volcano notes

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Epicenter
Pre-Lab

Epicenter
Lab

Instructions

Grab a handout from the front

Tome un folleto del frente

Poll

How was your weekend??

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Volcanoes and Magma

What is Magma?

• Magma is hot, molten

rock that forms
beneath the Earth’s
surface

• Once magma erupts on

the surface, it is called
lava

• Contains solid mineral

crystals, water vapor,
and dissolved carbon
dioxide

What’s inside magma?

• Most important chemical compound is silica

(SiO2)
– Determines its viscosity (resistance to flow),

which influences the type of eruption

– Higher the silica content, the greater the

viscosity

Match

Match the following

• High silica

• low solica

• viscosity

more explosive

less explosive

resistance to flow

• more explosive

• less explosive

• resistance to flow

Types of Magma

• Basaltic

– Low silica content
– More fluid lava

• Andesitic

– Intermediate silica content

• Granitic

– High silica content
– Thick and sluggish lava
– More violent eruptions

Reorder

Reorder the following from LEAST to MOST explosive

• Balastic

• Andesitic

• Granitic

1

2

3

• 1
• 2
• 3

Pyroclastic Material

• Also called tephra
• Different from magma,

but also found at
volcanoes

• Composed of mineral

pieces and ash

• Common at the most

violent type of
eruptions
– Ex: Mt. St. Helens

Where do we find volcanoes?

• At a subduction zone (where one plate

sinking below another)

• At a spreading center (divergent boundary)

• At hot spots in the middle of plates

Drag and Drop

Where do we find volcanos?​

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Drag these tiles and drop them in the correct blank above

spreading center

subduction zones

transform boundary

in the maze

hot spots

the attic

What is a Hot Spot?

• A hot spot is a unusually hot area in the

mantle layer

• Hawaii, Iceland, and Yellowstone are

examples of hot spots

Hawaii Hot Spot

• Pacific plate moves

northwest at 9 cm a year

• As the plate moves, the hot

spot does not, creating a
chain of volcanic islands

• The “Big Island” of Hawaii is

the newest island

Open Ended

The hawaiian islands are created because the pacific plate is moving over a ___ ____

What decides how violent a

volcanic eruption is?

• Three factors involving the magma…

– Composition
– Temperature
– Amount of gases dissolved

Multiple Choice

What is NOT a factor in how violent an eruption is?

• dissolved gases

• temperature of magma

• composition

• distance from the moon

Volcano Types

• There are three main types of volcanoes…

Shield Volcanoes

• Large volcanoes with gently-sloping sides
• Made of liquid lava
• Often occur at “hot spots”

Shield Volcanoes

• Kilauea, Hawaii
• Mauna Loa, Hawaii

Multiple Choice

What type of magma does a shield volcano have?

• liquid

• solid

• sticky

• think

Cinder Cone Volcanoes

• Small volcanoes with steep sides
• Frequently occur in groups
• Made mostly of pyroclastic material

Cinder Cone Volcano – Paricutin,

Mexico

• Developed in a

cornfield in 1943

• Grew to 6 ft after 1

day

• Reached 164 ft the

next day, 500 ft by the end of the week.

• Current elevation is

10,400 ft

Parícutin: The Birth of a Volcano | Smithsonian National Museum of Natural History

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Composite Volcano

• Also called stratovolcanoes
• Formed by alternating layers of lava and

rock fragments

• Usually form tall, snow-capped peaks
• Most of Earth’s composite volcanoes are in

the “Ring of Fire”

• Most violent type of volcanic activity
• Most common type of volcano

Composite Volcanoes

Multiple Choice

What type of volcano is formed by alternating layers

• shield

• composite

• cinder cone

Composite Volcanoes

• Mt. Vesuvius,

Pompeii

• Mt. St. Helens,

Washington

• Mt. Fuji, Japan
• Mt. Shasta,

California

Categorize

Options (7)

gently sloping sides

liquid lava

small with stee sides

made of pyroclastic material

formed by alternaing layers of lava and rock fragments

tall snow-capped peaks

most violent

Organize these options into the right categories of volcano

Shield Volcanoes

Cinder Cone

Composite

Open Ended

Any questions?