Volcanic Hazards

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• Streams of molten rock Causes extensive damage or total destruction by burning, crushing or burying everything in their paths

1. Speed of lava flow

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   • 1. Type of lava erupted 2. Steepness of ground 3. Rate of lava producection
2. Effects of lava flow

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   • Bury homes and agricultural land Block roads and highways that may serve as the only evacuation route -> people die

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• High density mixtures of hot, dry rock fragments and hot gases that move away from the vent at high speeds Two parts: Basal flow of coarse fragments and a turbulent cloud of ash above it

1. Speed

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   • SUPER FAST!!!! 30m/sec up to 30~30km from the source
2. Effect

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   • Destroys nearly everything in its path Knock down, shatter, bury or carry away all objects and structures in their way Cause combustible material to burn

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• Fragments of volcanic rock and lava regardless of size that are blasted into the air by explosions 2mm to 1m in diameter

1. Effects

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   • Death - direct exposure to tephra Roof and building collapse Damage public utilities Damage agricultural land Respiratory problem Power facilities shut down Roads become impassable coz ash is slippery Waste water system may clog

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• Water vapour, carbon dioxide and sulfur dioxide

1. Effects

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   • SUPER HAZARDOUS SO2 Lowering of surface temp Depletion of ozone layer

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• Hot or cold mixture of water and rock fragments 

1. Speed

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   • Varies
2. Formation of Lahar

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   • 1. From heavy rainfall on loose volcanic debris 2. Rapid melting of snow and ice 3. Volcano erupts through a crater lake

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• Huge sea wave

1. Formation of Tsunami

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   • 1. Earthquake beneath the ocean 2. Earthquake must be strong, at least 6.5  3. Earthquake must rupture the Earth's surface 4. Eqarthquake must cause vertical movement
2. Effects of Tsunami

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   • Objects are lifted and carried inland by waves Destruction to buildings

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• Ash particles collecting waterdroplets causes condensation and forms unexpected heavy rain

1. Effects

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   • Can form lahar Stream explosions Acid rain

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• Earthquake under the volcano Collapse of slop

1. Formation

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   • 1. Explosive eruptions 2. Intrusion of magma into a volcano 3. Large earthquake directly below or nearby a volcano 4. Intense rainfall that saturates ejected volcanic materials may move downslopes due to increased pore water pressure causing landslides
2. Effects

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   • 1. Death 2. Debris avalanche leading to lahar 3. Debris avalanche leading to volcanic eruption

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• Coz of sulfur compounds into the Earth's atmosphere

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• 1. Lowering of global temperature (Volcanic ash can cause reflection of solar radiation and causes temp to be cooler) 2. Increase in temperature (greenhouse gases)

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• Crops die Humans die Everybody die Breakdown of swwage system

1. Recurrence Interval

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   • Measure of the frequency of occurrence of an event base on historical records
2. Seismic Monitoring

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   • Seismic activity is common near volcano The frequency and intensity of the tremours will increase when magma is approaching
3. Monitoring of Ground Deformation

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   • Using tiltmeters and Electronic distance measurement instrument
4. Monitoring of Gas Emissions and other Precursor Phenomenon

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   • Direct gas sampling and lab analysis Continuous on site sampling through sensors
5. Remote Sensing

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   • Statellite

1. Modifying the Event
   1. Lava dam and artificial barriers

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      • Block the flow of the lava and divert it away Problem Expensive Lava flow can change path too Need to be at least 30m high to withstand the speed and strength of pyroclastic flows Eg. Japan
   2. Bombing

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      • Divert flow Alter the topography Eg. Mount Etna 30% of flow diverted
   3. Water spray

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      • Cools the lava and forms internal barriers within the flow and divert the flow elsewhere
   4. Hazard resistant design

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      • Strong and steep sloping roof so that ash can shed off easily Requires $$$$$ and cordinated efforts between govt and the people
2. Modifying the Vulnerability

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   • Depends on weath and technical ability of the country, level of education and awareness and degree of effectiveness of collaboration of different stakeholders
   1. Prediction and warning

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      • Only accurate to some extent Economic and social costs if evacuation was for nothing May cause distrust too
   2. Community preparedness

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      • Advanced preparation and management structures to organise the evacuation, temp housing food etc are needed Public education and awareness programmes
   3. Land use planning

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      • Land use using hazard zoning maps as a basis  Problems Only an estimation, base on assumption that future eruptions will behave in a similar manner Many countries do not have maps and accurate past records needed Not applicable to existing developments
3. Modifying the Loss
   1. Aid and insurance

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      • Insurance -> to spread the costs incurred
      1. Technical aid

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         • For monitoring and forecasting eruptions
      2. Financial aid

1. Community Preparedness
2. Provision of support services for refugees

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   • Transportation Medical treatment, shelter Clean drinking water Medical personnel Psychological and emotional care Ressettlement issues