Managing tectonic hazards

Earthquakes and volcanic eruptions cannot be prevented, but their impact can be reduced through prediction, preparation and protection. CCEA examiners expect you to evaluate these strategies and to compare the ability of high-income countries (HICs) and low-income countries (LICs) to manage tectonic hazards.

The three Ps: Prediction, Preparation, Protection

Prediction

Volcanic prediction is relatively successful:

• Seismometers detect small earthquakes (tremors) caused by magma moving underground.
• Tiltmeters measure ground bulging as magma pressure increases.
• Gas monitors detect increases in sulphur dioxide (SO₂) — rises sharply before eruptions.
• Infrared cameras detect heat changes on the volcano's surface.
• Success example: Mount Pinatubo 1991 — monitoring allowed the evacuation of 58,000 people. Without prediction/evacuation, the death toll could have been 20,000+.

Earthquake prediction is much less successful:

• Scientists cannot reliably predict the timing of earthquakes, only identify zones of risk.
• Short-term precursors (unusual animal behaviour, radon gas, ground uplift) have been studied but are not consistently reliable.
• The best that can be done is probabilistic risk mapping — identifying which areas are most likely to experience earthquakes over the coming decades.

Preparation

Community preparation (education and training):

• Earthquake drills — Japan runs nationwide earthquake drills (Disaster Prevention Day, 1 September).
• Public education about what to do during a quake: "Drop, Cover, Hold On."
• Emergency planning — hospitals, schools, bridges prioritised for strengthening.

Early warning systems:

• Japan has a ShakeAlert-style system that detects P-waves (which arrive seconds before damaging S-waves) and broadcasts warnings via TV, radio and phone, giving 30-60 seconds of warning — enough to stop trains, pause surgery, open fire station doors.

Protection

Earthquake-resistant building design (the most important long-term measure):

• Cross-bracing and steel frames: allow buildings to sway without collapsing.
• Rubber shock absorbers (base isolation): buildings mounted on rubber pads that absorb seismic vibrations.
• Counterweight dampers: massive pendulums in tall buildings that swing opposite to the building's movement (Taipei 101, Taiwan).
• Reinforced concrete and shear walls.
• Retrofitting: adding earthquake protection to existing buildings.

Volcano management:

• Exclusion zones around active volcanoes.
• Lava diversion channels (used in Hawaii and Etna, Italy).
• Emergency evacuation routes.

HIC vs LIC comparison

Factor	HIC (e.g. Japan)	LIC (e.g. Nepal, Haiti)
Building quality	Strict codes; earthquake-resistant	Poor quality; unreinforced brick/concrete
Emergency services	Well-trained, well-equipped	Limited numbers, basic equipment
Early warning	Advanced seismograph networks	Few instruments
Public education	Regular drills; high awareness	Limited education/drills
Medical care	Many hospitals, well-equipped	Few hospitals; overwhelmed
Reconstruction	Rapid; government-funded	Slow; dependent on international aid
Death toll for same magnitude	Far lower	Far higher

Key conclusion: the level of development (not just the magnitude of the hazard) determines the scale of the disaster. A Mw 7.0 earthquake in Japan might kill hundreds; the same magnitude in Haiti killed 220,000.

Case study comparison: Japan vs Nepal

Japan (HIC): 2011 Tōhoku earthquake (Mw 9.1). Death toll ~19,500 — mostly from the tsunami, not the earthquake itself. Buildings performed well; emergency response was swift. However, the scale of the tsunami overwhelmed even Japan's defences.

Nepal (LIC): 2015 Gorkha earthquake (Mw 7.8). Death toll ~8,900 — from earthquake alone, with no tsunami. Poor construction, limited emergency services.

Japan had a far more powerful earthquake but fewer deaths per million people — because of preparation, prediction and protection.