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Volcanoes and Earthquakes

Volcanoes and Earthquakes. Weak spot in crust where molten material (magma) comes to the surface. What is a volcano?. What are plate tectonics ? theory which describes the motions of the earth’s crustal plates What causes plate tectonics ? convection currents in the mantle

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Volcanoes and Earthquakes

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  1. VolcanoesandEarthquakes

  2. Weak spot in crust where molten material (magma) comes to the surface What is a volcano?

  3. What are plate tectonics? • theory which describes the motions of the earth’s • crustal plates • What causes plate tectonics? • convection currents in the mantle • Volcanic belts around plate boundaries • Ring of Fire • Converging plate boundaries • Plates come together • Diverging plate boundaries • Plates seperate Volcanoes and Plate Boundaries

  4. Magma erupts through Earth’s crust • Can happen anywhere • Yellowstone Hot Spot Volcanoes

  5. Quiet Eruptions • Low-silica, low-viscosity magma • Hawaii • Explosive Eruptions • High-silica, high viscosity • Pyroclastic flow • Mt. St. Helens Volcanic Eruptions

  6. Active-is erupting or may erupt at any time • Dormant- Might become active in future • Extinct- dead, unlikely to erupt again Volcano Life Cycle

  7. Energy comes from magma under Earth • Hot Springs- groundwater heated by magma and forms pool • Geysers- Hot water, steam erupts from ground • Geothermal energy- water heated naturally • Used to warm houses • electricity (steam) Volcano Energy

  8. Shaking and trembling that results from the movement of rock beneath Earth’s surface What is an earthquake?

  9. Tension- stretches rock, divergent • Compression- Squeezes rock until it folds or breaks, convergent • Shearing- rocks move in opposite directions Stress in Earth’s Crust

  10. Normal Faults- diverge, footwall above hanging wall • Reverse Faults- Compression, hanging wall above footwall, converge • Strike-slip Faults- plates move past each other Faults

  11. Carry energy from an earthquake away from the focus (center) through Earth’s interior, and across surface Seismic Waves

  12. P waves- first to arrive, longitudinal waves, move in solids and liquids • S waves- second to arrive, transverse waves, only in solids • Surface waves- ground moves like ocean waves, transverse waves Types of Seismic Waves

  13. Detects seismic waves • Used to map and monitor faults Seismograph

  14. Shaking- triggers landslides, avalanches, destroys buildings and water mains • Liquefaction- loose, soft soil turns to mud • Aftershocks- smaller earthquakes following big earthquake • Tsunamis- large wave Damage from Earthquakes

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