Transcript Types of Volcanoes

Types of Volcanoes
Effects on Earth
Learning Target
I will explain how different types of
volcanoes are made and what kind of
impact volcanoes have on Earth.
Shield Volcano
• broad with gently
sloping sides
• built of layers of lava
(runny)
• quiet eruptions (like
Hawaii)
• largest mts. on Earth
(Mauna Kea)
Cinder Cone Volcano
• Steep sides & loosely
packed
• Made of pyroclastic
material (medium
eruptions)
• Erupt for short time
• Occur in clusters; on
sides of shield &
composite volcanoes
Paricutin
On February 20, 1943, Paricutin, a cinder cone
volcano in Mexico, formed from the crevasse in a
cornfield and grew to be several hundred meters
tall in just a few days. This volcano continued to
erupt for 9 years and grew to be over 1,300 feet
tall.
Composite Volcanoes
“Stratovolcanoes”
• Most common volcano
• Broad bases & sides that get
steeper towards the top
• Eruptions start explosive,
followed by quieter
eruptions of lava
• mostly at convergent
boundaries
• the tallest volcanoes in the
world (Mt. Fuji in Japan)
Composite Volcano
Mt. Saint Helens
Krakatau
•In August of 1883, a composite
volcano, Krakatau in Indonesia
erupted with such force that the
island it was on disappeared,
killing more than 36,000 people.
•It launched a series a Tsunamis
that devastated the surrounding
coastlines.
•It affected the world’s weather
and climate for a couple of years.
Craters & Calderas
•Crater – a funnelshaped pit at the top
of the central vent
•Caldera – when the
magma chamber
empties & its roof
collapses
Sunset Crater
near Flagstaff, Arizona
Copyright © 2006 Pearson Prentice Hall, Inc.
Katmei Caldera
Formation of Crater Lake
Lava Plateaus
• Fissures – long cracks
in the Earth’s crust
- Quiet eruption;
runny lava
- Spreads evenly over
thousands ft²
• Lava plateau – resulting
landform (Columbia
River Plateau)
Impact on Earth
• Ash (fall-out)
-
Block out sun for days
Weight can collapse buildings
Smother plants & animals
Blanket towns
Dam up rivers & cause floods
Climate change
• Trees & buildings blown down or burnt
• Build mountains
• Melt glaciers
• Avalanche & flood (mahars)
Climate Change
• Volcanic ash & sulfur-rich gases can reach
the upper atmosphere
• Ash can block out enough sunlight to cause
the average global temperature to drop
noticeably
• Example: 1991 Mt. Pinatubo dropped global
temp by 0.5°C
• Can cause milder, wetter summers &
harsher, longer winters