Lecture 2 - Intro to Hazards and Environ Systems

  • Created by: nicola
  • Created on: 01-04-11 14:37

DEFINITION OF HAZARD = potential threats facing human society by events originating and being transmitted through the environment.

Countries with higher levels of development often able to invest more in R&D.

Disaster trend -> increased frequency with increased populations - however development of technology and technical quality has reduced casualty numbers

Hazard = (cause) a potential threat to humans and welfare

Risk = (likely consequence) probability of a situation occurring

Large numbers of people killed/ injured/ affected - known as a disaster

The Earth’s population is increasing:

  • More people living in hazard-prone areas
  • Populations are becoming hyper-concentrated, increased consumption of resources

Today there are 6 billion people on Earth ( ~ 50% live in cities)

By 2025, there will be ~8 billion people (~ 66% in cities) of these cities, 40% are coastal - prone to severe storm and tsunami damage and a large majority lie in areas subject to other geohazards (e.g. volcanoes, earthquakes, landslides, debris flows etc.)

Perspectives of how to deal with hazards has changed from engineering initiatives pre 1950 where large structures were built to defend people to more complex approaches post 1990, emphasising complex interactions between nature and society (Smith and Petley, 2009).

(see attached figure)

3 major categories of environmental hazards (Smith and Petley, 2009)

  • Natural Hazards - extreme geophysical and biologocial events e.g. earthquakes, volcanic eruptions, floods and wildfires
  • Technological Hazards - major accidents e.g. car crashes, industrial explosions, structural collapse
  • Context Hazard - global environmental change e.g. sea level rise, deforestation, meteor impact

Although natural hazard is a natural event or process in the earth system, the risks and impacts are fundamentally human and socio-economic/cultural in terms of settlement, landuse, planning, policies, attitudes, construction methods and standards, etc.

Most casualties occur from droughts - large scale phenomenon Increasing trends of disasters in recent years - climate change increasing the frequency and often intensity e.g. of hurricanes, floods and droughts.

 Vulnerability is a possible future state that implies high risk  combined with an inability to cope. Determined by physical, social, economic, political and environmental factors.

Developing countries are more vulnerable to damaging impacts from  natural disasters, and suffer greater and more long-term setbacks. Most vulnerable people tend to be concentrated in two population groups:

  • Urban dwellers from the informal settlements


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