Transcript Ch 13 Volcanoes

Chapter 13
Mrs. Horton- Earth Science
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Vent
Cone
Magma
Lava
Lava bomb
Eruption
Crater
Pyroclastic Material
Viscosity
Silicon
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3 Types:
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Shield
Composite
Cindercone
 Hot spot
vent
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cone
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conduit
magma
chamber
A volcano is a vent or
'chimney' that connects
molten rock (magma)
from within the Earth’s
crust to the Earth's
surface.
The volcano includes the
surrounding cone of
erupted material.
1.
VENT- the vent is
the opening from
which lava flows.
Dust, ash, noxious
gases, and rock
particles can also
be thrown out of
the vent!
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Cone: Material
such as lava flow,
pyroclastic
material, ash which
is built up around
the vent
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Magma: Under the
crust
Lava: Above the
crust
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A projectile of
burning lava
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Crater: funnel
shaped pit at the
top of a volcano
from a previous
eruption
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Pyroclastic
Material: derived
from Greek for Fire
and broken rock.
Usually explosive
eruptions
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Viscosity: the
ability for a fluid to
flow. High
viscosity means it
does not flow well,
and low viscosity
means it flows
easily
There are 3 types
of Volcanoes:
Shield
Cinder Cone
Composite
 They are
classified by
how they form.
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Wide and
somewhat flat.
It forms from a
quiet eruption.
Mauna Loa in
Hawaii.
Has tall, very steep
sides.
 Has explosive
eruptions. Lots of
Cinder and ash.
 Paricutin: Corn
field in Mexico,
1200 feet 1943
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Extremely large
Powerful
explosive
eruptions
followed by
smooth flow
Mt. Rainier, Mt
Fuji, and…
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A Caldera is a
large circular
depression that
forms when the
magma chamber
below a volcano
empties and sinks
into the ground.
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Hotspots are
responsible for the
formation of
Hawaiian Islands
Put simply, Hot
spots are vents in
the plates that
erupt periodically
while the plates
move
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Explosive eruption: High viscosity, and lots of trapped
gasses (H2O, CO2, S)… Pressure builds until the gasses
escape violently
Effusive (Quiet) eruption: Low viscosity, and little gasses
(H2O, CO2, S)… Pressure does not build
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Three products from
an explosive
eruption
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Ash fall
Pyroclastic flow
Pyroclastic surge
Pyroclastic flows on
Montserrat, buried
the capital city.
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Effusive eruptions are
characterised by
outpourings of lava on to
the ground.
Hawaii
Courtesy of www.swisseduc.ch
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Courtesy of www.swisseduc.ch
Pyroclastic flow
Lahars/Mud flows
Pyroclastic fall
Lava flow
Noxious Gas
Earthquakes
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For example,
eruption of
Vesuvius in 79
AD destroyed
the city of
Pompeii
On August 24, 79AD Mount Vesuvius literally
blew its top, erupting tonnes of molten ash,
pumice and sulfuric gas miles into the
atmosphere. Pyroclastic flows flowed over
the city of Pompeii and surrounding areas.
Pyroclastic flows of poisonous gas and hot
volcanic debris engulfed the cities of
Pompeii, Herculaneum and Stabiae
suffocating the inhabitants and burying the
buildings.
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It is not just explosive volcanic activity that can
be hazardous. Effusive (lava) activity is also
dangerous.
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Earthquake activity commonly precedes an eruption
 Result of magma pushing up towards the surface
 Increase volume of material in the volcano shatters the
rock
 This causes earthquakes
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