The concept of hazard in a geographical context Flashcards
(89 cards)
1
Q
How is a hazard defined
A
A hazard is defined as a perceived natural/ geophysical event that has the potential to threaten both life and property.
2
Q
What general impacts can a hazard have
A
A hazard has impacts that are social (loss of life and injury) , economic (property damage, employment prospects and community loss) and environmental.
3
Q
A geophysical event would not be hazardous without some…
A
Human occupancy of the location affected.
4
Q
Tell me about the different types of hazards
A
Geophysical
Hydrological
Atmospheric
Geomorphic
Biohazards
Multiple hazardous zones
5
Q
What are examples of a geophysical hazard
A
All the tectonic hazards of volcanos, earthquakes and tsunami
6
Q
What are examples of a hydrological hazard
A
Essentially the extreme of wet weather, is droughts and floods
7
Q
What are atmospheric hazards
A
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)
8
Q
What are geomorphic hazards
A
Landslides and avalanches
9
Q
What are biohazards
A
Wildfires and locust plagues
10
Q
What are multiple hazardous zones
A
Places that experience a combination of any of the previously mentioned hazards
11
Q
Are hazards entirely natural
A
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.
12
Q
Define vulnerability
A
The risk of exposure to hazards combined with an inability to cope with them.
13
Q
What’s a disaster
A
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.
14
Q
Define resilience
A
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.
15
Q
What is risk
A
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.
16
Q
How do people consciously place themselves at risk
A
Consider, for example all the people who live in the shadow of volcanoes.
17
Q
What’s a risk assessment
A
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.
18
Q
What does vulnerability imply
A
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.
19
Q
When examining the impact of any such event, what should we always consider
A
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.
20
Q
Why do people react to the threat of hazards in different ways
A
Because of the way In which individuals receive and process information, in turn based on their economic and cultural background.
21
Q
What factors influence hazard perception
A
Socioeconomic status Level of education Occupation and employment status Religion Ethnicity Family and marital status Past experience Values, attitudes and expectations
22
Q
What will perception of hazard ultimately determine
A
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.
23
Q
Why is there often a great difference in the perception of a hazard between peoples of differing levels of economic development
A
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.
24
Q
What are the 3 ways people perceive natural hazards
A
Fatalism
Adaptation
Fear
25
Tell me about the way people perceive natural hazards involving fatalism
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
26
Tell me about the way people perceive natural hazards involving adaptation/adjustment
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.
27
Tell me about the way people perceive natural hazards involving fear
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.
28
Define adaptation/adjustment
The changing of lifestyles or behaviours to cope with the threats and impacts before and after a hazardous event.
29
Define prediction
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.
30
The factors leading to disaster can be related to both the...
Physical profile of he hazard event and the human context in which it occurs.
31
List me the physical factors influencing the relationship between hazard and disaster
Magnitude
Frequency
Duration
Areal extent
Spatial correlation
Regularity
32
Tell me about the physical factor leading to a disaster: magnitude
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.
33
How is earthquake magnitude measured
Magnitude is now measured by the logarithmic moment scale (MMS), a modification of the earlier Richter scale.
34
How are the damaging effects of an earthquake measured
The damaging effects are measured by the Mercalli scale (useful for the impacts of shaking)
35
How is volcano magnitude measured
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.
36
Tell me about the physical factor leading to a disaster: frequency
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)
37
Define mitigation
The reduction of the amount and scale of threat and damage caused by a hazardous event.
38
Tell me about the physical factor leading to a disaster: duration
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.
39
Tell me about the physical factor leading to a disaster: areal extent
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.
40
Tell me about the physical factor leading to a disaster: spatial concentration
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.
41
Tell me about the physical factor leading to a disaster: regularity
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.
42
What’s gap theory
Where there has been a gap in time since the last event, then it is more likely to occur in that location.
43
List the human factors that influence the relationship between hazard and disaster
Economic factors, including level of development
Social factors
Political factors
Technological factors
44
Tell me about the human factor influencing disasters: economic factors, including level of development
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.
45
Tell me about the human factor influencing disasters: social factors
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.
46
Tell me about the human factor influencing disasters: political factors
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.
47
Tell me about the human factor influencing disasters: technological factors
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.
48
Summarise how the factors influence the relationship between hazard and disaster
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.
49
Natural risks pose a risk to...
Human life, livelihoods and possessions
50
What scales can the response to hazards occur at
Individual to the local community, regional, national or international level, and, for large events, at a global scale.
51
What’s a major factor in influencing how many resources are devoted to reducing the impact of hazards in general
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.
52
List me the physical factors that can affect responses to a hazard
Geographical accessibility of the location/region affected
Type of hazard, ie scale, impact, magnitude, frequency
Topography of the region affected
Climatic factors
53
Tell me the human factors that can affect responses to a hazard
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
54
Define community preparedness/risk sharing
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.
55
Tell me about the hazard response framework
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.
56
What are the 4 strategy’s in the hazard response framework
Modify the loss (adaptation)
Modify vulnerability (adaptation)
Modify the event (mitigation)
Modify the cause (mitigation)
57
Tell me the suggested policies for the strategy: modify the loss (adaptation)
Provide aid
Provide insurance
58
Tell me the suggested policies for the strategy: modify vulnerability (adaptation)
Predict and warn (forecasting)
Prepare the community (risk sharing)
Educate to change behaviours and prevent hazards becoming disasters.
59
Tell me the suggested policies for the strategy: modify the event (mitigation)
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
60
Tell me the suggested policies for the strategy: modify the cause (mitigation)
Have total environmental control - prevent the hazard at source (only possible for some small scale hazards)
61
What is the parks disaster response model
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.
62
Tell me about the different stages of the parks disaster response model
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)
63
Parks model is sometimes placed in a circular format, when it is know as...
The hazard management cycle.
64
What does the hazard management cycle look like
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
65
What are responses to hazards controlled by
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.
66
What does the theory of plate tectonics suggest
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.
67
Where do the tectonic plates float
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..
68
What’s the lithosphere
The lithosphere is the crust and upper mantle (80-90km thick), which form the plates
69
What’s the asthenosphere
The lower part of the mantle
70
How do oceanic and continental plates more
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.
71
Why do plate tectonics remain just a theory
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.
72
When destructive plate margins occur
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.
73
Define destructive (or convergent) plate margins
Where crust is destroyed as one plate dives under another.
74
What are the 3 main types of destructive plate margins
Oceanic/continental convergence
Oceanic/oceanic convergence (island arcs)
Continental/continental convergence
75
Tell me about oceanic/continental convergence
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.
76
Tell me an example of oceanic/continental convergence
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.
77
Tell me about oceanic/oceanic convergence (island arcs)
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.
78
Tell me about continental/continental convergence
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.
79
Where do constructive plate margins occur
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.
80
Define constructive (or divergent) margins
Where new crust is generated as the plates pull away from each other
81
Tell me an example of a mid ocean ridge
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.
82
Tell me about a deep Rift Valley
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.
83
Ridge push is also known as
Gravitational sliding
84
What’s sea floor spreading
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.
85
Where do conservative plate margins occur
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.
86
Define conservative (or transform) margins
Where crust is neither produced nor destroyed as the plates slide horizontally past each other.
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?
Yes.
88
Tell me about the Hawaiian islands an an exception to the theory of plate tectonics explaining the distribution of continents, volcanoes and earthquakes
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.
89
Define hotspot
Area in which heat under the earth’s crust is localised. At such points, rising magma can produce volcanoes.
