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What are earthquakes?

What are earthquakes?. Earthquakes occur mainly at plate boundaries. http://vulcan.wr.usgs.gov/Imgs/Gif/PlateTectonics/Maps/map_quakes_volcanoes_plates.gif. Pressure. Pressure builds up as plates move. Eventually rocks break at a fault . Energy is released as seismic waves . (3 kinds).

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What are earthquakes?

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  1. What are earthquakes? • Earthquakes occur mainly at plate boundaries. http://vulcan.wr.usgs.gov/Imgs/Gif/PlateTectonics/Maps/map_quakes_volcanoes_plates.gif

  2. Pressure • Pressure builds up as plates move. • Eventually rocks break at a fault. • Energy is released as seismic waves. (3 kinds)

  3. Types of Forces and Faults

  4. Normal Faults Tension – pulling rocks apart

  5. Reverse Faults Compression– pushing rocks together

  6. Strike-Slip Faults • Caused by shearing

  7. Describing the location • Earthquakes occur underground. • The spot underground where the rock breaks is the focus. • The spot on the surface directly above that is the epicenter. http://www.harcourtschool.com/scienceglossary/images/gr4/epicenter4.jpg

  8. Types of Waves Primary Waves(first) – longitudinal waves that travel the fastest - originate at the focus These are the first sign of an earthquake http://astro.uchicago.edu/cara/outreach/se/ysi/1999/intro2.html

  9. Secondary Waves TransverseWaves that start out at the focus http://astro.uchicago.edu/cara/outreach/se/ysi/1999/intro2.html

  10. Surface Waves Originate at the epicenter (on the surface) Cause the most destruction http://www.gly.fsu.edu/~salters/GLY1000/Chapter4/Slide18.jpg

  11. How far away? • The lag time between the primary and secondary waves is used to determine how far away the earthquake occurred

  12. Measuring an Earthquake Seismometers– instruments used to sense and record earthquake data http://www.thetech.org/exhibits/online/quakes/seismo/

  13. Measuring an Earthquake Seismographs– recordings of seismic waves produced by seismometers http://www.thetech.org/exhibits/online/quakes/seismo/

  14. http://www.inel.gov/env-energyscience/seismic/network.shtml

  15. Amplitude • The height of a wave

  16. Locating the epicenter 3 Seismograph stations are required to triangulate the location http://www.tecedu.com/about/images/us-map.gif

  17. Richter Scale Measures the magnitude of earthquakes using the distance from the epicenter and the amplitude of the largest wave. http://www.wanadoo.jo/medias/img/SGE.GXY52.050904182653.photo00.default-245x208.jpg

  18. Determining Richter scale

  19. Richter Scale Each number increase on the Richter scale indicates an increase of 10x’s in amplitude 32 x’s more energy http://www.wanadoo.jo/medias/img/SGE.GXY52.050904182653.photo00.default-245x208.jpg

  20. Historic Earthquakes

  21. http://www.tfhrc.gov/pubrds/03nov/images/mccarthy2.jpg http://epod.usra.edu/archive/images/augustanack3.jpg http://www.tfhrc.gov/pubrds/03nov/05.htm http://www.disasterrelief.org/Disasters/010326alaskaquake1964/Images/rail.gif http://earth.geol.ksu.edu/sgao/g100/plots/1031_earthquake_trig.jpg Alaska 1964, 9.2

  22. Modified Mercalli Scale Measures intensity or damage caused by an earthquake I -XII http://elearning.niu.edu/simulations/images/S_portfolio/Mercalli/Mercalli_Scale.swf

  23. Moment magnitude scale Used to record energy released by an earthquake and takes into account the size of the fault rupture.

  24. Tsunamis

  25. Tsunamis • are large fast moving waves that are produced by moving crust under the ocean

  26. Recent Tsunami’s

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