Question
Option D — Geophysical hazards
The map shows the thickness of the lava flows on the lower slopes from Kīlauea, a shield volcano, following its eruption in 2018.
Answer either part (a) or part (b).
Either
(a) Examine the importance of physical and human factors in increasing mass movement events.\([10]\)
Or
(b) Examine how economic and social factors may reduce the vulnerability of communities to geophysical hazard risk.\([10]\)
▶️Answer/Explanation
Ans:
Marks should be allocated according to the markbands.
Mass movements (landslides, mudflows, rock-falls, and avalanches); commonly occur on steep slopes in mountainous areas. Physical and human factors may lead to an increase in the magnitude and frequency of mass movements. Tectonic activity and climatic factors, such as heavy rainfall, snowfall, and frost action, may increase slope instability, triggering mass movement. Increases in magnitude/frequency may result from climatic change and increased tectonic activity. However, human factors may be of more immediate importance, especially in areas of rugged terrain. Population increases and urbanization, removal of vegetation cover, deforestation and increases in slope steepness due to construction will increase slope instability. Mass movement events may not increase in all places, as slope stabilization measures and effective management strategies may be undertaken.
Possible applied themes (AO2) demonstrating knowledge and understanding (AO1):
- Mass movement events frequently occur on steep slopes in mountainous areas.
- Caused by both physical and human factors, which may result in an increase in the frequency and magnitude of mass movement.
- Tectonic activity, including earthquakes and volcanoes, and climatic factors, such as heavy rain and snowfall, may upset slope stability and trigger mass movement.
- Short- and long-term climatic change may result in increased mass movement, as will changes in tectonic activity.
- However, human factors may be of more immediate importance, especially in areas of rugged terrain.
- Increased population pressure, urban growth, deforestation, and increases in slope steepness caused by infrastructure development will increase slope instability.
- Magnitude/frequency may not increase in all places because slope stabilization measures and effective management strategies may be undertaken, especially in economically more developed places
- Human actions may result in a decrease in mass movement events e.g. through slope stabilization.
Good answers may be well structured (AO4) and may additionally offer a critical evaluation (AO3), which examines the relative importance of physical and human processes affecting the magnitude and frequency of mass movement in different places. Another approach might be to examine how future risks vary between places over different time scales. Mass movements might be decreasing in some places.
For 5-6 marks, expect some weakly-evidenced outlining of at least one physical or human factor increasing a mass movement event.
For 7-8 marks, expect a structured account which includes:
- either an evidenced explanation of how physical and human factors may lead to an increase in magnitude/frequency of mass movement.
- or a discursive conclusion (or ongoing evaluation) grounded in geographical concepts and/or perspectives.
For 9-10 marks, expect both of these traits.
(b)
Marks should be allocated according to the markbands.
The vulnerability of people to geophysical hazard risk is affected by a variety of economic and social factors. These include levels of wealth and education, past experience, personal knowledge, preparedness and risk perception. These will vary between and within different local communities, and they may change over time.
Possible applied themes (AO2) demonstrating knowledge and demonstrating knowledge and understanding (AO1):
- Geophysical hazards represent a significant threat to many communities around the world; many large cities are located on plate margins, close to active volcanoes and earthquake zones.
- Vulnerability is a product of the likelihood/probability of a hazardous event occurring and the consequences in terms of injury, death and destruction.
- Economic factors affecting vulnerability include wealth and infrastructure and communications, planning.
- Social factors include perception of the risk; population characteristics, education and literacy levels.
- Perception of the hazard will affect management and levels of preparedness to reduce risk from future events.
Good answers may be well-structured (AO4) and may additionally offer a critical evaluation (AO3) which examines the relationship between risk and vulnerability and why levels of vulnerability vary between communities in different places. Another approach might be to examine the relative importance of social and economic factors, or how other factors (such as political) may affect economic/social vulnerability.
For 5-6 marks, expect some weakly-evidenced outlining of at least one economic and/or social factor(s) reducing vulnerability to geophysical hazards.
For 7-8 marks, expect a structured account which includes:
- \(\quad\) either an evidenced explanation of a variety of social and economic factors reducing vulnerability to geophysical hazards in different communities
- or a discursive conclusion (or ongoing evaluation) grounded in geographical concepts and/or perspectives.
For 9-10 marks, expect both of these traits.
