1. Volcanoes
Chapter 8
Section 2

2. Class Outcomes Describe a volcano
Name and describe the 4 types of volcanoes
Differentiate between Pahoehoe and Aa lava

3. Volcano
Area where magma and gases are released to the Earth’s surface.
Area where magma becomes lava
Magma = under surface
Lava= above surface
Have circular shaped openings called craters
Release Tephra, or solid lava, that enters the air during an eruption.

4. Subduction Zone Volcanoes
Oceanic plate dives under and melts. The newly formed magma rises to the surface and creates a volcano.

5. 4 types of volcanoes Shield Volcanoes Cinder Cone Volcanoes
Composite Volcanoes
Fissure Eruptions

6. Shield Volcanoes Made from basaltic lava Gradually sloping sides
Thin and easy flowing
“pahoehoe”
Gradually sloping sides
Broad/ largest volcanoes on earth
Hawaiian Islands/Iceland

8. Mauna Loa

11. Cinder Cone Volcanoes Short in height (less than 300m) Made of tephra
Violent eruptions from gas buildup
Lava and gas shoot high in the air and cool to form volcano
Short eruption time

16. Composite Volcanoes Steep sided mountain
Composed of alternating layers of basaltic lava and tephra
Explosive eruptions followed by lava flows
Mt. St. Helens, Mt. Ranier, Mt. Shasta

17. Composite = pyroclastic flows
Hot gases and ashes released at the beginning of a composite eruption
2000 degrees Fahrenheit
Up to 450 miles/hour
Deadliest event of a composite eruption
Pyroclastic Flow

18. Composite = “Lahars”
Mud Flows caused by the super heating of glaciers on the top of these high mountains.
Water + Ash = Lahar
2nd deadliest aspect of these giants.

20. Mt. Shasta, California

23. Fissure Eruptions Basaltic lava flows from cracks in the earth’s crust
Thin and flows easily
Form flat landforms known as lava plateaus/flood basalts.

24. Volcano Tour on Google Earth

26. Fissure Eruption, Kilauea Volcano field, Hawaii

27. “Pahoehoe vs. Aa” Pahoehoe lava Aa lava Thin and flows easily
Thick and chunky and doesn’t flow, but breaks apart as it moves.

28. ? Aa

29. ?
Pahoehoe

30. What kind of volcano would be the best to have in your backyard?
Extinct
Have no magma chamber or source.
Active
Have regular, predictable eruptions that never gain strength.
Dormant
Have irregular, unpredictable eruptions and can be very catastrophic in strength.

31. Enjoy the Show
Mountains of Fire