Hazardous Environments Flashcards
Types of Hazards
What is a hazard?
Ahazardis an event which has the potential to cause harm to the environment, people or the economy
What is a natural hazard?
event caused by environmental processes
What is a disaster?
disasteroccurs when harm actually occurs to the environment, people or the economy
What is a natural disaster?
Damage and destruction caused by a physical event such as an earthquake.
What are the 4 causes that can be used to categories natural hazards?
Tectonic & Geological
Climatic & Meteorological
Biological
Technological
Give example of 2 tectonic natural hazards:
Earthquake, volcanic eruption and tsunami
Give example of 2 Climatic natural hazards:
Storms, Floods, Droughts and Tornadoes
Give example of 2 Biological natural hazards:
Pests and Diseases
What other ways can natural hazards be categorised?
Magnitude- Strength/Power of event
Frequency- how often the event occurs
Size- area covered by hazard
Duration- time a hazard event lasts
Location- where it occurs
What is a tropical cyclone?
Tropical cyclones are rotating, low pressure systems (below 950mb)
They are known ashurricanes, cyclonesandtyphoonsin different areas of the world
What are the characteristics of a tropical cyclone?
Heavy rainfall
High wind speeds (Over 119kmph)
High waves and storm surges
Calm eye at center.
How is the magnitude of a tropical cyclone measured?
Saffir-Simpson Scale from 1 to 5
Explain the distribution of a tropical cyclone:
They develop in tropical regions between 5 and 30 degrees north and south of the equator.
What is an earthquake?
A sudden violent shaking of the ground. Earthquakes are the result of pressure building when tectonic plates move.
What is the epicentre?
The point on the Earth’s surface directly above the focus.
What is the focus?
The point at which the earthquake starts below the Earth’s surface.
How is the magnitude of an earthquake measured?
Richter Scale
How is the damage of an earthquake measured?
Mercalli Scale
Explain the distribution of earthquakes:
- Earthquakes are found at all types of plate margins.
- Earthquakes can occur anywhere there is a fault or weakness in the crust.
- There is an ‘earthquake belt’ around the world where plate activity gives rise to earthquakes.
- This belt is most noted in a circle around the Pacific Ocean, known as the Pacific Ring of Fire
- Also seen in a line through the Mid Atlantic Ridge.
What is a volcano?
- When magma erupts onto the Earth’s surface as lava.
- An opening in the earth’s crust through which lava, volcanic ash and gases escape.
How is the magnitude of a volcanic eruption measured?
Volcanic Explosivity Index (VEI)
What is a hotspot?
Hotspots occur away from plate boundaries and are plumes/columns of magma which escape the earth’s crust
Explain the distribution of volcanoes:
Most volcanoes occur at constructive and destructive plate boundaries.
The majority of active volcanoes are located around the rim of the Pacific Ocean called the ‘Ring of Fire’.
Tropical Cyclones
What are the causes of tropical cyclone hazards?
- Low-pressure areas (less than 950mb)
- Between 5° and 20° north and south of the equator
- Low wind shear
- A deep layer of humid air
What are the stages of tropical cyclone formation?
- Warm, moist air rapidly rises forming an area of low pressure
- Air from high-pressure areas rushes in to take the place of therising air
- This air then rises forming a continuous flow of rising air
- As the air rises it cools and condenses. This releases heat energy which helps to power the tropical cyclone
- Air at the top of the storm goes outwards away from the centre of the storm
- TheCoriolis forcecauses the rising air to spiral around the centre.
- Some of the air sinks in the middle of the storm forming thecloudless, calm eye.
- The tropical cyclone moveswestwardsfrom its source
- When a tropical cyclone makes landfall or moves over an area of cold water it no longer has a supply of warm, moist air and it loses speed and temperature. Rainfall and winds decrease
What are the features of Tropical Cyclones?
- Heavy rainfall
- High wind speeds (over 74kmph)
- Storm surges
- Calm eye
- Highest winds and heaviest rain the wall of the eye
- Diameter up to 800km
What is wind shear?
Sudden changes in wind speed and/or direction.
What is the coriolis force?
The invisible force that appears to deflect the wind. The coriolis force applies to movement on rotating objects.
What is the coriolis effect?
Describes the pattern of deflection taken by objects not firmly connected to the ground as they travel long distances around the earth.
Tectonic Hazards
What is a plate boundary?
Border between 2 tectonic plates.