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Volcano Section 3 Homework
#1 What is a volcanic crater and how
does it differ from a caldera?
• A crater is a bowl shaped depression, less than
1km in diameter. Calderas are large craters
that can be up to 50 km in diameter.
Describe the different kinds of tephra
•
•
•
•
•
Dust - < 0.25mm
Ash – 0.25 mm – 2 mm
Lapilli 2-64 mm
Blocks
Bombs
#3 Explain why volcanic blocks would
be uncommon on shield volcanoes.
• Blocks are created in explosive eruptions.
Shield volcanoes are not usually explosive.
#4 What is pyroclastic flow? What are
the characteristics of a pyroclastic flow
that make them so dangerous?
• Pyroclastic flows are clouds of tephra that
travel down the flanks of volcanoes. They
move at high speeds, are very hot, and
contain poisonous gases.
#5 Where are Earth’s major volcanic
belts located?
• Earth’s major volcanic belts are located at
plate boundaries.
• Name two:
– Convergent
– Divergent
#6 What are hot spots?
• Hot spots are high-temperature plumes of
material that rise through the mantle to form
volcanoes far from plate boundaries.