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Volcanoes
are
Hot Stuff
By
Shana Huffaker And Doreen Snyder
Modified by Mr. Kennedy
What is a Volcano?
• Volcano- Areas of earth’s surface through which
magma and volcanic gases pass
• Volcano comes from the Roman word Vulcan,
which means “fire”
 Magma rises because it is less dense than the
solid rock around it.
What are the parts of a
Volcano?
1. VENT- the vent
is the opening
from which lava
flows. Dust, ash,
and rock
particles can also
be thrown out of
the vent!
A lava flow is the area covered by
lava as it pours out of a vent
A crater is a bowl-shaped area
that may form at the top of a
volcano around the central vent
Craters, Calderas, and Lava
Plateau
Crater
• From explosions of material out of
the vent and the collapse of material
back into vent
Caldera
• Much larger depression that
forms when magma chamber
empties and its roof collapses
Lava Plateau
• Forms when lava erupts from long cracks, or fissures,
and spreads out evenly (thousands of km)
How are
volcanoes
formed?
Deep in the earth it is very
hot. It is so hot that
rocks melt. The
melted rock is called
magma. The magma is
lighter than the rocks
around it so it rises.
Sometimes it finds a
crack or hole in the
earth’s crust and bursts
through. This is how a
volcano begins.
Why do
volcanoes
erupt?
Pressure builds deep in the earth
where the magma is. Suddenly
the gases escape and violently
explode. It is kind of like
toothpaste squirting out of a tube
when you give it a hard squeeze.
What are the
different
kinds of
volcanoes?
Volcanoes do not all look alike.
Their shape is based on what type
of materials they erupt. There are
three main kinds, or shapes, of
volcanoes.
3.
Volcanic
cone- is the
pile of lava,
dust, ashes,
and rock
around the
vent. It can
be found in
different
shapes!
Types of Volcanoes
Shield volcano
Cinder cone volcano
Composite volcano
Shield
Volcanoes
Volcanoes that build up from
many slow, steady, flows of hot
lava, are called shield volcanoes.
This kind of volcano is low and
broad with gently sloping sides.
They look like a warriors shield.
Shield Volcano
• Is wide and
somewhat flat.
• It forms from a
quiet eruption.
• Lava flows out
quietly and for
great distances.
Cinder Cone
Volcanoes
Cinder cone volcanoes form
when solid rock and ash shoot
up into the air and fall back
around the volcano opening.
The cinder cone volcano has
steeply sloped sides.
Cinder Cone Volcano
Has tall, very
steep sides.
Has explosive
eruptions.
This eruption
produces a lot of
cinder and ash.
Strato
or
Composite
Volcanoes
Strato volcanoes, also called
composite volcanoes, erupt with
molten lava, solid rock, and ash.
The layers pile up much like
layers of cake and frosting. The
layers form into symmetrical
cones, and the slopes are steep.
Composite Volcano
Form from
explosive
eruptions.
Produce a lot of
lava and ash.
Is small, with
steep sides.
What’s inside a volcano?
• Magma
Chambermolten rock that
feeds a volcano
• Vents- cracks in
the crust
• What is the
difference
between magma
and lava?
Types of Volcanoes
• Shield Volcano
a) Built from layers of
lava
b) Non-explosive
eruptions
c) Not very steep, but
can be big
Types of Volcanoes
•
Cinder Cone
Volcano
a) Built from
pyroclastic material
b) Moderately
explosive, short
eruptions
c) Small in size, steep
slopes
Types of Volcanoes
•
Composite
Volcanoes
a) Most common type
b) Explosive eruptions
and lava flow
c) Built from
pyroclastic material
AND lava
What Erupts from a
Volcano?
Blocky lava
Lava can be
thick or thin.
Pahoehoe
Aa
Pillow lava
What Erupts from a Volcano?
Pyroclastic material
• Rock fragments created by
eruptions
•magma explodes from volcano and solidifies in the air
•existing rock is shattered by powerful eruptions
Lapilli
Volcanic bombs
Volcanic blocks
Volcanic ash
How do volcanologists predict
eruptions?
• Measuring Small Quakes
– Before eruption, increase in number & intensity
• Measuring Slope
– Bulges may form with magma (tiltmeter)
• Measuring Volcanic Gases
– Outflow of volcanic gases
• Sulfur dioxide, carbon dioxide
• Measuring Temperature from Orbit
– Measure changes in temperature over time
There is much more about volcanoes
out there. Look in books and on the
internet . Have Fun!
Pictures, Images, and information From:
Soames Summerhays/Photo Researchers, Inc.
Kraft-Explorer/Photo Researchers Inc.
Masao Hayashi-Dung/Photo Researchers Inc.
Why Do Volcanoes Blow Their Tops? By Melvin and
Gilda Berger
www.usgs.gov/education/learnweb/volcano/index.ht
ml