3. Chart All About Volcanoes
What I Know
What I Would
Like To Know
What I Have Learned
4. What Is a Volcano?
A volcano is a mountain made from
an accumulation of rock and ash.
Molten rock (magma), gases, and ash
erupt from an opening at the top or
vents that form on the sides. Once
erupted, the molten rock becomes
lava and flows down the
mountainsides.
5. Why does a volcano erupt? Magma
builds up in a chamber beneath Earth's
surface. As the pressure builds, the
molten rock moves through channels in
the rock. The molten rock exits to the
surface, becoming lava. Some volcanic
eruptions are explosive, while others are
a slower flow of lava.
6. What Is Our Earth Made Of?
crust
This is the outer layer of Earth. It varies in thickness from 3 to about 50
miles thick. It is not even and is made up of pieces which overlap to cover
the entire planet. These pieces are called “tectonic plates.”
a
b
+
d
inner core
This is a solid layer and is made of iron and nickel. It is the hottest part of
Earth and can reach temperatures of close to 10,000ºF!
outer core
The outer core is a liquid layer made out of molten iron and nickel. This
liquid metal creates Earth's magnetic field.
c
mantle
The mantle is approximately 1,800 miles thick and is made of a solid, rocky
substance called molten rock or magma. This is what escapes when a
volcano erupts.
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7. How Are Volcanoes Formed?
Deep inside the Earth, it is extremely hot. It is so hot that rocks melt and
form magma, which makes up the mantle of the Earth.
The upper mantle mixes and moves,
creating pressure underneath the crust.
This pressure can sometimes cause the
mantle to leak out onto
Earth’s surface
– this is a volcano!
Over time, as the magma leaks out as
lava and then cools, the volcanic
mountain will get bigger and bigger.
8. Why Do Volcanoes Erupt?
The movement causes friction
which causes earthquakes and
volcanic eruptions near the
edges of the plates. The theory
explaining this process is called
“plate tectonics.” The plates
move in different directions and
at different speeds. Sometimes
they collide or brush past each
other, causing earthquakes and
volcanic eruptions.
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find out what it means!
friction: the resistance created
when one surface rubs
against another
Huge slabs called tectonic plates make up the Earth's crust. These fit
together like a jigsaw puzzle, and they sometimes move.
9. Parts of a Volcano
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An opening in Earth’s
surface through which
volcanic materials, such
as magma, can escape.
A cloud of ash
and smoke. It is
formed by
volcanic
explosions.
vent ash cloud
The mouth of a volcano.
It surrounds the vent.
crater
throat
The entrance of a
volcano. It ejects lava
and volcanic ash during
a volcanic explosion.
conduit
An underground
passage which magma
travels through.
A large underground pool
of liquid rock found
beneath Earth’s surface.
This liquid rock is
called magma.
magma reservoir
10. Classification of Volcanoes
Active
An active volcano has
erupted recently, and
there is the possibility
that it may erupt again.
Dormant
A dormant volcano has
not erupted for a long
time. However, it may
still erupt in the future.
Extinct
An extinct volcano has
erupted thousands of
years prior, and it will
probably never erupt
again.
11. Where Are Most Volcanoes Located?
The “Ring of Fire”
is an area of the
Pacific Ocean that
is shaped like a
horseshoe. It is
home to 90% of
the world's
earthquakes and
75% of the
world's volcanoes.
It contains a string
of 452 volcanoes
stretching from the
southern tip of
South America, up
along the coast of
North America,
down through
Japan, and into
New Zealand.
equator
12. Types of Volcanoes
Composite Volcano
This type of volcano has steep slopes and
thick, sticky lava. It looks like a regular
mountain. Because the lava is so sticky, it
will clog the passageways out of the
volcano. Pressure builds up, and
eventually, the volcano explodes violently.
However, the lava is so sticky that it does
not flow quickly or far. A composite
volcano erupts far less frequently than
other types of volcanoes.
13. Types of Volcanoes
Cinder Cones
This type of volcano is comprised of cinders
(darkly-colored volcanic rocks) called
scoria. A cinder cone volcano differs from a
composite volcano in that it has a bowl-
shaped hole, or crater, at the top. The
magma underneath the volcano contains
gas bubbles, which cause pressure to build
up within it. Eventually, the volcano erupts,
and lava will fly into the air. The ejected lava
accumulates around it and ultimately
contributes to the body of the volcano. The
cinder cone volcano is the most common
type of volcano worldwide.
14. Types of Volcanoes
Shield
This type of volcano has very fluid lava that
easily runs down the sides and travels long
distances before cooling. A shield volcano
does not have very steep sides because the
lava that erupts cannot pile up. The lava
forms long, gentle slopes that look like a
warrior's shield, which is how this type got
its name. Shield volcanoes do not often
explode.
15. Turn and Talk
Discuss the similarities and differences between the
three types of volcanoes: composite, cinder cone,
and shield.
16. Famous Volcanic Eruptions
A volcano can cause vast
amounts of damage to
communities living near
or around it.
On a morning in A.D. 79,
Mount Vesuvius erupted
near the Roman city of
Pompeii. Many of the
citizens living in Pompeii
were buried beneath tons
of volcanic ash and
debris that fell from the
sky from the
eruption.
The site of Pompeii was
rediscovered in the mid-
1700s when archeologists
excavated or cleared the
area of debris. Scientists
and historians have
studied Pompeii and its
demise for hundreds of
years. Mount Vesuvius is
still considered an active
volcano but is in a state of
rest now.
17. Famous Volcanic Eruptions
Mount St. Helens, located in Washington State, is the most
active volcano in the Cascade Range. This volcano erupted
in 1980 and was the largest eruption in the continental
United States since 1915. Gas and rock spewed from the
sides of the mountain at speeds up to 400 miles per hour.
The blast from the volcano blew everything away in its
path. The explosion destroyed over 200 square miles of
forest near the volcano.
It is still an active volcano and is expected to erupt
again in the future.
