1. Volcanoes

2. What is Magma?
dr evil

3. Magma
Magma: Liquid rock under Earth’s surface

4. Magma forms when…
The temperature rises above the melting point of the rock
The pressure is lower, which lowers the melting point of rock
The addition of water lowers the melting point of the rock

5. Volcano 101 video
The video says that volcanoes are “both creators and destroys”.
What does this mean? What are examples of this?
volcanoes 101

6. Volcanism
Volcanism: the movement of magma onto Earth’s surface

7. Volcanism
Lava: magma on top of Earth’s surface

8. In your packet: Explain the difference between magma and lava.

9. Volcanism
Volcano: an opening in earth’s surface through which magma and gases are expelled

10. Major Volcanic Zones
Most volcanoes form along convergent or divergent plate boundaries

11. Volcanoes at Divergent Boundaries
Divergent boundaries: mid-ocean ridges
The largest amount of lava rises at divergent boundaries
Most are unnoticed by humans because it happens underwater

12. Iceland
Iceland: the only place on Earth where a divergent boundary is above sea level

13. Convergent Boundaries
Volcanoes at Convergent boundaries: Volcanic mountain chains or volcanic island arcs
Examples: Japan, Alaska Aleutian Islands, Mount Saint Helens
The ring of fire is mostly made up of convergent boundaries

15. Draw triangles on your map on page 1 to represent volcanoes on plate boundaries

16. The Ring of Fire
The Ring of fire: an area surrounding the Pacific Ocean where a large number of volcanoes and earthquakes occur.

17. What about Hawaii?

19. Hot Spots
Hot spots: areas on Earth’s surface where magma is close to the surface
Also called mantle plumes

22. Hot Spots Hawaii and Yellowstone are examples of hot spots
Hawaii and Yellowstone are examples of hot spots
The PLATE moves NOT the hot spot!!!
Yellowstone

23. Studying volcanoes
Volcano Hazards:

24. Types of Magma
Mafic magma: rich in iron and magnesium and forms dark colored rock
Example: Oceanic crust
Produces: runny, quiet eruptions

25. Types of Magma
Felsic magma: rich in silicate materials and forms light colored rock
Example: continental crust
Produces: thick, explosive eruptions
Magma with more dissolved gases is more explosive

26. Types of Eruptions
The flow of magma or lava depends on the viscosity of the magma
Viscosity: how much a fluid resists flowing
High Viscosity= lava that moves very slowly
Low Viscosity= lava that moves quickly
High Viscosity
Low Viscosity

27. Quiet Eruptions
Quiet eruptions: mafic magma flows out slowly and has a high viscosity
Examples: Hawaii

28. More explosive because it has more dissolved gases in it
Explosive Eruptions
Explosive Eruptions: Felsic magma that is thicker and has a low viscosity
More explosive because it has more dissolved gases in it

29. Types of Lava pahoe 2014
1. Pahoehoe lava: mafic lava that flows slowly and forms a wrinkled crust
lava flows

30. Lava Flows
2. Aa lava: mafic lava that flows faster and has a chunky texture
Aa lava flow

31. Lava Flows
3. Blocky Lava: cooled lava at surface breaks into large chunks

32. Types of pyroclastic materials
4. Pyroclastic Material: Escaping gases send molten and solid rock into the air
pyroclastic flow

33. Types of Pyroclastic Material
Classified by particle size
Ash: less than 2mm diameter

34. Cont. Types of Pyroclastic Material
Volcanic bombs: molten rock larger than 64 mm in diameter
Volcanic blocks: solid rock that can be larger than a house

35. BOOM! Volcanic eruptions can be more powerful than atomic bombs!!
Marum Crater