 1983: Kilauea, Hawaii 2000: Popocatepetl, Mexico

Terms you will need to know Pyroclastic Flow- Ground hugging avalanche of tephra and gases Lahar- Mudflow with rock fragments Caldera- A crater like depression left from a prior eruption SuperVolcano- a volcano created from a hot spot that has the power to cause substantial damage

Volcano Carousel Read your article Fill in graphic Organizer Create a poster of your volcano to present to the class

Warm-Up The volcano handout you picked up!

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Pompeii RAFT Role: Pompeii villager Audience: yourself Form: Journal entry Topic: Pompeii eruption Be sure to include at least 5 volcanic facts in your Narration Type of volcano Type of lava flow Type of Emissions Type of Eruption How the volcano formed

Study Guide Work with a partner to complete your study guide You have until 1:40