The concept of hazard in a geographical context

Question 1

How is a hazard defined

Answer 1

A hazard is defined as a perceived natural/ geophysical event that has the potential to threaten both life and property.

Question 2

What general impacts can a hazard have

Answer 2

A hazard has impacts that are social (loss of life and injury) , economic (property damage, employment prospects and community loss) and environmental.

Question 3

A geophysical event would not be hazardous without some…

Answer 3

Human occupancy of the location affected.

Question 4

Tell me about the different types of hazards

Answer 4

Geophysical

Hydrological

Atmospheric

Geomorphic

Biohazards

Multiple hazardous zones

Question 5

What are examples of a geophysical hazard

Answer 5

All the tectonic hazards of volcanos, earthquakes and tsunami

Question 6

What are examples of a hydrological hazard

Answer 6

Essentially the extreme of wet weather, is droughts and floods

Question 7

What are atmospheric hazards

Answer 7

Tropical storms (known by a variety of names - hurricanes, typhoons, cyclones and willy willies), tornadoes and extra tropical storms (such as deep depressions affecting the British isles)

Question 8

What are geomorphic hazards

Answer 8

Landslides and avalanches

Question 9

What are biohazards

Answer 9

Wildfires and locust plagues

Question 10

What are multiple hazardous zones

Answer 10

Places that experience a combination of any of the previously mentioned hazards

Question 11

Are hazards entirely natural

Answer 11

Few hazards are entirely natural. Their relationship with disaster is the result of human vulnerability. Some hazards, such as wildfires, can be naturally occurring, or they can be caused by the direct or indirect impact of human actions - deliberately setting vegetation alight or carelessness. In many cases, human actions intensify the impact of natural hazards, for example exacerbating earthquake risk by building inappropriate buildings.

Question 12

Define vulnerability

Answer 12

The risk of exposure to hazards combined with an inability to cope with them.

Question 13

What’s a disaster

Answer 13

A disaster is the realisation of a hazard, when it causes a ‘significant impact’ on a vulnerable population. It causes serious disruption of the functioning of a community of society, involving widespread/serious socioeconomic and environmental losses that exceed the ability of a community (local/national) to cope. In other words, it exceeds their capacity and resilience level.

Question 14

Define resilience

Answer 14

The degree to which a population or environment can absorb a hazardous event and yet remain within the same state of organisation, i.e. its ability to cope with stress and recover.

Question 15

What is risk

Answer 15

Risk is the probability of a hazard occurring and creating a loss of lives and/or livelihoods. It might be assumed that risk to a hazard is involuntary, but in reality many people consciously place themselves at risk.

Question 16

How do people consciously place themselves at risk

Answer 16

Consider, for example all the people who live in the shadow of volcanoes.

Question 17

What’s a risk assessment

Answer 17

Risk assessment defines the likelihood of harm and damage. For this we should consider the probability of an event occurring and the severity of the hazard when it does occur. If both are high, then the disaster is likely to be greater in magnitude.

Question 18

What does vulnerability imply

Answer 18

Vulnerability implies a high risk of exposure to hazards combined with an inability to cope with them. In human terms it is the degree of resistance offered by a social system to the impact of a hazardous event.

In turn this depends on the resilience of the individuals and communities, and the reliability and functioning of management systems that have been put in place to deal with the event. Poverty and low economic status can amplify vulnerability.

Question 19

When examining the impact of any such event, what should we always consider

Answer 19

The relationship between environmental hazards and the potential impacts on the people and areas is a very complex one.

When examining the impact of any such event, you should always consider its magnitude, duration and extent, but also the degree to which the people affected can cope and respond. The former are inherently physical in nature, whereas the latter are more functions of the human geography of the area affected.

Question 20

Why do people react to the threat of hazards in different ways

Answer 20

Because of the way In which individuals receive and process information, in turn based on their economic and cultural background.

