Geography unit one - World at risk


Geography Revision; World at risk...

Geographical hazards - results from geological and/or geomorphological processes. May cause the loss of life or injury, property damage, social and economic disruption or environmental degration.

Hydrometeorological hazards - results from atmospheric or hydrological processes. May cause the loss of life or injury, property damage, social and economical disruption or environmental degration.

Geographical hazards;

  • Tsunami
  • Volcanic eruption
  • Avalanche
  • Earthquake
  • Land slide

Hyrdometeorological hazards;

  • Flood
  • Tornado
  • Storm
  • Sand storm
  • Drought
  • Hail storm
  • Hurricane

Natural Hazard: A naturally occuring process or event that without the interaction of people, purely becomes a natural event.

Disaster: The realisation of a hazard, although there is no universally agreed definition of the scale.

Risk: The probability of a hazard occuring.

Vulnerability: The conditions determined by physical, social, economic and environmental factors or processes, which increase the susceptibility of an individual or community to the impact of the population.

Disaster risk equation...

Risk = Vulnerablility X Hazard

               Capacity to cope

Six main types of hazards found in this unit;

  • Floods
  • Earthquakes
  • Droughts
  • Landslides/avalanches
  • Huricanes
  • Volcanoes

Types of vulnerability;

Economic: Cannot prepare effectively for hazard nor recover quickly afterwards due to a lack of economic support.

Social: People see hazards as being beyond their control (externalisation) and so they have no incentive to act against said hazard.

Educational: Lack of education means people cannot act even if they want to.

Environmental: Degration of the environment may reduce the overall ability to withstand the hazard disaster.

Frequency: How often an event of a certain size (magnitude) occurs.

Magnitude: The size of an event. E.g. the force of a gale on the Beaufort Scale.

El Nino; (ENSO)

Is the periodic occurrence of a warm water 'cell' in the eastern Pacific Ocean. It is the widespread disruption that this causes to the circulation of the atmosphere and the ocean around the Pacific. Occurs currently every 3 to 7 years and can last on average from 12 to 18 months.

Normal conditions: Trade winds blow westwards across the ocean. Water in the west (Australia and Indonesia) increases in temperature by up to 8 degrees. Water 'pools' in the west with sea level rise of up to 40cm. Low pressure systems and convestions bring heavy rain.

Over in the east (Peru and South America) cooler ocean currents. High pressure systems and cool currents contribute to desert conditions. Little effect upon wider global circulation.

El Nino conditions: Water stays steady, due to a drop in trade winds. The warm surface water doesn't travel so little convectional rainfall occurs. The thermocline deepens in the East, which reduces the efficiency of cold water upwells. This affects the primary productivity.

La Nina: Is an exaggerated version of normal conditions. Occasionally happens at the end of an El Nino cycle. Causing extreme flooding in Australia and drought in South America.


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