Tectonic Processes & Hazards - EQ3 - 1.8 Flashcards
Can earthquakes be predicted
- cannot be predicted,
- but we can predict roughly where they might happen using hazard maps
- because over 90% of earthquakes occur on or near plate boundaries
What has research on earthquake predicting focused 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
what can be predicted with earthquakes
- Only areas at high risk can be identified (risk forecasting),
- plus areas that are likely to suffer severe ground shaking and liquefaction;
- this can be used for land-use zoning purposes
what does prediction (of tectonic hazards) mean
- knowing when are where a natural hazard will strike on a spatial and temporal scale that can be acted on meaningfully in terms of evacuation
what is the difference in precision between forecasting & prediction
- Forecasting is much less precise than prediction,
- and provides a percentage change of a hazard occurring (e.g. a 25% of a magnitude 7.0 earthquake occurring in the next 20 years)
How effective are the strategies of earthquake prediction
- prediction doesn’t have accurate data
- don’t know duration, location or time
- cannot provide early warnings for evacuation
- heavily reliant on the government’s capacity to cope
Can volcanoes be predicted
- There are signs warning of an eruption before most volcanic eruptions
- can predict in short term but not longterm
Explain how volcanoes are predicted using gas spectrometre
- monitors which measure gas movement, whihc can point to increased likelihood of erruption
Explain how volcanoes are predicted usings sesiometres
- ecord minor earthquake events indicating magma movement
What are the signs of a volcanic erruption
- 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
Improved prediction of volcanic eruptions has led to a…
decrease in the death toll
how effective are volcanic erruption predictions
- don’t show scale just how soon until it will come
- changes they measure could happen for weeks, months or years before the erruptions happen
Can tsunamis be predicted
- Can be partly predicted
- An earthquake-induced tsunami cannot be predicted
- However, seismometers & water level networks can tell an earthquake has occurred and locate it, then ocean monitoring equipment can detect tsunami in the open sea
- This information can be relayed to coastal areas, which can be evacuated
Describe a failure of tsunami warning systems
- 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
- despite there being many hours in which to have evacuated people
which areas face limitations to tectonic hazard warning systems
- In many developing countries, volcano monitoring and tsunami warning may not be as good as they could be because of the cost of technology
- It may be more difficult to reach isolated, rural locations with effective warnings
how do they decide if a earthquake is gonna turn into a tusnami
- preliminary seismic information such as magnitude, location & depth of earthquake can be used tod ecide if an earthquake could have geneearted a tsunami & if they should have issue a message
Strength of tsunami prediction in developed nations example?
- highly effective for US 7 Canadian citizens where scientists are able to issue messages within 5 minutes, giving alert levels, preliminary information & evaluation of threat
what is the hazard management cycle
- illustrates the different stages if managing hazards in an attempt to reduce the scale of disaster by informing planning and preparation for the next hazard event
While will the time taken for each stage of the hazard management cycle vary
- Level of development
- Magnitude of the hazard
- Quality of governance
- Aid available
What are the 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
What are the 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
who does the cycle involve
- governments at all levels - local, regional, national & international
- also businesses & communities
How can stages in hazard managemnt cycle overlap
- e.g making buildings earthquake resistant (mitigation) will reduce problems in responding and recovering from earthquakes
what are the 4 stages in the hazard management cycle
- response
- recovery
- mitigation
- preparedness
Hazard Management Cycle
Mitigation means…
Preventing hazards or minimising their effects
Hazard Management Cycle
Recovery means…
getting back to normal
Hazard Management Cycle
Response means…
Responding effectively to a hazard event
Hazard Management Cycle
Preparedness means..
Preparing to deal with an event
what does mitigation involve
Identify potential hazards and take steps to reduce their impact- mostly by helping communities to be less vulnerable
How is mitigation done
- Zoning and land-use planning
- Building codes and enforcement of these codes
- Building defensive structures (E.g.: tsunami walls)
What does preparedness involve
- Minimising loss of life and property, facilitating response and recovery stages
- Developing and implementing emergency plans in governments and aid organisations
How is preparing done
- Making preparedness plans
- Setting up early warning systems
Creating evacuation routes - Stockpiling aid, equipment and supplies
- Raising awareness apan (education and drills)
What does response involve
- Search and rescue
- Evacuation if needby
- Restoring critical infrastructure (power and water)
- Supporting critical services such as hospital and the police
What is response
Immediate help in the form of rescue to save lives and aid to keep people alive, emergency shelter, food and water.
What is recovery
- Short term recovery - Focuses of people’s immediate needs (overlaps with response stage) and may last several weeks
- Long term - as above but may last months or years. It includes taking steps to reduce future vulnerability so has some overlap with mitigation stage
What does short term recovery involve
- Health and safety services
- Power and water is permanently restored
- Transport routes are rebuilt
- Food and temporary shelter
- Financial assistance
What does long term recovery involve
- Rebuilding homes and structures
- Rebuilding and repairing infrastructure
- Re opening businesses and schools
what does the recovery stage depend upon
- the magnitude of the disaster - bigger means longer
- development level - lower means longer, as poorer people are more severely affected
- governance, because well governed places will divert resources more effectively to recovery efforts.
- external help, i.e. aid and financing to help the recovery effort
What are the advantages of the 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
What are the disadvantages of the 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
What is the Parks model - Disaster Curve response
- It shows how a country or region might respond after a hazard event
- It can be used to directly compare how areas at different levels of development might recover from a hazard.
Parks model
What is the pre-disaster phase
- Quality of life is normal
- People do their best to prepare for hazards e.g. public education on what to do when a hazard strikes
Parks model
What is the relief phase
- The immediate response, focus is on saving lives and property
- Teams from outside the immediate area help with search, rescue and care operations
- Urgent medical supplies, rescue equipment, clothing and food may be brought in
- This can last from hours to day
Parks model
What is the rehabilitation phase
- More complex than relief, this may last for several months, efforts are made to restore physical and community structures, at least temporarily.
- Very rarely shown in the media.
Parks model
What is the reconstruction phase
- Permanent changes are introduced to restore the quality of life and economic stability to the pre-disaster level, or better
- This can also include mitigation and preparedness - they learn from the previous mistakes
Parks model
Different hazard events have different impacts, shown by the…
speed of the drop in quality of life, the duration of the decline, and the speed and nature of recovery
What might the differences in the 3 lines be related to on the Parks model
- type of hazard,
- degree of preparedness,
- speed of the relief effort,
- the nature of recovery and rebuilding
- aid both national & international
