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Volcanoes and Mountains and Earthquakes, Oh My!

Volcanoes and Mountains and Earthquakes, Oh My!. Part 1: Volcanoes. What IS a Volcano, Anyway?. A place where magma erupts through the crust and reaches the surface Also an insight into what goes on inside our planet. Life Next to a Volcano. Dangerous, duh! Lava Gases

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Volcanoes and Mountains and Earthquakes, Oh My!

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  1. Volcanoes and Mountains and Earthquakes, Oh My! Part 1: Volcanoes

  2. What IS a Volcano, Anyway? • A place where magma erupts through the crust and reaches the surface • Also an insight into what goes on inside our planet

  3. Life Next to a Volcano Dangerous, duh! • Lava • Gases • Earthquakes (but can be useful)

  4. Life Destroyed by a Volcano… Mt. Saint Helens – May 17th, 1980

  5. Mt. Saint Helens – May 18th, 1980

  6. Mt. Saint Helens – Sometime Later

  7. From Above

  8. Mt. Saint Helens – Today

  9. It Starts Back Simple…

  10. And Gets Better

  11. Life Far From a Volcano Not immune! • Some gases from eruptions form acid rain • Dust from eruptions be scattered throughout atmosphere and remain for years • 1780’s: Eruptions in Japan and Iceland led to coldest year in Europe in the 1700’s (1789): crops failed and Ben Franklin said sun looked “hazy”

  12. Famous Volcanoes

  13. Mt. Vesuvius: Pompeii, Italy – 79 AD

  14. Tambora, Indonesia - 1815 • Largest eruption in last 200 yearss • 1816 – “Year without a Summer”. Snowed in New England in summer!

  15. Krakatoa, Indonesia - 1883 4 times the explosion of today’s most powerful nuclear bomb 36,000 people died, mainly from the resulting tsunami Destroyed 2/3 of island, but has since been rebuilt by volcano Anak Krakatoa (Child of Krakatoa)

  16. Paricutin, Mexico - 1943 Volcano formed in a cornfield! Grew 450 m in 1st year Stopped erupting in 1952 Destroyed 2 villages and buried a church up to its belltower

  17. Mt. Saint Helens, WA - 1980

  18. Mt. Pinatubo, Philippines - 1991

  19. Mauna Lo….

  20. Mt. Redoubt – Right Now!

  21. 5 Deadliest in Recent History • Tambora, Indonesia (1815) – 92,000 dead • Krakatau, Indonesia (1883) – 36,000 dead • Mt. Pelee, Martinique (1902) – 28,000 dead, only 1 survivor • Nevada del Ruiz, Colombia (1985) – 25,000 dead • Unzen, Japan (1792) – 14,000 dead

  22. Remember This? Where would you find a volcano?

  23. Where Volcanoes Form • Divergent plate boundaries • Ocean-ocean convergent boundary • Ocean-continent convergent boundary • Random places (intraplate volcanoes)

  24. Divergent Boundary Volcanoes As found at Mid-Atlantic Ridge and African Rift Valley

  25. Ocean-Ocean Convergent Volcanoes

  26. Ocean-Continent Convergent Volcanoes

  27. Random (Intraplate) Volcanoes

  28. The Classic Intraplate Volcano: Hawaii

  29. Anatomy of a Volcano

  30. Eruptions 2 Types of eruptions: • Ka-blooey! Explosions(and here too) • Slow but steady “oozing” of lava The type of explosion depends on the magma

  31. Ka-blooey! Explosions Magma generally: • Has a lot of dissolved, trapped gases (up to 6% of total debris ejected) (think of a shaken bottle of soda, or Diet Coke and Mentos) • Is viscous (thick and syrup-like) • Mineral composition is rich in silicates • Magma “not as hot” (whatever that means)

  32. Slow-but-Steady Oozing Eruptions Magma generally: • Has little dissolved gas (only 1% or so) • “Runny” (nonviscous) • Mineral composition is poor in silicates • Hotter

  33. Shape of a Volcano Can Predict Type of Eruption - Slow-but-steady Oozing - Thar-she-blows! - Once-and-done explosion

  34. 3 Main Types of Volcanoes • Shield volcanoes • Composite cones • Cinder cones

  35. 1. Shield Volcanoes • Extremely large, gently-sloping volcanoes • Built up slowly over time by oozing of lava • Looks vaguely like a warrior’s shield…

  36. An Example of a Shield Volcano Mauna Loa, Hawaii – the world’s largest volcano! 4200 meters above sea level + 5000 meters below sea level = one big volcano! (9,200 meters. For comparison, Mt. Everest is only 8,848 meters tall)

  37. 2. Composite Cone • Much smaller in size but much steeper sides • Formed from thick, viscous lava which can only flow a short distance before hardening • Typically explodes violently when it erupts

  38. Examples of Composite Cones • Mt. St. Helens, other volcanoes in Cascade Mountains, Andes Mountains, and throughout the Ring of Fire

  39. Another Composite Cone:Mount Fuji, Japan

  40. Another Frightening Picture of Mt. Pinatubo, acomposite cone -1991

  41. 3. Cinder Cones • Tiny volcanoes (relatively speaking): less than 400 meters tall • Formed when volcano spews out rocks and rapidly-cooling lava. Debris falls as “cinders” around vent, forming a cone • Lava then often flows out of vent, coating the volcano • Once and done: volcano becomes extinct

  42. Sunset Crater, Arizona Only ~1,000 years old 300 meters tall Mt. Paricutin, Mexico Only 60 years old! 400 meters tall Extinct in only 9 years! Examples of Cinder Cones

  43. Other Interesting Volcanic Formations • Calderas • Volcanic necks

  44. 1. Calderas Craters formed from collapsed volcanoes

  45. Crater Lake, OR: A Caldera

  46. 2. Volcanic Necks • Remains of solidified magma pipe in volcano, after rest of volcano has eroded away Ship Rock, New Mexico

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