Hazardous environments- 3 Flashcards
Define natural hazard
An extreme event or condition in the natural environment causing harm to people, properties or livelihoods.
Why do natural hazards lead to natural disasters?
Natural hazards only lead to natural disasters because people live in hazardous areas
What are the two types of natural hazards?
Tectonic and geological, climatic and meteorological
What are examples of tectonic and geological natural hazards?
Earthquakes, volcanoes, tsunamis, landslides
What are examples of climatic and meteorological natural hazards?
Tropical cyclones, drought, floods, tornadoes
What are the different characteristics of hazards and disasters?
Magnitude, frequency, regularity, areal extent, spatial concentration/dispersion, speed of onset, duration
Define magnitude
Size of event
Define frequency
How often the event of a certain size occurs
Define regularity
How regular or random the event is
Define areal extent
The size of the area covered by the hazard
Define spatial concentration/dispersion
The distribution of hazards over space
Define speed of onset
Speed of event which can vary from very rapid events to slow timescale events
Define duration
Length of time that the natural hazard exists
What is a hurricane?
An intense, low pressure system that brings heavy rainfall, strong winds and high waves, and can cause other hazards such as flooding and mudslides. They are large-scale features with a diameter of up to 800km and a calm central area called the eye. Most hurricanes take place in tropical and sub-tropical regions.
What is an earthquake?
A sudden violent shaking of the earth’s surface
Why do earthquakes occur?
They occur when a build up of pressure causes rocks and other materials to give way. Most of this pressure occurs at plate boundaries when one plate is moving against the other
Why do people continue to live in areas at risk from hazardous events?
People may think that the advantages of living in the area outweigh the risks and also poor people may have little choice in where they live, forcing them to live in unsafe areas such as steep slopes or floodplains.
Where are tropical storms found in the world?
Central and South America, western and central Africa, Southeast Asia, and Australia. (Close proximity to equator)
When in the year are tropical storms found in different parts of the world?
Late summer and autumn
What are the different factors that affect tropical storms?
Ocean temperature, atmospheric pressure, wind shear and Coriolis force
What must the ocean temperature be for a tropical storm?
Over 27 degrees
How deep should the ocean be for a tropical storm?
At least 70m
Where must the low pressure area be for a tropical storm?
It should be far enough away from the equator so that the Coriolis force creates rotation in the rising air mass