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.
The map shows the thickness of the lava flows on the lower slopes from Kīlauea, a shield volcano, following its eruption in 2018.
Answer the following question.
Refer to the map on page 4 of the accompanying resource booklet.
The map shows the thickness of the lava flows on the lower slopes from Killauea, a shield volcano, following its eruption in 2018.
(a) (i) State the lava thickness that covers the largest area.\([1]\)
(ii) State the line of longitude nearest to the lava flow.\([1]\)
(b) Outline one reason why the lava from a shield volcano spreads over a wide area.[2]
(c) Explain how two different communications technologies can help with the post-event management of geophysical hazards.[3+3]
▶️Answer/Explanation
Ans:
(a) (i) 0-19 (m) (only answer)
(ii) \(155^{\circ} \mathrm{W}\) (must have \(\mathrm{W}\) )
(b) Award [1] for a valid reason and [1] for development.
For example: The magma is low in silica and gas/non-explosive/basaltic [1] and produces thin runny/low viscosity lava [1].
Award [1] for stating a valid communications technology and up to [2] for
development/explanation.
For example: Use of phone/laptop [1] enables information to be posted about missing children [1] allowing users to track and find children [1].
Other possibilities include:
• Drones – to envisage damage caused by hazards
• Satellite images/remote sensing – to map hazards
• Disaster management plan via internet/computer technology
• Social media
Question
(i) Describe what is meant by hazard risk.
(ii) Describe what is meant by vulnerability to hazards.[4]
Explain how building design and land-use planning can limit the potential damage from one named hazard type.[6]
“The faster the speed of onset, the greater the impact of the hazard event.” Discuss this statement, with reference to examples.[10]
▶️Answer/Explanation
Markscheme
(i) Risk is the probability of a hazard causing deaths, injuries, property and environmental damage [1 mark]. Award [1 mark] for developing the idea by means of exemplification or identification of a factor that affects risk (location/magnitude/frequency/recurrence).
(ii) Vulnerability refers to the conditions (demographic, social, economic or environmental) that affect the susceptibility of people to a hazard [1 mark]. Award [1 mark] for developing the idea by means of exemplification or identification of a vulnerable group in a population (elderly/poor/gender).
Building design: hurricane/flood surge protection may refer to large, raised shelters or individual house construction methods (metal shutters, thick concrete walls, secure roofs, stilts). Earthquake designs might include reinforced concrete foundation platforms, metal frames, shock absorbers, counterweights, safety glass, or in LEDCs light wooden frames, woven cane walls, light roofs, cement footings, concrete stilts in tsunami areas. In volcanic areas, buildings that have reinforced roofs to withstand the weight of ash or steep roofs to shed ash, or prefabricated sectioned homes that can be moved to avoid damage by lava flows.
Land-use planning: there are many possibilities, depending on the hazard type chosen, including prohibited development in areas with a known risk, evacuation routes, shelter access, buffers, mangroves, land-use zoning, building height restrictions.
Award [1 mark] for each idea, and additional marks for exemplification or extended explanation.
A simple list of factors without an explanation should not be awarded more than [3 marks].
If only building design or only land-use planning is addressed, award up to a maximum of [4 marks].
Accept answers that explain a number of designs in general or fewer detailed explanations.
Responses should examine at least two different, named hazard events with varying speeds of onset and discuss the relationship between the speed of onset and the impact of the hazard event. A balanced argument is required that takes into account hazard events with a rapid speed of onset, such as earthquakes, tsunamis or volcanic explosions, and those with slower onset, such as hurricanes or droughts which may have an equally large impact in the longer term.
Responses that do not make use of examples should not progress beyond band D.
Candidates might focus either on different hazard types (eg drought compared to earthquakes) or different events of the same hazard type (eg volcanic eruptions).
At band D responses are likely to be descriptive.
At band E expect a reasoned discussion between at least two different hazard events and an attempt at a conclusion.
At band F there should be a well balanced conclusion.
Marks should be allocated according to the markbands.
Question
The diagram shows how an earthquake or volcanic eruption impacts on a population’s quality of life.
With reference to either earthquakes or volcanic eruptions, describe two ways in which people’s quality of life deteriorates at point A on the diagram.[4]
With reference to either an earthquake or a volcanic eruption, distinguish between the types of response to the hazard event that occur at point B and point C on the diagram.[6]
“Improved building design is the most effective way for people to reduce their vulnerability to hazards.” Discuss this statement.[10]
▶️Answer/Explanation
Markscheme
Award [1 mark] for each impact on people (eg their home lost) and [1 mark] for how this affects quality of life (eg have to sleep in the open), or some detail of how the hazard led to this (ground shaking, liquefaction, volcanic ash).
Accept other valid statements.
B represents short-term response such as:
- emergency search and rescue of collapsed buildings
- the provision of emergency aid/food/shelter
- the arrival of specialist personnel (external agencies)
- evacuation in case of aftershocks/further eruptions
- other valid short-term suggestions.
C represents longer term organized response, such as:
- reconstruction (possibly with improved design or land zoning)
- wreckage clearance
- salvage operations
- care and rehabilitation (physical/mental)
- other valid long-term suggestions.
Award [1 mark] for each appropriate response that is outlined and [1 mark] for any further development of that point (may use examples, or qualify statements in other ways).
Award up to [4 marks] for either B or C; balance is not expected. Maximum [3 marks] if ideas do not relate to earthquake or volcano.
Improvements in building design could include modifications such as steel reinforcement, base isolators, movable hydraulic joints, strategies to reduce building shaking, shatter proof glass, deep foundations. Low cost designs include wooden buildings that shake in an earthquake, low density buildings, buildings on stilts, reinforced roofs etc. Similar improvements in building design/modification could be discussed with reference to volcanoes, hurricanes and other hazards.
A detailed description of building design is not required, although there should be a sound understanding of its importance.
Discussion should include other ways to reduce vulnerability including land-use zoning, early-warning systems, hard engineering structures such as sea walls, soft engineering structures such as mangrove swamps and belts of trees, response and awareness training, evacuation planning, emergency shelters, investment in emergency services, improved monitoring and prediction of natural hazards, insurance schemes.
At band D, responses are likely to be descriptive and might only cover building design or other simple ways of reducing vulnerability.
At band E, responses should either consider more ways in greater depth or offer some more explicit evaluation eg, a combination of ways is needed.
At band F, expect both.
Marks should be allocated according to the markbands.
Examiners report
Many candidates could describe an impact of an earthquake or volcanic eruption, such as destruction of homes, but did not then go on to describe how this affects the quality of life.
This was a straightforward question. However, many candidates did not clearly distinguish between points B and C, or interpret the diagram correctly to show the differences between short- and long-term responses. Where points B and C were distinguished there were some very clearly developed answers.
Stronger candidates had few problems with this question and were able to discuss the statement explicitly with good knowledge of building design and modifications and other ways of reducing vulnerability. Weaker responses mentioned building design, but with no detail or development, and focused on general ways to reduce vulnerability. A few did not include anything on building design at all.