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More Earth Science

More Earth Science. Landforms Earthquakes Seismic Waves Shadow Zone. Landforms. Mountains. A mass of rock rising more than 600 meters above the surrounding land Relief vs. Elevation. Types of Mountains. Fold Mountain. Fold Mountains.

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More Earth Science

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  1. More Earth Science Landforms Earthquakes Seismic Waves Shadow Zone

  2. Landforms

  3. Mountains • A mass of rock rising more than 600 meters above the surrounding land • Relief vs. Elevation

  4. Types of Mountains

  5. Fold Mountain

  6. Fold Mountains • Usually made mostly of sedimentary rock folded by compression forces • These are the tallest and most common of all mountains

  7. Examples of Fold Mountains Appalachian Mountains

  8. Rocky Mountains

  9. Alps

  10. Himalaya Mountains

  11. Fault-Block Mountain

  12. Fault Block Mountain Ranges are cause by a series of normal faults

  13. Examples of Fault block Mountain ranges

  14. Sierra Nevada Mountains, CA

  15. Grand Tetons, WY

  16. Wasatch Mountains, Utah

  17. When the Earth SHAKES Earthquakes

  18. What causes earthquakes?

  19. Volcanic eruptions can cause earthquakes but most earthquakes are caused by FAULTING • These are often called TECTONIC earthquakes

  20. Theory VS. Law • A THEORY is a logical idea that has not been proven directly but it often can be proved mathematically • It is a working set of rules that define a body of knowledge • A LAW is observable and can be proven- to a point. Nothing is 100% sure in a Universe as vast as ours

  21. Elastic Rebound Theory The Elastic Rebound Theory was first proposed by American geologist Harry Fielding Reidafter the 1906 San Francisco Earthquake

  22. Elastic Rebound • The sudden release of progressively stored strain in rocks, resulting in movement along a fault • After the stress becomes too great, the rock layers break, vibrating back and forth until eventually coming to a rest

  23. As the rock layers are shaking back and forth they send out waves of vibration called Seismic Waves • “Seismic” always has to do with earthquake activity

  24. Seismic Waves are waves of vibration sent out in all directions from the FOCUS

  25. FocusThe point below the surface where the rock layers break and move • EpicenterThe point on the surface, directly above the focus. Where the greatest damage usually occurs

  26. Epicenter Fault Focus Seismic Waves

  27. Measuring Earthquakes

  28. Charles Richter26 April 1900 – 30 September 1985

  29. Seismograph A machine that measures earthquake (seismic) waves

  30. Zhang Heng seismograph is almost 2000 yrs old

  31. Early Seismograph Operates on the principle of Newton’s First Law

  32. Seismogram The recorded information of earthquake waves

  33. Seismogram The Richter Scale is based on MAGNITUDE

  34. Each # is TEN TIMES larger than the # before it… Magnitude 1 Magnitude 2 Magnitude 3

  35. Pennies as an example: Mag. 1 = 1 penny Mag. 2 = 10 pennies Mag 3 = 100 pennies Mag. 4 = 1000 pennies Mag. 5 = 10,000 pennies Mag. 6 = 100,000 pennies Mag. 7 = 1,000,000 pennies Mag. 8 = 10,000,000 pennies Mag. 9 = 100,000,000 pennies Mag. 10 = 1,000,000,000 pennies (that’s $10 million in pennies!!)

  36. Richter Magnitudes Earthquake Effects Less than 3.5 Generally not felt 3.5-5.4 Often felt, little damage Under 6.0 Slight damage to buildings 6.1-6.9 Destructive to about 100 km from epicenter 7.0-7.9 Major earthquake. Can cause serious damage 8 or greater Large earthquake. Serious damage for hundreds of km

  37. Anatomy of a basic wave

  38. Crest – the highest point on a wave (A, F) • Trough – the lowest point on a wave (D, I) • Amplitude – the distance between the midpoint & crest or trough • Wavelength – distance between any two successive points on a wave • Frequency - # of vibrations/ second (Hertz)

  39. Types of Seismic Waves

  40. Body Waves are waves that travel through the body of the earth Surface waves only travel along the surface of earth

  41. Body Waves

  42. Primary WavesAKA P-Wave • Type of Longitudinal Wave • Causes back and forth motion • Follows the same direction as the energy transfer

  43. P-Waves • Type of COMPRESSIONAL wave (like sound) • Will travel through solid, liquid or gas • Travels at: • 7.8 – 8.5 kps in mantle • 7.2 kps in oceanic crust • 3.5 kps in continental crust

  44. Primary Wave • http://sunshine.chpc.utah.edu/labs/seismic/surface.swf

  45. Secondary WaveAKA S-Wave • Particle motion is perpendicular to direction of energy transfer • Transverse or Shear Wave • Will travel only through solids • Travels 4 – 5 kps

  46. Secondary Wave • http://sunshine.chpc.utah.edu/labs/seismic/surface.swf

  47. Surface Waves

  48. Two main types of surface waves: • Love Wave • Rayleigh Wave • Recent evidence show s that L-Waves attenuate (gradually disappear) more slowly in older rock (eastern US) and more quickly in younger rock (western US)

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