Download Volcanoes

Volcanoes
Chapter 9
Sections 1, 2,and 3
Pages 250-265
Write down the underlined items.
What is a volcano?
• A volcano is an area of the Earth’s surface
through which magma and volcanic gases
pass: a place on Earth where magma &
gases come out
• Most volcanoes are located at plate
boundaries. WHY?
• 75% of the volcanoes in the world are
located in the Ring of Fire.
Ring
of
Fire
Ring of Fire
3 Types of Volcanoes
• Shield Volcano
• Cinder Cone Volcano
• Composite Volcano
Shield Volcano
• Here are 4 of the volcanoes that comprise the big island of
Hawaii. They are Mauna Kea (MK), Mauna Loa (ML), Hualalai
(H), and Kohala (K). The photo was taken from near the summit
of East Maui volcano (EM). These are the largest volcanoes on
Earth.
Volcanic Eruption Island of Stromboli, November 2006
Shield Volcano—nonexplosive
• Named for its shape; shaped like a shield
• Built from layers of lava released from
non-explosive eruptions
• Lava spreads out over a wide area.
• Have gently sloping sides.
• Mount Kea, in Hawaii, is the largest shield
volcano on Earth; measured from its base on the
sea-floor, it is taller than Mount Everest.
Shield Volcano
Belknap Shield Volcano in Oregon.
Cinder Cone Volcano
Veniaminof, Alaska
Mount Etna, Italy
1
2
NOTICE HOW
THE CONE
GETS BIGGER
AS THE
ERUPTION
CONTINUES .
3
Cinder Cone Volcano
• Made of pyroclastic material (hardened blobs
of magma, small pieces of hardened magma
and ash)
• Produced from moderately explosive
eruptions
•
•
•
•
have steep slopes
are usually small
often occur in clusters
erode very quickly because the pyroclastic
material is not cemented together
Composite Volcanoes
Mount Ranier, Washington
Composite Volcanoes
• Sometimes called stratovolcanoes.
• Most common type of volcano.
• Composite volcanoes form from
alternating explosive and nonexplosive eruptions.
• Composite volcanoes have broad bases
and sides that get steeper toward the
top.
COMPOSITE VOLCANO
SHIELD VOLCANO
CINDER CONE VOLCANO
What is a crater?
• The area around the central vent of a
volcano is called a crater.
Crater Lake, Oregon
What is a Hotspot?
•A hot spot is an area of
persistent volcanic
activity.
• Hot spots originate at
unusually hot areas of
the mantle-core
boundary.
• Overlying mantle melts
forming plumes of
magma that rise and
penetrate the crust
forming volcanoes.
Hot Spots Continued
• Hawaii, Iceland, and Yellowstone are
examples of hot spots.
• Hot spots are generally characterized by
large outpourings of basaltic lava for
relatively long periods of time.
Review
• 1. Largest type of volcano:
• 2. Volcano with alternating layers of lava and pyroclastic material:
• 3. Volcano made of pyroclastic material:
• 4. Volcano made of layers of lava released from a non-explosive
eruption:
• 5. The area around the central vent of a volcano:
• 6. Volcanoes that usually form in clusters:
• 7. What is pyroclastic material?
• 8. Volcano that forms from explosive eruptions:
• 9. What is a hotspot?