Download Earthquakes and Deformation of the Crust

Earthquakes and
Deformation of the Crust
Earthquakes and Deformation of the
Crust
1
Deformation of the Crust
• Stress
–Force that causes pressure in the
rocks of the earth’s crust
• Strain
–Change in the shape or volume
of rocks from stress
Earthquakes and Deformation of the
Crust
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Rock Layers Experience
shearing
compression
tension
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Crust
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Folding
• When rock becomes
permanently deformed
without breaking
–Anticline
–Syncline
–Monocline
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Crust
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Anticline
• When rock layers are folded
and uplifted into arch like
patterns
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Crust
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Syncline
• Downward folds like a
bowl
• Or sink
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Crust
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Monocline
• Gently dipping fold in the rock
layers
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Crust
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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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Crust
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Folds Vs. Faults
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Crust
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Footwall & Hanging Wall
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Crust
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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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Crust
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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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Crust
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Thrust Fault
• Special kind of reverse fault
• Fault angle is less than 45°
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Crust
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Strike Slip
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Crust
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Reverse
Thrust
Strike
Slip
Normal
Blind Thrust
Oblique
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Crust
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Mountain Formation
• Smallest to Biggest
–Mountain
–Mountain range
–Mountain system
–Mountain belt
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Crust
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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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Crust
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Folded Mountains
• Formed when
tectonic
movements
have
squeezed the
rock layers
together like
an accordion
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Crust
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Crust
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Fault Block Mountain
• Formed when faulting breaks
the Earth’s crust into large
sections
• The sections are uplifted and
tilted
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Crust
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Crust
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Fault Block Mountain
and Graben
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Crust
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Grabens
• long narrow valley formed by
faulting and downward slippage
of a crustal block
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Crust
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Volcanic Mountains
• Formed when molten rock
erupts onto the earth’s
surface
•
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Crust
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Dome mountains
• Created when molten rock
pushes up rock layers on the
Earth’s surface
• Then the layers then are
worn away in places, leaving
separate high peaks.
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Crust
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Crust
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Earthquake
• vibration of the Earth
• produced by the rapid
release of energy
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Crust
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• Elastic Rebound Theory
explains the cause of
earthquakes.
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Crust
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Elastic Rebound
Theory
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Crust
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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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Crust
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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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Crust
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• Most earthquakes occur
along or near the edges of
the earth’s
– lithospheric plates
• Fault Zone
– group of interconnected faults
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Crust
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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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Crust
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San Andreas Fault zone
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Crust
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Aftershocks
• tremor that follows a major
earthquake
• is smaller
• Caused or related to
the major earthquake
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Crust
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Focus
• zone along a fault where
slippage first occurs
• produces an earthquake
• 0rigin of the quake
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Crust
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Epicenter
• point on the Earth’s directly
above the focus of an
earthquake
• May or may not be the point
of greatest shaking, most
damage
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Crust
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Focus and Epicenter
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Crust
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Seismograph
• instrument
for
recording
seismic
waves
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Crust
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Seismograph
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Crust
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Seismograph
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Crust
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Modern Day Seismograph
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Crust
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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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Crust
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Seismic Waves
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Crust
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P waves
S waves L waves
Speed
Fastest
Middle
Slowest
Amplitude
Smallest
Middle
Largest
Period
Shortest
Middle
Longest
Medium Solid,
Solids
gas, liquid
On the
Surface
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Crust
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Earth Quake Location
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Crust
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Earth Quake Location
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Crust
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Earth Quake Location
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Crust
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