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41 Cards in this Set
- Front
- Back
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minerals are:
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natural solids with a regular crystal structure and chemical
composition. |
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most of the minerals in the earth's crust are:
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silicates
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the three major rock categories:
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igneous, sedimentary, metamorphic
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two main types of waves produced by an earthquake
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body waves, surface waves
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compression and tension produce:
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vertical movement along faults
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three types of plate boundaries
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convergent, divergent, and transform.
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lithosphere
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the crust and upper mantle. rigid, forms plates
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who developed the theory of continental drift?
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Alfred Wagener
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What evidence confirmed seafloor spreading? Be brief but to the point
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Reversals of the Earth’s magnetic field are preserved in ocean-floor basalt, as
matching patterns across the mid-oceanic ridge. The youngest ocean-floor basalt is at the ridge. |
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Distinguish between Earth’s crust, lithosphere, asthenosphere, and mantle
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Earth’s crust overlies mantle – distinguished by composition: oceanic crust is
basaltic composition and continental crust is “granitic” composition. Earth’s lithosphere overlies asthenosphere – distinguished by rock properties/behavior/strength: lithosphere is more-rigid; asthenosphere is moreplastic/ easily deformed. |
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What are the main types of lithospheric plate boundaries in terms of relative
motions? Provide a real example of each (by name or location). |
* rift (or spreading) zones: Mid-Atlantic ridge
* subduction zones: Cascadia subduction zone * continental collision zones: India against Asia (Himalayas) * transform faults: San Andreas Fault |
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What does oceanic lithosphere consist of and how thick is it?
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* Earth’s crust and uppermost mantle (basalt over peridotite)
* about 100 km |
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Along which type of lithospheric plate boundary are earthquakes common?
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* convergent, divergent, and transform
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Along which type(s) of lithospheric plate boundary are andesite stratovolcanoes
common? Provide an example. |
continent – ocean plate collision (Cascadia subduction zone/ Cascade volcanoes)
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What is the approximate highest frequency of vibration (of back and forth shaking) in
earthquakes? |
* 20-30 cycles/second
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Which type of earthquake waves shake with the largest amplitudes (largest range of
motion)? |
* Surface waves
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What is meant by the “elastic rebound theory”?
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* Rocks across a fault are stressed and bent elastically. Ultimately they fracture during
an earthquake and the two sides straighten out, leaving them offset across the fault. |
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What does the Richter Magnitude Scale depend on?
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* maximum amplitude of earthquake waves on a seismograph (of a specific type)
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In addition to ground motion along a fault and shaking of a building, what types of
ground failure can lead to severe damage of a building? |
* liquefaction – compaction and flow of the ground, from rearrangement from loose
packed grains to closer-packed grains. * quick clays – clays arranged as “a house of cards” can collapse and flow if shaken. |
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Why do the floor or deck beams of parking garages and bridges sometimes fail
and fall during an earthquake? |
* The ends of the beams rest loosely on ledges to permit heat expansion. Flexing of the
support posts can pull the beams off their ledges. |
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What is a seismic gap, and what is its significance?
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* A part of a fault that has not had recent earthquakes, even though adjacent parts have
had earthquakes. * That part of the fault may be next to break in an earthquake. |
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What is the nature of the major fault boundary or boundaries in the westernmost
United States? |
* San Andreas Fault, a strike-slip fault in most of California
* Cascadia subduction zone just offshore of Oregon, Washington, and southwestern Canada. |
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Where are three other significant and active earthquake zones in the continental United
States and southern Canada? |
* “Intermountain Seismic Belt” (or east edge of the Basin and Range of Utah,
southeastern Idaho, to southern Montana) * New Madrid fault zone (or NE Arkansas, SE Missouri, western Tennessee and western Kentucky. * Eastern South Carolina, eastern New England to southern Quebec. |
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The North Anatolian Fault in Turkey caused more than 30,000 deaths in 1999. What
North American Fault is it similar to and in what way? |
* Similar to the San Andreas Fault: in length, rate of movement (or size of earthquakes),
and the nature of motion (strike-slip motion) |
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ION
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an atom w/ an electron surplus or deficit (charged atom)
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CATION
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less electrons than protons (+)
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ANION
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more electrons than protons (-)
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IGNEOUS
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formed from crystallization of molten rock (magma)
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SEDIMENTARY
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from the compaction, and cementing of sediments or precipitation out of water.
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METAMORPHIC
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transformation of minerals in pre-existing rocks
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PLUTON
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a body of intrusive rock
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MAFIC
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igneous rock. Low amounts of Silica, dark in color.
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INTERMEDIATE
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igneous rock. more silica in magma, gray color
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FELSIC
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from magma w/ >62% silica. light color
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age of earth
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4.6 billion yrs.
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oceanic crust v. continental crust
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OC- mafic rock, 5-10km thick, created from and recycled into mantle. CC- intermediate and felsic rock. 10-70 km thick. less dense
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hot spots
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rising plumes of mantle. not part of plate techtonics... plates move over hotspot, creating chains of volcanoes.
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subduction zones
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cooling asthenosphere sinks, one plate subducts under another. crust and sediments in sinking plate release water. Asthenosphere in overlying parts is fluxed, and melts.
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p waves
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primary. a train of compressions and expansions
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s waves
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secondary. slower, arrive later. up/down wriggling motion
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earthquake intesity is based on what scale?
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Mercalli
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