Key Words

• Natural hazard


  A natural event that threatens people or has the potential to cause damage, destruction and death
• Hazard risk


  The probability or chance that a natural hazard may occur
• Earthquake


  A sudden or violent movement within the Earth's crust followed by a series of shocks
• Earthquake focus


  The exact point in the crust where the earthquake happened
• Earthquake epicentre


  The point on the Earth's surface which is directly above the focus of an earthquake
• Earthquake seismic waves


  The waves of energy which travel outwards from the focus of an earthquake
• Monitoring


  Recording physical changes to help forecast when and where a natural hazard might strike
• Prediction


  Attempts to forecast when and where a natural hazard will strike based on current knowledge
• Planning


  Actions taken to enable communities to respond to, and recover from, natural disasters, through measures such as evacuation plans and emergency communications
• Protection


  Actions taken before a hazard strikes to reduce its impact such as education and design. Building structures before a hazard strikes to reduce its impact e.g. sea walls, shutters on windows
• Climate change


  A long-term change in the Earth's climate, especially a change due to an increase in the average atmospheric temperature
• Glacial episode


  A period of time marked by colder temperatures and glacier advances. Usually 100,000 years
• Interglacial episode


  A period of time marked by warmer global average temperature. Lasting usually 10,000 years between two glacial periods
• Proxy data


  Natural recorders that estimate what conditions were like
• Mitigation


  When people reduce the causes of a hazard to their lives
• Adaptation


  When people adjust to change to reduce the impacts or to take advantage of the change
• Insolation


  The amount of incoming solar radiation an area receives
• Coriolis effect


  The deflection, or bending, of the wind due to the rotational spin of the Earth
• Winds blow from areas of high pressure to areas of low pressure
• High pressure


  An area where air has cooled down and so it sinks so there is more air pressing down on the earth below as the air has become 'heavier'. In general this leads to settled weather conditions
• Low pressure


  An area where air has warmed up and so it has risen so there is less air pressing down on the earth below as the air has come 'lighter'. In general this leads to unsettled weather conditions
• Latitude


  A line drawn from west to east on a map showing where places lie relative to the Equator and poles
• Convection cell


  When differences in air temperature lead to the formation of areas of high and low pressure; they become linked by flows of warmer and cooler air
• Intertropical convergence zone (ITCZ)


  The low air pressure zone around the equator, between the tropics
• Primary effect


  Something that happens straight away as a direct result of the tropical storm e.g. people's homes are washed away
• Secondary effect


  Something that happens later on, usually a knock on effect e.g. loss of tourism
• Immediate response


  What happens in the first few days to ensure people is safe
• Long term response


  What happens over the months and years to get life back to normal and sometimes prevent it happening again
• Extreme weather


  When a weather event is significantly different from the average or usual weather pattern, and is especially severe, unseasonal or lasts for an unusual length of time (breaks records)
• Flash flood


  A sudden flood that is usually caused by heavy rain followed by rapid surface runoff
• Precipitation


  Moisture falling from the atmosphere as rain, hail, sleet or snow
• Saturated (Ground/soil)


  Filled with water
• Impermeable


  A material (e.g. a rock) that does not allow water to infiltrate (pass) through it
• Surface runoff


  Water moves across the surface of the earth becoming a stream, tributary or river
• Hydro-meteorological hazards


  Natural hazard caused by atmospheric processes and any associated flooding