Question 21

What factors influence hazard perception

Answer 21

Socioeconomic status
Level of education
Occupation and employment status
Religion
Ethnicity 
Family and marital status
Past experience
Values, attitudes and expectations

Question 22

What will perception of hazard ultimately determine

Answer 22

It’s determines the course of action taken by individuals in order to modify the event or the responses they expect from governments and other organisations.

Question 23

Why is there often a great difference in the perception of a hazard between peoples of differing levels of economic development

Answer 23

In wealthier areas there is a sense that the better you are prepared, the more able you will be able to withstand the impact of the hazard and perhaps even prevent the disaster from taking place. This is usually based upon government and community action, and is backed by capital that will fund technology based solutions. The sense of helplessness in the face of natural hazards tends to increase with the level of poverty and the deprivation of the people. Even in wealthier countries there are groups of disadvantaged people who tend to look upon natural hazards as part of their way of life as they are seen as unavoidable, just as the bulk of people in poorer countries see the impacts of these events as being part of the conditions of poverty.

Question 24

What are the 3 ways people perceive natural hazards

Answer 24

Fatalism

Adaptation

Fear

Question 25

Tell me about the way people perceive natural hazards involving fatalism

Answer 25

Fatalism (acceptance): such hazards are natural events that are part of living in an area. Some communities would go as far as to say that they are God’s will. Action is therefore usually concerned with safety first. Losses are accepted as inevitable and people remain whee they are

Question 26

Tell me about the way people perceive natural hazards involving adaptation/adjustment

Answer 26

People see that they can prepare for, and therefore survive, the events by prediction, prevention and or protection depending upon the economic and technological circumstances of the area in question.

Question 27

Tell me about the way people perceive natural hazards involving fear

Answer 27

The perception of the hazard is such that people feel so vulnerable to an event that they are no longer able to face living in the area, and move away to regions perceived as safe.

Question 28

Define adaptation/adjustment

Answer 28

The changing of lifestyles or behaviours to cope with the threats and impacts before and after a hazardous event.

Question 29

Define prediction

Answer 29

The ability to give warnings so that action can be taken to reduce the impact of hazard events. Improved monitoring and use of ICT have meant that predicting hazards and issuing warnings have become more important.

Question 30

The factors leading to disaster can be related to both the…

Answer 30

Physical profile of he hazard event and the human context in which it occurs.

Question 31

List me the physical factors influencing the relationship between hazard and disaster

Answer 31

Magnitude

Frequency

Duration

Areal extent

Spatial correlation

Regularity

Question 32

Tell me about the physical factor leading to a disaster: magnitude

Answer 32

Magnitude (the size of the event) is perhaps the key physical factor, but the correlation between magnitude and level of disaster is far from direct. The term ‘intensity’ is often used when describing the magnitude of a tropical storm, and relates to the low level of atmospheric pressure within the storm.

Question 33

How is earthquake magnitude measured

Answer 33

Magnitude is now measured by the logarithmic moment scale (MMS), a modification of the earlier Richter scale.

Question 34

How are the damaging effects of an earthquake measured

Answer 34

The damaging effects are measured by the Mercalli scale (useful for the impacts of shaking)

Question 35

How is volcano magnitude measured

Answer 35

It’s measured by the volcanic Explosivity index (VEI), based on the volume and column height of ejections. This index is very closely related to the type of magma that influences the type of eruption. This can be related back to the type of plate boundary on which the volcano is located.

Effusive eruptions of basaltic lavas with low VEI are associated with constructive margins or plumes, whereas explosive eruptions (with high VEI) of andesitic or rhyolitic lava are associated with destructive margins.

Question 36

Tell me about the physical factor leading to a disaster: frequency

Answer 36

Frequency refers to how often an event occurs and is sometimes called the recurrence interval, such as ‘a one in 100-year event’. For most hazards there is usually an inverse relationship between frequency and magnitude. The effect of frequency on severity of impact is difficult to gauge but theoretically, areas experiencing frequent tectonic events usually have a plethora of both adaptation and mitigation measures, ranging from extensive monitoring, education and community awareness of what to do (for example, public education programmes, practice of evacuation procedures, the storage of emergency medical and food supplies, and planning for their delivery), to various technological strategies for shockproof building design. (Eg Tokyo, Japan and San Francisco, USA) or protection (eg Japanese tsunami walls)

Question 37

Define mitigation

Answer 37

The reduction of the amount and scale of threat and damage caused by a hazardous event.

