Tectonic Processes And Hazards

Question 1

Convergent plate

Answer 1

. Denser oceanic crust is forced underneath the continental rust. This is know as slab pull
. Deep trench forms where oceanic plate is pushed under
. Composite volcanoes
. Tsunamis
. Earthquakes

Question 2

Divergent

Answer 2

. Magma rises and seeps through the gap created as the plates move apart
. A ridge underwater
. Volcanic mountains
. Earthquakes

Question 3

Collision

Answer 3

. Plates of similar weight collide and force upwards
. Built up of pressure suddenly releases
. Earthquakes
. Fold mountains

Question 4

Conservative

Answer 4

. Plates rub against eachorher because they’re going at different speeds causing friction
. Release of friction causes fault lines in the ground
. Fault lines
. Earthquakes

Question 5

Hotspots

Answer 5

. Occur in centre of plates where there is a hot mantle plume rising to surface that triggers the coast

Question 6

Why do plates move?

Answer 6

Heat rises and falls, pulling the plated apart and making them move. This is done using convection currents

Question 7

Tsunamis

Answer 7

. Triggered by an earthquake which occurs under an ocean
. When plate jolts, ocean above is forced upwards providing extra energy to the waves

Question 8

Time of evidence supporting plate tectonics

Answer 8

. 1915: fossils collected by Wegener
. WW1: Found geologic features on ocean floor
. 1919: proposed concection currents exist
. 1946: ocean floor is mapped with solar technology
. 1954: first world mapf of volcanic eruptions is published
. 1960: hess and Dietz develop theory of sea floor spreading
. 1963: magnetic Rock reveals pattern of spreading away from centre of Atlantic ocean
. 1965: Wilson proposed idea that earth’s crust made of plates
. 1983: first gps made available

Question 9

Shockwave body

Answer 9

. Two types- primary and secondary
. Travel through interior of earth’s layers
. Primary- faster but not felt
. Secondary- slower and do most damage

Question 10

Shockwave surface

Answer 10

. Two types- love and Rayleigh
. On the surface and cause the most damage
. Love are transverse
. Rayleigh push ground forward and back
. Only found on shallow earthquakes

Question 11

Secondary earthquake impacts

Answer 11

. Tsunamis
. Landslides
. Liquefaction
. General groun displacement

Question 12

Volcanic explosivity

Answer 12

. Has a range from gentle fissures to explosive composite areas
. Links to energy of eruption
. Supervolcanoes are the largest
. Basaltic and andesitic
. Use of volcanic expolsivity index

Question 13

Secondary volcano impacts

Answer 13

. Jokulhoup- flood causes by melted glacier
. Lahars- water mixed with volcanic deposits
. Most significant things involve water

Question 14

Basaltic lava

Answer 14

. Hottest (1000-1200)
. Low gas content
. Thin and runny
. Gentle
. Location: ocean hot spots, mid ocean ridges and shield volcanoes

Question 15

Andesitic lava

Answer 15

. Temp: 800-1000
. Gas content 3-4%
. Slow flow
. Violent eruption
. Location: composite cone volcanoes

Question 16

Rhyolitic lava

Answer 16

. Temp: 650-800
. Gas content 4-6%
. Thick flow
. Violent eruption
. Location: super volcanoes

Question 17

Primary volcanic impacts

Answer 17

. Lava flows
. Pyroclastic flow
. Tephra and ashfall
. Gas eruption

Question 18

Secondary volcanic impact

Answer 18

. Lahars
. Jokulhoup

Question 19

How are tsunamis formed

Answer 19

. Caused by large underwater earthquakes along subduction zones
. Energy released during earthquake causes sea floor to uplift, displacing the water column above
. This displaced water forms the tsunami wave

Question 20

Difference between a disaster and hazard

Answer 20

Disaster- a hazard becomes a disaster when 10 or more people are killed and/or 100 or more people are affected

Hazard- a perceived natural/geophysical event that has the potential to threaten both life and property

Question 21

Why do people remain exposed to hazards?

Answer 21

. Unpredictability
. Lack of alternatives
. Changing levels of risk
. Russian roulette (optimistic it won’t happen to them)
. Cost vs benefit

Question 22

Define hazard vulnerability

Answer 22

The capacity of a person or group to anticipate, cope with, resist and recover from the impact of a natural hazard