Faults and Fault Movement

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Faults and Fault Movement
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Faults Fault movements

• There are a variety of_________________
  ________________________

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Faults vs. Fractures

• ____________ is simply a creak or a break in the
  rock.
• Also called a ______.

• ________ are fractures along which there is
  movement.

4
Fault Planes Fault Traces

• The _________ is the surface along which a fault
  moves during an earthquake.
• A ______ is where the fault plane intersects the
  ground surface.

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Hanging Wall Foot Wall
Hanging wall
The _______________ is one block of a dip-slip
fault. Remember it as the one you would hang a
lantern on.
The ___________ is one block of a dip-slip
fault. Remember it as the one you would walk on.
Foot wall
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Normal Fault

• A _____________ Fault
• Hanging wall moves _____ relative to fault plane.
• Caused by ______ forces.
• _________ is measured from horizontal to the
  fault plane. It is an angle lt 90

Dip Angle
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Reverse Fault

• A ____________ Fault
• Hanging wall moves ____ relative to fault plane.
• Caused by __________ forces.
• If the dip angle is less than 45º, it is usually
  called a ___________.

Thrust Angle lt 45
Reverse Angle gt 45
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Strike-Slip Fault

• Not a Dip-Slip Fault
• __________ hanging wall or foot wall.
• Caused by ________ forces.
• Come in two flavors
• _____________
• _____________

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Left Right Lateral?

• Picture yourself standing on the fault, one foot
  on either side.
• If you twist ______________ during fault movement
  then the fault is Right lateral.
• If you twist ______________ during fault movement
  then the fault is Left lateral.

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Oblique Faults

• Most faults are actually ____________.
• Oblique faults have features of both________
  ________________.
• Moves___________ and _____________.
• Caused by a combination of forces.

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Creep vs. Slip

• Creep is a ___________________ along a fault due
  to tectonic deformation.
• Creeping faults ______________ have many large
  earthquakes.

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Sustained creep can cause _______________ as
shown on the road surface to the right. This road
is located over the ____________ in the San
Francisco area
13

• Slip can be large in places. Photo shows movement
  of a manure pile that occurred during 1906 San
  Francisco Earthquake. The fault goes directly
  under this barn.Movement was about 10 feet!

Post Quake
Pre-Quake