Question 38

Tell me about the physical factor leading to a disaster: duration

Answer 38

Duration refers to the length of time that a hazard exists. Often the initial event is followed by aftershocks (eg Christchurch, New Zealand) or a series of subsequent eruptions. While individual earthquakes often last for only 30 seconds, the damage can be very extensive. Secondary hazards often prolong the duration and the damage. For example, the triple whammy of the 2011 Tokyo multi disaster(earthquake, tsunami and nuclear accident) or the secondary hazards associated with volcanic eruptions such as lahars.

Question 39

Tell me about the physical factor leading to a disaster: areal extent

Answer 39

This is the size of the area the hazard covers. This can have a very clear impact, as was the case in the Icelandic ash clouds after Eyjafjallajökull in 2012. These disrupted the whole of the northern hemisphere air transport system for a weak, leading to widespread economic losses.

Question 40

Tell me about the physical factor leading to a disaster: spatial concentration

Answer 40

This refers to the areal distribution of types of hazards over space, such as earthquakes and volcanoes associated with types of plate boundary. In theory, hazardous regions are avoided for permanent settlement, although the opportunities fertile soils provide encourage agricultural settlements. Active tectonic landscapes, especially volcanic examples, also encourage tourism. Generally, spatial concentration promotes sound strategies for management of the hazard, and disasters are rare.

Question 41

Tell me about the physical factor leading to a disaster: regularity

Answer 41

Regularity refers to the temporal distribution of hazards, which can add to their disaster potential. While gap theory can increase the possible prediction of the ‘big one’, earthquakes are, in reality very unpredictable. Volcanic eruptions can be hard to predict precisely, even with close monitoring.

Question 42

What’s gap theory

Answer 42

Where there has been a gap in time since the last event, then it is more likely to occur in that location.

Question 43

List the human factors that influence the relationship between hazard and disaster

Answer 43

Economic factors, including level of development

Social factors

Political factors

Technological factors

Question 44

Tell me about the human factor influencing disasters: economic factors, including level of development

Answer 44

Human vulnerability is closely associated with levels of absolute poverty and the economic gap, or inequality, between rich and poor. Poverty exacerbates disasters. The poorest countries lack money to invest in education, social services, basic infrastructure and technology, all of which help communities to overcome disasters. Economic growth, however, increases economic assets and therefore raises potential risk levels unless managed effectively.

Question 45

Tell me about the human factor influencing disasters: social factors

Answer 45

World population is growing, especially in developing nations, with higher levels of urbanisation and many people living in dense population concentrations in unsafe living settings, such as poorly sited squatter settlements. Some huge cities are very vulnerable to post earthquake fires, as was the case in Kobe, Japan. Relief, rescue and recovery efforts are difficult for some areas.

For example, in Kashmir following the 2014 India-Pakistan floods, isolation, low temperatures and the regions frontier position complicated relief and recovery. An increasingly ageing population, as in Sichuan China escalates vulnerability to the problems associated with emergency evacuation and survival.

Question 46

Tell me about the human factor influencing disasters: political factors

Answer 46

The lack of strong central government produces a weak organisational structure. Equally, a lack of financial institutions inhibits both disaster mitigation and emergency post disaster recovery. A good, strong central government leads to highly efficient rescue.

Question 47

Tell me about the human factor influencing disasters: technological factors

Answer 47

While community preparedness and education can prove absolutely vital in mitigating disasters, technological solutions can play a major role, especially in building design and prevention and protection.

