End of Chapter 2

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End of Chapter 2
2
Mountain Building - Faulting

• Over millions of years, fault movement can change
  a flat plain into a towering mountain range.
• Fault-block Mountain when normal faults uplift
  a block of rock (When two normal faults form
  parallel to each other)

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Mountains Folding

• Rock stressed by compression may bend slowly
  without breaking
• Folds bends in rock that form when compression
  shortens and thickens part of the Earths crust
• Collision of two plates

4
Anticlines and Synclines

• Anticlines a fold in rock that bends upward
  into an arch
• Black Hills (South Dakota)
• Syncline fold in the rock that bends downward
  in the middle to form a bowl
• Where a valley dips between two parallel ranges
  of hills (Illinois Basin)

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Plateaus

• Forces that raise mountains can also raise
  plateaus
• Plateau a large area of flat land elevated high
  above sea level
• Many different flat layers, is wider than it is
  tall
• Colorado Plateau 4 corners
• Arizona, Utah, Colorado, and Nevada

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Chapter 2-2
7
Measuring Earthquakes

• Focus point beneath Earths surface where rock
  that is under stress breaks, triggering an
  earthquake
• Epicenter the point on the surface directly
  above the focus

8
Seismic Waves

• Vibrations that travel through Earth carrying the
  energy released during an earthquake
• Move like ripples in a pond
• Diagram page 65

9
Categories of Seismic Waves

• Primary (P) Waves first to arrive
• Compress and expand ground accordion
• Can travel through solids and liquids
• Secondary (S) Waves second waves to arrive
• Vibrate from side to side shake ground back and
  forth
• Can only travel through liquids
• Surface Waves last to arrive, more slow, but
  produce the most severe ground movements

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Detecting Seismic Waves

• Seismograph records ground movements caused by
  seismic waves as they move through the Earth
  (electronic)

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Measuring Earthquakes

• Magnitude measurement of earthquake strength
  based on seismic waves and movement along faults
• Mercalli Scale rates intensity (Strength of
  ground movement) The same earthquake can measure
  differently based on damage
• Richter Scale rating of the size of the seismic
  waves that was once measured mechanically (Does
  not work well for large or distant earthquakes)

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Measuring Earthquakes

• The Moment Magnitude Scale rating system that
  estimates the total energy released by an
  earthquake
• Can be used to rate earthquakes of all sizes,
  near or far.

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Locating an Epicenter

• By using seismic waves
• Travel at different speeds
• Measure the difference between arrival times of P
  and S waves
• The farther away the earthquake, the greater the
  time between the arrival of the P waves and S
  waves

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