Tectonic Processes

Question 1

What are three pieces of evidence of continental drift?

Answer 1

1. jigsaw fit
2. fossil remains of freshwater reptile in South America and Africa
3. Coal in Antarctica (couldn’t form there at current latitude)

Question 2

explain mantle convection

Answer 2

radioactive decay in the inner core causes magma in lower mantle to rise into the asthenosphere. it cools and sinks in a circular motion causing a convection current.

Question 3

What is paleomagnetism?

Answer 3

the study of the earth’s magnetic field

Question 4

What is seafloor spreading?

Answer 4

magma is forced up from the asthenosphere, forcing apart the crust and hardens to form new crust

Question 5

How does paleomagnetism prove seafloor spreading?

Answer 5

the change in direction of the earth’s magnetic field every 400,000 years matches the change in the direction of the minerals inside the rock (cooled lava). hence new rock formed at the same time on both sides

Question 6

What is subduction and what does it prove the earth is not doing?

Answer 6

two plates collide, the denser subducts and melts. hence showing the earth is not expanding

Question 7

What is slab pull?

Answer 7

crust pulls apart and subducts due to the weight of the magma

Question 8

what are the two different types of waves?

Answer 8

Body waves and surface waves

Question 9

what are body waves and what are the two types of body waves?

Answer 9

body waves move through the earth’s ‘body’.

1. P waves
2. S waves

Question 10

what are surface waves and what are the two types of surface waves?

Answer 10

move through the surface/ crust only

1. Love waves
2. Rayleigh waves

Question 11

what are the four characteristics of P waves?

Answer 11

1. fastest wave
2. first to reach surface
3. travel through solids and liquids
4. compress/ expand crust

Question 12

what are the four characteristics of S waves?

Answer 12

1. 60% speed of p waves
2. travel through solids
3. move crust up/ down
4. more damaging than p waves

Question 13

what are the three characteristics of Love waves?

Answer 13

1. fastest surface wave
2. move crust side to side
3. most damaging

Question 14

what are the two characteristics of Rayleigh waves?

Answer 14

1. travel with rolling motions

2. move crust up/ down

Question 15

what are the two theories to explain intraplate earthquakes?

Answer 15

1. stress builds along ancient faults causing them to become active
2. crust that was once weighted down by glaciers is slowly rebounding from mantle

Question 16

what are the two primary effects of earthquakes?

Answer 16

1. ground shaking

2. crustal fracturing

Question 17

what are the four secondary effects of earthquakes?

Answer 17

1. Tsunami
2. Liquefaction
3. Fire
4. Landslide/ avalanches

Question 18

what are the four primary effects of volcanoes?

Answer 18

1. lava flows
2. pyroclastic flow
3. tephra
4. gas eruptions

Question 19

what are the two secondary effects of volcanoes?

Answer 19

1. Jokulhlaup

2. Lahars

Question 20

explain effects of ground shaking

Answer 20

infrastructure collapse, killing/ injuring those nearby

Question 21

explain effects of crustal fracturing?

Answer 21

crust cracks at surface

Question 22

explain liquefaction

Answer 22

surface rocks lose strength and become more like liquid. the ground loses the ability to support weight

Question 23

explain how earthquakes cause a fire

Answer 23

underground power/ gas pipes are severed

Question 24

explain how earthquakes cause landslides or avalanches

Answer 24

shaking puts pressure on slopes causing them to fail

Question 25

what is lava flow?

Answer 25

liquid rock expelled from the crown or flank of a volcano

Question 26

what is pyroclastic flow?

Answer 26

dense masses of gases and lava fragments flow down the sides at high speed

Question 27

explain jokulhlaup

Answer 27

water/ ices released from a glacier by heat from lava

Question 28

what are lahars

Answer 28

volcanic mudflow caused when ash mixes with some kind of water

Question 29

what is tephra?

Answer 29

the ash which is projected to a great height, falling to cover land and property

Question 30

what are gas eruptions?

Answer 30

poisonous sulphur dioxide/ monoxide released before, during and after eruptions. CO2 and water vapour are the most common gases coming from a volcano.

Question 31

Explain how Tsuanmis forms

Answer 31

1. displacement of a large area of the sea floor caused by uplift fault blocks or crust rebounding causes a water column to rise 2. the wave radiates in all directions from the source 3. as the water shallows the waves slow down and increase in heigh due to friction 4. wave energy is crowded into a smaller volume of water