Natural Hazards

Question 1

What is a natural hazard?

Answer 1

A natural hazard is a natural event or process which has potential to affect people eg) causing loss of life or injury, economic damage, disruption to people’s lives or environmental degradation.

Question 2

What 3 types can natural hazards be divided into?

Answer 2

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

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

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

Question 3

Define disaster

Answer 3

When a hazard actually seriously affects humans.

Question 4

Define risk

Answer 4

The likelihood that humans will be seriously affected by a hazard.

Question 5

Define vulnerability

Answer 5

How susceptible a population is to the damage caused by a hazard.

Question 6

How do people’s circumstances affect their perception of hazard? ( affected by social, economic and cultural background)

Answer 6

Wealth - eg) richer may be able to afford to move to areas less hazard prone, or build homes to withstand so may perceive risk as smaller.
Religion - eg) some view hazards as acts of God sent to punish.
Education - eg) people with more education may have a better understanding of hazard risks.
Past experience - eg) people living in hazard-prone areas may have experienced hazards before which may affect perfection.
Personality - eg) some fear hazards and others might think of them as exciting.

Question 7

What does the park model show?

Answer 7

How responses progress during a disaster

Question 8

What are the stages of the park model?

Answer 8

Pre-disaster - before event, normal situation
Disruption - during and directly after hazard event occurs, destruction.
Relief - aftermath of event, rescue efforts focus on saving people and preventing further damage.
Rehabilitation- people start to resolve longer-term problems once immediate impacts are under control.
Reconstruction- involves rebuilding permanent houses can return area to normal if same standard as before or improve vulnerability if higher standard than before.

Question 9

What are the four stages of the hazard management cycle?

Answer 9

Mitigation
Preparedness
Response
Recovery

Question 10

What is mitigation? (Hazard management cycle)

Answer 10

Aims to minimise impacts of future disasters, and can happen before or after a hazard occurs.
Eg) building flood defences

Question 11

What is preparedness? (Hazard management cycle)

Answer 11

About planning how to respond to a hazard
Eg) making sure there are warning systems in place or educating people

Question 12

What is response? (Hazard management cycle)

Answer 12

How people react when a disaster occurs.
Eg) emergency services or evacuation

Question 13

What is recovery? (Hazard management cycle)

Answer 13

About getting the affected area back to normal
Eg) repairing or rebuilding houses and restoring services

Question 14

What do the impacts of a hazard depend on?

Answer 14

the proximity of the hazard to areas of population
density of the population in the affected area
the level of development of the affected area
the magnitude or size of a hazard
the duration or frequency of a hazard

Question 15

Why is the potential threat of a hazard less if people have a more accurate perception of it?

Answer 15

Minimise risk and aid survival - people know what to do and when to

Question 16

What is meant by a person’s ‘perception’ of something?

Answer 16

How people respond to a hazard links to their perception

Question 17

What factors can affect a person’s perception to hazard ?

Answer 17

Socio-economic status
Level of formal education
Occupation/employment status
Region, cultural/ethnic background
Family and marital status
Past experience
Values, personality and expectations

Question 18

What do the United Nations use to judge whether a hazard is recorded as a disaster?

Answer 18

10 or more people are killed
100 or more people are affected
Government declares state of emergency or requests international assistance.

Question 19

What is acceptance?

Answer 19

(Fatalism) people may simply accept that natural hazards are a part of life or ‘gods will’. Losses accepted as inevitable so people remain where they are.

Question 20

What is prediction?

Answer 20

Improvements in technology have increased our ability to predict hazardous events more accurately.

Question 21

What are most modern management techniques based upon?

Answer 21

Identification of hazard
Analysing risk
Establishing priorities
Treating risk and implementing a risk reduction plan
Developing public awareness and community strategy
Monitoring and reviewing the whole process.

Question 22

What is community risk sharing?

Answer 22

Governments can try and act to reduce vulnerability is to try and change attitudes and behaviour to natural hazards.
Involves measures to reduce loss of life and property damage through public education and awareness, evacuation procedures and emergency medical and food supplies.

Question 23

What was Alfred Wegener’s theory?

Answer 23

All continents were once joined in an ancient supercontinent called Pangea.
At sometime the land masses had drifted apart until they occupied current position

Question 24

What couldn’t Wegener’s theories explain?

Answer 24

How continental movement could have taken place

Question 25

What is the evidence for Wegener’s theory?

