Download Earthquakes

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Ch. 8 Sct. 1
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When rocks strain and potential energy builds
up over time.
When the potential energy is released
because the rock breaks, vibrations are
released through the rocks.
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The surface of a break in the earth’s
rocks/crust
99% of earthquakes occur at a fault
 Normal
 Reverse
 Strike Slip-Fault
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Divergent
Dip-Slip Fault
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Convergent
Thrust Fault
•San Andreas pics.
•1906 quake.
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Waves released by earthquakes
 Primary Waves (P)
 Secondary Waves (S)
 Surface Waves
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P waves
Travel fastest through rock
Move like compression waves/sound waves
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S waves
Travel second fastest through rock
Move like transverse waves/light waves
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Slowest and largest seismic waves
Travel outward from epicenter in a variety of
forms
 Ocean waves
 Backward rolling waves
 Side to side, swaying motion
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Most destructive seismic wave
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Focus
 Deep within the earth’s crust where the actual
rock structure snaps
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Epicenter
 The point on the earth’s surface directly above the
focus.
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Seismograph
 Records the magnitude of earthquakes
Based on measurements of seismic wave heights
from seismograph readings
 Difference between 1.0 and 2.0
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 10x higher waves on seismograph
 32x more energy in earthquake
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The strongest recorded earthquake in history.
 1960 off the coast of Chile 9.5
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The strongest recorded earthquake in North
America.
 1964 near Anchorage, Alaska 9.2
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Measure the intensity/damage of an
earthquake.
Specific to the distance away from the
epicenter.
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Occur when earthquakes happen on the
ocean floor.
The energy from the quake is transferred to
the water and causes huge waves to form.
Waves don’t gain height until they near the
land.
See page 216 of text.