The big idea: Pre-event management is everything a place does before a geophysical hazard strikes to lower human vulnerability — the risk of death, injury and damage.
You cannot stop an earthquake or eruption. But you can:
- Predict it.
- Warn and evacuate people.
- Plan where they build.
- Design buildings to survive.
Attack vulnerability, not the hazard: So the same hazard kills far fewer people in a prepared place than an unprepared one. Vulnerability = how exposed and unable to cope a population is. Pre-event strategies attack vulnerability, not the hazard itself.
The four families of pre-event strategy
- Prediction & monitoring — instruments (seismometers, GPS, gas sensors) watch for warning signs of an eruption or quake.
- Warning & evacuation — sirens, phone alerts, drills and evacuation routes move people out of the danger zone in time.
- Land-use zoning — mapping the hazard, then banning or limiting building in the most exposed zones.
- Resilient building design — hazard-proof construction: cross-braced frames, lava-diversion walls, slope gabions and netting.
Before vs after the event: Pre-event = prediction, warning, zoning, resilient design (this micro).
Post-event = the emergency response and recovery after the hazard hits (the next micro). The exam usually asks about the pre-event stage — the cheaper, life-saving 'prepare' side.
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How this is tested: A short data-response often opens this option with a bar chart of deaths from similar-sized quakes in different places.
How the marks build up
Read the chart
You Describe the contrast or Estimate a value straight off the bars, with no reasons needed yet.
Explain [3]
How one named strategy lowers vulnerability.
Explain [6]
Two strategies, marked 3 + 3.
A full Explain answer
- Name the strategy.
- Give the chain to fewer deaths or less damage.
- Add an example.
- Every strategy has a strength and a limit that powers the [10] essay later.
Read the axis first. The biggest quake (8.8) caused the fewest deaths — why might that be?
Interactive diagram
Explore the labelled diagram, charts and maps for this topic in full study mode.
Describe what the bar chart shows about deaths in the three earthquakes.
Model answer plan
See the answer broken into clear points, with guidance on how each point earns marks.
Pre-event hazard-management strategies (before the event)
| Strategy | What it does | Strength | Limit | Real example |
|---|---|---|---|---|
| Prediction & monitoring | Instruments (seismometers, GPS, gas sensors) watch for warning signs | Can give days of notice for an eruption | Earthquakes still cannot be predicted reliably | GPS + gas monitoring at Etna detects magma rising |
| Warning & evacuation | Sirens, apps and drills move people out of the danger zone in time | Saves lives even when property is lost | Useless if the warning is late, ignored or unreachable | Japan's earthquake early-warning gave Tohoku (2011) seconds' notice |
| Land-use zoning | Bans or limits building in the most exposed zones (low coast, lahar paths) | Cheap and permanent once mapped | Hard to enforce where land is scarce or poverty forces people in | Lahar hazard maps after Nevado del Ruiz (1985, ~23,000 deaths) |
| Resilient building design | Hazard-proof construction (cross-bracing, lava walls, slope gabions) | Buildings stay standing and shelter people | Expensive, so poorer places cannot afford it | Cross-braced design kept Chile 2010 losses far below Haiti 2010 |
Answering an 'Explain how a strategy reduces vulnerability'
- Name the strategy (e.g. land-use zoning).
- Give the mechanism — the chain (maps the lahar path → bans building there → fewer people exposed).
- Link to lower vulnerability (so fewer people are killed or made homeless). Add an example for the third mark.
Tie it to vulnerability, not the hazard: You cannot change the size of an eruption — so never write 'it stops the eruption'. Write that the strategy reduces the number of people exposed or helps them survive. Zoning → fewer people in the danger zone → fewer deaths.
Explain two pre-event strategies that can reduce people's vulnerability to a volcanic eruption.
Model answer plan
See the answer broken into clear points, with guidance on how each point earns marks.
Personal resilience: insurance and new technology
- Insurance — helps households rebuild quickly; New Zealand’s national scheme paid out widely after the Christchurch earthquakes, but few people are insured in lower-income countries.
- Phones and apps — earthquake early-warning alerts (as in Japan and Mexico) give seconds to take cover; maps and alerts tell people when to evacuate.
- Household preparedness — emergency kits, secured furniture and agreed family plans reduce injuries and speed recovery.
Know your predicted grade
Take timed mock exams and get detailed feedback on every answer. See exactly where you're losing marks.
No strategy is perfect — each works in some places and fails in others.
How the [10] essay is won: The [10] essay is won by knowing where each strategy succeeds and where it falls short, anchored to real named events. Below are the case studies that power a top answer.
Haiti 2010 vs Chile 2010 — building design: Weeks apart, Haiti had a magnitude 7.0 quake and Chile a far larger magnitude 8.8. Yet Haiti suffered around 220,000 deaths and Chile only a few hundred.
Why? Chile enforced earthquake-resistant building codes (cross-braced, flexible frames); poverty-stricken Haiti did not. Lesson: resilient design saves lives — but only if a country is rich enough to afford and enforce it.
Tohoku 2011 — warning works, but limits remain
Japan's earthquake early-warning system gave people and trains tens of seconds of notice before the 2011 quake, and sirens triggered tsunami evacuation.
But the tsunami was higher than the sea walls were built for, so over 18,000 people still died. Lesson: warning and defences save many lives, yet a hazard larger than planned for can overwhelm them.
Eyjafjallajokull (Iceland, 2010)
- Closely monitored, so people were evacuated.
- No one died locally — though the ash cloud grounded European flights.
Nevado del Ruiz (Colombia, 1985)
- Hazard maps warned of lahars, but warnings were not acted on.
- A mudflow killed about 23,000 people in Armero.
Eyjafjallajokull 2010 & Nevado del Ruiz 1985 — prediction's value: Lesson: prediction only saves lives if the warning is communicated and acted on.
Lava diversion — Etna and Heimaey
Engineers have diverted lava away from towns: barriers and channels on Mount Etna, and seawater spraying that chilled and slowed a flow on Heimaey, Iceland (1973).
Lesson: engineering can protect property from slow lava flows — but it is costly and useless against fast hazards like pyroclastic flows or earthquakes.
A steep, high-rainfall mountain region is at risk of rapid mass movement (landslides and mudflows). Suggest two pre-event strategies that would reduce the harm, and explain how each works.
Model answer plan
See the answer broken into clear points, with guidance on how each point earns marks.
How this is tested — the markband essay: Paper 1 Option D ends with a [10] essay marked on markbands, using the big AO3 verbs: Examine, Evaluate, or To what extent.
The recurring question: How effective pre-event strategies (technology and planning) are at reducing vulnerability.
Top band (9-10) needs both
- An evidenced explanation of a range of strategies.
- A balanced critical evaluation that weighs their success against cost, technology, funding and level of development across places.
- Finishing on a clear judgement.
"Pre-event strategies greatly reduce people's vulnerability to geophysical hazards." Evaluate this statement.
Model answer plan
See the answer broken into clear points, with guidance on how each point earns marks.
Always weigh by development level: The strongest judgement links effectiveness to wealth and governance: the same strategy that saves lives in Japan or Chile is unaffordable or unenforced in Haiti. Use that contrast as your central argument.