Earthquakes and Deformation of the Crust

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Earthquakes and Deformation of the Crust
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Deformation of the Crust

• Stress
• Force that causes pressure in the rocks of the
  earths crust
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• Strain
• Change in the shape or volume of rocks from
  stress

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Rock Layers Experience
shearing
compression
tension
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Folding

• When rock becomes permanently deformed without
  breaking
• Anticline
• Syncline
• Monocline

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Anticline

• When rock layers are folded and uplifted into
  arch like patterns

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Syncline

• Downward folds like a
• bowl
• Or sink

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Monocline

• Gently dipping fold in the rock layers

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Faulting  

• Fault
• Break in rock
• Rocks on either side of the break move
• Fracture
• Break in rock with no movement.

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Folds Vs. Faults
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Footwall Hanging Wall

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Normal Fault

• Fault plane is 45 or more
• Hanging wall drops relative to the footwall
• Divergent boundaries

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Reverse Fault
Fault plane is 45

• Hanging wall moves up relative to the footwall
• Due to compression

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Thrust Fault

• Special kind of reverse fault
• Fault angle is less than 45

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Strike Slip
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Normal
Reverse
Blind Thrust
Thrust
Strike Slip
Oblique
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Mountain Formation

• Smallest to Biggest
• Mountain
• Mountain range
• Mountain system
• Mountain belt

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Mountain Belts

• Evidence that mountains are created when
  lithospheric plates collide
• Name some examples
• Appalachians?
• Formed where plates collided in the past 

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Folded Mountains

• Formed when tectonic movements have squeezed the
  rock layers together like an accordion

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Fault Block Mountain

• Formed when faulting breaks the Earths crust
  into large sections
• The sections are uplifted and tilted

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Fault Block Mountain and Graben
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Grabens

• long narrow valley formed by faulting and
  downward slippage of a crustal block

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Volcanic Mountains

• Formed when molten rock erupts onto the earths
  surface
•  

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Dome mountains

• Created when molten rock pushes up rock layers on
  the Earths surface
• Then the layers then are worn away in places,
  leaving separate high peaks.

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Earthquake

• vibration of the Earth
• produced by the rapid release of energy

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• Elastic Rebound Theory explains the cause of
  earthquakes.

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Elastic Rebound Theory
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Elastic Rebound Theory

• Rocks are moving slowly on either side of a
  fault
• if the fault is locked in place, stress in the
  rocks increases
• Rocks that are strained past a certain point will
  fracture, move, and spring back to their original
  shape

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Locked

• When friction prevents the rocks on either side
  of a fault from sliding past each other

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• Geologists use the elastic rebound theory to
  explaina. the cause of tsunamis
• b. the speed of seismic waves c. the intensity
  of an earthquake d. the cause of an
  earthquake  

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• Which of the following best describes
  aftershocks?a. a series of small tremors
  occurring after a major quake b. seismic
  waves that cannot travel through liquid c.
  areas along a fault where slippage and
  fracturing first occur d. giant ocean waves that
  originate at a fault line

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• Most earthquakes occur along or near the edges of
  the earths
• lithospheric plates
• Fault Zone
• group of interconnected faults

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San Andreas Fault Zone

• has formed where the edge of the Pacific plate is
  slipping north along the North American plate

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San Andreas Fault zone
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Aftershocks

• tremor that follows a major earthquake
• is smaller
• Caused or related to the major earthquake

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Focus

• zone along a fault where slippage first occurs
• produces an earthquake
• 0rigin of the quake

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Epicenter

• point on the Earths directly above the focus of
  an earthquake
• May or may not be the point of greatest shaking,
  most damage

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Focus and Epicenter
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• The place where slippage first occurs is called
  an earthquakes
• a. focus
• b. epicenter
• c. dip plane
• d. fracture  

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Seismograph

• instrument for recording seismic waves

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Seismograph
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Seismograph
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Modern Day Seismograph
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Richter Scale

• Measure of the magnitude of a quake, or energy
  released
• 31.7 times more energy is released for every
  whole number
• 3.1 to 5.1?
• 31.7 x 31.7 approx. 1000

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• Which seismic wave is the fastest?a. P waves  

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Seismic Waves
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Earth Quake Location
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Earth Quake Location
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Earth Quake Location
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• What is the difference in strength between an
  earthquake that measures 4.5 versus one that
  measures 5.5 on the Richter scale?a. 1 b.
  10 c. 100 d. 1000