natural hazards

natural hazards

1. natural hazards are an extreme event caused by nature that has the potential to cause damage to humans, properties and the environment. or has the potential to cause damage, destruction and death.

2. Natural events, such as volcanic eruptions or earthquakes that occur away from humans and properties are not considered natural hazards.

3. Different factors affect the hazard risk from natural hazards.

   • urbanisation
   • level of economic development
     • HICs are better equipped to cope with natural hazards than LICs.
       • This is because they have a better infrastructure, emergency response and systems for monitoring and predicting natural hazards. They also have better health care systems and more money to protect people
   • geographical location
     • some places are more at risk of natural hazards because of where they are

4. Earthquakes and volcanic eruptions are the result of physical processes:

   • Plate tectonics theory.
     • What is Continental Drift?
       • The evidence for continental drift
         • the same types of fossilised plants and animals are found in South America and Africa
         • the west coast of South America fits the east coast of Africa like a jigsaw puzzle
         • rock formations and mountain chains match in South America and Africa
         • similar mineral deposits and natural resources such as coal exist along the east coast of Africa and the west coast of South America.
       • continental drift is the theory that the continents were once joined forming a supercontinent (called Pangaea) Over 180 million years ago this supercontinent began to “break up” due to continental drift.
     • Plate tectonics was a theory developed in the 20th century. The theory suggested that the crust of the Earth is split up into seven large plates and a few smaller ones, what can all slowly move around on the Earth’s surface. They float on the semi-molten mantle.
   • Where do volcanoes and earthquakes happen?
     • Volcanoes and earthquakes typically happen where tectonic plates meet.
       • Earthquakes occur at all three types of plate margins: constructive, destructive and conservative.
       • Volcanoes are found at constructive and destructive plate margins. An exception to this are hot spot volcanoes.
   • Plate Boundaries
     • is where two or more plates meet is known as a plate boundary. There are four main types of plate boundary. These are constructive, destructive, conservative and collision margins.
       • A constructive plate boundary occurs when two plates move away from each other.
       • A destructive plate boundary occurs when an oceanic plate is forced under (or subducts) a continental plate.
       • A conservative plate boundary occurs when two plates slide past each other.
       • Collision plate boundaries occur when two continental plates move towards each other.

5. The effects of, and responses to, a tectonic hazard

   • effects of tectonic hazards
     • Primary effects (things that happen immediately as a result of a hazard).
       • earthquake
         • People killed and injured. Property, buildings and homes destroyed. Bridges, roads, ports and railways destroyed. Gas and water pipes and electric cables are broken.
       • volcanic eruption
         • Farmland and property destroyed. People and livestock killed and injured. Air travel restricted or cancelled due to ash in the atmosphere. Contaminated water supplies.
     • Secondary effects (things that happen in the hours, days and weeks after the initial hazard).
       • earthquake
         • The economy slowing due to money being spent repairing damage and business activity reduced. Blocked transport infrastructure restricts emergency services from rescuing people. Burst water pipes lead to a shortage of fresh water, poor sanitation and illness. Fires starting due to broken gas pipes and fallen electricity cables.
       • volcanic eruption
         • Emergency services struggle to arrive. Glaciers covering volcanoes melt, causing flooding. Rainfall and meltwater mix with volcanic ash to create mudflows (lahars). Tourism increases with people interested in seeing the impact of the volcanic eruption. Ash provides fertile soil for agriculture.
     • Immediate and long-term responses to a tectonic hazard
       • Long-term responses are those that go on for months and years after a disaster.
         • Rebuilding and repairing properties, Rebuilding and repairing transport infrastructure, Improving building regulations, Restoring utilities such as water, electric and gas, Resettling local people, Developing opportunities for the economy to recover, Install monitoring equipment
       • Short-term or immediate responses occur in the days and weeks immediately after a disaster has happened.
         • Issuing warnings, Rescue teams searching for survivors, Providing treatment to injured people, Food, drink and shelter provided, Bodies recovered, Fires extinguished
   • vary between areas of different levels of wealth.

