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Earthquakes, Volcanoes, and Tsunamis

Earthquakes, Volcanoes, and Tsunamis. Where do they occur, and why?. Earth Zones: The Earth is like an egg. Core (the yolk): a very hot, dense zone under intense pressure from the weight of the overlying rock material

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Earthquakes, Volcanoes, and Tsunamis

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  1. Earthquakes, Volcanoes, and Tsunamis Where do they occur, and why?

  2. Earth Zones: The Earth is like an egg. • Core (the yolk): a very hot, dense zone under intense pressure from the weight of the overlying rock material • Mantle (the egg white): a zone of thick molten rock called magma, slowly moving in broad currents • Crust (the eggshell): a thin, brittle shell broken into seven pieces called plates, and floating on the mantle

  3. Pangea and Continental Drift

  4. Tectonic Plates

  5. Where are active volcanoes? What patterns do you see?

  6. Where do earthquakes occur, and why?

  7. Earthquakes • The shaking or trembling • caused by the sudden release of energy • Usually associated with faulting or breaking of rocks • Continuing adjustment of position results in aftershocks September 1985, Mexico City, Mexico

  8. Where Do Earthquakes Occur and How Often? ~80% of all earthquakes occur in the circum-Pacific belt • most of these result from convergent margin activity • ~15% occur in the Mediterranean-Asiatic belt • remaining 5% occur in the interiors of plates and on spreading ridge centers • more than 150,000 quakes strong enough to be felt are recorded each year

  9. Seismic Waves • FOCUS- underground point of origin • EPICENTER- aboveground of origin; most violent shaking occurs at the epicenter • The three main types of seismic waves are: P waves, S waves, and L waves

  10. John Milne- 1893 • Seismograph-measures and detects seismic waves • Seismogram- Paper record of waves who study earthquakes • Seismologist- scientist • Richter Scale- a scale that allows scientists to determine earthquake strength based on many readings • 1-10 levels at which an earthquake is measured on amount of damage caused; Above a 6 is very destructive

  11. The Economics and Societal Impacts of EQs Damage in Oakland, CA, 1989 • Building collapse • Fire • Tsunami • Ground failure

  12. Five Deadliest Earthquakes since 1995 (Haiti, 2010 image)

  13. Tsunami of 2006 (Southeast Asia image)

  14. By KUALA MUDA KEDAH, Malaysia, 1 September 2006 I was watching TV when my neighbour came to my house to tell me to look at this long white line in the sea. When I saw the giant waves in the distance I thought to myself, how beautiful! I had never seen anything like it before. But as I stood watching the wave, I saw boats capsizing in the distance. I had no idea what was happening until a fisherman shouted at me to run, because the wave was coming towards us,” recalled 13‐year old Siti of her terrifying brush with death. Like so many other villagers in Kuala Muda Kedah, Siti had never heard the word “tsunami” before that day in December 2004. Unsure of exactly what was happening, the courageous young girl, from a single parent household, helped her ailing mother and younger brother to safety. Most villages around the Indian Ocean affected by this disaster were coastal fishing communities. Despite their relatively close ties to the sea, little was known about the killer waves or how to react in the face of this type of disaster.

  15. Tsunami Clip: What is a Tsunami? Recognizing Dangerous Ways and Evacuation. http://tsunamivideoclips.com/tsunamiteacher-usa-tsunami-basics/

  16. Volcanoes

  17. VOLCANOES • Volcano- place on Earth’s surface that allows magma and other material to erupt • Magma- found beneath the Earth’s surface, it is liquid rock • Lava- magma that reaches the Earth’s surface

  18. Crater- funnel shaped pit, or depression at top of volcano Caldera- when a crater becomes too large, it collapses: also can form when the top of a volcano collapses or explodes Dormant- sleeping volcano Extinct- not known to have erupted in modern history Active- Erupts fairly regularly Volcanic Terminology

  19. Volcanic Dust -less that 0.25 mm in diameter (flour) Volcanic Ash -more than 0.25 less than 5 mm (rice) Volcanic Bombs - few cm to several meters. Cinders - volcanic bombs the size of golf balls Volcanic Fragments

  20. Types of Volcanoes • Cinder Cones- made of mostly of cinders; formed from explosive eruptions • Shield- Made of quiet lava flows • Composite- made up of alternating layers of rock particles; explosive eruptions, then quite lava flows

  21. Volcano Clip • http://video.nationalgeographic.com/video/environment/environment-natural-disasters/volcanoes/volcano-lava/ -Lava erupting http://video.nationalgeographic.com/video/news/environment-news/west-mata-submarine-volcano-vin/ -Underwater volcanic explosion

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