Download What is a volcano? - Mr. LaFranca`s Earth Science Class

Notepack # 10
October 1, 2014
AIM: How are volcanoes formed?
Do Now: Look at the 2 pictures below, which
one is a volcano? What are some clues that
lend you to your decision?
Review - 3 types of plate boundaries
Convergent – moving together
Divergent – moving apart
Transform – sliding past one another
What is a volcano?
• Volcano are areas of the Earth’s surface
through which magma makes it way through
the crust to the Earth’s surface.
• The word, “Volcano” comes from the Roman
word Vulcan, which means “fire”
What are some famous Volcanoes?
Don’t Copy!!
• Mt Vesuvius near Pompeii
79 AD
What are some famous Volcanoes?
Don’t Copy!!
• Mt Kilauea
• Mt St. Helen
Present
What are some famous Volcanoes?
Don’t Copy!!
• Mt St. Helen
1980
What are some famous Volcanoes?
Don’t Copy!!
• Krakatau
1883
What’s inside a volcano?
• Beneath the volcano is
the Magma Chamber.
• The Magma Chamber is
filled with molten
(melted) rock that comes
up from the Mantle.
• Magma inside the volcano
is always under pressure.
When the pressure gets
too great, an eruption will
occur to release this
pressure.
Crust
Magma
Chamber
What’s inside a volcano?
• Down the center of the
volcano is the vent.
• During an eruption, this
vent fills with magma,
(now called lava),
transports it out of the
volcano.
• Once the lava reaches
the top of the vent, it
slides down the side of
the volcano. When the
lava cools, it turns into
rock causing the volcano
to grow taller and wider.
Vent
What’s inside a volcano?
Sill
• Because the magma is
under pressure, sometimes
small vent break through
the side of the vent making
secondary vents.
• If these smaller vent go
across layers of rock, it is
called a dike.
• If the vent stops between
layers, allowing magma to
get sandwiched between
layers, it is called a sill.
Dike
Ash
Lava
Crater
Dike
Vent
Magma
Sill
Cone
Types of Volcanoes
• There are three types of volcanoes:
– Shield Volcanoes
– Cinder Cone Volcanoes
– Composite Volcanoes
Types of Volcanoes
• Shield Volcano
a) Built from layers of lava
which cool into solid
rock.
b) Non-explosive
eruptions
c) Not very steep, but can
be big
d) Hawaiian Islands are
shield volcanoes
Types of Volcanoes
• Cinder Cone Volcano
a) Built from pyroclastic
material (ash)
b) Almost no cooled lava
on its sides
c) Moderately explosive,
short eruptions
d) 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 (ash) AND
lava
Volcanoes
Quiet
lava
flows
• http://www.youtube.com/watch?v=90XFpu65JY&feature=relmfu
• http://www.youtube.com/watch?v=_nBMsKj_c4
• http://www.youtube.com/watch?v=JmPuypqIQE&feature=related
Volcanoes
Mt. St. Helen before the explosive eruption
Volcanoes
Volcanoes
Time lapse of the eruption
Volcanoes
Mt. St. Helen after the eruption
Materials that come from Volcanoes
• There are many things that can come out of a
volcano:
• Lava is magma that reaches the surface of the crust.
Affects are very localized
• Pyroclastic Ash is a mixture of tiny rocks and dust
that form huge clouds. Affects are localized and
regional.
• Pyroclastic Ash can be very thick and block out
sunlight destroying crops.
• The ash can settle on local land, burying towns.
• Ash also can suffocate the area, making it hard to
breathe.
Materials that come from
Volcanoes (cont)
• Volcanic gases- Very hot and poisonous ( CO2,
HCl, SO2, HF) Affects are localized, regional
global- Greenhouse effect.
• These gases can raise global temperature as solar
heat is trapped in the atmosphere.
• http://www.youtube.com/watch?v=vPRoTQYX
wuY
• http://www.youtube.com/watch?v=ssa3S1Lx3
6Y&feature=related
Where are volcanoes located?
Where are volcanoes located?
• Usually located near plate boundaries.
• Convergent subduction zones is where most
of our land volcanoes are located (and the
most dangerous).
• Divergent plate boundary is where fissure,
sea-mount, and shield volcanoes occur.
• The biggest volcanoes on the Earth are located
over top of hot spots.
Pacific Ring of Fire
• The Ring of Fire is a zone of frequent
earthquakes and volcanic eruptions that
encircles the basin of the Pacific Ocean.
• 90% of the world's earthquakes and 81% of
the world's largest earthquakes occur along
the Ring of Fire.
Pacific Ring of Fire