Kobe, Japan

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Kobe, Japan
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TYPES OF FAULTS
DIP-SLIP FAULTS
Exhibit vertical movement. Fault blocks move up
or down relative to each other.
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TYPES OF FAULTS
DIP-SLIP FAULTS
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TYPES OF FAULTS
NORMAL DIP-SLIP FAULTS
In a NORMAL DIP-SLIP FAULT the hanging
wall moves down relative to the foot
wall. Produced by tensional stresses. Found at
divergent plate boundaries. Mid-oceanic
divergence zone is gt60,000 km long.
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TYPES OF FAULTS
NORMAL DIP-SLIP FAULTS
Can produce steps in the landscape. Steps are
called FAULT SCARPS.
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TYPES OF FAULTS
NORMAL DIP-SLIP FAULTS
Tension can produce sequences of normal
faults. Results in production of HORSTS and
GRABENS. Such is the East African Rift Valley and
Connecticut River Valley.
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TYPES OF FAULTS
HORSTS AND GRABENS
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TYPES OF FAULTS
REVERSE DIP-SLIP FAULTS
Hanging wall moves up relative to the foot
wall. Produced by compressional forces. Found at
convergence zones. Carries older rocks up over
younger rocks.
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TYPES OF FAULTS
REVERSE DIP-SLIP FAULTS
A low-angle reverse fault (lt45?) is called a
THRUST FAULT. A very low angle reverse fault
(lt10?) is called an OVERTHRUST. Large slabs of
rock can move horizontally over large distances.
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TYPES OF FAULTS
REVERSE DIP-SLIP FAULTS
OVERTHRUST FAULT. Going to the Sun Mtn. Glacier
National Park, MT
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BUILDING MOUNTAINS
MOUNTAIN
Part of the Earths crust that stands gt 300 m
(1000) above the surrounding landscape. Has a
discernable top or summit. Possesses sloping
sides.
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BUILDING MOUNTAINS
Every continent has mountains. Every ocean basin
has mountains.
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BUILDING MOUNTAINS
Some mountains are isolated peaks. Some mountains
occur in ranges or systems.
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BUILDING MOUNTAINS
Form in a variety of ways
Catskill Mtns., NY Eroded Peaks
Mauna Loa, HI Basaltic Outflowing
Alps Sedimentation and Continental Collision
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BUILDING MOUNTAINS
Mountains are being continuously created. Some
are young -- Himalaya and Andes Some are old --
Appalachians Some are really old -- CONTINENTAL
SHIELD Shield areas generally are so old that
they have been eroded flat. Local example
includes the Canadian Shield. Forms the core of
North America.
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BUILDING MOUNTAINS
CONTINENTAL SHIELD (Canadian Shield)
Composed of highly deformed and metamorphosed
rocks. Shield rocks are eroded flat.
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BUILDING MOUNTAINS
CONTINENTAL SHIELD (Canadian Shield)
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OROGENESIS (Mountain Building)
Two main mechanisms 1. Volcanism
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OROGENESIS (Mountain Building)
2. Deformation and Uplift A. Fold and Thrust
Mountains Produced by plate collisions. Result
s in high mountain systems. Usually marine
sediments that become highly folded and
metamorphosed. Commonly have igneous
intrusions. Examples include the Alps, the
Himalaya, the Urals and the Canadian Rockies.
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OROGENESIS (Mountain Building)
2. Deformation and Uplift Fold and Thrust
Mountains
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OROGENESIS (Mountain Building)
2. Deformation and Uplift B. Fault Block
Mountains Bounded by high angle normal
faults. Produced by tensional forces. Horsts
and grabens common. Examples include the Great
Basin of the western United States.
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TYPES OF FAULTS
HORSTS AND GRABENS
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OROGENESIS (Mountain Building)
2. Deformation and Uplift C. Upwarped
Mountains Large area of continent is domed
up. Very little deformation of rocks. Located
far from plate boundaries. Not exactly sure how
they form. Example Adirondack Mountains, NY
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OROGENESIS (Mountain Building)
C. Upwarped Mountains Adirondack Mountains, NY
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EARTHQUAKE
A sudden release of energy accumulated in
deformed rocks causing the ground to tremble or
shake. Causes rupturing or brittle failure of
crustal rocks. Energy is released. Movement of
fault blocks takes place along a fault plane.
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After energy is released, friction between the
adjacent fault blocks prevents further
movement. Stress resumes and builds up
again. Friction between the blocks is
overcome. Another earthquake occurs.
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FOCUS or HYPOCENTER -- Precise underground spot
at which rocks begin to break or move. EPICENTER
-- The point on the Earths surface directly
above the focus.
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AFTERSHOCKS are continued shaking of the
Earth after an earthquake that results from the
rocks trying to find a new equilibrium in new
positions.
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SEISMIC WAVES
When rocks break in an earthquake, energy is
released. The energy released has high velocity
and moves rapidly though the adjacent
rocks. Energy is transmitted via SEISMIC
WAVES. These waves are generally low frequency
sound waves. Generally they are so low that we
cant hear them.