Transcript EarthquakefaultsPowerpointnew

Tectonic Plates…Keep on
Moving
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For hundreds of millions of
years, the forces of Plate
Tectonics has shaped the
Earth.
As Tectonic Plates slowly
move over, under and past
each other, they build
mountains, form new sea
floor, create earthquakes
and volcanoes.
Earthquakes…Earth’s Way of
Releasing Stress
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• An earthquake is a
sudden movement
of the Earth’s crust
caused by the
abrupt release of
stress…which has
built up over a long
time.
Earthquake Faults
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• When enough stress
builds in the Earth’s
crust, the rock
breaks, creating a
fault.
• A fault is a break in
Earth’s crust where
slabs of crust slip
past each other
Where Faults Happen
• Faults often occur at plate boundaries - but
not always. They can appear in the center of
a plate!
• Each type of fault is often associated with a
specific type of plate boundary.
• It is possible for more than one type of fault to
happen on one plate boundary.
Three Main Types of Faults
• 1. Strike-Slip Fault - associated with
Transform Boundaries.
• 2. Normal Fault - associated with
Divergent Boundaries.
• 3. Reverse Fault - associated with
Convergent Boundaries.
Strike-Slip Fault
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• Vertical fault, blocks
slide past one another
horizontally.
• Happens in areas
where the crustal blocks
are sliding past one
another.
• Created by shearing
stress.
• Example: San Andreas
Fault
Normal Fault
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• The fault is at an angle,
and the block above the
fault, the hanging wall
moves down relative to
the block below the fault
(the foot wall).
• Occurs in areas where
there is pulling of the
crustal blocks.
• Caused by tension
stress.
Reverse or Thrust Fault
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• The fault is at an angle,
and the hanging wall
moves up relative to the
foot wall.
• Same structure as normal
fault, but the blocks move
in opposite direction.
• Happens in areas where
the crustal blocks are
being pushed together.
• Caused by compression
stress.