Geography A-Level Edexcel

• Mitigation meaning

  • strategies meant to avoid, delay, or prevent hazard events.
• Adaptation examples:

  survival kits

  public education

  moblie plane technology

  early warning system
• mitagation examples:

  lava flow diversion channels

  land zoning

  hazard modelling

  crisis mapping
• Philippines is a multiple hazard zone
• Philippines is known as a hazard hotspot with:

  tsunamis

  typhoons

  landslides

  earthquakes

  volcanoes
• Guinsagon landslide:

  mudslide that covered 3km^2 of ground and killed 1150 people.
• guinsagon landslide:

  physical causes:

  • La Nina
  • unseasonal rain
  • earthqauke - magnitude 2.6

  human causes:

  • deforestation
  • loss of soil protection - poor farming techniques
• 2.2% deaths are caused by natural hazards ie. Earthquakes
• deaths by volcanoes are 0.1%
• most deaths are from onset hazards such as famine or drought
• Christchurch and Haiti:

  2 similar earthquakes but with different outcomes

  mag for Christchurch : 7.1

  mag Haiti : 7.0
• Christchurch and Haiti:

  christchurch : had more management strategies to deal with such events because they had good a government and a wealthy background.

  Haiti: were not prepared for the earthquake and has poor connections with government and politics due to the lack of help and aid given to them
• Christchurch and Haiti are a good example of the social and economic impacts of natural hazard events.
• Montserrat volcanic eruption: July 18th 1995
• Montserrat volcanic eruption:

  small eruption happened leading to earthquakes and tremors this caused evacuation to be put in place, pyrocastic flows followed shortly.

  after evauations the volcano was monitored carefully and studied. led to the biggest erupption recored in June 1997.

  from this a large ash cloud was submitted into the atmosphere causing fertile lands to be destroyed as well as more pyroclastic flows destroying villages and trees nearby.
• eyjafallajökull - Iceland
• eyjafallajökull —> jökullhaup

  volcano was covered by an ice cap when this exploded the ice cap flew off and melted creating jöjkullhaups to run down the volcano, flooding Iceland’s ring road.
• primary hazards during volcanoes and erruptions are the main things that come straight after the eruption has happened
• primary hazards:

  • lava flows - streams of molten rock that ooze from the volcano ie. Hawaii
  • pyroclastic flows - ie. Montserrat
  • ash fall - clouds of ash released from the volcano when it erupts ie. Eyjafallajökull
  • gas eruptions - a release of gases into the air like CO2 ie. Mount St. Helens
• magma types:

  balsatic - basic magama

  andestic - intermiadte magma

  rhyolitic - acidic magma
• eruption types:

  gas content, cyrstal content and temperature
• crystal content:

  if higher crystals are found in the magma, the more viscous it is and more explosive it is
• gas content:

  if gas builds up over time and it’s harder to scape this means the magma is more viscous
• temperature:

  higher temp = erupt effusively and cools down more slowly

  lower temp = cannot flow easily and erupts exposively.
• tectonic plate movement theory

  5 factors:

  1. mantle convection
  2. subduction
  3. slab pull theory
  4. paleomagnetism
  5. seafloor spreading
• paleomagnetism / sea floor spreading:

  the earths magnetic currents change direction every time, therefore rocks can be imprinted with the change in direction because of the magnetic currents.
• subduction:

  the disappearance of th plate after is subducts underneath the other plater.
• slab pull theory:

  the more cooling down the plate does the more denser it gets, therefore it will be pulled under the other plat because of the high density
• mantle convection:

  heat rises in the mantle and cools down when falling back down. this happens in a constant circle causing the plates to be pulled apart
• evidence of tectonic plate movement theory

  1. continental drift- the earth was all joined up at one point creating the word known as Pangea
  2. paleontology - study of fossils
  3. paleomagnetism - the earth’s magnetic currents
  4. climatic change - glaciers being found in the tropics and coal being found in Antarctica (coal is made in hot areas like the tropics)
  5. geology - rocks that have similar characteristics ie. rocks found on the shore of USA and wales match together