The Universe is not a friendly place - it is out to get us! The Earth itself is not much friendlier - we are constantly at risk from volcanoes, earthquakes, tsunamis, landslides...
What the Syllabus - and the Details
There is a range of geological events that can be hazardous - click the links to see videos of them in action!
• earthquakes which are caused when layers of rock break under stress to produce a fault cause shaking and can trigger landslides - for example this one in Sichuan China.
• volcanic eruptions produce flows of lava, ash, pyroclastic flows and mud flows.
• landslides [and related subsidence]
The level of risk of a hazard is associated with life and property and relates to
• population density - the more people there are in the area the more likely it is that lots of people will be affected.
• technology - if the local buildings are constructed to stand up to an earthquake then damage will be less, if an area has lots of road and rail links then there is more chance that some of them will still be useable to bring in help after the event.
• development...
economic situation - richer areas are more likely to be able to provide help after the event, education - people are more likely to react well if they know what is happening and have been trained in what to do.
communication - if there are more links then there is more chance to ask for and receive help.
The level of accurate hazard prediction is limited - we can say where earthquakes, volcanic events etc are most likely to occur but we don't have the ability to say when.
The methods of reducing risk include appropriate building design and regulation, prediction, warning schemes, evacuation. You need to be able to describe the following methods used in hazard prediction: hazard interval patterns (seismic gaps), ground deformation (tiltmeters), groundwater changes, gas emissions, early warning systems. These are covered in the blog on Predicting Earthquakes.
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