1 / 42

Chapter 18

Chapter 18. Volcanic Activity. Lesson 5. Volcanoes: The Basics. Think About It…. What happens when you shake a can of soda and then open it?. Focus Question…. How does the composition of magma affect its explosiveness?. http://www.pbs.org/wgbh/nova/volcanocity/anat-08.html.

caradoc
Download Presentation

Chapter 18

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 18 Volcanic Activity

  2. Lesson 5 Volcanoes: The Basics

  3. Think About It… What happens when you shake a can of soda and then open it?

  4. Focus Question… How does the composition of magma affect its explosiveness?

  5. http://www.pbs.org/wgbh/nova/volcanocity/anat-08.html • What is magma? • A mixture of molten rock, suspended mineral grains, and dissolved gases deep beneath Earth’s surface Nyiragongo Volcano East African Rift Valley

  6. http://www.ncgeology.com/Eno_interactive_webs/Geologic_Principles_igneous%20rocks.htmlhttp://www.ncgeology.com/Eno_interactive_webs/Geologic_Principles_igneous%20rocks.html 2. Types of Magma: Basaltic… • Gas Content • 1 – 2 % • Silica Content • 50% • Viscosity • low • Explosiveness • least • Origin/Location of Magma/Lava • oceanic/continental crust • Example • Mt. Kilauea in Hawaii Mt. Kilauea A Hot Spot Volcano

  7. Types of Magma: Andesitic… • Gas Content • 3 - 4 % • Silica Content • 60% • Viscosity • intermediate • Explosiveness • intermediate • Origin/Location of Magma/Lava • continental margins • Examples… • Mt. St. Helens and Mt. Rainier (Washington) • http://vulcan.wr.usgs.gov/Volcanoes/MSH/Images/july_22_images.html

  8. Mt. St. Helens – From the Summit of Mt. Rainier

  9. Types of Magma: Rhyolitic (Granitic) Yellowstone Volcano • Gas Content • 4 - 6 % • Silica Content • 70% • Viscosity • high • Explosiveness • greatest • Origin or Location of Magma/Lava • continental crust • Example • Yellowstone Supervolcano in Wyoming

  10. Yellowstone…

  11. http://www.hbci.com/~wenonah/history/img/krakatoa.jpg Types of Magma… 3. The higher the silica content… • the higher the viscosity (resistance to flowing)… • the greater the explosiveness! Krakatoa – Highly viscous and explosive!

  12. http://romanmythology.wikia.com/wiki/Pluto Intrusive Activity… • What is a pluton? • An intrusive igneous rock body Pluto – god of the underworld http://earthsci.org/mineral/rockmin/chart/iroccur.gif

  13. http://www.yosemiteriversideinn.com/ Batholiths 2. A batholith is the largest of plutons common in the interiors of major mountain chains. Yosemite – Part of the Sierra Nevada Batholith

  14. Intrusive Activity… 3. Where did all the magma come from? • Scientists hypothesize that… • At subduction zones, a plate subducts, • melts, • cools into a pluton. http://herramientaslinker.com.ar/convergent-boundary-subduction&page=7

  15. http://www.smate.wwu.edu/teched/geology/vo-eruption2.html Volcanoes… • What is lava? • molten rock that has reached Earth’s surface • What is a volcano? • A mountain or opening in Earth’s crust from which lava erupts Paricutin in Mexico, 1943

  16. 3. The Anatomy of a Volcano… • Vent – the opening in the crust through which lava erupts • Crater – bowl-shaped depression around the vent • Caldera – larger depressions around a vent where the volcano has collapsed into the magma chamber d. Magma chamber – area under the volcano which holds the magma

  17. Slides of Crater, Caldera… • Crater Lake • Yellowstone Caldera

  18. 4. Label the Volcano… http://rbaadvisors.com/what-are-the-main-features-of-a-volcano&page=3

  19. Types of Volcanoes… http://www.cnn.com/2014/10/28/us/hawaii-volcano/index.html IN THE NEWS… • Type of Volcano • Shield • How It Forms • Basaltic lava builds up (Quiet eruptions) • Description • Wide with gently-sloping sides • Example • Kilauea in Hawaii (hot spot) • Iceland (divergent) http://www.discoverhawaiitours.com/blog/tag/kilauea/

  20. Types of Volcanoes… • Type of Volcano • Cinder cone • How It Forms • Ejected tephra falls back to earth and piles up (Explosive) • Description • Small but steep • Example • Paricutin in Mexico • Convergent boundary Paricutin, Mexico http://volcano.oregonstate.edu/vwdocs/volc_images/img_paricutin.html

