Volcanoes

Volcanoes

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A ​

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is a structure that forms in Earth's ​

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when ​

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material or ​

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reaches the Earth's ​

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PARTS OF A VOLCANO

• MAGMA: It is molten mixture of rock-forming substances, gases, and water from the mantle.

• LAVA: magma that reaches Earth's surface.

• VENT: It is any opening at the Earth's surface through which magma erupts or volcanic gases are emitted.

• CINDER CONE: It is built from particles and blobs of congealed lava ejected from a single vent.

Multiple Choice

What is lava?

• It is magma that reaches Earth's surface.

• It is molten rock under the crust.

• It is built from particles and blobs of congealed lava ejected from a single vent.

Multiple Choice

What is magma?

• It is magma that reaches Earth's surface.

• It is molten rock under the crust.

• It is built from particles and blobs of congealed lava ejected from a single vent.

Multiple Choice

What is a cinder cone?

• It is magma that reaches Earth's surface.

• It is molten rock under the crust.

• It is built from particles and blobs of congealed lava ejected from a single vent.

Open Ended

Type the difference between lava and magma

• ​Form when plates move apart and rock rises to fill the space.

• Most occur at mid ocean ridges so they aren't usually seen.

​​Divergent boundaries

• ​When subduction happens, trapped water leaves the plate and mixes with the material of the mantle making it melt. If the magma makes it to the surface before cooling, a volcano forms.

• If the volcano gets big enough it can form a volcanic island.

Convergent Boundaries

Volcanoes and Plate Boundaries

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• A hot spot is an area where lava frequently erupts at the surface.

• A hot spot is fixed in the Deeper Mantle and doesn't move.

• As the plate moves over the hot spot, volcanic islands are formed making an island chain.

Hot spot volcanism

Multiple Choice

What geologic feature will occur at a hot spot ?

• volcano

• folded mountain

• deep sea trench

• crevasse

Multiple Choice

Which of the following will move with time ?

• a hot spot

• the plate the hot spot is over

• neither move

• both move

• Below the volcano is a magma chamber where the magma collects

• When erupting, the magma moves though the main vent to the crater or though the side vent and out into the world.

• If the eruption is explosive, the lava cools in the air and falls to earth in 3 forms.

  • Bombs: large chunks

  • Cinders: pebble size

  • Ash: finest particles.

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Parts of a volcano

Labelling

Label the parts of a volcano

Drag labels to their correct position on the image

Crust

Lava

Central vent

Side vent

Ash cloud

Crater

Poses very little threat to people. This is often the case with Hot spot volcanoes that have moved away from the hot spot.

Extinct

​Like a sleeping volcano. Little threat but could wake up some day.

Dormant

More of an immediate threat. It could potentially erupt at any time. Volcanologists monitor these closely.

Active

Types of volcanoes

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There are three types of volcanoes

• ACTIVE

• DORMANT

• EXTINCT

• AWAKE

• SLEEPY

​This will happen if the magma is hot or low in silica.

The lava will be thin and runny.

Not necessarily safe! Lava still moves very quickly.

Quiet Eruptions

• This will happen if the magma has a lot of silica. Silica makes the lava thick and sticky so it will build up pressure.

• An explosive eruption can send ash and other byproducts high into the atmosphere affecting MANY continents.

Explosive Eruptions

Volcano Hazards

• Volcanologists can use a devise called a tiltmeter to measure the volcano swelling as the magma chamber fills up.

• Seismographs detect rumblings in the volcano

Tools

• We can monitor the gas emissions from volcanoes to check for an increase in sulfur dioxide. This can indicate an eruption can happen.

Gas emissions

How we predict Volcano Hazards

Multiple Choice

How much ___ that is in a volcano's magma helps to decide whether it will be explosive or quiet.

• silica

• rock

• air holes

• soil

Multiple Choice

Where do volcanoes typically form?

• At plate boundaries.

• In the middle of tectonic plates.