Wildfires

Question 1

The nature of wildfires

Answer 1

They are uncontrolled fires that destroy grassland, forests and other areas of vegetation.
They usually occur in rural areas but if they reach inhabited ones they will also destroy inhabited land and settlements.

Question 2

Surface fires

Answer 2

The most common type of wildfire
Leaf litter or low-lying vegetation burns, resulting in an either low or high intensity fire.
They burn at around 900 degrees, however they cool quickly and are relatively easy to control.

Question 3

Ground fires

Answer 3

When the ground itself burns (organic matter in the soil such as peat and tree roots).
It is a slow, smouldering fire with no flame and little smoke.
They burn at around 540 degrees for long periods of time.

Question 4

Crown fires

Answer 4

Burn through the canopy, which is the top layer of foliage.
Loose bark allows fire to spread up the trunks of trees.
They can generate temperatures of around 1100 degrees.
They are intense, fast moving and difficult to maintain.

Question 5

Vegetation type

Answer 5

Thick undergrowth or closely spaced trees allow fires to travel easily.
Some trees such as pine contain lots of oil so will burn easily.

Question 6

Fuel characteristics

Answer 6

Fine, dry material (long grass, thin twigs) catch fire and burn easily.
Large amounts of fuel that form a continuous fire will burn for longer and spread quickly.

Question 7

Climate and recent weather

Answer 7

Rainfall must be sufficient for vegetation to grow so there’s lots of fuel.
They usually require a significant dry season when rainfall is low for a significant time.
Strong winds provide oxygen to help the fire burn and spread.
When humidity is below 7% the risk is much higher, it tends to be the lowest in the early afternoon.

Question 8

Fire behaviour

Answer 8

Different types of fire burn in different ways, creeping fire moves across the ground fairly slowly whereas running fire spreads rapidly.
Fire can throw out burning debris called firebrands that help the fire to spread.

Question 9

Natural causes

Answer 9

Lightning can start fires if it occurs without much rain.
Volcanic eruptions can produce every hot lava which can start fires.
They can also start from sparks from rock falls.

Question 10

Hot vs cold lightning

Answer 10

Cold Lightning has an intense electrical current but has a short duration.
Hot Lightning has a lower voltage but occurs for a longer period of time - it is particularly long last hot lightning that causes wildfires.

Question 11

Human causes

Answer 11

90% of fires in the USA are started by people leaving campfires unattended, dropping cigarettes, lighting agricultural fires or arson.

Question 12

Multiple causes

Answer 12

E.g. In south east Australia Feb 2009, fires were caused by lightning, a downed power line and arson.

Question 13

Social impacts

Answer 13

People killed, injured or left homeless
Power lines destroyed, reservoirs damaged, meaning that people don’t have electricity or clean water.
Inhaling smoke can lead to long term breathing difficulties.

Question 14

Political impacts

Answer 14

Governments can face criticism when fires have severe impacts.

Question 15

Economic impacts

Answer 15

Businesses destroyed
Insurance increases
Costs to fight fires
Tourists are discouraged

Question 16

Environmental impacts

Answer 16

Habitats destroyed, some species may not return to the area after the fire, changing the Eco system
Soils are damaged as fires remove organic matter
Smock causes pollution and water becomes contaminated with ash.

Question 17

Australia wildfire key facts

Answer 17

Wildfires burned for a month in the state of Victoria.
The worst conditions occurred in forested areas.
The fires followed 10 years of drought, temperatures of over 40 degrees and strong winds.
There was a large amount of dry oil-rich material to fuel the fire.

Question 18

Impacts - Australia social

Answer 18

173 people killed, 400 injured
Rise in stress and depression
2000 homes in 78 communities destroyed

Question 19

Short term responses

Answer 19

Trying to put the fire out or diverting it from settlements
Evacuating people
Spraying water onto the roofs of houses to prevent embers from setting them alight.

Question 20

Prevention

Answer 20

Public education about e risks of campfires

Fire beaters can be provided by authorities to put out small fires before they spread

Question 21

Preparedness

Answer 21

Households may have emergency plans or supplies of food, water or medicine
Emergency shelters may also be made available

Question 22

Adaptation

Answer 22

Using non-flammable building material
Drive ways and patios may act as a barrier
Sprinkler systems
Fire breaks such as gaps in trees around settlements stop fires spreading

Question 23

Australia wildfire responses - evacuation

Answer 23

The Australian Bureau of Meteorolgy predicted how the fires would spread and told residents they could either evacuate or stay put.
Evacuation reduced deaths but people were put at risk by choosing to stay.

Question 24

Australian wildfire - economic impacts

Answer 24

60 businesses destroyed

Cost of fire = $4 billion

Question 25

Australian wildfire environmental impacts

Answer 25

4300km^2 of land burned, including national parks

Rare species such as the spotted tree frog were killed.

Question 26

Australian wildfire - other responses

Answer 26

20,000 fire fighters and volunteers helped to put fires out and support victims.
$400 billion was donated to rebuild homes however fire-resistant material increased the cost so not everyone could afford to finish building

Question 27

Australian wildfire- long term responses

Answer 27

Fire shelters, warning systems and evacuation strategies are recommended as long term responses.