plate tectonics

Question 1

what are the layers of the earth?

Answer 1

crust
mantel
outer core
inner core

Question 2

what makes earthquakes shake ?

Answer 2

seismic waves that are sent through the earth

Question 3

How are earthquakes recorded?

Answer 3

with seismographs

Question 4

what are the 4 different types of seismic waves?

Answer 4

P-wave
S-wave
Rayleigh wave
love wave

Question 5

how does the p-wave work?

Answer 5

compression-extension, caused by pressure

Question 6

How does the s-wave work?

Answer 6

up and down, looks like a sideways s, sheer

Question 7

what happens to a wave when the density changes?

Answer 7

waves deflect
the velocity changes
the direction of the wave changes

Question 8

s-waves cannot:

Answer 8

travel through liquid
be recorded after an earthquake

Question 9

which layer of the earth is liquid?

Answer 9

the outer core

Question 10

the earths crust is enriched with which two materials?

Answer 10

silicon and oxygen

Question 11

how do we know about the earth’s composition?

Answer 11

seismic data– density
volcanic rock–samples of mantle
meteorite sample–reflect earth

Question 12

how did the earths layers form?

Answer 12

heating from bombardment
gravitational compression
radioactive decay

Question 13

how do elements in the earth’s interior float or sink?

Answer 13

less dense elements float, denser elements sink

Question 14

characteristics of continental crust?

Answer 14

thick (20-80km)
rich in Al and Si
low density

Question 15

characteristics of oceanic crust?

Answer 15

thin (5-10km)
rich in Fe and Mg
high density

Question 16

what is the lithosphere?

Answer 16

stiff
uppermost mantel
attaches to the crust
solid

Question 17

what is the aesthenosphere?

Answer 17

just under the lithosphere
soft and can flow
solid

Question 18

what is the mesosphere?

Answer 18

last 2/3 of the mantel
harder than the aesthenosphere
can flow
solid

Question 19

why do the mechanical layers of the mantel behave differently?

Answer 19

because they have different temperatures and pressures due to the pressure temperature gradient

Question 20

what are lithospheric plates?

Answer 20

plates that move and interact in response to force within the earth

Question 21

what is a plate boundary?

Answer 21

the place where two plates meet

Question 22

divergent boundary

Answer 22

plates move away from each other
creates spreading zone
on ocean floor

Question 23

What does seafloor spreading produce?

Answer 23

continuous row of volcanoes called a mid ocean ridge

Question 24

convergent boundary

Answer 24

plates move toward each other

Question 25

why is the oceanic crust subducted under the continental crust in a convergent boundary?

Answer 25

because the oceanic crust is denser

Question 26

what happens in a continental-continental convergent boundary/

Answer 26

large mountains are created

Question 27

transform boundary

Answer 27

side to side plate movement, plates move Parallele to each other

Question 28

what causes plate movement?

Answer 28

convection currents caused by heat =

Question 29

why do plates move?

Answer 29

the aesthenosphere is weak and the lithosphere can move over it
ocean plates are dense and can dive under continental plates

Question 30

dominant forces of plate movement?

Answer 30

plates pulled down into trenches
plates driven down the slope from ridge to trench by gravity

Question 31

opening an ocean

Answer 31

plates pulled apart
rift valley forms
magma erupts from mantle
new oceanic crust added to plate
continued spreading creates new ocean

Question 32

closing an ocean

Answer 32

plates recycled into the mantle through subduction
plates gradually pulled closer together
continents collide closing the ocean