WHAT ARE VOLCANOES?

WHAT ARE VOLCANOES?

How do Volcanoes Form? Plate Tectonics!

Oceanic and Continental Plates

Volcanic Belts

Ring of Fire

Plate Boundaries

Yellowstone Cauldera

Hawaiian Islands are a Hot Spot

The Aleutian Islands are an Island Arc

Quick Review1.What is a volcano?2.How do volcanoes grow in size?3.How are plate tectonics and volcanoes

connected?4.What is a volcanic belt?5.Where is the Ring of Fire?6.What is a hot spot volcano?7.How are island arcs formed?

How it WorksWhen magma rises to the surface, the pressure of the surrounding rock decreases. this allows the dissolved gas in the magma to expand. the force of the expanding gas pushes magma from the chamber up into the pipe until it flows or explodes. Once magma escapes from the volcano, it becomes lava.

All magma is not equal

All magma is not equal

Volcanic eruptions

Quiet Eruptions Explosive Eruptions

Low silicaLow viscosity

Runny, thin lava

High silicaHigh viscosity

thick, chunky lava

Quiet Eruptions

Explosive Eruptions

Pyroclastic Flow

Pyroclastic Flow

Deadly Results

Pyroclastic Flow Debris

Ash: less than 2 mms Ash covering

Pyroclastic Flow Debris

Cinders: 2mms-64mms

Pyroclastic Flow Debris

Bombs: larger than 64 mms A field of pyroclastic bombs

Can you repeat that please?1. How does a volcano work?

2. What is a crater?3. What are the two types of lava?4. What is viscosity?5. How many types of eruptions are

there?6. What is a pyroclastic flow?7. How do you classify pyroclastic

debris?

3 different volcano types

Lava Plateau

Shield Volcano

Shield Volcano

Cinder Cone Volcanoes

Cinder Cone Volcanoes

Composite Volcano

Composite Volcano

Composite Volcano

Caulderas

Caulderas

A Volcano’s Life CycleACTIVE

a volcano that is erupting or has shown it may erupt in the future

DORMANT a sleeping volcano that can awaken in

the future and become activeEXTINCT

a dead volcano that is unlikely to erupt again.

Let’s get it straight.

1.What are the three main types of volcanoes?2.Name two other active volcano landforms.3.Name the different types of eruptions.4. Which volcanoes have quiet eruptions?5. Which volcanoes have explosive eruptions?6.Which volcano landform is the tallest and

steepest?7.Name the three sections of a volcano’s life

cycle.

Landforms from Magma

Volcanic NecksDikes, SillsBatholiths

Dome mountains

Volcanic Neck

Dike

Sill

Batholith

Dome Mountain

Half Dome Yosemite

Geothermal Activity

Hot SpringsGeysers

Geothermal Energy

Hot Springs

Geyser: Old Faithful

Geothermal Energy

Geothermal Energy

Let’s Review (one last time)

• What do volcanic necks, dikes, sills, and batholiths have in common?

• What heats a hot spring?• Can you name a famous geyser? How often

does it erupt?• What does geothermal mean?• Name two ways to use geothermal energy.• Name one benefit of geothermal energy.