Theoretical Frameworks (Edexcel A Level Geography)

• The accuracy of prediction and forecasting of tectonic hazards depends on the type and location of the hazard
• Scientists use prediction and forecasting to help with planning and preparation for hazards
  • Prediction is knowing when (temporal scale) and where (spatial scale) a hazard will occur 
  • Forecasting gives a percentage chance of a hazard occurring over a set period of time

Earthquakes

• It is not possible to predict earthquakes
  • An understanding of tectonic activity can help scientists identify areas most at risk
  • Over 90% of earthquakes occur on or near plate boundaries
• Scientists are constantly researching to improve forecasting - research has focussed on:
  • Seismic gap theory - to highlight areas at high risk as they have not experienced an earthquake for some time
  • Radon emissions
  • Animal behaviour
• No method has yet proved to be reliable

The United States Geological Survey have made forecasts about the chances of an earthquake in the Los Angeles area that 'within the next 30 years there is a 60% probability of a 6.7 magnitude earthquake'

Volcanic eruptions

• There are signs warning of an eruption before most volcanic eruptions
• Volcanologists (scientists who studied volcanoes) monitor changes using GPS, tilt meters, satellites, seismometers and gas detection
• Signs of an eruption include:
  • Magma rising which can be detected by heat sensors and satellites
  • Changes in surface level as rising magma causes bulges
  • Increased emissions of sulphur dioxide and other gases
  • Increased seismic activity caused by magma movement detected by seismometers

Methods of monitoring volcanoes

• Improved prediction of volcanic eruptions has led to a decrease in the death toll

Tsunami

• For earthquake-induced tsunami scientists are unable to predict the earthquake itself
• When the earthquake happens this will be detected by the global network of seismometers, these will locate the epicentre of the earthquake
  • Ocean monitoring technology can then be used to detect tsunami
  • Warnings can then be issued to coastal areas which may be affected

Tsunami warning system

• Improvements and advances in technology are constantly changing prediction and forecasting
• Systems are regularly updated and reviewed particularly after a hazard event
• In the Asian 2004 tsunami errors in the system increased the number of deaths
  • In Indonesia the sensor system had been struck by lightning so did not work
  • In India the warning went to the wrong official
  • The sensors in the region were limited 
• In the 2011 Japanese tsunami the height of the tsunami was underestimated so the warnings were not accurate

• The hazard management cycle is how the events of one hazard event inform planning and preparation for the next hazard event
• The time taken for each stage will vary due to:
  • Level of development
  • Magnitude of the hazard
  • Quality of governance
  • Aid available
• These factors will have most impact on the response and recovery stages

The hazard management cycle

Advantages of the hazard management cycle

• It can be used by organisations and individuals
• The cycle enables them to both prepare for and respond to hazardous events
• It identifies potential hazards
• Reduces the risks and saves lives
• Improves the level of preparation

Disadvantages of the hazard management cycle

• It may not be possible for smaller or less wealthy communities/countries to implement the hazard management cycle
• Some hazards are less predictable, which means hazard management cannot account for every eventuality
• Implementation of strategies may face opposition from local communities
• Communication of the strategies may not reach all communities 

• Park's model is also known as the disaster response curve
• This shows the impact of a hazard event on people's quality of life over time

Disaster response curve - Park's model

• The curve demonstrates where different management strategies are implemented before, during and after the event
• The curve will vary for each event and area depending on the level of:
  • Preparation and planning
  • Development 
  • Aid both national and International

Disaster response curve comparison of developed and developing countries

• Developing countries tend to be impacted more and recover more slowly
• This can be clearly seen on the disaster response curve

Advantages of Park's model

• It can be applied to a range of hazards
• The model can be used to assess risk and provide a framework for preparedness
• The level of economic activity and social stability are shown, which makes it easy to compare differences based on the level of development
• Useful to analyse the responses to a hazard event and the sequence of events

Disadvantages of Park's model

• It only shows the impact of a single event
• Quantitative data, such as the number of deaths and building destruction, is not shown
• Preventative measures are not shown
• The resources required may mean that smaller/less developed communities can not afford to implement it