Referring to either earthquakes or volcanoes, briefly outline:

(i) one scale used to measure the magnitude of the hazard event; 

(ii) why some hazard events are categorized as disasters.

Referring to either earthquakes or volcanoes, briefly explain their occurrence:

(i) at a destructive (convergent) plate margin; 

(ii) in areas other than along a plate margin.

Discuss why some hazard events are easier to predict than others.

(i) 

• identifies a scale [1]
• provides detail of the scale [1].

Example: (earthquakes) The Richter scale [1] gives values for magnitude on a logarithmic scale [1].

Accept other valid details about the scale.

(ii) 

• outside help is needed to deal with the disruption
• provides further detail or an example.

(i) Earthquakes:

• two plates move towards each other [1] and one is subducted/sinks due to density [1]
• this results in friction/tension that generates earthquakes [1] may give additional details eg deep focus events to a depth of 700 km [1]
• provides a clear diagram in support [1].

Volcanoes:

• two plates move towards each other [1] and one is subducted/sinks due to density [1]
• this results in melting/partial melting to produce magma [1] may give additional details eg viscous lava resulting in explosive eruptions [1]
• provides a clear diagram in support [1].

(ii) Earthquakes:

• transform/minor faults [1] run hundreds of kilometres perpendicular to plate boundaries [1] may give example [1]
• may occur at volcanic hotspots [1] due to thin plate/highly active plume [1] may give example [1]
• human-induced hazards eg reservoir construction [1], mining or fracking [1] may give example [1]
• provides a clear diagram in support [1].

Volcanoes:

• may occur at volcanic hotspots [1] due to thin plate/highly active plume [1] may give example [1]
• volcanoes at destructive boundaries may be some distance from actual margin due to the angle of subduction [1] may give details [1]
• provides a clear diagram in support [1].

The most likely framework will be to explain, in turn, some combination of different types of hazard events: hurricanes, tectonic hazards, droughts and human-induced (technological) hazards. Two named types must be discussed in some depth for the award of full marks.

Credit should be given for the use of an alternative conceptual framework, for instance looking at the probability of high-impact/high-magnitude events as opposed to low-impact events with different recurrence intervals. Another approach is to look at spatial and temporal probabilities. We may predict where, but not when (San Andreas fault); or we may predict when, but not where (next year’s hurricane season).

Good answers might critically discuss:

• the general predictability of hurricane activity but lack of ability to predict actual paths/intensities/landfall
• how our ability to predict in the short-term is actually improving/dynamic, eg analysis of earthquake “swarms” or GIS applied to detect magma chamber expansion
• the varying capabilities of countries at differing levels of development and their ability to predict/anticipate hazards
• unpredictability of human-induced hazards.

Only credit answers that refer to one or more of the four types of hazard included in the syllabus.

At band D, expect answers which describe some basic reasons for differences in our ability to predict where/when different hazards may strike.

At band E, expect either more detailed explanation of our varying ability to predict where/when different types of hazard will strike or some critical discussion of the statement

At band F, expect both.

Marks should be allocated according to the markbands.