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Volcanoes

Discover the fascinating world of volcanoes, from the formation of magma to explosive eruptions. Learn about different types of volcanic rocks, the role of vents and magma chambers, and the factors that determine the type of eruption. Explore famous volcanic sites like the Hawaiian Islands and the Ring of Fire. This educational guide provides an in-depth understanding of volcanoes and their impact on the Earth.

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Volcanoes

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  1. Volcanoes

  2. Volcano Weak spot in the crust where magma comes to the surface

  3. Magma • Molten mixture of rock-forming substances, gases, and water vapor from the mantle

  4. Lava • Magma that reaches the surface.

  5. Magma that has surfaced is called what? Lava

  6. Ring of Fire • Major Volcano Belt • Formed by many volcanoes that rim the Pacific Ocean

  7. Island Arc • A string of islands

  8. Hot Spot • An area where magma from deep within the mantle melts through the crust like a blow torch.

  9. Hot Spot Example: Hawaiian Islands

  10. Hawaiian Islands What is the perfect example of a hot spot?

  11. Obsidian Pumice Two Types of Volcanic Rock

  12. Magma Chamber • Magma collects in a pocket

  13. Where is magma under a volcano held? Magma Chamber

  14. Pipe • Long tube in the ground that connects the magma chamber to the surface.

  15. Vent: Molten rock and gas leave the volcano through an opening

  16. Small lava fountain erupts from a new vent on the flank of a cinder cone on Kilauea Volcano, Hawaii.

  17. In May 1980, Mount St. Helens in the state of Washington erupted explosively. These photographs and diagrams show the first few minutes of the eruption. What is the term for the openings from which lava erupts? Vent

  18. Lava Flow • Area covered by lava as it pours out of a vent.

  19. Lava has made a river flow toward the ocean. When it cools off it will become rock.

  20. Dragon's teeth (in Maui) is a unique lava flow that was influenced by high waves as the ancient lava flow hit the ocean.

  21. Crater • Bowl-shaped area that may form at the top of a volcano around the volcano’s central vent.

  22. Do you see the two people standing around the top of the crater?

  23. Silica • Material that is formed from the elements oxygen and silicon. • The more silica magma contains the thicker it is.

  24. What determines the type of eruption? Explosive or Quiet? • The silica content in magma helps determine the type of eruption.

  25. What causes a volcanoes eruption to be quiet? • An eruption will be quiet when lava flows easily. • Little water and little silica produces a quiet eruption.

  26. What causes a volcanoes eruption to be explosive? High water and high silica will cause an explosive eruption.

  27. What type of eruption is this? Explosive or Quiet?

  28. Is this an explosive eruption or quiet?

  29. Besides water, what material in a volcano’s lava causes it to have an explosive or quiet eruption? Silica

  30. Pahoehoe • Fast-moving, hot lava • Looks like solid mass of wrinkles, billows, and ropelike coils.

  31. PahoehoePahoehoe is a Hawaiian term for basaltic lava that has a smooth or ropey surface. A pahoehoe flow advances as a series of lobes and toes that continually break out from a cooled crust. The surface texture of pahoehoe flows varies widely, displaying bizarre shapes often referred to as lava sculpture.

  32. Aa • Lava that is cooler and slower-moving, not smooth

  33. Pyroclastic Flow • Occurs when an explosive eruption hurls out ash, cinders, and bombs as well as gases.

  34. Mt. Saint HelensPhreatic eruption at the summit of Mount St. Helens, Washington. Hundreds of these steam-driven explosive eruptions occurred as magma steadily rose into the cone and boiled groundwater. These eruptions preceded the volcano's eruption on 18 May 1980.

  35. Cinder BlockA volcanic block is a solid rock fragment greater than 64 mm in diameter that was ejected from a volcano during an explosive eruption. Blocks commonly consist of solidified pieces of old lava flows that were part of a volcano's cone.

  36. Active Volcano • Live • Erupting or has shown signs that it may erupt in the near future.

  37. Kilauea volcano is active today. Inside the volcano is Halema'uma'u crater in the background.

  38. These are active volcanoes. Where are they located? They are located around plate boundaries. This area is called Ring of Fire.

  39. Dormant Volcano • Sleeping • Expected to awaken in the future and become active.

  40. Mount Shasta from Mount Eddy The two main peaks formed within the last 10,000 years. Over the last 4,500 years, Mount Shasta has erupted on average every 600 years. It last erupted around 1786 A.D. It is a dormant volcano.

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