Volcanic Hazards (workbook 3)

Types of magma

BASALTIC- hotspots and constructive margins, low viscosity, 1000 degrees +, less hazardous

ANDESITIC- destructive plate margins, sticky viscosity, 800 degrees, very hazardous

RHYOLITIC- continental hotspots, collision boundaries, high viscosity, 700 degrees, very hazardous

magnitude measured on VEI, volcanic explosivity index

primary hazards

Lava Flows

  • flows of magma extruded from the volcano vent
  • less dangerous as people can move out of the way
  • economic impacts

Volcanic Gases

  • includes carbon dioxide, carbon monoxide, hydrogen sulphide, sulphur dioxide and chlorine
  • e.g Lake Nyos, Cameroon

secondary hazards

Lahars

  • happens when volcanic ash combines with water e.g rain or a typhoon
  • travels at up to 50 km/h
  • can include melted snow and ice
  • 1985 Nevado del Ruiz

Flooding

  • the melting of glacial sources (Jokulhlaup)
  • e.g Grimsvotn volcanic eruption in Iceland 1996

Volcanic Landslides

  • mass movement occurs on the side of a volcano
  • e.g Mt St Helens in 1980

Tsunamis

  • debris from volcanic landslides can cause water displacement
  • e.g Krakatoa Indonesia 1883- killed 36,000 people

Acid Rain

  • volcanoes emit sulphur which combines with atmospheric moisture
  • caused damage to vegetation and corrodes buildings

Climate Change

  • the debris ejected can reach the troposphere (upper layer of atmosphere)
  • reduce temperatures by deflecting incoming solar radiation (insolation)

Pyroclastic fallout

  • 64mm = volcanic bombs

  • 2-64 mm = lapilli
  • <2mm = ash
  • if ash lands on buildings it can cause them to collapse or it can suffocate crops and clog rivers

Nuee Ardente/ Pyroclastic Flows

  • 'glowing cloud'
  • occurs when lava dome collapses
  • over 800 degrees
  • 700 km/h
  • most explosive volcanoes/ most dangerous
  • Mt Vesuvius, 79 AD

Management

mitigation

prepardness

prevention

adaptation

diverting or cooling lava flows

risk assesments

monitor changes in the relief of the land to identify the swelling of a volcano

examine the changes in the level or the chemical composition of groundwater

monitor seismic activity to see whether magma is moving towards the surface

issue warnings to evacuate and enforce

inform land use planning so that buildings do not take place in high risk areas

sea water sprayed onto lava to cool it

dig diversion channels and concrete blocks dropped in the lava

build barriers to stop the lava flow

alarms and drills

build resistant structures

Eyjafjallajokull

Mid-Atlantic Ridge

  • North American and Eurasian Plate
  • constructive plate margin
  • moves at 23mm per year
  • located above a hotspot

Hazards

  • volcanic bombs
  • small ash particles
  • gases ( water vapour, carbon dioxide, sulphur dioxide)

social

  • 800 local people were evacuated
  • drinking water was poisoned
  • flights delayed
  • health problems (eye irritations and dry throats)
  • asthma
  • tourism
  • no fly ban
  • decline in air and noise pollution

economic

  • tourism (travel agents in the UK lost an estimate of £6 million each day)
  • increase in tourism (10,000 people visited by end of March)
  • car rental firms and taxi companies increase in business
  • channel tunnel and ferries got extra business

environmental

  • flooding due to ice cap melting
  • ash fall more than 10cm
  • nutrients released into the soil
  • fresh fish imports badly affected
  • 2.8 million tonnes less of co2 emitted during the period

management

short term

long term

  • evacuation
  • emergency services
  • cancelling and redirecting flights
  • preparing airports across Europe
  • Breathing masks handed out
  • water supplied in tankers
  • ash was tracked by many countries
  • predict and forecast monitor (GPS sensoring)
  • preparing airports across Europe
  • Icelanders become more aware of the issues
  • further research into the effects of ash on aircrafts
  • new Futurevolc project set up