Question 48

Summarise how the factors influence the relationship between hazard and disaster

Answer 48

In summary, while the intrinsic physical properties of a hazards profile can lay the foundations for the development of a disaster, it is the extrinsic human profile that impacts vulnerable communities and societies, and causes disasters. The most vulnerable people, such as those suffering from chronic malnutrition, disease, armed conflict, chaotic and ineffective governance and lack of educational empowerment, are generally channelled into the least resilient environments.

Question 49

Natural risks pose a risk to…

Answer 49

Human life, livelihoods and possessions

Question 50

What scales can the response to hazards occur at

Answer 50

Individual to the local community, regional, national or international level, and, for large events, at a global scale.

Question 51

What’s a major factor in influencing how many resources are devoted to reducing the impact of hazards in general

Answer 51

As people and organisations have limited resources and time to make decisions, the relative importance of the physical risk natural hazards pose, compared with other priorities such as providing jobs, education, health services and defence, will be a major factor in Influencing how many resources are devoted to reducing the impact of hazards in general.

Question 52

List me the physical factors that can affect responses to a hazard

Answer 52

Geographical accessibility of the location/region affected

Type of hazard, ie scale, impact, magnitude, frequency

Topography of the region affected

Climatic factors

Question 53

Tell me the human factors that can affect responses to a hazard

Answer 53

Number of people involved or affected

Degree of community preparedness/risk sharing

Technological resources

Scientific understanding and expertise

Level of general education and training

Economic wealth of the region affected

The quality and quantity of the infrastructure in the area, ie roads, railways, airports, health facilities

The political framework, ie government competency and organisation

Question 54

Define community preparedness/risk sharing

Answer 54

Involves prearranged measures that aim to reduce the loss of life and property damage through public education and awareness programmes, evacuation procedures, and the provision of emergency medical, food and shelter supplies.

Question 55

Tell me about the hazard response framework

Answer 55

When taking an overview of hazardous events and their ability to develop into disasters, one approach is to develop a framework of possible strategies.

The choice of which strategies included in the framework to utilise will vary during the different stages of a hazard, as shown in the parks disaster response model.

Question 56

What are the 4 strategy’s in the hazard response framework

Answer 56

Modify the loss (adaptation)

Modify vulnerability (adaptation)

Modify the event (mitigation)

Modify the cause (mitigation)

Question 57

Tell me the suggested policies for the strategy: modify the loss (adaptation)

Answer 57

Provide aid

Provide insurance

Question 58

Tell me the suggested policies for the strategy: modify vulnerability (adaptation)

Answer 58

Predict and warn (forecasting)

Prepare the community (risk sharing)

Educate to change behaviours and prevent hazards becoming disasters.

Question 59

Tell me the suggested policies for the strategy: modify the event (mitigation)

Answer 59

Provide some environmental controls to reduce impact

Avoid hazards by land use zoning

Design buildings that are hazard resistant

Retro-fit buildings to offer some protection

Question 60

Tell me the suggested policies for the strategy: modify the cause (mitigation)

Answer 60

Have total environmental control - prevent the hazard at source (only possible for some small scale hazards)

Question 61

What is the parks disaster response model

Answer 61

This is an attempt to model the impact of a disaster from before the event to after the event. It also considers the role of emergency relief agencies and rehabilitation. With each hazard event, different areas affected may have a different response curve, as the physical and human factors may vary in impact.

Question 62

Tell me about the different stages of the parks disaster response model

Answer 62

Stage one is normality, pre disaster, this would be where we modify the cause and event (mitigation)

Stage 2 is where the hazardous event occurs, the curve moves downwards (deterioration) and we use use of vulnerability strategies (adaptation)

Stage 3 is in the relief time zone (hours to days) where we search, rescue and care.

Stage 4 is in the rehabilitation time zone (days to weeks) may include national/international help. Includes use of modifying the loss (adaptation) eg aid, temporary housing and services) curve is rising upwards

Stage 5 is the reconstruction (weeks to years) nature of the recovery related to the need to reduce vulnerability and/or restore normality.