Question
Describe the difference between a hazard and a disaster.[2+2]
Explain why some sections of a community are more vulnerable to hazards than others.[6]
Compare the effectiveness of the methods used to predict the occurrence of two different natural hazard types.[10]
▶️Answer/Explanation
Markscheme
A hazard constitutes a threat to people, property and/or the environment [1 mark]. It can be natural or human in origin [1 mark].
A disaster results from a hazard event that has major impacts on people, economic and/or environmental impacts [1 mark] and which the area or country cannot deal with unless there is outside aid [1 mark].
Award up to 3 marks for each section of a community whose vulnerability is well explained or for a single factor which is well explained.
Vulnerable sections could include: different age categories, income groups, people with disabilities, location, gender, and ethnicity. (Do not accept MEDC/LEDC differences.) Not all of these are needed for 6 marks.
6 marks may also be awarded for a brief explanation of six valid factors. Factors might include: knowledge of the hazard, education level, warning systems, insurance, communications, population density, income level, building types and construction codes.
Answers depend on the hazard types chosen.
The two hazard types should be clearly identified and must be natural hazards. (It is expected that these will be chosen from volcanic hazards, earthquakes, hurricanes or drought, but other natural hazard types such as tsunamis may be credited.) Answers should clearly outline the methods used to try to predict the named hazard types and make comparisons as to their reliability in forecasting hazard events.
Responses that compare the effectiveness of methods used to predict one of the hazard types should be credited, but comparisons between the methods used for different types of hazard should form the bulk of the argument to essentially determine which hazard is the more predictable.
To access bands E and F, answers should effectively compare the methods used.
Marks should be allocated according to the markbands.
Examiners report
Candidates either knew the IB definitions of hazards and disasters or they did not – this differentiated those who scored 2, 3 or 4 out of 4.
There were some excellent answers which identified parts of the community (aged, young, women, infirm, poor, disabled) and explained why they are at increased risk. However, too many went for the MEDC/LEDC contrast and did not appreciate the scale involved in the question.
Answers frequently examined the methods used to predict their chosen hazards rather than evaluating their effectiveness. The two most frequent natural hazards chosen were hurricanes and earthquakes, which lend themselves to a very good contrast. However, answers needed to compare the effectiveness of the methods to predict to access the higher bands (E and F).
Question
Outline the methods used to describe the magnitude (strength) of two hazard types.[2+2]
Suggest three reasons why some people continue to live in places with a known hazard risk.[3×2]
“Economic factors and not physical factors determine the severity of the impacts of hurricanes (typhoons, cyclones).” Discuss this statement using examples.[10]
▶️Answer/Explanation
Markscheme
The most likely types selected will be earthquakes (Richter or Mercalli scale), volcanoes (VEI scale) and hurricanes/cyclones/typhoons (Saffir–Simpson scale). In each case allow 1 mark for naming the relevant scale and 1 mark for a brief description. Responses that refer to hazards not in the syllabus, such as tornadoes, but that outline the relevant scale, should be credited.
Award 1 mark for each reason stated (for example, soil quality, poverty, lack of knowledge, historical inertia) and 1 mark for an extended explanation or detail of the hazard risk.
A number of approaches are possible but most answers will refer to the contrasting effects of hurricanes on countries with contrasting levels of development. It is important that the answer refers to physical factors such as the strength of the hurricane, the size of the storm surge or the landscape of the area affected, as well as economic factors that may determine levels of preparation and protection, warning systems, evacuation, aid and recovery responses.
The strongest answers that access bands E and F should focus on at least two hurricane events and balance the relative importance of these factors in assessing the severity of the impact in terms of loss of life, environmental damage and loss of property (economic cost).
Answers that simply describe the impacts, or just describe physical and economic factors without discussing their relative importance, should not move above band D.
Similarly, answers that do not refer to examples should not be able to access bands E and F.
Marks should be allocated according to the markbands.
Examiners report
The most common scale chosen was the Richter scale, though few candidates at standard level were able to describe how it relates to earthquake strength. Many candidates who chose hurricanes were unable to refer to the Saffir–Simpson scale and simply referred to wind speeds.
Generally well done with a wide range of reasons, though weaker responses failed to refer to the actual risk that faced the inhabitants.
Responses were much stronger on economic factors than physical factors, with a surprising number of answers failing to mention that the consequences might depend on the category of the hurricane, its speed of movement, height of the storm surge and the type of coastline at landfall. Equally, the term “severity” was often interpreted in a very narrow sense with candidates apparently not realizing that such terms include a perceptual component (what is severe to one person is not to another).
There were however many excellent case studies included at both levels.