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39 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Where do convection currents occur?
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in the mantle
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what can a P-wave not travel through?
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the core
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What can an S-wave not travel through?
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outer liquid core
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Define Ridge-Push
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involves the oceanic lithosphere sliding down the oceanic ridge under the pull of gravity
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Define Slab-Pull
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cool dense oceanic crust sinks into the mantle and pulls the trailing lithosphere along
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Convection currents(thermal convection) that drive plate motion is caused by an uneven distribution of what?
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heat
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Whole-Mantle convection
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cold oceanic lithosphere goes into the mantle
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Deep-Layer convection
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some flows upwards as mantle plumes
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Best guess of magnetic field explanation
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the movement of the liquid outer core over the solid inner core generates the earths magnetic field
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Divergent Boundary
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a region where the rigid plates are moving apart
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Convergent Boundary
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two plates move together
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Transform Boundary
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two plates slide past each other without creating or destroying lithosphere
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Hot Spot
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a concentration of heat in the mantle capable of producing magma, which rises to earths surface
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Seafloor Spreading
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plate tectonics create new oceanic lithosphere at ocean ridges
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plates move and create what?
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Magnetic polarity supports seafloor spreading how?
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rocks show a bounded pattern of polarity reversals
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Rock ages (distance from MOR) support seafloor spreading how?
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near the coasts shows ages, older spreads
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three factors that plate tectonics cannot explain yet
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1. details of driving mechanism
2. global pattern of plates 3. location of many small plate fragments |
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Define Moho
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boundary between crusts and upper mantle
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Define Focus
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the point within the earth where an earthquake originates
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Define Fault
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a fracture in earth along which movement has occured
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define epicenter
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the location earth's surface directly above the focus or origin of an earthquake
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what does a Richter scale measure?
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the magnitude of earthquakes
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define locked faults
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sections that are not moving
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Elastic rebound theory
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when rocks are deformed the break apart releasing the stored energy that results in the vibrations of an earthquake
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where do most earthquakes occur?
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along the coasts
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Define Liquifaction
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soils and other non consolidated materials saturated with water are turned into a liquid that cannot hold a building
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viscosity
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very thick
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describe the shape of a cinder cone
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steep, cone with slopes of 30-40 degrees small usually between 30-300 meters rarely exceed 700 meters in height
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describe the shape of composite (strato)volcanoes
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large rarely symmetrical structure
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decribe the shape of shield volcanoes
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broad slightly domed structure that resembles a warriors shield
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on average, lithospheric plates move?
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a few centimeters a year
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Lithospheric plates contain both _______ and _________ crust
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continental and oceanic
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How do landslides occur?
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rock, earth or debris flows on to slopes due to gravity
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what are smaller quieter volcanic explosions are due to what?
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higher amounts of viscosity
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violent volcanoes are due to what?
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lower levels of viscosity, gases and structure
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Lithospheric plates contain both _______ and _________ crust
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continental and oceanic
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How do landslides occur?
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rock, earth or debris flows on to slopes due to gravity
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what are smaller quieter volcanic explosions are due to what?
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higher amounts of viscosity
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violent volcanoes are due to what?
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lower levels of viscosity, gases and structure
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