Volcanic & Seismic Hazards (podcast)

Seismic Hazards: Ground Shaking & Rupture

• Cause: fault zone slips during earthquake > visible breaking/displacement of Earth's surface along fault line

• Characteristic: only occurs along fault zone; shallow-focus earthquakes most likely to cause it; major risk to large engineered structures (dams, bridges, nuclear plants) built across fault lines

• Result: infrastructure collapse, permanent landscape change

• CS – Haiti 2010 (contrast): unusually, no surface rupture occurred despite Mw 7.0 — movement entirely underground. This meant the main damage mechanism was shaking rather than rupture, but collapsed buildings still caused near-total destruction of Port-au-Prince civic infrastructure

Seismic Hazards: Seismic Shockwaves

• Cause: seismic waves radiating from focus > travel through crust to reach surface

Characteristics:

• P(rimary) waves: fastest, high frequency

• S(econdary) waves: half as fast, high frequency, travel through mantle (not core)

• L (surface love) waves: slowest but most damage (as side-to-side rather than just compression)

• Rayleigh waves: low frequency

• Depends on: magnitude, geology, distance from epicentre

• Result: M7, soft sedimentary plains, epicentre 15km from Port-au-Prince = 223,000 deaths, 294,000 buildings destroyed

Seismic Hazards: Soil Liquefaction

• Cause: earthquake shaking > water pressure in saturated soils increases rapidly > soil particles lose contact with each other > soil behaves like liquid

• Characteristic: affects saturated, loose soils; causes sand boils, mud volcanoes, lateral spreading; civil engineering structures suffer severe foundation failure; covers large areas rapidly

• Result: greater threat to structures than directly to human life — but collapsing structures = major mortality risk

• CS – Haiti 2010: liquefaction at main Port-au-Prince port > pier/wharf destroyed, gantry cranes collapsed, storage damaged > port inoperable > relief supplies could only arrive by air > single runway bottleneck > 3 months before port partially functional (restored via US Navy floating pontoons). Massively delayed humanitarian response

Seismic Hazards: Landslides

• Cause: seismic shaking destabilises slopes > mass movement of rock, debris, soil. Submarine landslides can trigger tsunamis

• Characteristic: average 10mph, up to 35mph; lasts minutes but damage is catastrophic; local scale primarily, but submarine landslides = transnational via tsunamis

• Result: destruction of roads/infrastructure, burial of communities, cuts off escape/aid routes

• CS – Haiti 2010: 30,828 landslides triggered, covering 15.736 km², ~29.7 million m³ of accumulated material (majority rockfall). Combined with soil liquefaction = infrastructure collapse across multiple districts

Seismic Hazards: Avalanches

• Cause: seismic tremors dislodge fresh powder snow > slides and accumulates mass down slope

• Characteristic: can reach 80mph within 4 seconds; death by burial/disorientation; sudden onset = near-zero warning

• Result: high mortality especially in mountain communities

• CS – Nepal 2015: Mw 8.1 earthquake > avalanche onto Everest base camp; deadliest on record (22 deaths); tents destroyed/blown across North Glacier.

• AO2: illustrates how secondary hazards can exceed primary in specific geographic contexts (high altitude, concentrated populations)

Seismic Hazards: Tsunamis

• Cause: shallow-focus undersea earthquake (most common) > vertical displacement of sea floor > entire water column displaced > wave energy radiates outward. Also caused by: volcanic eruption, submarine landslide, caldera collapse (e.g. Krakatoa 1883 — 35m waves, 36,000 deaths)

• Characteristic: open ocean — <1m height, wavelength up to 200km, speed 700–800km/h (barely noticeable); shoaling — slows to ~80km/h, height increases rapidly (energy flux conserved); run-up height can exceed 30m. 90% generated within Pacific Ring of Fire. First wave NOT always highest

• Result: coastal obliteration, saltwater contamination of farmland/wells, destruction of fishing fleets/tourism, long-term economic disruption

• CS – Boxing Day 2004 (Indian Ocean): Mw 9.1 off NW Sumatra > Indian plate subducting under Burma microplate at 6cm/year > megathrust (400km rupture in 200 seconds) > 3m vertical sea floor displacement > wave split east/west. Sri Lanka hit within 2 hours: 35,000+ dead, 552,641 displaced, 100,000+ homes damaged, 130,000 fishing/tourism jobs lost, 50,000 wells contaminated. Run-up height up to 32m

Seismic Hazards: Fires

• Cause: ground shaking ruptures gas mains/power lines > ignition

• Characteristic: local scale; particularly dangerous in densely built urban areas with gas infrastructure; can destroy natural habitats

• Result: economic damage (infrastructure repair), homelessness, habitat loss, potential nuclear risk

• CS – Japan 2011 (Tohoku): Mw 9.0 > fires in Miyagi; 5 nuclear plants shut down; Fukushima reactor meltdown risk (no radioactive leak confirmed).

