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Natural Disasters: Earthquakes

Natural Disasters: Earthquakes. Review…. Most of the world’s earthquakes and volcanoes are located along the Pacific Ring of Fire Earthquakes occur along plate boundaries. Earthquakes. Sudden movement or shaking of the Earth Results in breakage of the Earth’s brittle crust .

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Natural Disasters: Earthquakes

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  1. Natural Disasters: Earthquakes

  2. Review… • Most of the world’s earthquakes and volcanoes are located along the Pacific Ring of Fire • Earthquakes occur along plate boundaries

  3. Earthquakes • Sudden movement or shaking of the Earth • Results in breakage of the Earth’s brittle crust http://www.youtube.com/watch?v=FW-TkpvKPl0

  4. Shallow or Deep? • Earthquakes occur at different depths in the Earth and can either be deep or shallow • FOCUS = place deep within the Earth and along the fault where rupture occurs • EPICENTER = geographic point on surface directly above focus

  5. Faults • Faults are cracks where plate sections are moving in different directions • Faults cause friction as plates move • Recall: the San Andreas Fault in California

  6. Earthquake Zones • Transform: along sliding boundaries; severe, shallow quakes • Divergent: along ocean ridges; shallow quakes • Convergent: associated with ocean trenches; deep quakes

  7. Earthquake Waves • Seismographs record earthquake waves • They show • Amplitudeof seismic waves (how much rock moves or vibrates) • Distance to the epicenter • Earthquake direction

  8. Earthquake Magnitude • Measures the size of seismic waves (the energy released by the earthquake) • World’s largest recorded earthquake: “The Great Chilean Earthquake” in 1960 with a magnitude 9.5

  9. What can sometimes follow an earthquake and cause extreme damage?

  10. Tsunamis • A tsunami is a series of ocean waves that sends surges of water, sometimes reaching heights of over 100 feet (30.5 meters), onto land. • Tsunami is a Japanese word meaning “harbour wave”.

  11. When the ocean floor at a plate boundary rises or falls suddenly it displaces the water above it and launches the rolling waves that will become a tsunami.

  12. Tsunamis • Tsunamis race across the sea at up to 500 miles (805 kilometers) an hour—about as fast as a jet airplane. • At that pace they can cross the entire expanse of the Pacific Ocean in less than a day. • http://www.youtube.com/watch?v=dJBS94GVyuo • http://www.youtube.com/watch?v=qryJaTbASs0

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