Cyclone
Yasi
Report
Natural Hazards
Ella Ottaviano
Cyclone Yasi – Natural Hazards Research
Report
What is a Cyclone?
A tropical cyclone is a strong low-pressure system that develops over warm oceans (around the
Equator). It is a system of spiralling winds and storm clouds. In the Southern Hemisphere the winds
rotate clockwise and are called cyclones whereas it is the opposite in the Northern Hemisphere
where they are also often referred to as hurricanes or typhoons. The most common features are
destructive winds and heavy rainfall that can lead to flooding. Tropical cyclones can cause
devastating damage once they reach land; powerful winds and rain destroy almost everything in its
path. In order for it to be categorised as a cyclone, its average sustained wind speed needs to
exceed 63 kilometres per hour. To be classified as severe, the average sustained wind speed needs
to exceed 118 kilometres per hour. Although tropical cyclones have a reputation for being
unpredictable, much effort has been dedicated to improving the forecasting skill of both location
and intensity by the Bureau of Meteorology
Causes of Cyclone Yasi
Yasi was formed and developed the same way as most other cyclones. Cyclones occur over warm
seas (a temperature greater than 26°C) near the equator. Heated air rising over warm seas causes
low pressure systems to develop. As the air rises it becomes more and more moist. The moist air
condenses into large storm clouds. Cool air rushes down to fill the void but because of the turning of
the Earth, the air is bent inwards and begins to spiral upwards with extreme force. The swirling
winds create a large circle in the centre of the clouds, and this becomes the eye of the storm, where
the winds are fairly calm and there is no rain or cloud cover. The cyclone builds up and is sustained
by the warm,
moist air
condensing.
When the cyclone
hits land or
travels over
cooler sea there
is no warm air
and the cyclone
begins to lose
intensity.
Diagram of how a
cyclone works
Location of Cyclone Yasi
Cyclone Yasi travelled over the ocean for some time before hitting land in the early hours of
Thursday, 3 February in north
Queensland at Mission Beach. Mission
Beach is located at 17° 52' 16" S latitude
and 146° 06' 19" E longitude and sits 10
meters above sea level. The nearest
major town is Innisfail and is
approximately 40km away from Mission
Beach. Some of the places inflicted with
the worst damage were around the
areas of Tully, Tully Heads,
Silkwood, Mission
Beach, Innisfail and Cardwell.
Path of Cyclone Yasi
Landform and Climate
Mission Beach is situated on the coast on the very north side of the beach. Just off the coastline
there is a small part of the Great Barrier Reef. Surrounding the area is farmland and mountains with
tropical rainforests with the lush, thick dense coverage of trees and plants. Mission beach climate is
often very humid and hot, generally tropical climate. Mission Beach has a monsoonal or ‘Wet
Season’ from January to May when most of the 3000mm of rain per year falls. At this time that is
both hot and wet (this was the period when the Yasi hit – lots of warm, moist air). The ‘Dry Season’,
from June to September, is much like a northern hemisphere summer with warm sunny days and
cooler nights. The cyclone season occurs from
November through to April. When Cyclone
Yasi hit land at Mission Beach it was very
powerful and destroyed the homes and killed
many native animals like Echidnas and
possums, the vast numbers of birds and
animals living on the rainforest covered
mountains as well as destroying crops, such as
bananas, on farms impacting severely on the
town community.
A climate graph of
Innisfail for 2011.
Social, Economic and Environmental Changes
Social Changes
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Cyclone Yasi brought not only the whole of Queensland together but reached out to the
whole of Australia with people from everywhere helping to rebuild.
Families coping with sadness of injury, destruction of property etc.
Many local communities are coming together to raise money for victims of the hazard, both
affected communities and non.
Neighbours coming together to help clean up.
More than 400 Red Cross volunteers assisting.
Economic Changes
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Estimated $3.6 Billion dollars worth of damage to Queenslanders.
Economy will slow down due to destruction of businesses and industries and tourism
declining after the natural hazard.
National levy (one-off).
Loss of income for people (destruction of businesses)
Increased prices of food due to shortage because crops were destroyed.
Closure of businesses.
Rise of rent, due to the increased need to rent because homes have been destroyed.
Rise of insurance premiums because of the amount of claims.
Environmental Changes
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Many trees plants were destroyed by the cyclone along with the homes of the animals that
inhabit these places.
Many native animals were
either killed or injured.
There was also rubbish blown
everywhere, some people (on
the coast) reported pumice and
coconuts washed up on their
lawn.
Destroyed infrastructure must
be demolished and rebuilt along
with destroyed crops and farms.
70 year old Michael Geyer
looks through his
destroyed banana crop
Evaluation of Responses
Individuals

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Helping care for the injured wildlife. “One wildlife carer we spoke to had accepted 34 birds
in one day, and had six more on the way.”
Individuals have shown resilience through Aussie larrikin attitude. A sign in a boarded up
cafe window read ‘Kiss my Yasi’.
Helping others clean up damage and mess.
Groups
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The Red Cross has more than 400 volunteers working with victims and helping to raise
money.
Local Disaster Management Groups have helped out, restoring power and search for missing
people.
Emergency services answered numerous calls for help throughout the night and day.
The police and paramedics helped by making, emergency repairs water and sewerage pipes,
bringing supplies and equipment for stranded families and provided medical assistance to
injured.
Government

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The government introduced a nation one-off levy to assist victims in rebuilding their lives.
Prime Minister Julia Gillard said today all Army 4000 troops based in Townsville would aid
north Queensland's recovery.
Extra 150 police and 500 State Emergency Service personnel are being sent to north
Queensland to help the clean-up.
The Australian Army also helped evacuate
people in immediate danger (coastal areas)
when warnings of the cyclone came in.
Helped rebuild towns and repair damage.
Army personnel helping
clean up streets.
Bibliography
Sites used:
 http://www.bom.gov.au/cyclone/history/yasi.shtml
 http://www.bbc.co.uk/schools/gcsebitesize/geography/natural_hazards/hurricanes_rev1.sh
tml
 http://library.thinkquest.org/10136/cyclones/cycltq.htm#how
 http://www.cairns.com.au/article/2012/01/28/202881_cyclone.html
 http://www.mission-beach-au.com/weather-and-climate
 http://www.missionbeachtourism.com/about-mission-beach/cyclone-yasi.php
 http://weather.ninemsn.com.au/climate/station.jsp?lt=site&lc=32025
 http://moneybasics.nab.com.au/the-economic-impact-of-the-floods-and-yasi-267.html
 http://www.ifaw.org/united-states/node/2607
 http://www.heraldsun.com.au/opinion/aussie-spirit-will-beat-cyclone-yasi/story-e6frfhqo1225999136927
 http://www.heraldsun.com.au/news/special-reports/queensland-cyclone-yasi/storyfn7rxoal-1225998348468
 http://www.ga.gov.au/hazards/cyclone/cyclone-basics/what.html
 http://www.ema.gov.au/www/ema/schools.nsf/Page/Get_The_FactsCyclones