Geography - Hazardous Environments

Hazardous Environments

• Objectives:-
• - The characteristics of 3 different types of natural hazards
• ~ Tropical cyclones, volcanic eruptions and earthquakes.
• - The causes of tropical cyclones
• - The causes of volcanic eruptions an earthquakes
• -The scales used in the measurement of different natural hazard
• - The primary and secondary impacts of one volcanic eruption and one earthquake
• -The reasons why people continue to live in hazardous environments
• -That individual tropical cyclones can differ in their impact
• -How people predict and prepare for earthquakes
• -Steps in the recovery from a natural hazard

Different types of hazards

• A hazard is an event that threatens, or actually causes damage and destruction to people, their property and settlements.
• A natural Hazard is one produced by environmental processes. Such as, storms, floods, earthquakes and volcanic eruptions.
• Some places are more hazardous than others;
• - Some places experience more than one type of Natural hazards
• - Some places experience natural hazards more frequently
• - In some places the Hazards are more destructive than in others.
• -Some places are better able to cope with the damaging impacts of natural hazards.
• Hazards could also be caused by people.
• Hazard classification based ion their causes:
• - Geological; earthquakes, volcanic eruptions and landslides.
• - Climatic; storms, flood and drought.
• - Biological; fires, pests and diseases.
• - Technological; nuclear explosions, transport accidents and pollution.

Tropical cyclones

• A tropical cyclone starts when high temperatures cause air to rise from the surface of the sea. The rising air causes local thunderstorms.
• Occasionally these small storms come together and create a strong flow of warm, rapidly rising air, which produces an area of increasingly low pressure.

Diapositiva 4

• Conditions that have to be met if these local thunderstorms are to develop into a tropical cyclone;
• -A deep layer of humid, warm (>27ْC) and unstable air.
• - A supply of energy (heat and moisture) from the surface of the sea.
• - The sea must b e at its warmest (during late summer)
• - A circulatory motion of the air, anti-clockwise in the northern hemisphere, encouraged by the Coriolis effect.
• - Small changes in wind speed and direction with increasing altitude (wind shear); this encourages the circulatory motion within the cyclone.
• When all these conditions occur, a tropical cyclone is likely to develop very quickly and gather enormous energy and strength.