plate tectonics

Question 1

crust

Answer 1

• outer layer
• thick
• 5-50 km thick

Question 2

mantle

Answer 2

• 2900km thick
• upper sections solid and part of lithosphere
• asthenosphere > movement in the asthenosphere causes plates to move
• lower mantle = solid due to density

Question 3

outer core

Answer 3

• provided heat
• solid, iron, nickel
• 2400km thick

Question 4

inner core

Answer 4

• solid, iron, nickel

- very hot, 2400km thick

Question 5

features of continental crust

Answer 5

• 35 to 70 km thick
• very old, 1500 million yrs
• light, less dense
• light in colour, granite

Question 6

features of oceanic crust

Answer 6

• 6 to 10km thick
• young, less than 200 million yrs
• heavier, more dense
• dark, crystals are very small, basalt

Question 7

types of boundaries

Answer 7

• convergent = can be two oceans or two continental plates as well as one oceanic and one continental
• divergent
• transform

Question 8

divergent plate boundary - names

Answer 8

North American and eurasian plates

Question 9

features of divergent boundary

Answer 9

• mid ocean ridge
• shield volcanoes (lave, basic runny)
• transform faults
• rift valleys
• earthquakes

Question 10

convergent boundary - names

Answer 10

Nazca and South American plates

Question 11

features of convergent boundary

Answer 11

• earthquakes
• fold mountains
• acid lava cones
• deep ocean trenches

Question 12

transform boundary - names

Answer 12

pacific and North American plates

- san Andreas fault

Question 13

features of transform boundary

Answer 13

• earthquakes

- transform faults

Question 14

epicentre

Answer 14

the point on the ground surface directly above the focus.

This is where most of the damage happens

Question 15

focus

Answer 15

• the point in the crust where the movement actually takes place
• the most damaging quakes are those where the focus is shallow i.e. near the surface

Question 16

p - waves

Answer 16

• Arrive first, spread outwards on all sides from the focus of the quake
• they compress and stretch the material they move through
• travel quickly, hear them as a boom

Question 17

s - waves

Answer 17

• Come later and shift the materials up and down causing major damage
• only travel through solids but can cause liquefaction of the soil
• liquefaction can cause major landslides

Question 18

surface waves

Answer 18

• Travel along the Earth’s surface, arrived last
• can be most destructive
• travels slow

Question 19

fault strike

Answer 19

• Fracture in the rocks of earth’s crust in which rock masses slip past one another parallel to the strike
• due to the movement of two plates against one another and the release of built up strain

Question 20

fault plane

Answer 20

• the line of opening that takes place from the focal point, along which the crustal rock may slide

Question 21

Richter scale

Answer 21

• quantifies the strength of the earthquake (the amount of energy released). it uses a logarithmic scale

Question 22

moment magnitude scale

Answer 22

• more accurate

- gives an estimate of the total energy released by an earthquake

Question 23

mercalli scale

Answer 23

• measures the intensity of an earthquake

- bases its measurements on the observed effects of the earthquake and describes its intensity

Question 24

faulting

Answer 24

• where part of the crustal rock layers crack and break, opening and moving in different directions
• Direction of movement depends on the type of pressure under which the rocks are placed

Question 25

landslides and earthquakes

Answer 25

• a landslide is the movement of rock, debris or earth down a slope. They result in failure of the materials which make up the Hill slope and are driven by the force of gravity
• earthquakes are often one of the major natural causes of landslides. The sudden movement of the crustal rocks or the shock waves that follow can trigger the movement of loose material down steep slopes