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passage 4
P1
According to the generally accepted theory of plate tectonics, the earth's crust consists of a dozen or so plates of solid rock moving across the mantle—the slightly fluid layer of rock between crust and core. ████ ███████████ ███ ████ ██ █████████ ██ █ ██████ ██ ███ ████████ ██ █████ ██████ ███████ ███ ███████ ██ ████ ████████ ███
Phenomenon & hypothesis ·
Earthquakes explained by plates colliding
Details of hypothesis ·
Collision causes subduction which causes earthquakes
Explains seismic hot zones: high levels of subduction produce many earthquakes
Phenomenon ·
But subduction can also occur without causing earthquakes
P2
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Hypothesis ·
Type of collision makes a difference
Collision type 1 ·
Plates moving toward each other
Occurs in seismic hot zones (many earthquakes)
Collision type 2 ·
Plates moving in same direction
Occurs in quiet zones (few earthquakes)
Analogy ·
Collision type 2 behaves like boat's oar
Collision zone moving across mantle (fluid layer) like boat over water; subducting plate descends steeply into mantle like oar in water
Evidence for hypothesis ·
Collision type 2 involves little contact (friction) between plates
Less friction means less likely to cause earthquake
Evidence for hypothesis ·
Collision type 1 involves more contact (friction) between plates
Collision zone not moving across mantle, so colliding plates remain in contact with each other. More friction means more likely to cause earthquake.
Analogy ·
Collision type 1 behaves like sheets of sandpaper
Colliding plates slide across each other; high resistance (friction)
P3
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Implication ·
of hypothesis
Regions with little subduction (plate collision) could still cause earthquakes, depending on collision type (collision type 1 causes greater risk)
Passage Style
Phenomenon-hypothesis
Single position
26.
According to the information in ███ ████████ █████ ███ ██ ███ █████████ █████ ██ ███████ ███████████ ███ ████ ████████████
a
regions where the ██████ ██ ███ █████████ ███████ ██████ ██ ████ ████ ███ █████ ████████ ███████ ████ ███ ██████
b
regions where resistance ████ ███ ██████ ██████ ██████████ ██ ████████
c
regions where subduction ██████ ██ ███████ ██████
d
regions where there ██ ███ ████████ ██████ ██ ██████████
e
regions where plates ███ █████████ ██ ███ ████ ███████ █████████