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This website was created by The Australian Hazards Task Force to inform you about a dangerous natural hazard in Australia, Tropical Cyclones. They can have disastrous effects and it is important to know how to reduce those effects by knowing how they are caused and how to stay safe. The website will inform you of 4 things and will include a case study - Severe Tropical Cyclone Justin in :
1. about tropical cyclones, a brief description
2. Case study, the environmental causes
3. The social, environmental and economic effects of the case study
4. How to protect yourself and keep safe against tropical cyclones, Management strategies


A tropical cyclone is a low pressure system and an intense storm that produces strong winds and heavy rain. The winds are clockwise in the Southern Hemisphere and counter clockwise in the Northern hemisphere. Tropical cyclones are caused by a tropical ocean being over 26.5 degrees for it to form and within 5 degrees and 22 degrees N and S of the equator.
Tropical cyclones rely on the heat when moist air rises causing condensation, and low pressure systems to develop. As the rising air forms clouds they create more heat causing the air to keep rising which then makes a tropical storm. The winds get stronger towards the eye wall and the moist air gets drawn to the centre. Light winds outside the cyclone steer it and cause it to grow. When they have contact with land they weaken.
Tropical cyclones that have winds exceeding 33 metres are given names such as cyclone Tracy and cyclone Justin. Strong winds increase the sea level in the center of the tropical cyclone causing a storm surge
Tropical cyclones are classified into 5 categories depending on the zone of maximum winds:

Strongest Gust (km/h)
Typical effects
1 tropical cyclone
Less than 125 km/h

Minimal house damage. Damage to some crops, trees and caravans. Boats may drag moorings.
2 tropical cyclone
125 - 164 km/h
Destructive winds

Minor house damage. Significant damage to signs, trees and caravans. Heavy damage to some crops. Risk of power failure. Small boats may break moorings.
3 severe tropical cyclone
165 - 224 km/h
Very destructive winds

Some roof and structural damage. Some caravans destroyed. Power failure likely.
4 severe tropical cyclone
225 - 279 km/h
Very destructive winds

Significant roofing and structural damage. Many caravans destroyed and blown away. Dangerous airborne debris. Widespread power failures.
5 severe tropical cyclone
More than 280 km/h
Extremely destructive winds

Significant roofing and structural damage. Many caravans destroyed and blown away. Dangerous airborne debris. Widespread power failures.
Chart 1

Coastal Impacts of cyclones 1886-2000, Queensland coast

Chart 2
Tropical Cyclones in Australia over the past 150 years

Cyclones in Australia are prone to mainly imapcting the coastal regions
of queensland, the Northern Territory and Western Australia as shown in
the chart 2.
Above it shows the Impacts of cyclones over the past years on Queensland East Coast in Chart 1.


Tropical Cyclone Justin was a major cyclone that impacted greatly on Northern Queensland in Australia on the 6th of March to the 24th of march, 1997. It caused 7 deaths and had major economic and environmental impacts. The picture below shows the size from an aerial view

Severe tropical cyclone justin from aerial view
Severe tropical cyclone justin from aerial view

Severe Cyclone Justin formed on the 6th of March, 1997 to the 24th of March and was the largest cyclone to hit Northern Queensland in 1997. It was a category 2 when it first crossed the Queensland coast on the 22nd of March after being a coral-sea cyclone for a long period of time (8 Days) but its highest peak was a category 3 severe, tropical cyclone. Its maximum winds were 93 km/h. When it first formed in the Pacific Ocean its waters were at least 27 degrees and its position was: Latitude- 17.0S longitude- 153.5E. Its central pressure ranged from 955 hPa to 1004 hPa.
It started as a monsoon trough that became tropical cyclone Justin, reaching maximum intensity on 9 March as a very large system. It stayed almost motionless and because of low sea surface temperatures the cyclone couldn’t grow stronger and therefore was relabeled as a tropical low on the 13th of March. Although on the 14th it drifted into high surface temperatures and intensified into a strong cyclone again. Before it reached Queensland’s coast it reached a peak of intensity before weakening when it reached Queensland’s coast.


These included:
There were 7 total losses of lives, 5 of these were caused when a yacht sank as an effect of the cyclone, one person was electrocuted by a falling power line, and another from a landslide caused by Justin. Earlier in Papua New Guinea Cyclone Justin also caused the loss of 30 lives. Strong winds caused severe damage on power lines causing the power to be out for 36 hours effecting many people and local communities. Many houses, buildings, vehicles and roads were also damaged. The graph below shows the injured and deaths associated with cyclones and other hazards and that injuries are more commen than deaths.

chart 3

These included:
The region between Townsville and Cairns lost 60% of their banana crop which cost $80million.Damage to paw paws is estimated to be $5million. The total horticultural and sugar cane damage cost $150 million as the crops could no longer be exported or sold. This affected the prices of papaws and bananas as they were more expensive as there were not enough products. Damage to roads and bridges are expected to exceed $20million. The power lines were out for 36 hours which effected businesses and there incomes. Cyclone Justin also effected employment. There were loss of jobs for many drivers who exported the crops and jobs involving tourism were also ceased until the wreckage of Justin was repaired. But jobs involving the business industry and manufacturers were affected positively as the need for repairs and building jobs increased. With damages to many buildings etc, thousands of insurance claims were made which resulted in a price raise for premiums to cover the costs of the claims. The graphs below show the amount of costs caused by natural diasters including the many cyclone expenses

Chart 4
chart 5

chart 6


These included:
One of the most major impacts were on one of the largest coral reefs in the world, the Great Barrier Reef. It caused 15 – 20 % of damage of the coral colonies and a lot of the reef was severely damaged. The strong waves caused by cyclone Justin caused the coral to break which a lot of other organisms relied on to live. The northern Queensland beaches were also affected as the storm surges and high tides caused erosion. Salt water went into many areas from Cooktown to Frasier Island causing many plant life, that is unable to live in salty water, to die. Cyclone Justin’s strong winds caused huge losses to sugar cane, fruit and vegetable crops. The region between Townsville and cairns lost 20-30% of its sugarcane crop, 60 % of their banana crops and flooding caused in the burdekin region resulting in delays in vegetable planting. The charts show the losses associated with cyclones including cyclone justin.

chart 7
chart 8


There are many ways to reduce the impact of a tropical cyclone for you and your property. Before the cyclone season starts check with your local council or your building control authority to see if your home has been built to cyclone standards. This will allow you to make sure that you property will be protected from cyclones. Also check that the walls, roof and eaves of your home are secure. Trim treetops and branches around your home, and fit shutters, or at least metal screens, to all glass areas. Clear your property of loose material that could blow about and possibly cause injury or damage during strong winds. For preperation In case of a storm surge/tide warning you should know your nearest safe high ground and the safest access route to it. You should prepare an emergeny kit containing items that would be helpful during a tropical cyclone warning. This should be located in an easy accessable place
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Make sure your informed on what to do during a cyclone warning or evacuation. Check your TV and radio for cyclone watchs and know the strongest part of your house (e.g a cellar, bathroom, hallway or doorway. When a cyclone strikes turn of all electrical appliences, lock your doors and go to the strongest part of the house with your safety kit and protect yourself with rugs, blankets and matresses. Always keep a battery powered radio with you to listen for information and updates.


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