1. VOLCANOES

2. Lava & Magma Lava vs. Magma…What’s the difference?
Lava- magma that flows into Earth’s surface; the rock that forms when magma cools & solidifies.
Magma- liquid rock produced under the Earth’s surface.

3. Major Volcanic Zones
1. Subduction Zone- one tectonic plate moves under another.
-deep trenches form
-island arcs form
2. Mid-Ocean Ridges- plates pulling apart from one another. -Produces the most magma from underwater volcanoes.
-Mid-Atlantic Ridge and Iceland are examples.
3. Hot Spots- happen with the interior of plates.
-example = Hawaiian islands
-made by mantle plumes

4. Where volcanoes form
Hot Spots
Mid Ocean Ridges
Subduction Zones

5. Hot Spots

7. Types of Magma Mafic -made up of magnesium and iron -dark in color
-oceanic and continental crust
Felsic
-made up of silicates
-lighter in color
-continental crust

8. Types of Eruptions Quiet Eruptions -mafic magma
-oceanic volcanoes (Hawaii)
-low viscosity
Explosive Eruptions
-felsic magma
-continental volcanoes
-high viscosity
-throw off large amounts of pyroclastic material

9. STRUCTURE Tephra (pyroclastics) – ash and rock ejected from a volcano.
Vent – conduit or pathway for magma.
Strata – layers of rock.
Magma chamber – storage place for magma.

10. LAVA

11. LAVA

12. Pahoehoe

13. AA

14. Pillow Lava

15. Tephra (pyroclastic material)

16. Volcanic Ash – the small stuff
Volcanic Ash is small, but it is the most deadly.

17. Volcanic Blocks

18. Volcanic Bombs

19. Types of Volcanoes
1. Shield – Broad at the base, gently sloping sides, quiet eruptions, largest volcanoes. (Exp- Hawaiian Islands.)
2. Cinder Cone – Explosive eruptions, very steep slopes, only a few 100 meters high.
3. Composite of Stratovolcano – Explosive eruptions, pyroclastic flows can be deadly, very large volcanoes. (Exp- Mt. St. Helens, Mt. Pinatubo)

20. TYPES OF VOLCANOES

21. CINDER CONE

22. CINDER CONE

23. SHIELD VOLCANO Mauna Kea, Hawaii

24. SHIELD

25. COMPOSITE VOLCANO Mt. Fuji

26. Craters & Calderas
Crater- opening of the volcano where magma and or pyroclastic material is released.
Caldera- when the magma chamber of a volcano empties and collapses on itself.

27. CRATER

28. CRATER

30. CALDERA

31. Crater Lake in Oregon Mt. Mazama

32. EXTRATERRESTRIAL VOLCANOES
VOLCANOES FOUND ON MARS, IO (MOON OF JUPITER), OUR OWN MOON
MARS – OLYMPUS MONS, 28 KM ABOVE THE SURFACE, 600 KM ACROSS, CALDERA IS 70 KM ACROSS.
IO – ACTIVE VOLCANOES ON SURFACE (FIRST PLANETARY BODY TO HAVE ACTIVE VOLCANOES)

36. MOUNT ST. HELENS

39. MT. ETNA

40. Predicting Volcanic Eruptions
-changes in earthquake activity around an earthquake.
-increase in pressure of the surrounding rocks.
-temperature changes
-fracturing of rock
-sections of the volcano may bulge
The End!