IB Geography D.5.2 Spatial Scales of Processes and Challenges Notes

Events and Aftermaths Operate at Different Spatial Scales

1. Nested scale means a site-level collapse can create local service failure, national fiscal costs and international aid needs at the same time.
2. Analytical scale changes the pattern visible in data because neighbourhood contrasts disappear when values are averaged nationally.
3. Management scale should match the process, since evacuation routes require local detail while insurance and reconstruction finance may require national coordination.
4. Site scale concerns the immediate hazard zone; building collapse, lava inundation or slope failure may be concentrated within a small area.
5. Local scale covers settlements and service areas; blocked roads, evacuation centres and damaged utilities connect the event to nearby communities.
6. National scale includes system-wide disruption; central government finance, transport corridors, insurance and reconstruction priorities redistribute impacts across a country.
7. Regional and global scales arise through networks; ash clouds, trade interruptions, migration and international assistance can extend consequences across borders.
8. Scale is not the same as severity; a locally concentrated disaster can be catastrophic for one community while a wide disturbance may cause smaller losses in each place.

Each Hazard Has a Distinct Spatial Signature

1. Earthquake footprint combines a broad shaking field with concentrated zones of surface rupture, liquefaction, landslides and building collapse.
2. Volcanic footprint is directional because valleys channel dense flows while wind carries ash across a different and wider area.
3. Mass-movement footprint links a source zone, travel path and deposit, which may cross administrative boundaries despite narrow width.
4. Earthquake shaking covers a broad area but varies locally; distance from the epicentre, ground conditions and building quality produce sharp differences in damage.
5. The 2015 Gorkha earthquake combined scales; regional shaking triggered local landslides while national infrastructure damage and international relief widened the aftermath.
6. Volcanic hazards divide into zones; pyroclastic flows and lava are usually concentrated near the volcano, whereas ash can travel hundreds or thousands of kilometres.
7. Eyjafjallajökull had a networked international footprint; limited Icelandic damage contrasted with extensive disruption to European airspace.

1. Mass movements are often spatially narrow; Vajont nevertheless produced a wider downstream disaster because displaced reservoir water transferred energy beyond the failed slope.

Scale Changes Through Time

1. Impact expansion occurs when blocked transport, displacement and supply disruption spread after the physical event has ended.
2. Recovery divergence appears when accessible commercial centres reopen while remote or low-income communities remain displaced.
3. Risk memory declines during long recurrence intervals, weakening preparedness even as exposure grows.
4. Onset may be measured in seconds or minutes; earthquake shaking and rapid landslides leave little time for protective action.
5. Emergency impacts unfold over hours and days; search and rescue, medical demand, temporary shelter and access restoration become the main priorities.
6. Secondary hazards may persist for months; aftershocks, lahars and unstable slopes can repeatedly close areas that appeared to be recovering.
7. Reconstruction operates over years; housing, livelihoods, schools and transport links may recover at different rates and reproduce earlier inequalities.
8. Memory and preparedness operate across generations; a long quiet interval can reduce awareness even when the physical hazard remains.

Management Must Match the Operating Scale

1. Subsidiarity assigns decisions to the lowest level with sufficient capacity while higher levels supply finance, regulation and specialist support.
2. Cross-boundary coordination is necessary where ash, tsunami, rivers, transport or displaced populations move beyond one jurisdiction.
3. Vertical integration connects national standards with local implementation and household action rather than treating levels as separate.
4. Household action is suited to immediate protection; secure furniture, emergency plans and supplies reduce harm but cannot restore regional infrastructure.
5. Local government manages place-specific exposure; zoning, evacuation routes and shelters require detailed knowledge of settlement patterns and access needs.
6. National government coordinates systems; building regulation, large infrastructure, insurance and fiscal support exceed the capacity of most local authorities.
7. International cooperation supports exceptional demand; specialist teams, satellite mapping and finance can supplement national capacity after a major event.
8. A scale mismatch weakens management; a local authority cannot solve a national transport failure, while a national plan may overlook neighbourhood barriers to evacuation.

Evaluate Scale Through Extent, Duration and Connectivity

1. Direct extent maps the physical hazard, while indirect extent maps network disruption, displacement and economic effects.
2. Functional duration asks how long services and livelihoods remain impaired rather than measuring only the seconds or hours of the event.
3. Scale-sensitive judgement identifies which scale dominates the chosen outcome, since mortality, fiscal loss and displacement may peak at different levels.
4. Extent asks how far direct and indirect effects reach; use mapped zones and named networks rather than labels such as local or global alone.
5. Duration asks how long each process remains important; distinguish the event, emergency, rehabilitation and reconstruction phases.
6. Connectivity asks what links places; roads, aviation, utilities, markets and governance explain why impacts spread unevenly.
7. Comparison should hold one factor constant where possible; events of similar magnitude such as Gorkha and Kaikōura reveal how exposure, capacity and network design alter outcomes.
8. A justified judgement identifies the dominant scale; the answer may change between mortality, economic loss, displacement and recovery.