Question
The diagram shows some of the factors affecting vulnerability to hazards.
Suggest what factor A on the diagram might be.[1]
Explain how two of the other factors (other than factor A) shown on the diagram affect vulnerability to hazards.[2+2]
Analyse why communities may underestimate the probability of a hazard event occurring.[5]
For one or more hazards of your choice, examine how estimates are made for the probability and likely impact of a major hazard event.[10]
▶️Answer/Explanation
Markscheme
Factor A might be earthquake drills in schools, or presence/absence of early warning systems. Award 1 mark for any valid suggestion, which must be related to education/information.
Award 2 marks for each explanation, which must be related to the concept of vulnerability, and not, for instance, to the severity of the hazard itself.
Underestimating the probability of a hazard event occurring may stem from many causes including a community’s misplaced optimism, having insufficient evidence available for a more accurate assessment, and an unrealistic belief that “it can’t happen (again) here”. Award 1 mark each for these or other valid statements, and a further 1 mark for each subsequent development of any point, up to the maximum of 5 marks.
There are many techniques used in risk assessment. They include the identification of trends and patterns, based on previous events. An example of the former would be working out the return intervals for major hurricanes; an example of the latter would be using gap theory to predict the location of the next major earthquake along a plate boundary. If the historical record is long enough, it is possible to calculate the probability of an event of any particular magnitude occurring with some degree of reliability. Assessing the likely impact of a major hazard event depends on the spatial analysis of the vulnerability of the population (lives and property). This may involve the use of GIS to identify areas where, for instance, housing types are less resilient to earthquakes, or where families cannot afford insurance against a specific hazard and have no financial reserves to recover quickly if a hazard event occurs.
Depending on the hazard event examined, there are numerous possible approaches to this question, but answers considering both aspects of the question (probability and likely impact) in some detail are likely to be credited at bands E/F. It is not necessary for the two aspects to be treated in equal detail.
A specific hazard event is a specific requirement of the question; it is expected in those answers achieving band D and above.
Marks should be allocated according to the markbands.
Question
Explain three conditions necessary for the formation of tropical hurricanes.[6]
“Poorer communities are more vulnerable to the impacts of hazard events than richer communities.” Discuss this statement.[10]
▶️Answer/Explanation
Markscheme
Award [1] for each relevant point and [1] for further development.
Conditions include:
• formation over warm tropical oceans / sea temperatures at least 26°C / significant depth of warm water in order to provide energy and moisture
• sufficient distance from the equator for the Coriolis force to be significant
• convergence of warm, moist air towards a centre of low pressure
• rapid uplift of air causes condensation and the formation of clouds/rain
• release of energy (latent heat) due to condensation results in further rapid uplift
• cooler air descends in the eye of the hurricane; as it descends the air warms and no clouds develop.
For example, the Coriolis force must be sufficiently strong [1] to impart rotation of the air, so hurricanes rarely form close to the equator [1].
The vulnerability of a community to hazard events is affected by the demographic, social and economic characteristics of the population. Examples might be given at a variety of scales, from both rural and urban populations. Poorer communities are often more vulnerable because they often live in hazardprone areas, they lack education and awareness, and are unable to afford measures that might be taken to reduce the impact of hazards. Richer communities are more able to plan and prepare for hazard events, have greater awareness and are better able to respond to the effects of a hazard. Technological hazards may affect rich and poor communities alike, but poorer
people may live closer to the source of the hazard (as in Bhopal).
Good answers will discuss the vulnerability of poorer communities to hazards and the inability to respond to their effects, and will discuss the vulnerability of poorer and richer communities in different areas. Another approach is to discuss the scale of the hazard event, recognizing that all communities can be equally vulnerable, eg tsunamis. Another approach is to discuss temporal aspects of the hazard event, such as a poor community’s long-term vulnerability to diseases after the hazard event.
Accept both countries and communities.
For band D, expect some description of the vulnerability of poorer communities and/or richer communities to hazard events.
For band E, expect either a more structured and detailed explanation of the vulnerability of poorer and richer communities, or a discussion that reflects critically on diverse communities, hazards of different scales, different types of vulnerability.
For band F, expect both of these elements.
Marks should be allocated according to the markbands.
Question
Outline two factors that can influence the vulnerability of a community to the impacts of a tectonic hazard event.[4]
Briefly explain the occurrence of either volcanoes or earthquakes at constructive plate margins.[3]
Briefly explain the occurrence of either volcanoes or earthquakes at destructive plate margins.[3]
Examine the effectiveness of short- and long-term responses to one recent disaster caused by a hurricane (tropical cyclone/typhoon).[10]
▶️Answer/Explanation
Markscheme
Award [1] for each factor and [1] for further development relating to vulnerability of a community to a tectonic hazard event.
For example, a high degree of poverty [1] means that people cannot afford to build earthquake-resistant housing that does not collapse [1].
Other possible factors include:
- lack of insurance
- elderly population
- a level of corruption
- time of day
- preparedness
- geographical location.
Award up to [3] for any of the following points:
Volcanoes
- are formed when two plates diverge as magma wells up to fill the gap [1]
- example of constructive plate margin, such as mid-Atlantic Ridge [1]
- usually begins as submarine volcano, but may later become island [1].
Earthquakes
- are formed when two plates diverge as a result of friction and movement [1]
- the plate movement is explained, eg convection currents [1]
- example of plate margin, such as mid-Atlantic Ridge [1].
Credit other valid points and/or the use of suitable annotated diagrams.
Award up to [3] for any of the following points:
Volcanoes
- explanation of two plates converging [1]
- one plate sinks / is subducted [1]
- are formed due to melting, producing magma [1]
- differences in plate density causing subduction, causing magma to rise [1]
- additional detail, eg explosive eruptions around the margins of the Pacific plate [1].
Earthquakes
- explanation of two plates converging, eg convection currents [1]
- subduction of denser oceanic plate [1]
- are formed due to friction between the plates [1]
- further detail, eg deep-focus [1]
- additional locational detail, eg around the margins of the Pacific plate [1].
Credit other valid points and/or the use of suitable annotated diagrams.
Responses considered should be both short-term and long-term.
Short-term responses might include search and rescue, providing essential medical care, emergency food and water supplies, combating the threat of disease, establishing essential communications and alerting outside relief agencies.
Long-term responses continue for several months or years after the disaster, and might include rebuilding destroyed housing and infrastructure, re-establishing the local economy, undertaking protective measures and educating the local community in case of a future disaster, land-use zoning, establishing early-warning systems, planning evacuation routes.
Good responses will examine a range of different types of response to a recent named hurricane disaster, and consider their effectiveness in different timescales.
At band D, expect a descriptive account of different types of response to a hurricane disaster.
At band E, expect either a more detailed account of a range of short- and long-term responses, or some explicit examination of their relative effectiveness.
At band F, expect both.
Marks should be allocated according to the Paper 2 HL and SL markbands.