  21. Types of Volcanoes… • Type of Volcano • Composite • How It Forms • Tephra eruptions alternate with lava flows • Description • Large & steep • Example • Krakatoa • Mt. St. Helens • Convergent Mt. St. Helens -Before and After! http://pubs.usgs.gov/fs/2005/3045/images/fig1.jpg

  22. Mt. St. Helens… as seen from the crater of Mt. Rainier!

  23. A Composite Volcano… • http://www.pbs.org/wgbh/nova/volcanocity/anat-flash.html

  24. Lesson 6 Volcanoes: Effects on the Lithosphere

  25. Tephra… 1. What is tephra? • Rock fragments thrown into the air during a volcanic eruption Tephra classified by size… • dust  ash  lapilli  bombs  blocks 2. A pyroclastic flow is… • an eruption of gas, ash, and other tephra • These types of eruptions can be extremely violent and deadly because… the PC flow moves very fast and is very hot. 3. Ash and dust from a pyroclastic flow blocks sunlight and lowers global temperatures.

  26. Effects of a Volcanic Eruption… Lahars • A lahar is a mixture of mud & debris created when… • heat from an eruption melts snow OR • rain forms around dust or ash in the atmosphere. http://volcanoes.usgs.gov/hazards/lahar/index.php

  27. Earthquakes, Landslides and Tsunamis… • Earthquakes are caused when… Magma breaks rocks as it makes its way to the surface. • Landslides are caused in two ways… … a volcanic earthquake (EQ) or the eruption itself causes land to slide • Tsunamis are caused when… … the volcanic landslide “bulldozes” water ahead of it

  28. Earthquakes, Landslides and Tsunamis… http://volcanoes.usgs.gov/hazards/landslide/index.php http://volcanoes.usgs.gov/Imgs/Jpg/Unzen/MayuyamaSlide_large.jpg

  29. Earthquakes, Landslides and Tsunamis…

  30. 5. Hawaii and Yellowstone… • … are formed at hot spots (very hot places in the mantle/crust) • … away from plate boundaries

  31. 6. Kilauea: Effects on Land… Basaltic lava… • burns vegetation and buildings • creates new land (16 acres a year!) http://www.ncgeology.com/Eno_interactive_webs/Geologic_Principles_igneous%20rocks.html

  32. 7. Krakatoa: Effects on Land… The eruption of Krakatoa… • Created a caldera when it blew the island apart • Caused a pyroclastic flow and tsunami (1883) http://www.ncgeology.com/Eno_interactive_webs/Geologic_Principles_igneous%20rocks.html

  33. 8. Iceland: Effects on Land… Iceland’s volcanoes in the rift valley are causing it to grow bigger – with older rocks on the east and west sides of the island.

  34. Convergent Boundary Volcanoes • Ocean plates subduct under other plates and melt to form magma • Location – the Pacific Ring of Fire, the Mediterranean Belt Mt. Vesuvius and Pompeii Victims http://mrbpielglobal.edublogs.org/files/2010/12/vesuvius_24417-1qnp5rt.jpg

  35. The Ring of Fire… http://pubs.usgs.gov/gip/dynamic/graphics/Fig22.gif

  36. Divergent Boundary Volcanoes • As plates move apart, magma is forced upward into fractures and faults • Location – East Africa Rift Valley, mid-ocean ridges, Iceland

  37. http://rajeshsivananth.files.wordpress.com/2010/07/surtsey.jpghttp://rajeshsivananth.files.wordpress.com/2010/07/surtsey.jpg Divergent Boundary Volcanoes… Iceland Surtsey Volcano

  38. A Plethora of Plutons… Stocks • Stocks are irregularly-shaped plutons similar to batholiths but smaller. http://belmont.sd62.bc.ca/teacher/geology12/photos/volcanoes/plutons.jpg

  39. A Plethora of Plutons… Laccoliths http://facweb.bhc.edu/academics/science/harwoodr/geol101/study/Plutons.htm • Laccoliths are mushroom-shaped plutons with a round top and a flat bottom.

  40. http://facstaff.gpc.edu/~pgore/geology/geo101/plutons.php A Plethora of Plutons… Sills • A sill is a pluton that forms when magma intrudes parallel to layers of rock. The Palisades Sill, NY

  41. A Plethora of Plutons… Dikes http://www.exstrom.com/hbaromega/irondike.html • A dike is a pluton that cuts across preexisting rocks. Iron Dike Intrusion, Ironclads, Colorado

  42. The Great Dike of Zimbabwe…

More Related