Hazardous Environments 3.8 Predicting and Preparing for Earthquakes Flashcards
What are the most basic steps for managing most natural hazards? (7)
- identifying natural hazard threats in particular locations
- risk assesment
- prediction
- preparation
- HAZARD EVENT
- recovery
- evaluation/judgement
risk (2)
- risk is about the probability of a particular event happening and the scale of its possibe damage
- risk is also what people take when they know that they are exposed to a natural hazard
What do we need to be aware of in order to assess the risk of a particular type of hazard? (4)
- its DISTRIBUTION
- its FREQUENCY
- its SCALE - does the natural event vary in its degree of hazard and impacts? (mercalli scale and moment magnitude scale)
- its PREDICTABILITY - does the hazard always behave the same? tropical cyclones tend to be more predictable, while earthquakes and volcanoes are more individual
Why is the destructive energy of an earthquake often most threatening at the coast?
this is because earthquakes often occur out at sea and it is the resulting tsunamis that cause much of the damage
what does an earthquake-warning-system need to do? (2)
- give people time to move to ‘safe’ locations, usually means leaving all buildings and moving to open spaces
- put emergency services on immediate alert
difficulties with earthquake-warning-systems (3)
- the main problem is the speed with which the shock waves radiate outwards from the epicentre
- once it has started, warnings of only minutes are usually possible
- only areas far from the epicentre might benefit
Possible preparation actions to reduce the effects of earthquakes and tsunamis (4)
- construction
- warning systems
- remote sensing and GIS
- Education
Construction (preparation action to reduce effects of earthquakes and tsunamis) (2)
- often it is the houses in which people are in at time of earthquake that kills them
- earthquake tremors cause walls (especially brick and unreinforced concrete blocks), to collapse and the roof to cave in
what are some ways that buildings can be better constructed to reduce the effects of earthquakes and tsunamis? (4)
- using lighter materials such as timber, aluminium and carbon fibre
- building materials are fire resistent
- foundation sunk into bedrock, avoiding clay
- interlocking steel frame ‘birdcage’, that sways during earth movements
warning systems (preparation action to reduce effects of earthquakes and tsunamis) (4)
- impossible to predicts earthquakes precisely
- but once an earthquake has started, equipment such as seismometers, accelerometers, computers and satellites are able to raise the alarm and send warning to those areas that are likely to be affected
- these alarms are linked to plans for the evacuation of people
- compared to those for earthquakes, warning systems for tsunamis are more effective, because the waves of seawater move more slowly than earthquake tremors
Remote Sensing and GIS (preparation action to reduce effects of earthquakes and tsunamis) (2)
- images of the affected area immediately after the earthquake can provide valuable information for search and rescue operations
- satellite images are also part of the remote sensing that puts together geographic information systems (GIS) about various aspects of the earthquake hazard
what aspects of earthquake hazards do remote sensing and GIS put together? (3)
- mapping the degree of earthquake risk
- detailing the locations of settlements, transport networks and economic activities within those high-risk areas
- identifying areas where landslides are likely to be triggered by an earthquake
Education (preparation action to reduce effects of earthquakes and tsunamis) (2)
- aim is to make sure people know what they should do both during and after an earthquake
- includes knowing where to find safe open spaces and locations beyond the reach of the earthquake
