| Date | May 2021 | Marks available | 6 | Reference code | 21M.1.bp.7 |
| Level | SL and HL | Paper | 1 | Time zone | |
| Command term | Explain | Question number | 7 | Adapted from | N/A |
Question
The diagram shows mass movement on slopes in the Swiss Alps between 1995 and 2016. Each dot represents one mass movement.
The varying altitudes of the mass movement and the direction each slope faces are shown.
[Source: Kenneth Davis, geovisualist.com, data from WSL Institute for Snow and Avalanche Research SLF.]
Identify the altitude range within which the majority of mass movements occur.
Estimate the number of mass movements occurring above the altitude of 3500m.
Outline one physical factor affecting the speed of a mass movement.
Explain two possible strategies to reduce human vulnerability to rapid mass movement hazards in a mountainous area such as this.
Markscheme
2000–2999 (m not needed).
11 (allow 10–12).
Award [1] for physical factor and [1] for development.
For example: Gradient/slope [1] influences the effect of gravity on how fast material moves [1].
Other possible factors include:
- water content
- sediment size
- vegetation
- rainfall amount.
In each case, award [1] for outlining the strategy and up to [2] for the explanation and development/exemplification of how the strategy reduces human vulnerability.
For example: Land-use zoning keeps people away from dangerous areas [1]. This could be at the base of rock faces where debris might fall/slide [1]. This prevents loss of life/economic loss [1].
Other possible strategies include:
- insurance
- slope stabilization, e.g. netting, rock armour, revetments, snow fences
- excavation and infilling of slopes to realign them
- improving groundwater drainage / diverting water
- diverting roads/infrastructure from known areas
- evacuation warnings / education
- banning logging on hillsides
- controlled explosions
- housing design, to withstand impact of mass movement.
Examiners report
(a)(i) and (ii) Straightforward questions which were answered well.
(a)(i) and (ii) Straightforward questions which were answered well.
Most were able to get at least 1 mark but failed to develop the factor affecting the speed.
There were a lot of good responses for this question as many candidates had solid knowledge and understanding of possible strategies. Most had at least one strategy but struggled with a second so ended up with something generic. Also, many did not explain how the strategy reduced human vulnerability.