As the curve reaches pre disaster level and begins to rise into the improvement zone, use strategies to modify vulnerability to prevent further disasters (adaptation)

Question 63

Parks model is sometimes placed in a circular format, when it is know as…

Answer 63

The hazard management cycle.

Question 64

What does the hazard management cycle look like

Answer 64

4 quadrants. At the top in between top 2 quads it says hazard.

After hazard it goes clockwise, to rescue, relief to rebuilding and rehabilitation to mitigation and prevention and finally evacuation warning and preparation to hazard again

Question 65

What are responses to hazards controlled by

Answer 65

The capability of the people, individuals and groups involved in the management and/or mitigation of those hazards. You should be able to consider and discuss the role of the major players in hazard management, such as government, non governmental organisations (NGOs), insurance people, engineers and the media.

Question 66

What does the theory of plate tectonics suggest

Answer 66

Suggest that the earth’s crust is split up into seven large, rigid plates and several smaller ones, all of which are able to move slowly on the earth’s surface.

Question 67

Where do the tectonic plates float

Answer 67

They float on the semi molten mantle.

Some geoscientists have suggested that the crust/mantle division is more complicated and have introduced terminology to reflect this..

Question 68

What’s the lithosphere

Answer 68

The lithosphere is the crust and upper mantle (80-90km thick), which form the plates

Question 69

What’s the asthenosphere

Answer 69

The lower part of the mantle

Question 70

How do oceanic and continental plates more

Answer 70

The centre of the earth (the core) is very hot (over 5,000 degrees C), which is caused by both primordial heat and radioactive decay. Some of this heat moves upwards into the asthenosphere as convection currents. As the convection currents slowly move laterally below the earth’s surface, they drag the crust that lies over them. This causes the continental and oceanic plates to move.

In addition, this mechanism largely explains the global distribution of volcanoes and earthquakes - they occur mainly at plate margins.

Question 71

Why do plate tectonics remain just a theory

Answer 71

Because the logistics and cost of drilling down to the Mohorovičić discontinuity (known as the Moho) - the boundary between the earth’s crust and upper mantle, at its thinnest a distance of just 10km - remain insurmountable.

Question 72

When destructive plate margins occur

Answer 72

Where two plates converge and one plate plunges under the other due to the movement of the convection current. At this point the plate is re-incorporated into the upper mantle and crust. The area where this material is lost is called the subduction zone.

Question 73

Define destructive (or convergent) plate margins

Answer 73

Where crust is destroyed as one plate dives under another.

Question 74

What are the 3 main types of destructive plate margins

Answer 74

Oceanic/continental convergence

Oceanic/oceanic convergence (island arcs)

Continental/continental convergence

Question 75

Tell me about oceanic/continental convergence

Answer 75

Here, part of the ocean floor is dragged down by a downward gravitational force (known as slab pull) beneath a continental crust, with the sinking crust forming a very deep trench , parallel to the coast.

The friction between the sinking oceanic plate and the continental plate creates great heat and melting, resulting in volcanoes along the length of the mountain chain. Strong, destructive earthquakes and the rapid uplift of mountain ranges are common in this region.

Question 76

Tell me an example of oceanic/continental convergence

Answer 76

An example is the Peru/Chile trench off the west coast of South America, where the Nazca and South American plates converge. In turn, the overriding South American plate is being lifted up, creating a chain of young fold mountains, the Andes.

Question 77

Tell me about oceanic/oceanic convergence (island arcs)

Answer 77

When two oceanic plates converge, one usually sinks (subducts) under the other and in the process a trench is formed.
For example, the Marinas trench marks where the fast moving Pacific plate converges against the slower moving Philippines plate. Subduction processes in oceanic/oceanic plate convergence also result in the formation of volcanoes that, over millions of years, pile up lava on the ocean floor until a submarine volcano rises above sea level to form an island volcano. Such volcanoes are typically strung out in curved chains called island arcs. The descending plate also provides a source of stress as the two plates interact, leading to frequent moderate to strong earthquakes.