• AO2: in HICs, fire suppression technology limits mortality but economic/energy impacts severe — contrast with Haiti where no such systems existed

Seismic Hazards: Haiti 2010: Social Impacts

1. (Primary) 222,570 deaths

2. 22.3 million displaced

3. All hospitals in Port-au-Prince destroyed

1. (Secondary) 8,000+ died in cholera outbreak months later

2. 300,000 "restavek" child trafficking cases post-quake

3. Breakdown of law and order (sporadic looting/violence)

• AO2: 72% lived below $2/day pre-quake — poverty = inadequate building materials (brittle steel, dirty sand cement) = deaths far beyond what Mw 7.0 should cause. Class-quake in action.

Seismic Hazards: Haiti 2010 — Economic Impacts

1. $7.8bn damage (120% of GDP)

2. Port destroyed by liquefaction = aid bottleneck for 3 months

3. Only 53% of $5.5bn pledged aid actually released after 2 years

• AO2: pre-existing debt + corruption + 195 days to register a business = reconstruction costs overwhelmed a country with no fiscal buffer.

• Contrast: Japan 2011 suffered $360bn damage but recovered without aid dependency — development level determines economic resilience.

Seismic Hazards: Haiti 2010 — Political Impacts

1. 13 of 15 ministry buildings destroyed

2. Fraudulent elections (Nov 2010) meant only 38% of $1.4bn donated aid spent

3. 4,000 prisoners escaped when main prison collapsed

• AO2: governance destruction = self-reinforcing collapse — no ministries = no plan = no aid distribution = prolonged suffering.

• Political capacity is the key variable in Park Model recovery speed.

Seismic Hazards: Haiti 2010 — Environmental Impacts

1. 30,828 landslides covering 15.736 km²

2. Cholera from excrement contaminating drinking water (environmental health crisis)

3. Hurricane Tomas + tornado hit before recovery complete (compound hazard)

• AO2: Haiti's pre-existing deforestation = heightened landslide susceptibility = environmental vulnerability amplifies seismic impact.

• Secondary hazards interrupted recovery repeatedly — Park Model's rehabilitation phase was not linear.

Seismic Hazards: Short-Term Responses — Haiti 2010

1. What worked: US deployed 3,500 troops + 6 ships within days;

2. "Hope for Haiti" telethon raised £35m

3. GIS/Google Earth mapping by 500 scientists identified 10,000+ damaged buildings within a fortnight — directed logistics >

1. What failed: US military bottlenecked airport

2. Debris blocking WFP + Médecins Sans Frontières

3. Only 3 of 450 camps had potable water; tents provided for only 25% of homeless in first 2 weeks

1. AO2: chaotic response = function of destroyed governance + communications collapse, not lack of international will. Park Model disruption phase extended because the very infrastructure needed to coordinate response was itself destroyed.

Seismic Hazards: Long-Term Responses: Haiti 2010

1. Only 5% of rubble cleared after 1 year (proves slow recovery)

2. World Bank suspended debt for 5 years + $11bn pledged at World Summit

3. Only 1,179 permanent houses built nationwide in year one

• AO2: pledged ≠ delivered (53% released) + 70% of Haitians lack land ownership documentation = resettlement legally impossible = camps became semi-permanent

• Financial capacity is necessary but not sufficient — governance quality determines whether money reaches the ground.

Volcanic Hazards: Nuées Ardentes (Pyroclastic Flows)

• Cause: crust melted at destructive > high silica/low basalt + high-pressure/viscous magma > eruption column/volcanic dome > acid volcano

• Characteristic: >800*C, dense, gravity-driven gas avalanche & <100mph, rock fragments

• Result: obliteration & near-100% mortality rate

CS - Mt. Pelée:

• AO1: 100mph cloud, Saint-Pierre destroyed, ~30,000 deaths (only 1 survivor)

• AO2: Severity: highest mortality rate of any hazard

  • Scale: gravity > only ~50km radius

  • Management: only prediction/evacuation viable

Volcanic Hazards: Lava Flows

• Cause: magma reaches surface at hotspots/constructive margins > basic or shield volcano (as low silica/high basalt)