6. Management can reduce the effects of a tectonic hazard

   • Why do people live close to volcanoes
     • People live close to volcanoes because Geothermal energy can be harnessed by using the steam from underground. used to drive turbines in geothermal power stations to produce electricity. Countries such as Iceland and New Zealand use this method of generating electricity.
     • Volcanoes, hot springs and geysers attract millions of tourists. This creates many jobs for people in the tourism industry. (e.g. work in hotels, restaurants and gift shops). Often locals are also employed as tour guides.
     • Volcanic areas often contain some of the most mineral rich soils in the world. which can produce healthy crops and rich harvests. This is ideal for farming
     • Volcanoes have problematic or beneficial effects on humans.
   • Can the risks of volcanic eruptions and Earthquakes be reduced?
     • Volcanoes and Earthquakes are natural hazards that can be unpredictable but several strategies are used to reduce the risk.
       • monitoring
         • Volcanoes. monitoring can be done in several ways . Before volcanic eruptions, volcanoes tend to change shape as magma rises through them. Tiltmeters and satellites are used to detect changes in the surface shape of a volcano. Monitoring levels of gas around the volcano, e.g. radon and sulphur gases, are also used as these are often released before volcanic activity. Thermal heat sensors can be utilised.As magma rises, this can cause small earthquakes. Seismometers and lasers are used to monitor the earth movements that can often occur before a volcanic eruption.
       • prediction
         • Volcanoes. By monitoring the movement of tectonic plates and changes in the surface of the volcano, scientists can predict the likelihood of a volcanic eruption and forecast which areas should be prepared for one. allows time for evacuation plans to be initiated.
         • Typically earthquakes happen along plate margins. it is possible to predict the general locations where earthquakes are likely to occur. However, predicting the time, date, magnitude and exact location is much more difficult. Technology is used to try to predict and monitor tectonic hazards. Seismometers are used to measure foreshocks (smaller earthquakes that happen before large earthquakes). The location of earthquakes and their times form patterns, predictions are made about when and where the next earthquake might occur. Animal can also act strangely when an earthquake is about to happen.
       • Protection
         • Volcanoes. Protection is one of the most challenging aspects of reducing the risks of a volcanic eruption. Lava flows, lahars and ash fallout cannot be protected against. As a result of this evacuation is the only real way of reducing the risks associated with volcanic eruptions.
         • onstructing buildings that withstand earthquakes is known as mitigation. buildings and roads are built more resistant to the impacts of earthquakes is common particular in HICs e.g. Japan. Although these buildings help reduce injury and death they may need to be repaired following a major earthquake buildings that withstand the impact of earthquakes include the use of seismic isolators, cross bracing, shear walls and counterweights. Seismic isolators or base isolators are shock absorbers in the foundations of buildings that absorb the tremors.
       • planning
         • Volcanoes. An effective ways of reducing the risk of a volcanic eruption is having an evacuation plan. This includes ensuring evacuation strategies are in place along with emergency shelter and food supplies being planned for. Local people can also be educated about actions they can take to reduce the risk of death or injury. People are taught that if unable to evacuate what they should do to protect themselves.
         • In some countries, people are encouraged to fasten down furniture so they are less likely to fall over. Preparing emergency aid supplies and organising how they will be distributed helps in the aftermath of a tectonic hazard. Earthquake drills helps train people how to respond when an earthquake occurs. If residents know how to turn off gas, electric and water supplies this helps reduce the risk of secondary effects such as fires.

7. Weather Hazards

   • global atmospheric circulation
     • The movement of air in the atmosphere in response to differences in temperature at the equator (warm) and the poles (cold).
   • Tropical storms
     • Tropical Storms are areas of extreme low pressure. This means air is rising, causing ‘low pressure’ on the earth’s surface.
     • Hurricanes are classified into five categories based on their wind speed, central pressure, and damage potential.

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