1. Volcanoes

2. Origin of Magma
Magma forms in the crust and upper mantle when solid rock partially melts.
Formation of magma depends on:
Heat
Pressure
Water Content
Magma that has reached the surface is called lava.

3. Volcanoes
A volcano is a mountain formed of lava and/or pyroclastic material.
A crater is the depression at the summit of a volcano.
A conduit, or pipe, carries magma to the surface.

4. Which of the following does not determine the formation of magma?
Heat
Pressure
Salinity
Water Content

5. Magma that has reached the surface is called:
Pyroclastic Material
Lava
Conduit
Crater

6. A crater is a: Depression at the top of a volcano.
Pipe carrying lava to the surface.
Mountain made of lava.
Partially melted rock.

7. Volcanoes and Plate Tectonics
Divergent plate volcanism
Convergent plate volcanism
Intraplate volcanism

8. Divergent Boundary Volcanism
The greatest volume of volcanic rock is produced along the oceanic ridge system.
Lithosphere pulls apart.
Less pressure on underlying rocks,
Partial melting occurs
Large quantities of fluid basaltic magma are produced.

9. Convergent Boundary Volcanism
Slabs of oceanic crust are pushed down into the mantle and melt.
The magma slowly migrates upward, forming volcanoes.
More than half of Earth’s active volcanoes are located in the “Ring of Fire,” an area of subduction zones around the Pacific Plate.

10. Intraplate Volcanism
A mass of hotter-than-normal mantle material, called a mantle plume, rises toward the surface.
Can result in a volcanic region called a hot spot (example: Hawaiian Islands.)
Most hot spots have lasted for millions of years.

11. What is the “Ring of Fire?”
Subduction zones encircling the Pacific Ocean.
Where over half the world’s active volcanoes are found.
A great old Johnny Cash tune.
All of the above.

12. “Ring of Fire” volcanoes are formed at which type of plate boundary?
Divergent Boundary
Convergent Boundary
Intraplate Boundary 2. 1.
Intraplate Boundary 3.

13. The Hawaiian Islands were formed by an Intraplate volcanic region called a:
Volcanic Island Arc
Continental Volcanic Arc
Hot spot
Mid-ocean ridge

14. Factors Affecting Eruptions
Viscosity of the magma
The more viscous the material, the greater its resistance to flow.

15. Factors Affecting Eruptions
Dissolved gases
Mainly water vapor and carbon dioxide
Provide the force to extrude lava
Violence of an eruption is related to how easily gases escape from magma.

16. Factors Affecting Eruptions
The viscosity of the magma, plus the quantity of dissolved gases and the ease with which they escape, determine the nature of a volcanic eruption.

17. The factors that affect volcanic eruptions are:
Permeability & dissolved metals
Permeability & dissolved gases
Viscosity & dissolved metals
Viscosity & dissolved gases

18. Fluid lava with a low gas content would produce a(n):
Quiet eruption
Violent eruption
Earthquake
I’m not sure because I really wasn’t paying attention.

19. Volcanic Materials
Depending on the type of eruption, volcanoes may produce any or all of the following materials:
Lava Flows
Basaltic – low viscosity & low percentage of gases
Andesitic – intermediate viscosity & gases
Rhyolitic – high viscosity & gases
Gases – can exceed thousands of tons each day.
Pyroclastic Materials

20. Two Types of Basaltic Lava
Pahoehoe
Hot, fast-moving.
Forms a smooth skin that wrinkles as it flows. Aa
Cooler, slower-moving.
Forms a surface of rough, jagged blocks.

21. Pyroclastic Materials
Particles produced in volcanic eruptions (ash, cinders, blocks, bombs, etc.)

22. Which of the following is not produced during volcanic eruptions?
Mantle plumes
Lava flows
Gases
Pyroclastic Materials

23. Which of the following is true of Aa lava?
Very hot
Fast-moving
Forms a smooth skin that wrinkles
Forms a surface of rough, jagged blocks

24. Particles given off during volcanic eruptions are called:
Lava
Magma
Pyroclastic Materials
Thermodynamic Materials

25. Types of Volcanoes

26. Shield Volcanoes
Broad, gently sloping volcanoes built from fluid basaltic lava flows.
Largest volcanoes on Earth (e.g., Mauna Loa.)
Relatively quiet eruptions.

27. Cinder Cones
Small volcanoes made from pyroclastic material, usually from a single eruption.
Steep slope angle
Rather small in size

28. Composite Cones (Stratovolcanoes)
Volcanoes composed of both lava flows and pyroclastic material.
Most are adjacent to the Pacific Ocean (e.g., Mt. Rainier).
Most violent type of activity.

29. Which type of volcanoes are the largest on the Earth?
Shield Volcanoes
Cinder Cones
Composite Cones

30. Which volcano is potentially the most dangerous?1.
Shield volcano
Cinder cone
Composite cone 2. 3.

31. Which type of volcanoes are often created from a single eruption?
Shield Volcanoes
Cinder Cones
Composite Cones

32. Caldera
A large depression in a volcano, formed by collapse.

33. Intrusive Igneous Structures
Volcanic Neck – hardened magma, exposed by erosion.
Lava Plateau – lava flows spread out over a wide area.
Plutons
Sills –magma flows between parallel layers of sedimentary rock.
Laccoliths – lens-shaped plutons that have pushed the overlying rock layers upward.
Dikes –magma flows into fractures that cut across rock layers.
Batholith – exposed surface of more than 100 square kilometers.

34. Forming Igneous Features and Landforms
Intrusive Igneous Structures
Forming Igneous Features and Landforms
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35. Underground igneous rock bodies are called:
Lava flows
Volcanoes
Plutons
Calderas

36. A large depression in a volcano, formed by collapse is called a:
Crater
Caldera
Pipe
Vent

37. What intrusive igneous feature in the diagram is labeled C?
A dike
A sill
A batholith
A laccolith

38. Volcanic Hazards
Lava flows

39. Volcanic Hazards
Volcanic ash

40. Volcanic Hazards
Pyroclastic flows

41. Volcanic Hazards
Mudflows (lahars)

42. Which of the following is not a common volcanic hazard?
Lava flow
Pyroclastic flow
Mud flow
Convective flow

43. What is a lahar? A tidal wave A mudslide An igneous intrusion
A small volcano

44. Which of the following is the term for an avalanche of glowing volcanic particles and gases?
Pyroclastic flow
Lahar
Lava flow
Tsunami