Geographers completed fieldwork after an earthquake affected a growing city on a transform fault. Fig. 1 shows their simplified cross-section through the fa...

(a) This part tests observation from a cross-section rather than explanation. Four observations that could be recorded are: a fault plane is present; the focus is 12 km deep; an epicentre is shown at the ground surface; and a water main is broken. Other acceptable observations are that homes and a hospital are close to the fault zone, soft river sediment is present, bedrock is present, and the plates are moving sideways. Any four. [4]

(b) At a transform fault, the two plates move horizontally past each other. Friction may prevent smooth movement, causing stress to build up along the fault. When the stress is released suddenly, energy travels as earthquake waves. At the ground surface, the ground may crack or be displaced, and infrastructure such as pipes, roads or buildings may be damaged. This gives the movement, the earthquake process and two surface effects. [5]

(c) Fieldwork data should be used to identify hazards and set priorities before rebuilding. Six valid uses are:

1. Map damaged buildings.
2. Map fault traces and unstable ground.
3. Identify areas underlain by soft sediment.
4. Inspect bridges and roads.
5. Locate broken water, gas and electricity lines.
6. Identify unsafe buildings that require demolition.

Further acceptable uses are identifying safe sites for shelters and prioritising repairs near hospitals or schools. The purpose is not merely to collect data: it is to decide where rebuilding is safe and where repairs are most urgent. Any six. [6]

(d) Shaking can be more severe above soft river sediment because soft sediment can amplify seismic waves, increasing movement at the surface. Loose material may also shake for longer than solid rock. If the sediment is waterlogged, it can compact or liquefy, meaning it temporarily behaves more like a fluid and loses strength. Foundations may then settle unevenly, causing buildings to tilt, suffer structural damage or collapse more easily. Bedrock is generally more rigid, so it tends to produce less amplification; lower surface movement can therefore mean less damage. The contrast is about the ground material, not simply distance from the focus. [7]

(e) A strong recovery and future-development plan includes all of the following:

1. Zone new development away from the fault.
2. Restrict building on unstable sediment.
3. Enforce earthquake-resistant building codes.
4. Retrofit hospitals and schools.
5. Install flexible water and gas pipes.
6. Strengthen bridges and key roads.
7. Train residents in evacuation and first aid.
8. Prepare emergency shelters and supplies.

Other creditworthy actions are improving warning and communication systems, providing insurance or repair funding for low-income households, and monitoring future ground movement with GPS. Together, these reduce exposure, make buildings and infrastructure more resilient, and improve emergency response. Any eight. [8]

Examination reminder: When explaining differing earthquake impacts, build the chain from ground type, to wave behaviour or liquefaction, to foundation performance, and finally to building damage.