tectonics eq1 (1)

Question 1

convergent/destructive plate boundary

Answer 1

plates involves- continental and oceanic

direction of movement- move towards each other

landforms created- volcanoes, earthquakes (subduction)

Question 2

Divergent/ constructive

Answer 2

plates involved- two oceanic plates

direction of movement- plates move apart

landforms created- volcano, earthquake

Question 3

conservative/ transform

Answer 3

plates involved- continental with continental or continental with oceanic

direction of movement- same direction with lots of friction

landforms created- earthquakes only

Question 4

collision zones

Answer 4

plates involved- continental with continental

direction of movement- towards each other

landforms created- earthquake, fold mountains

Question 5

slab pull

Answer 5

pull of gravity on a plate thats been subducted

Question 6

intra-plate

Answer 6

hazard (ie volcano) taking place within a single tectonic plate

Question 7

why does subduction happen?

Answer 7

continental plate has a lower density to the oceanic plate and gravity pulls the oceanic plate beneath the continental plate

Question 8

The wadati-benioff zone

Answer 8

area in which there is a concentration of earthquake hypocenters - shows evidence towards plate tectonics

Question 9

focus/hypocenter

Answer 9

the location in the earth where the earthquake starts

Question 10

seismic waves

Answer 10

vibrations caused by movement within the tectonic plates

Question 11

Name physical processes that cause hazards

Answer 11

• history and evidence of plate tectonic theory
• sea floor spreading, paleomagnetism
• subduction processes
• anatomy of an earthquake
• seismic waves

Question 12

Timeline of plate theory

What did Wegner propose in 1912?

Answer 12

Wegner proposed the theory of continental drift and in 1967 his theory was accepted.

Question 13

Timeline of plate theory

What did Holmes suggest in 1930?

Answer 13

Holmes suggests that convection currents fueled by radioactive decay in the earth’s core play a role in continental drift and driving the earth’s plates

Question 14

Where do aftershocks occur?

Answer 14

near the fault zone of the main earthquake

Question 15

What are aftershocks the result of?

Answer 15

the readjustment process which is when the plates settle back into their natural position after the initial earthquake

Question 16

Primary impacts

earthquakes

Answer 16

the direct impacts of the natural hazard, so they are caused by the earth shaking

Question 17

examples

What do primary impacts include?

earthquakes

Answer 17

death, injuries, buildings being destroyed

Question 18

What do secondary impacts include?

earthquakes

Answer 18

landslides, fires, tsunamis, habitat and historical buildings loss, people suffering from illness from diseased water, people become unemployed

Question 19

Where does sea floor spreading happen?

Answer 19

divergent plate boundaries

Question 20

paleomagnetism

Answer 20

is where lines of different type of rock, which are facing different poles, pull away from each other at divergent boundaries

Question 21

hot spots

Answer 21

A hot spot is an area on Earth over a mantle plume or an area under the rocky outer layer of Earth, called the crust, where magma is hotter than surrounding magma. The magma plume causes melting and thinning of the rocky crust and widespread volcanic activity.

Question 22

How is a chain of intra-plate volcanoes created?

Answer 22

Because the mantle plumes that cause them don’t move when the tectonic plates do

Question 23

Primary impacts of a volcano

Answer 23

• release of tephra
• release of volcanic gas into the atmosphere
  -pyroclastic flow
  -lava flow

Question 24

tephra

Answer 24

solid material that can range in size which are ejected into the atmosphere eg ash

Question 25

secondary impacts of a volcano

Answer 25

• lahars
• J​ökulhlaups

Question 26

pyroclastic flow

Answer 26

Very large, dense clouds of hot ash and gas at temperatures of up to 600’C. They can flow down the flanks of volcanoes and devastate large areas.

Question 27

lahars

Answer 27

Volcanic mudflows, which occur when rainfall mobilises volcanic ash. They travel at high speed down river systems and cause major destruction.

Occurs at:
Subduction zone volcanoes (composite)

Question 28

J​ökulhlaups

Answer 28

Devastating floods caused when volcanoes erupt beneath glaciers and ice caps, creating huge volumes of meltwater. They are common in Iceland.

Occurs at:
Constructive plate margin volcanoes (cinder cone, fissure eruption)