Download The Earth`s Structure

Types of Faults
Rocks Move Along Faults
• Fault:
– break in Earth’s lithosphere, where blocks of
rock move past each other
• At some parts of a fault, the rock slides
slowly or constantly. At others it sticks or
locks together.
– Rock bends and stretches as stress is put on
it ( think of a rubber band or popsicle stick)
Earthquake
• Earthquake
– shaking of the ground caused by the sudden
movement of large blocks of rock along a fault
– Occurs when there is a sudden release of
stress in the lithosphere.
• when the rocks break free from being stuck
• Strength of an earthquake depends on
– The amount of stress built up
– The distance the rocks move along the fault
The rocks that move
• Most faults are along tectonic plate boundaries
– Most earthquakes occur here
• The rocks that move during an earthquake are
smaller than tectonic plates
• Rarely do earthquakes happen in the middle of
the plate.
Types of faults
• Faults are classified by how they move
– This is determined by the kind of stress the
rocks are under
• More than one type of fault can happen at
a plate boundary
Normal Fault
• Occurs when stress pulls
the rocks apart
• One chunk goes down
the other shifts up.
• Earthquakes happen
where chunks of rock are
moving apart
– The Great Rift Valley of
Africa.
force
force
Movement of
rocks
Reverse Fault
• Occurs when stress
presses rocks
together
• One chunk ends up
on top of the other.
• Occurs near
convergent collisionzone boundaries
between plates
force
force
Movement of
rocks
Strike Slip Faults
• Occurs when stress
pushes rocks
horizontally
• Blocks of rock move
sideways on either
side of the fault plane.
• Happens when plates
scrape past each
other
Movement of
rocks