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Earthquakes & Seismic Waves

Earthquakes & Seismic Waves. An Earthquake occurs when energy is released through rapid movement along a fault. Current Earthquake Data. http://ds.iris.edu/seismon/. Focus. That is the point along the fault line where the rock under stress breaks. Epicenter.

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Earthquakes & Seismic Waves

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  1. Earthquakes & Seismic Waves

  2. An Earthquake occurs when energy is released through rapid movement along a fault.

  3. Current Earthquake Data http://ds.iris.edu/seismon/

  4. Focus • That is the point along the fault line where the rock under stress breaks.

  5. Epicenter • Is the point on the earth’s surface directly above the Focus.

  6. Focal Depth • This is the distance between the Focus and the Epicenter.

  7. Seismic Waves • Energy from an Earthquake is carried away from the focus as Seismic Waves. • There are many different types of waves. • We will concentrate on the two most prominent.

  8. Primary Waves • P Waves • The fastest seismic wave. • Arrives at recording stations first (Primary).

  9. Primary Waves • P waves are compressional waves. • The energy travels in the same direction as the wave travels.

  10. Primary Waves • P waves can travel through solids, liquids or gases.

  11. Secondary Waves • S Waves • Arrives at recording stations second (secondary).

  12. Secondary Waves • S waves are transverse waves. • Another term is shear waves. • The energy is perpendicular to the direction of wave travel.

  13. Secondary Waves • S Waves can only travel through solids.

  14. Surface Waves • Waves like L waves and R waves travel slightly slower then S waves but do tremendous damage.

  15. https://www.youtube.com/watch?v=yOGoKCK17a4

  16. Seismograph • Instruments that detect and measure seismic waves are called Seismographs. • They originally were a weight and pen suspended over a moving drum.

  17. Seismograph • The tracing on the drum is called a seismogram. • The different types of waves make different tracings on the seismogram.

  18. https://www.youtube.com/watch?v=VSgB1IWr6O4

  19. History of Earthquakes Largest In Magnitude • Date Location Magnitude • May 22nd, 1960 Chile9.5 • March 28th, 1964 Alaska 9.2 • December 26th, 2004 Sumatra (Ocean) 9.1 • March 11th, 2011 Japan (Ocean) 9.0 • February 27th, 2010 Chile8.8 Largest In Destruction • Date Location Deaths Magnitude • Jan 25th, 1556 China 830,000 8 • July 27th, 1976 China 655,000 7.5 • Aug. 9th, 1138 Syria 230,000 Unknown • Dec. 26th, 2004 Sumatra 227,898 9.1 • Jan. 12th, 2010 Haiti 222,570 7.0

  20. Locating an Earthquake Epicenter… • To find where the an Earthquake originates you need wave data from 3 recording stations. • Circles are drawn around these stations. • Where the 3 circles connect is where the earthquake originated.

  21. Underwater E-quake Fault movement along the ocean floor moves the water up and down which can create a massive wave called a “Tsunami”.

  22. Tsunami

  23. https://www.youtube.com/watch?annotation_id=annotation_1885845763&feature=iv&index=2&list=PLNspHwmzscYE2-cUkOfHo92ATHZUqqsPH&src_vid=j0YOXVlPUu4&v=pTtneXyhoPAhttps://www.youtube.com/watch?annotation_id=annotation_1885845763&feature=iv&index=2&list=PLNspHwmzscYE2-cUkOfHo92ATHZUqqsPH&src_vid=j0YOXVlPUu4&v=pTtneXyhoPA

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