1. Volcanoes

3. Volcano facts  How many eruptions? 15,110 volcanoes in last 10,000 years  The highest peak? 6,887 m, Ojos del Salado (Chile)  The biggest eruption? 2,500 km3, Yellowstone, 2.2 Ma (USA)  First volcanologist? 79 AD - Pliny the Younger  Total deaths 238,000 (1600-1982)

4. History  The word Volcano is derived from the name of the ancient Roman island of Vulcano. The Romans believed that Vulcan, the god of Fire and the maker of weapons, used the volcano on that island to forge his weapons.

5. Definition of a Volcano  1. An opening in the crust of the Earth from which magma and gases escape to the surface.  2. The mountain that is formed from volcanic processes.

6. Volcano Classification  Active- are either currently erupting or have erupted recently. Over 500 volcanoes are in this group.  Dormant- are not currently erupting but are considered likely to do so. Mt. St Helens was dormant for 123 years before it erupted in 1980.  Extinct- or dead volcanoes have not erupted in recent history and are not likely to erupt.

9. Anatomy of a Volcano  A volcano is a mountain formed of lava and/or pyroclastic material.  A crater is the depression at the summit of a volcano or that which is produced by a meteorite impact.  A conduit, or pipe, carries gas-rich magma to the surface.

10. Anatomy of a Volcano

11. Types of Volcanoes  The three main volcanic types are  shield volcanoes,  cinder cones  composite cones

12. Shield Volcanoes  Shield volcanoes are broad, gently sloping volcanoes built from fluid basaltic lavas.

15. Cinder Cones  Cinder cones are small volcanoes built primarily of pyroclastic material ejected from a single vent.  Steep slope  Small is size  Occur in groups

16. Cinder Cones

19. Composite Cones  Composite cones are volcanoes composed of both lava flows and pyroclastic material.  Most are located in the Ring of Fire  (Ex Mt. Rainer)  Large in Size  Most Violent Eruptions

20. Composite Cones

21. Mt. Rainer

22. Mount St. Helens Before and After the May 18, 1980, Eruption

24.  Composition of the Magma  Temperature of the Magma  Dissolved Gasses  Viscosity- is the measure of a material's resistance to flow.  Temperature- hotter magma’s are less viscous  Composition- Silica Content  High Silica- high viscosity  Low Silica – low viscosity Factors Affecting Eruptions

26. There Are Three Major Volcanic Zones  Subduction Zones  Mid-oceanic ridges  Hot spots

30. There are Two Different Types of Lava  Pahoehoe lava (resembles braids in ropes)  Aa lava (rough, jagged blocks)  Pyroclastic materials is the name given to particles produced in volcanic eruptions

31. Pahoehoe (Ropy) Lava Flow Fast Moving

32. Slow-Moving Aa Flow

36. Mt. Saint Helens Erupting Mount Saint Helens photographs 10-26-04 1980 Eruption

37.  http://www.youtube.com/watch?v=njV9ski1gB4 http://www.youtube.com/watch?v=njV9ski1gB4  http://www.youtube.com/watch?v=pGImksoOwtU&featur e=related http://www.youtube.com/watch?v=pGImksoOwtU&featur e=related  http://www.youtube.com/watch?v=1Vn6kxfD3Ek&feature =related http://www.youtube.com/watch?v=1Vn6kxfD3Ek&feature =related

38. Pompeii- Italy

40. Santorini Greece

41. Old Faithful- Yellowstone

42. Sunset Crater – Flagstaff Arizona

43. Mt. Merapi Nov 1, 2010

44. Eyjafjallajokull- Iceland

45. Kilauea Hawaii- Most active volcano

46. Popocateptl- Mexico

47. Mt Erebus Volcano- Antarctica  One of the worlds most active volcanoes