Tectonics

Question 1

relationship between seismic activity and plate boundaries

Answer 1

-very strong relationship
-earthquakes can occur on all plate boundaries
-they are most frequent on convergent boundaries
-highest magnitude on destructive boundaries
-intraplate activity caused by volcanic activity at mantle plumes, faulting mountains and human activity

Question 2

relationship between volcanic activity and plate boundaries

Answer 2

-very strong relationship
-90% of all active volcanoes are found around the pacific ring of fire, largely destructive plate margin
-intraplate activity primarily associated with mantle plumes and rifting
-most explosive volcanoes associated with destructive plate boundaries
-shield and fissure volcanoes associated with constructive boundaries

Question 3

processes at constructive plate boundary

Answer 3

-divergent movement of plates, driven by convection currents and slab pull
-graben region drops as plates pulled apart
-rising magma from the mantle

Question 4

processes at a destructive plate boundary

Answer 4

-convergent movement of oceanic and continental crust
-subduction of more-dense oceanic crust beneath the continental, due to slab-pull, to form the Benioff zone
-thickening/folding of continental crust
-rising magma

Question 5

processes at conservation plate boundary

Answer 5

-where one plate slides past another
-movement tend to be horizontal
-lithosphere is neither created nor destroyed

Question 6

define MOHO

Answer 6

boundary between the crust and the mantle

Question 7

define asthenosphere

Answer 7

fluid or plastic part of the mantle below the lithosphere

Question 8

evidence for theory of continental drift

Answer 8

the fit of the continents-jigsaw like fit
rock types-limestone formed in warm, shallow seas that contain corals indicating a tropical climate
fossils-glossopteris fern found in all southern continents showing they once were joined

Question 9

evidence for theory of sea-floor spreading

Answer 9

mid-ocean ridges- SONAR used to obtain bathymetric profile
high heat flow- thermal reading of high heat flower mid-ocean ridges as a result of rising basaltic magma
age of the ocean floor- rocks at the mid-ocean ridges are the youngest, and get older as you move away
magnetic anomalies- measurements of the direction of alignment have the same polarity

Question 10

how does the Wilson cycle explain plate movement

Answer 10

a continent rifts, forming an ocean basin in-between and then begins a process of convergence that leads to the collision of the two plates and closure of the ocean

Question 11

what does the volcanic explosively index show

Answer 11

volume of ejecta, height of the eruption column, duration of the eruption

Question 12

primary hazards of a volcanic eruption

Answer 12

lava flow, pyroclastic flows, ash falls, gas eruptions

Question 13

secondary hazards of a volcanic eruption

Answer 13

lahars, tsunami

Question 14

define the Benioff zone

Answer 14

an area of seismic activity that corresponds with the slab being the thrust downwards in a subduction zone

Question 15

define slab pull

Answer 15

where older plates sinks at the subduction zones, as they cool they become more dense than the underlying mantle, the cooler sinking plate pulls the rest of the warmer plate along behind

Question 16

how are tsunamis formed

Answer 16

-submarine earthquake along destructive boundary
-displacing the water column above
-tsunami has a long wavelength and small amplitude
- wavelength is shortened and amplitude is increased due to friction and topography
-producing a vacuum effect
-destruction on landform depends on land uses, population density, physical geography
-other triggers are volcanic activity and landslides

Question 17

Define risk

Answer 17

The probability of a hazard causing harmful consequences, involves the relationship between the vulnerability of a population and the nature of a hazard

Question 18

Define risk perception

Answer 18

Affected by: level of economic development, frequency of hazards of given a given magnitude

Question 19

Define natural hazard

Answer 19

This is a perceived natural event that has the potential to threaten both life and property

Question 20

Define disaster

Answer 20

The realisation of a hazard; when it causes a significant impact on a vulnerable population

Question 21

What does the degg model show

Answer 21

A model to illustrate the interaction between hazards, disaster and vulnerable populations. Importantly, disaster only occurs when a vulnerable population is exposed to a hazard

Question 22

Factors affecting risk

Answer 22

Probability of a hazard of a given magnitude occurring, level of vulnerability

Question 23

Factors affecting vulnerability

Answer 23

Level of perceived risk, level of economic development, social variables within a country, nature of the hazard: especially potential magnitude

Question 24

What is the pressure and release model

Answer 24

This model clearly shows the link between level of economic development in the root causes, leading to a progression of vulnerability, which then factors into hazard risk.The par model is an expansion of the degg model, identifying a range of factors that can affect vulnerability of a population

Question 25

What are hazard profiles

Answer 25

A way of examining the relative importance of the different physical characteristics of hazards

Question 26

3 scales that measure magnitude

Answer 26

Mercalli scale, richter scale, moment magnitude scale.

Question 27

What does volcanic explosively index measure

Answer 27

Volume, height, duration

Question 28

Define governance

Answer 28

Ability of an organisation/group of people to plan or manage hazard events effectively.

Question 29

What does the disaster risk-poverty nexus establish

Answer 29

1. Poverty is both a cause and a consequence of disaster impacts
2. Repeated disaster occurrence helps to sustain and maintain poverty in a region

Question 30

Define prediction

Answer 30

Knowing when and where a natural hazard will strike on a spatial and temporal scale

Question 31

Define forcasting

Answer 31

Less precise and provides percentage chances of hazards occurring in a particular place

Question 32

Draw hazard management cycle

Answer 32

Rescue, relief, rebuilding, rehabilitation, mitigation, prevention, preparation, evacuation warning.

Question 33

What does the park model show

Answer 33

Also known as the disaster response curve, shows the effectiveness of a hazard on quality of life over time

Question 34

Factors that influence hazard risk

Answer 34

Unpredictability, lack of alternatives, dynamic hazard, cost-benefit, Russian roulette reaction

Question 35

framework for response analysis

Answer 35

Modify the loss: aid vital for poor people
Modify vulnerability: prediction and warning
Modify the event: hazard-resistant design (engineering defences)

Question 36

Examples of modify the loss

Answer 36

Rapid response, search & rescue, medical aid

Question 37

Examples of modify vulnerability

Answer 37

Community preparedness, education, prediction & warning systems

Question 38

Examples of modify event

Answer 38

Building design and control, more sustainable materials

Question 39

Example of cost-benefit analysis

Answer 39

What are the costs for building a bridge to be earthquake proof: direct costs (building materials), indirect costs (costs of congestion when bridge is down)
What are the benefits: lives saved, benefits to business & emergency services

Question 40

Define vulnerability

Answer 40

The susceptibility of a community to a hazard, or to the impacts of a hazard event

Question 41

Define resilience

Answer 41

The ability of a system, community or society exposed to hazards to resist, absorb and recover from the effects of a hazard

Question 42

state the six characteristics of the hazard profiles

Answer 42

magnitude, speed of onset, areal extent, spatial predictability, duration, frequency

Question 43

explain the processes involved at a mantle plume

Answer 43

area in the mantle from which heat rises as a hot thermal plume from deep in the earth, high heat and low pressure at the base of the lithosphere enable melting of rock

Question 44

who are the players in emergency planning

Answer 44

government, rescue teams and NGOs