tectonics

• E10 Iceland may 2010

  constructive (divergent) plate boundary

  the volcano is 1660m high

  iceland is thought to be located over a hot spot
• events at E10 Iceland

  shallow earthquakes

  minor eruption to the SE of the volcano

  effusive eruption of basaltic laval

  then an eruption occurred and mixed with ice water causing more explosions and ash
• local effects of E10

  Livestock evacuated

  ash fluoride deposited onto grazing land

  local population evacuated

  local flooding as glacier melts

  fresh fish exports badly affected
• regional effects of E10

  All flights cancelled

  Airlines losing millions a day

  shares in airline businesses and travel companies fell

  Europe lost $2.6 billion of GDP
• global impacts of E10

  reduction in air traffic meant 2.8 million tonnes less of carbon dioxide was emitted

  closer of Europeans airport hubs mean disruption to global air traffic
• lithosphere


  upper layer of earths surface

  composed of crust and upper most mantel

  depth 80 - 200km
• asthenoshpere


  weak and ductile region of the upper mantle

  depth 80 - 200km
• crust 


  thinnest layer

  depth 6 - 70km
• oceanic crust 


  made up of silica and magnesium

  main rock type is basalt

  covers 60% of earths surface
• continental crust


  mainly silica and alumina

  main rock type is granite

  covers 40% of earths surface
• moho discontinuity 


  boundary between crust and mantle

  depth of 35km
• mantle 


  composed of silicates rich in iron and magnesium

  semi-molten state

  depth 2900 km

  average temp 5000 degrees
• core 


  composed of iron and nickle
• inner core


  solid due to high pressure

  depth 5100 km

  average temperature 6200 degrees
• outer core 


  semi molten

  depth 2900 - 5100 km
• Basaltic/basic lava 


  low viscosity

  hot

  lower silica content

  takes longer to cool and solidify

  creates gently sloping landforms

  eruptions are frequent but gentle
• andesitic/acid lava


  viscous

  not as hot as basaltic

  higher silica content

  eruptions are less frequent but violent due to build up of gas

  found at destructive plate margins
• hotspot 


  areas of elevated volcanic activity not associated with plate boundary. volcanic activity decreases as crust moves past plume
• mantle plume


  vertical column of extra hot magma that rises from the mantle, plume remains stationary whilst crust moves past it
• ridge push


  gravity acting on older denser lithosphere causing it to slide away from spreading ridge

  results in thinning lithosphere
• slap pull


  subduction zone where older denser portion of plate sink to mantle due to greater gravitational force acting on it pulling the remaining plate away
• composite volcano


  destructive(convergent) plate margin

  oceanic crust sinks beneath continental

  acidic lava

  viscous

  steep sided

  alternate layers of ash and lava
• shield volcano


  found at constructive(divergent) plate margin

  basaltic lava

  not viscous

  gentle sides

  less violent
• cinder volcano 


  irregularly shaped

  lava erupts into air and solidifies when it lands

  layers of cinder and ash
• pyroclastic flow


  dense, hot and fast moving flow of solidified lava pieces

  mixture of rocks, gas and ash
• lava flows


  streams of molten rock that pour or ooze from erupting vents
• ash falls 


  rain of airborne ash resulting from volcanic eruption
• lahars 


  hot or cold mixture of water and rock fragments that flow quickly down the slopes of a volcano
• jokulhlaup


  glacial megafloods that occur following subglacial eruptions
• volcanic landslides 


  downslope movement of soil, rock and organic materials under the effects of gravity
• toxic gas 


  carbon dioxide, sulfur dioxide and carbon monoxide
• body waves 


  travel through interior of the earth and have a higher frequency, travels faster than surface waves
• surface waves 


  travel only through the crust, has lower frequency and arrives after body waves
• p waves (primary) - body


  fastest wave

  first to arrive

  can move through solid and liquid rock

  caused by compression, pushing and pulling the rock as it moves
• S waves (secondary) - body wave


  slower than P waves

  only moves through solid rock

  responsible for a lot of damage

  moves rocks to right angles to the direction of the wave travel
• L waves - surface

  fastest surface wave

  moves ground side to side

  often causes greatest damage
• Rayleigh waves - surface 


  waves move ground up and down

  can be larger than other waves

  causes the shaking of an earthquake
• focus


  place inside the earths crust where earthquake originates
• epicenter 


  point on earths surface directly above the focus
• sendai japan - causes

  seabed east of Japan oceanic plates are being forced under the continental plates

  plates tend to stick together and energy is stored in the rocks at the same time the upper plate is pulled downwards

  when sufficient energy is stored in the rocks to over come the friction it results in a sudden movement

  the overlying plate pops back up lifting the seabed and water