Natural Hazards & Plate tectonics

Question 1

Define natural hazard.

Answer 1

Natural hazards are things caused by natural processes that is a potential threat to human life or property.

Question 2

What are the three types of natural hazard?

Answer 2

1= Geophysical
2= Atmospheric
3= Hydrological

Question 3

What are geophysical hazards?

Answer 3

Geophysical hazards (caused by land processes) include earthquakes, volcanic eruptions, landslides and tsunamis.

Question 4

What are atmospheric hazards?

Answer 4

Atmospheric hazards (caused by climatic processes) include tropical cyclones, storms, droughts, extremes of hot or cold weather and wildfires.

Question 5

What are hydrological hazards?

Answer 5

Hydrological hazards (caused by water movement) include floods and avalanches.

Question 6

Define disaster.

Answer 6

A disaster is when a hazard actually seriously affects humans.

Question 7

Define risk.

Answer 7

Risk is the likelyhood that humans will be seriously affected by a hazard.

Question 8

Define vunerability.

Answer 8

Vunerability is how susceptible a population is to the damage caused by a hazard.

Question 9

How does wealth affect the perception of a hazard?

Answer 9

Richer people may be able to afford to move to areas that are less prone to hazards, or to build their homes to withstand hazards, so they may be able to perceive the risk as smaller.

Question 10

How does religion affect the perception of a hazard?

Answer 10

Some people veiw hazards as acts of God, sent to punish people.

Question 11

How does education affect the perception of a hazard?

Answer 11

People with more education may have a better understanding of the risks, or believe they can mitigate those risks.

Question 12

How does past experience affect the perception of a hazard?

Answer 12

People who live in hazard-prone areas may have already experienced hazards, affecting their perceieved risk.

Question 13

Give an example of risk sharing.

Answer 13

People buy insurance to help them repair a property after a disaster. Most people wont be affectef, so lots contribute and the cost is shared. but - only in HICs.

Question 14

What does the park model show?

Answer 14

The park model shows how responses progress during a disaster, helping planners to predict what resources will be needed for each stage. It also shows the impact of a disaster.

Question 15

What are the stages of the park model?

Answer 15

1= Pre-disaster
2= Disruption
3= Relief
4= Rehabilitation
5= Reconstruction

Question 16

What does the disuption stage of the park model show?

Answer 16

The disruption stage shows the initial drop in quality of life during and directly after an event occurs. The steepness of this fall is based on the quality of infrastrucutre and size of the event.

Question 17

What does the relief stage of the park model show?

Answer 17

The relief stage shows the direct aftermath of a hazard event - where primary responses occur such as search and rescue.

Question 18

What does the rehabilitation stage of the park model show?

Answer 18

The rehabilitation stage shows how people begin to resolve long-term problems. Again, this is affected by the wealth of that country.

Question 19

What does the reconstruction of the park model stage show?

Answer 19

This involves rebuilding permenant housing and infrastructure. In some places it is rebuilt to a better standard, and in some its rebuilt to the same standard or even worse.

Question 20

What are the four stages of the hazard management cycle?

Answer 20

1= Mitigation
2= Preparedness
3= Response
4= Recovery

Question 21

What occurs in the mitigation stage of the hazard management cycle?

Answer 21

This aims to minimise the impacts of future disasters. It can happen before a hazard occurs or afterwards, when the area is recovering.

Question 22

What occurs in the preparedness stage of the hazard management cycle?

Answer 22

This stage is about planning how to respond to a hazard, e.g. warning signs and educating people on evacuation.

Question 23

What occurs in the response stage of the hazard management cycle?

Answer 23

This is how people react after a disaster occurs, such as search and rescue in the immediate aftermath of a hazard.

Question 24

What occurs in the recovery stage of the hazard management cycle?

Answer 24

This is about getting the affected area back to a normal state, such as rebuilding and repairing infrastructure.

Question 25

What are the different parts of the Earth's structure?

Answer 25

1= Crust 2= Mantle 3= Outer crust 4= Inner crust

Question 26

What is inside the core?

Answer 26

Iron and nickel.

Question 27

What is in the mantle?

Answer 27

Silicate rocks.

Question 28

What is the mantle and the crust called?

Answer 28

Lithosphere.

Question 29

Tell me about continental crust.

Answer 29

Continental crust is thicker (30-70km thick) and less dense.

Question 30

Tell me about oceanic crust.

