1A: Natural Hazards

• A natural hazard is a threat to people or property
• A natural hazard is a natural process which could cause death, injury or disruption to humans, or destroy property or possessions.
• A natural disaster is a natural hazard which has already happened
• Extreme events which do not pose any threat to human activity are not considered hazards.
• The two main types of natural hazard are geological and meteorological
• Geological hazards are caused by land and tectonic processes
• Examples of geological hazards include volcanoes, earthquakes, landslides and avalanches
• Meteorological hazards are caused by weather and climate
• Examples of meteorological hazards include hurricanes/typhoons, tornadoes, floods and droughts
• Hazard risk is the probability of people being affected by a hazard in a particular area.
• Vulnerability is how exposed an individual or community is to the effects of a hazard.
• The more people that are in an area exposed to natural hazards, the greater the probability they will be affected by a natural hazard.
• The better a population can cope with an extreme event, the lower the risk of them being severely affected.
• An area with high population density on a flood plain (like much of Bangladesh) is very vulnerable to flooding caused by extreme weather.
• An area with high population density at the base of a volcano (like Naples, Italy) is very vulnerable to volcanic eruptions.
• A city built on a fault line (like Los Angeles, USA) is very vulnerable to earthquakes.
• HICs are better able to cope with flooding because they can afford to build flood defences and evacuate people.
• In HICs there is usually good communication between emergency services so it's easier to coordinate rescue efforts.
• In LICs, poor infrastructure means that when disaster strikes, it takes longer to get aid to those who need it most.
• In LICs, poor infrastructure means that roads may be blocked or damaged making it difficult to get aid to those who need it.
• The impact of disasters is often worse in LICs as many people live in poverty and have little or no access to healthcare.
• The risk from some hazards is greater than others.
• Tropical storms can be predicted and monitored, giving people time to evacuate.
• Volcanic eruptions are unpredictable and sudden, leaving less time for preparation.
• Natural hazards that occur more frequently may carry a higher risk
• Magnitude - more severe natural hazards tend to have the greatest effects
• Three things that determine the nature of natural hazards are type, frequency, and magnitude
• A magnitude 9.0 earthquake in Japan in 2011 killed over 15000 people, whereas a 6.3 magnitude earthquake in Italy in 2009 killed around 300 people.
• The risk from natural hazards is affected by a range of factors
• Natural hazards have primary and secondary effects
• The primary effects of natural disasters are the immediate impacts of the hazard itself.
• Primary effects include damage to infrastructure and transport links, food and water supplies being destroyed or contaminated, injury or loss of life and electricity cables, gas pipes and communication networks being damaged.
• Secondary effects happen later on, often as a result of the primary effects.
• Initial hazards can trigger other hazards - this is a secondary effect
• Secondary effects include aid and emergency vehicles being unable to reach destinations due to blocked roads and bridges (leading to more deaths), a shortage of clean water and sanitation leading to the spread of disease, food shortages due to damaged supplies, weakened economy due to damage to businesses, unemployment, and expensive reconstitution processes.
• Human factors that increase vulnerability to natural hazards include poor building design, lack of warning systems, poverty, overpopulation, deforestation, and uncontrolled urbanisation.
• Poor building design increases vulnerability because buildings may not be strong enough to withstand earthquakes, hurricanes, tsunami waves etc. This means they collapse easily causing many fatalities.
• Lack of warning systems increases vulnerability because people do not know when a disaster will occur so cannot prepare themselves properly. For example, if there was no warning system for an earthquake then people would not evacuate their homes quickly enough which could lead to them getting trapped under rubble.
• The two types of response are immediate and long-term
• Some effects have to be dealt with before, during or immediately after the natural disaster to stop further loss of life, injuries or damage to properties.