Question 78

Tell me about continental/continental convergence

Answer 78

As the plates forming continental crust have a much lower density than the underlying layers, there is no subduction where they meet. Hence, as these plates move towards each other, their edges and the sediments between them are forced up to create fold mountains. There is NO volcanic activity, but the movement of the plates can trigger shallow focus earthquakes. Material can also be forced downwards to form deep mountain roots. An example of such a margin is wheee the Indo-Australian plate is being force northwards into the Eurasian plate, creating the Himalayas.

Question 79

Where do constructive plate margins occur

Answer 79

Where two plates diverge away from each other, allowing new magma to reach the surface. There are examples of constructive plate margins on both sea and land. For the former mid-ocean ridges are created, whereas for the latter, rift valleys occur.

Question 80

Define constructive (or divergent) margins

Answer 80

Where new crust is generated as the plates pull away from each other

Question 81

Tell me an example of a mid ocean ridge

Answer 81

Mid ocean ridges are formed at constructive margins

An example is the mid-Atlantic ridge (MAR). This is a submerged mountain range that runs north/south for 15,000km through the Atlantic Ocean, from Iceland to a point 7,200km east of southern South America. It breaks the ocean surface in several place, forming groups of volcanic islands such as island and Tristan da Cunha.

Question 82

Tell me about a deep Rift Valley

Answer 82

Formed at constructive margins, the MAR is split by a deep Rift Valley along its crest, 10km wide with walls 3,000m on either side. It marks the boundary between the two divergent plates of the oceans floor. This Rift Valley is widening at a rate of 3cm per year. Magma from beneath the earth’s surface rises to create high ridges on either side, which, with further gravitational sliding, push away the lithosphere in either side (known as ridge push). This means that the rocks of the ocean floor on either side of the ridge move sideways, a process known as sea floor spreading.

Question 83

Ridge push is also known as

Answer 83

Gravitational sliding

Question 84

What’s sea floor spreading

Answer 84

Seafloor spreading is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge.

Question 85

Where do conservative plate margins occur

Answer 85

A conservative plate margin exists where two plates do not come directly into collision but slide past each other, in parallel, along a fault. The most well known example of such a boundary is the San Andreas fault in California, USA, which separates the northward moving Pacific plate (moving at 6cm per year) and North American plate (moving 3cm per year). This is a zone of intense earthquake activity, because the movement along the faults is irregular rather than a smooth process of gradual creep.

Question 86

Define conservative (or transform) margins

Answer 86

Where crust is neither produced nor destroyed as the plates slide horizontally past each other.

Question 87

The theory of plate tectonics offers an all embracing explanation of the current distribution of the earth’s continents, volcanoes and earthquakes, are they some exceptions?

Answer 87

Yes.

Question 88

Tell me about the Hawaiian islands an an exception to the theory of plate tectonics explaining the distribution of continents, volcanoes and earthquakes

Answer 88

The Hawaiian islands are a zone of great volcanoes and yet they do not occur at the boundary of a plate. The islands have formed in the middle of the Pacific Ocean, more than 3,200km from the nearest plate boundary.

The island chain has resulted from the Pacific plate moving over a deep, stationary hotspot in the mantle, located beneath the present day position of the island of Hawaii (known as the big island). Heat from this hotspot produces a constant source of magma by partially melting the overriding Pacific plate. The magma, which is lighter than the surrounding solid rock, then rises through the mantle and crust (as a thermal magma plume) to erupt onto the sea floor.

Over time, countless eruptions have caused a volcano to grow until it finally emerged above sea to form an island. Continuing plate movement (from southeast to northwest) will eventually carry the island beyond the hotspot and volcanic activity will cease.

To the far northwest of the islands is a chain of underwater seamounts - the remnants of volcanic activity that took place even further back in time. This is further evidence that the plates on the earth’s crust are moving.

Question 89

Define hotspot

Answer 89

Area in which heat under the earth’s crust is localised. At such points, rising magma can produce volcanoes.