Download Shield volcanoes

Volcanoes
6.2
What happens when a
volcano erupts?
The magma in the
asthenosphere is under
great pressure. Magma
rises into the cracks
because magma is less
dense than the crust.
Hot Magma
Cool Crust
Dissolved
gases
As the magma rises toward
the surface, less pressure is
on the magma. This allows
dissolved gasses to separate
out.
During a volcanic eruption,
the dissolved gases rush out,
carrying the magma with
them.
Magma
Once the magma reaches
the surface and becomes
lava, the gases bubble out.
animation of volcano
What are the main parts
of a volcano?
Pipe
• A long tube
through which
magma moves
from the magma
chamber to Earth’s
surface
Vent
The opening
through which
molten rock and
gas leave a
volcano
Lava Flow
The area covered
by lava as it
pours out of a
volcano’s vent
Crater
• A bowl-shaped area
that forms around a
volcano’s central
opening
• Lava collects there
Crater
• A bowl-shaped
area that forms
around a
volcano’s central
opening
• Lava collects
there
Describe the 3 stages of
a volcano.
Active (live): volcano
that is erupting or has
shown signs that it may
erupt in the near future.
Dormant (sleeping):
volcano that is not
currently erupting but
may become active in
the future.
Extinct (dead): volcano is
unlikely to erupt again.
Active: Kilauea
Name: Kilauea
Location: Hawaii
Last eruption: erupting right now
Considered to be the world’s most active volcano
Active: Eyjafjallajokull
Name: Eyjafjallajokull
Location: Iceland
Last eruption: April 14, 2010
Caused the shutdown of air traffic across Europe in 2010
Dormant: Fujiyama
Name: Fujiyama (Mount Fuji)
Location: Japan
Last eruption: 1708
Dormant: Mount Shasta
Name: Mount Shasta
Location: California, USA
Last eruption: about 1810
Extinct: Kilamanjaro
Name: Mount Kilamanjaro
Location: Tanzania, Africa
Last eruption: 360,000 years ago
Extinct: Olympus Mons
Name: Olympus Mons
Location: planet Mars
Last eruption: unknown
Shield Volcano
• A wide, gently-sloping
mountain made of
layers of lava and
formed by quiet
eruptions
• Example: The Hawaiian
Islands
Cinder Cone
• A steep, cone-shaped
hill or mountain made
of volcanic ash, cinders,
and bombs piled up
around a volcano’s
opening
• NO SIDE VENTS!
• Example: Sunset crater
in Arizona
Composite Volcano
• A tall, cone-shaped
mountain in which layers
of lava alternate with
layers of ash and other
volcanic materials
• Example: Mount St.
Helens in Washington and
Mount Fuji in Japan
• Shield
• Stratovolcano
• Cinder Cone
Composite Volcano
Types of Volcanoes (simple version)
Relative Size of Volcano Types
Name that Volcano Type!
• Cinder Cone, Mojave Desert, CA
• View of the NNW flank of Mauna Loa Volcano
from the south side of Mauna Kea Volcano,
Hawai`i; both are shield volcanoes. The
largest volcanoes on Earth are shield
volcanoes.
• Cinder cone at Little Lake, California.
• Composite
• Colima Volcano, Mexico.
• A stubby andesite lava flow advances 900-1,200 m down the
southwest side of Colima Volcano. Lava was first observed in the
summit crater on November 20 and began spilling over the crater rim
the next day. Colima Volcano is the most historically active volcano in
Mexico.
• Cinder Cone: (Pu`u ka Pele) was erupted low on
the southeast flank of Mauna Kea Volcano. The cone is
95 m in height, and the diameter of the crater at the top
is 400 m. Hualalai Volcano in background.
• Composite
• Arenal volcano, in Costa Rica
• Shield volcanoes are among the largest
on Earth. The island of Hawaii is made of five
overlapping shield volcanoes, of which Mauna
Kea is the tallest.