VOLCANOES
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Describe the different
types of volcanoes and
volcanic eruption
What is A Volcano?
~An
opening in the earth's crust
through which molten lava, ash,
and gases are ejected.
~A similar opening on the surface
of another planet.
~A mountain formed by the
materials ejected from a
volcano.
Types Of Volcanoes
~ Shield Volcano
~ Cinder Cone Volcano
~ Composite Volcano
~ Caldera Volcano
~ Fissure Volcano
Shield volcanoes can span across
hundreds of miles and they can be
huge vertically that they can reach
the clouds of earth very easy. Shield
volcanoes have a slow slope and
consist of frozen lava after it is
hardened. Shield volcanoes almost
always have large craters at their
summit.
Cinder cone volcanoes consist of mostly
loose, grainy cinders and have very little
to no lava. Cinder cone volcanoes are
normally small about a miles span and
about one thousand feet vertically. Cinder
cone volcanoes have fairly steep slopes
and normally have a small crater at the
top.
Composite volcanoes have another
name called “Strato Volcanoes.”
Composite volcanoes consist of lava
that is mixed with sand or gravel
which in turn creates cinders or
volcanic ash.
Caldera volcanoes are circular
depressions in the ground over a magma
chamber. Sometimes the depression in
Caldera volcanoes are covered in with
lava and volcanic ash making it hard to
recognize.This type of volcano is easier
noticed from space due to the distance
and view point. When this volcano
erupts it can spew volcanic rocks for
miles and miles.
Fissure volcanoes are also hard to
recognize from the ground and
sometimes from space. Fissure
volcanoes have no main crater, the
ground just splits and lava pours out
through the cracks. After a fissure
volcano erupts and has cooled because
it’s a solid it will look mainly like the
plains.
Types Of Magma
Granite magma consist of lightcolored rock and is not as heavy
as basalt magma. Granite magma
is very sticky and flows rather
slowly.
Types Of Magma
Basalt magma consist of darkcolored rocks and is much
heavier then granite magma. It
flows more fluidly then molten
granite.
Volcano Environments
~In an island-arc
environment, volcanoes
lie along the crest of an
arcuate.
~In an oceanic environment,
volcanoes are aligned along
the crest of a broad ridge
that marks an active fracture
system in the oceanic crust.
~In the continental
environment, volcanoes are
located unstable,
mountainous belts that have
thick roots of granite or
granite like rock.
Where are volcanoes likely to
occur?
Volcanoes occur in weak spots in the
earth’s crust
There are many volcanoes along the
Pacific Ocean.
Many islands in the Pacific Ocean are
actually
volcanoes.
They form a ring around the ocean
which is called the “Pacific Belt of
Fire.”
Although there are some other “belts
of fire”, the
“Pacific Belt of Fire” is the biggest.
There are approximately five hundred
active volcanoes, that are known,
lying in these belts.
Volcanoes aren’t just a thing from
earth they also happen on other
planets as seen in this picture. But
while on other planets there is no
destruction as we have seen from
volcanoes on earth.
Volcanoes In Other Places
Mariner 9 imagery of Olympus Mons
volcano on Mars
When and how do eruptions occur?
Steam and gases from magma in the earth create
bubbles that expand and burst when the pressure
above them is lessened. These bubbles usually burst
with a tremendous force that along with escaping
gas comes magma too. In some cases, it takes years
for the magma to break through the surface of the
earth.The first recorded eruption was in 781 (Fuji,
Honshu, Japan)The most recent recorded eruption
was in 2002 (Etna, Sicily, Italy)
Why do eruptions occur?
Eruptions occur when underground
pressure is
released when blocks of the earth’s crust
shift.
For example, earthquakes.
Damages
The most devastating destruction from volcanoes
is the tremendous loss of life. Following an
eruption in 1815, there were 56 000 people killed
by a tidal wave from a eruption. Lava from the
volcano is hot enough to catch everything in its
path on fire, even the ash from a volcano is hot
enough to start fires. Lahar can wash away houses
and uproot trees. Magma can give off poisonous
gases such as carbon monoxide. Damages from
volcanoes are very expensive to repair or replace.
Our Own Model Of An Erupting
Volcano
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