• Characteristic: slow moving but incinerates, low viscosity

• Result: 0 deaths but buries roads/homes/farmland permanently

Volcanic Hazards: Mudflows/Lahars

• Cause: heavy rainfall/glaciers + loose ash/debris

• Characteristic: dense slurry (like wet concrete), 40mph

• Result: 23,000 deaths in Armero (due to Nevado del Ruiz)

Volcanic Hazards: Tephra

• Cause: destructive + explosion = solidified magma fragments ejected

• Characteristic: aerodynamically sorted - heavy volcanic bombs near eruptive vent (opening of volcano), fine ash (<2mm) travels 1,000s of miles

• Result: Transnational grounding (100k flights) + local livestock poisoning (Fluoride)

Volcanic Hazards: Ash Fallout

• Cause: destructive + phreatic eruption (1,200*C magma hitting glacier) > lava cools & shatters

• Characteristic: fine, aerosol ash (suspended particles), injected 11km into jet stream

• Result: carried transnationally east > 100,000 flights grounded (48% of Euro air traffic) > £130 million/day lost

• Kenya lost $1.3 million/day as 20% of economy exports perishable green veg/flowers

• 50k farmers temp. unemployed

• Agricultural poisoning (fluoride ingestion in sheep)

Volcanic Hazards: Flooding / Jökulhlaups

• Cause: phreatic eruption (1,200*C magma hitting glacier) > melting

• Characteristic: carries huge volumes of water/ice blocks/debris

• Result: 2,000 - 3,000 m³/s, destroys bridges/roads, forced immediate evacuations e.g. 700 Icelandic farmers

Volcanic Hazards: Volcanic Gases

• Cause: SO2 + water vapour injected high into stratosphere

• Characteristic: converts to H2SO4 aerosols, lifetime of 1-3 years

• Result: backscattering (reflecting solar flux away from Earth) > global dimming

Eyjafjallajökull: Immediate Response

• AO1: breached sections of Ring Road to allow meltwater from jökulhlaups to pass through to sea

• AO2: few metres lost (cheap) > saved multi-million bridge (which supports tourism, 10% of GDP & >500m predicted loss)

Eyjafjallajökull: Long-term Response

• AO1: £130 million/day lost due to disorganised “zero-tolerance” shutdown > Functional Airspace Blocks (FABs) for localised closures, 1.3 - 2.8m tonnes of CO2 emissions decrease

• AO2: closure good for safety but economic failure/political disputes over regulations, necessary but flawed

Seismic Hazards: Risk Management - Preparedness

1. Japan's Disaster Prevention Day (1 Sept annually) + school drills + smart gas meters (seismically triggered cut-off) = 63 deaths from Loma Prieta Mw 6.9 vs 25,000+ in Armenia Mw 6.8 same year

2. Indian Ocean EWS now gives 15-minute warning

3. FEMA (USA) — hazard zone mapping, earthquake-resistant construction incentives, emergency kit protocols Haiti failure: Enriquillo fault's last major event was 1770 — risk was known, preparedness was zero. Governance failure, not geological ignorance.

• AO2: preparedness is the highest-leverage, lowest-cost intervention — Iceland (Eyjafjallajökull) tracked 3,000 earthquakes, evacuated 700 farmers, 0 deaths. The preparedness gap between HICs and LICs IS the mortality gap.

Seismic Hazards: Risk Management — Mitigation

1. Aseismic building design (counterweights + rubber shock absorbers + cross-bracing) — Loma Prieta 1989: California's earthquake-proof buildings = 63 deaths vs Armenia's pre-cast concrete = 25,000+

2. Retrofitting older structures (elevated motorways)

3. Land-use planning (schools/hospitals in low-risk zones) Haiti failure: no building codes pre-2010 — brittle steel + dirty sand cement + steel rods terminated at stress points. New codes established post-quake but enforcement weak due to corruption.

• AO2: mitigation is technology-dependent = HIC advantage. But post-disaster adoption of codes (Haiti, Sri Lanka) shows LICs can adapt — enforcement capacity, not knowledge, is the binding constraint.

Seismic Hazards: Risk Management — Adaptation & Risk Sharing

1. World Bank suspended Haiti's debt for 5 years + considered full cancellation (risk sharing at international scale)

2. EU insurance systems compensated stranded passengers (Eyjafjallajökull — risk sharing at regional scale)

3. Sri Lanka's $102m Catastrophe Drawdown Fund (World Bank) = immediate liquidity post-disaster

• AO2: risk sharing redistributes loss but creates dependency risk (Haiti — 90% of USAID contracts to Washington firms, not Haitian companies = aid doesn't build local capacity).

• Most resilient adaptation = integrated approach: preparedness + mitigation + local economic development + international risk-sharing. No single strategy is sufficient alone.