Answer 30

Oceanic crust is thinner (6-10km thick) and more dense.

Question 31

Convection currents - The earths mantle is _________ close to the core, so lower parts of the _______________ heat up, become less ______ and ____. As they move up, they _____ down, become more dense and ____. These _________ movements of semi-molten rock are called ___________ __________.

Answer 31

hottest asthenosphere dense rise cool sink circular convection currents

Question 32

Explain the process of slab pull.

Answer 32

At destructive plate margins, denser crust is submerged under less dense crust. The sinking of the plate edge pulls the rest of the plate towards the boundary.

Question 33

Ridge push - At ___________ plate boundaries, magma rises and forms new _____, which is ___, heats up surrounding rocks and ________ and rise above the ________. The new crust cools and becomes ________, causing rock to move ___________ and away from the ________, causing the plates to _____ ______.

Answer 33

constructive crust hot expand surface denser downslope margin move apart

Question 34

What is sea-floor spreading and how does it lead to the formation of mid-ocean ridges?

Answer 34

Sea-floor spreading is where tectonic plates diverge, and magma rises through the gap and creates new crust. This crust is then dragged apart and new crust forms between the margin. It forms mid-ocean ridges.

Question 35

What is a constructive margin?

Answer 35

A constructive margin occurs where two plates are moving apart from eachother. It could also be known as a divergent plate boundary.

Question 36

What is a destructive margin?

Answer 36

A destructive margin occurs where two plates are moving towards each other. It could also be known as a convergent or submergent plate boundary.

Question 37

What is a conservative margin?

Answer 37

A conservative margin occurs where two plates are sliding past each other, or sliding the same way at different speeds.

Question 38

What events occur at constructive margins and why?

Answer 38

Volacanoes and earthquakes occur at constructive margins because pressure is released at the margin. Some magma is melted and rises due to being less dense - volcano. Ocean ridges and rift valleys also form at constructive margins.

Question 39

Explain the formation of an ocean ridge?

Answer 39

Where diverging plates are underwater, an ocean ridge forms due to sea-floor spreading. Underwater volcanoes erupt and the ridges could build up above sea level, such as Iceland.

Question 40

Explain the formation of a rift valley?

Answer 40

1= At constructive boundaries, magma rises and causes crust to fracture causing fault lines. 2= Crust drops down to form a valley. 3= Volcanoes are found at rift valleys!

Question 41

What formations occur at destructive oceanic-continental boundaries?

Answer 41

1= Volcanoes 2= Earthquakes 3= Deep sea trenches 4= Fold mountains

Question 42

What formations occur at destructive oceanic-oceanic boundaries?

Answer 42

1= Volcanoes 2= Earthquakes 3= Deep sea trenches 4= Island arcs

Question 43

How do volcanoes form at destructive boundaries?

Answer 43

At a submergence point, magma is less dense than the continental plate above, so it will rise back to the surface to form volcanoes. This can also occur underwater.

Question 44

How do earthquakes form at destructive boundaries?

Answer 44

As one plate moves under the other it may get stuck, causing pressure to build up. When it becomes too much it will release ginormous amounts of seismic activity at once as an earthquake.

Question 45

How do deep sea trenches form at destructive boundaries?

Answer 45

When the more dense oceanic crust is submerged under the less dense continental crust, it is subducted leaving a deep sea trench behind. This may also happen between two oceanic plates.

Question 46

How do island arcs form at destructive boundaries?

Answer 46

When underwater volcanic eruptions occur, island arcs may be created - they are clusters of islands that sit in a curved line, e.g the mariana islands.

Question 47

How do fold mountains form at destructive boundaries?

Answer 47

Fold mountains form at destructive boundaries. They are made up of sediments that have accumalated on continental crust. Fold mountains form when tectonic plates collide, compressing rock layers and forcing them upwards into folds.

Question 48

What formations occur at continental-continental boundaries?

Answer 48

1= Earthquakes 2= Fold mountains

Question 49

What formations occur at conservative plate boundaries?

Answer 49

Only earthquakes.

Question 50

Magma ________ can form volcanoes away from plate boundaries. They are vertical __________ of extra-hot magma that ______ up from the mantle. The plume remains ______________ but over time the crust moves above it, forming a _______ of ____________ volcanoes, e.g. Hawaii.

Answer 50

plumes away columns rises stationary chain dormant