Answer 25

Continental fit - some continents seem to fit if placed side by side
Geological evidence - rocks of same age/type display same formations and found in SE Brazil and South Africa.
Climatological evidence - places contain coal deposits from similar age formed in tropical conditions. No longer tropical climate zones so must’ve drifted apart.
Biological - similar fossil formations found on either side of Atlantic.

Question 26

How did greater knowledge of the ocean floor support Wegener’s theory?

Answer 26

Evidence for sea floor spreading
Surveys recorded much younger ages for places on or near mid-oceanic ridges and older for ocean floor rocks near continental land masses.
Old crust continuously being pushed aside by new crust - plates must be getting destroyed somewhere to make space for increase in size and mid-oceanic ridges

Question 27

What is slab pull?

Answer 27

Emerged as more dominant theory for plate movement over last decade.
At a destructive plate margin, the subducting ocean plate, usually composed of basalt, is denser than the surrounding material.
As the plate begins to sink into the mantle it pulls the rest of the plate behind it.

Question 28

What is ridge pull?

Answer 28

Occurred as a theory for plate movement recently.
Gravitational sliding occurs at mid-oceanic ridges at constructive boundaries. The magma that rises is very hot and heats surrounding rocks these expand, become elevated above sea floor, and form a slope. As new rock forms it cools and becomes denser. Gravity then causes it to slide down slope, away from mid-Atlantic ridge resulting in sea floor spreading, new crust formed through volcanic activity and plates move apart.

Question 29

What is a collision and named place example?

Answer 29

Two continental plates moving towards each other and collide.
Indian plate collided with Eurasian plate to form Himalayas fold mountains.

Question 30

What is a destructive subduction and named place example?

Answer 30

Oceanic plate meets continental at destructive margin, denser oceanic crust subducts under continental at an angle forming deep-sea trenches

Atacama Trench off the coast of Peru where the Nazca Trench is subducting beneath the South American Plate.

Question 31

What is a conservative plate margin and named example?

Answer 31

Plates rub past each other, either in same or opposite direction.
San Andreas Fault

Question 32

What are ocean ridges?

Answer 32

Oceanic ridges are the longest continuous uplift features on the surface of the planet. Where two plates pull apart there is a weaker zone in the crust and an increase in heat near the surface. The hotter expanded crust forms a ridge. The central part of the ridge may feature a central valley where a section of the crust has subsided into the magma below.

Question 33

What is a rift valley?

Answer 33

At constructive margins in continental areas, such as East Africa, the brittle crust fractures as sections of it move apart. Areas of crust drop down between parallel faults to form rift valleys. The largest of these features is the East African rift valley.
The area is associated with volcanic activity (e.g. Mt Kilimanjaro). The crust here is much thinner, suggesting that tension in the lithosphere is causing the plate to thin as it starts to split.

Question 34

What are convection currents?

Answer 34

Earth’s mantle is hottest close to the core, lower parts of asthenosphere heat and become less dense and slowly rise.
Cool down as they move towards top of asthenosphere, become more dense and sink
Circular movements of semi-molten rock called convection currents.
They create drag on base of tectonic plates causing them to move.

Question 35

What is the lithosphere?

Answer 35

Rigid top part of mantle and crust together are called the lithosphere.
Lithosphere is divided into lots of slabs called tectonic plates which move in relation to each other.

Question 36

What is a natural disaster?

Answer 36

The realisation of a hazard

Question 37

What makes an area more vulnerable?

Answer 37

Proximity to the hazard
Population density
Level of development
Magnitude of a hazard
Duration of a hazard
Frequency of a hazard
Demographic of the area

Question 38

Why do people put themselves at risk of hazards?

Answer 38

Hazard events are unpredictable
Lack of alternatives
Changing level of risk
Cost/benefit

Question 39

What is the risk equation?

Answer 39

Risk (R) = Hazard (H) x Vulnerability to the hazard (V) / Capacity to cope/recover (C)

Question 40

What is perception of a hazard?

Answer 40

Determines how people manage the hazard

Question 41

What factors influence a person’s perception of a hazard?

Answer 41

Socio-economic status
Level of education
Religion, cultural background
Family situation
Past experience
Personal values and personality

Question 42

How does perception affect response?
What are the 3 categories of response depending on people’s perception of hazard?

Answer 42

Fatalism
Adaptation
Fear