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Chapter 9 Section 2
Effects of Volcanic Eruptions
Objectives
• Explain how volcanic eruptions
can affect climate.
• Compare the three types of
volcanoes.
• Compare craters, calderas, and
lava plateaus.
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Volcanic eruptions and Climate Change
• During large-scale eruptions:
– Ejected: lots of ash and gases
– Can block sunlight
• global temperature drop
– Mount Tambora, Indonesia, 1815
• Darkness for 3 days
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Volcano Types
1. Shield Volcanoes
– Built by layers of
lava from
nonexplosive
eruptions
• Low viscosity –
spreads over wide
area
– Gentle sloping
sides
– Can be enormous
– Ex: Hawaii’s Mauna
Kea
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Volcano Types
2. Cinder Cone Volcanoes
– Made of pyroclastic material
• Moderately explosive
– steep slopes
– Small
– Erupt a short time
– Ex: Paricutin (Mexico)
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Volcano Types
3. Composite Volcanoes
(stratovolcanoes)
– Most common
– Formed from explosive
eruptions
• pyroclastic material
• Followed by quieter flows of lava
– Creates alternating layers of each
– Ex: Mount St. Helens, Hood,
Rainier, & Mount Shasta
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Other Volcanic Landforms
• Craters – funnel-shaped pit at
the top of a volcano
– Lava and pyroclastic material
builds at the top
• Less explosive eruptions
– Eruption stops
– Lava in the crater drains back
underground
– if it hardens, it will blast away
at next eruption
El Elegante Crater, part of the
Pinacate Biosphere Reserve in
northwestern Sonora, Mexico, is
a maar crater
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Other Volcanic Landforms
• Calderas – large, semicircular depression
around a volcano
– forms when:
• magma chamber partially empties
• roof collapses.
Caldera on the Erta Ale volcano in East Africa
Other Volcanic Landforms
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• Lava Plateaus – wide, flat landform caused by
repeated nonexplosive eruptions of lava that
spread over a large area.
– Common around rifts – low viscosity
The Columbia Plateau is
uniformly covered with
basaltic lava flows. It spans a
huge area in the U.S. states
of Idaho, Washington, and
Oregon.
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