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Natural Hazards and Disasters in Australia

OVERVIEW

Australia is an island continent extending from approximately 10 degrees to 45 degrees South in latitude and is subject to harsh extremes of climate. It has an area of 7.7 million square kilometres, a population of 18.5 million and a coastline over 25,000km long. Much of the land area is desert and the remainder varies from tropical rain forest to winter snowfields. It is a land that, because of its climate, physical geography, vegetation and patterns of human settlement along rivers, coasts and across marginal agricultural land, is prone to a range of meteorological, geological and biological hazards, including tropical cyclone, storm surge, bushfire, flood, severe storm, earthquake and landslide.

drought.bmp (126390 bytes)Other than the great influenza epidemic in 1918 that killed thousands, however, Australia has experienced relatively low loss of human life in comparison with other countries. This is largely because we have a stable continent, well-constructed homes and are not densely-populated. Even so, natural disasters have resulted in approximately 500 deaths and 6,000 injuries in Australia over the last 25 years and have caused annual average estimated losses of approximately A$1.25 billion (excluding drought). Since European settlement in Australia in 1788, the most deaths from a natural hazard have been as a result of several heatwaves and the most costly hazards in total estimated economic terms have been drought and flood, although the most costly events were the Newcastle earthquake in 1989 and Cyclone Tracy at Darwin in 1974.

Ten Hard Facts About Australia’s Natural Hazards

  1. BUSHFIRES - South-eastern Australia includes areas which are prone to the most severe and frequent wildfires in the world.
  2. FLOODS - The Great Floods of 1990 in southern Queensland, northern NSW and SE Victoria covered a total area larger than Germany.
  3. HEATWAVES - During the 20th Century, heatwaves have caused more deaths in Australia than any other natural hazard (except disease). The worst recorded killed well over 400 people.
  4. SEVERE STORMS - On average in Australia, severe storms (including hail and tornadoes) occur more frequently and cause more insured damage, per year, than any other natural hazard.
  5. DROUGHTS - On average, approximately three out of every 10 years bring drought which costs Australia more than any other natural hazard.
  6. CYCLONES - Tropical cyclones cross the northern, north-eastern and north-western Australian coastline 6 times per year on average.
  7. EARTHQUAKES - In Australia, an earthquake of Richter magnitude 5.5 (ie almost that of the Newcastle event in 1989) occurs every 15 months on average.
  8. TSUNAMIS - Numerous small tsunamis (seismic sea waves) have been recorded along Australia’s coastline and evidence suggests much larger ones occurred before European settlement.
  9. LANDSLIDES - In Australia, landslides have been responsible for approximately five times as many deaths as earthquakes but have caused only 5% as much economic damage.
  10. VOLCANOES - Although the vast majority of volcanoes in Australia are extinct, scientists believe further minor volcanic activity is possible from long-dormant ones in SA and Victoria.

METEOROLOGICAL HAZARDS - OVERVIEW AND SELECTED CASE STUDIES

Some meteorological hazards such as tropical cyclones, bushfires, floods and severe storms (including wind, rain, hail and tornado) occur frequently in Australia, from several to many times a year, causing regular disruptions and hundreds of millions of dollars of damage annually. Others, such as severe droughts occur once or twice a decade usually for extended periods, while still others such as severe cyclone storm surges have affected urban areas less frequently. The following case studies give an indication of the potential losses associated with a range of meteorological hazards occurring in Australia.

Tropical Cyclone Tracy struck the city of Darwin in the Northern Territory at 1.00am on 25 December 1974. Category 4 winds gusting up to an estimated 250km/h, caused enormous infrastructure damage, destroyed over 80% of all buildings, killed 65 people and injured 650. Over 35,000 people were left homeless and had to be evacuated. Insurance losses amounted to A$837 million and the total estimated cost of the disaster was A$4.2 billion (in Dec 1998 values).

The 'Ash Wednesday' bushfires broke out in very dry, heatwave conditions of 43oC across the states of South Australia and Victoria on 16 February 1983. Fanned by high winds, hundreds of wildfires burnt a combined total of over 520,000 hectares in 24 hours. Their severe toll involved: 76 deaths; 1,100 injuries; 3,700 buildings destroyed (including 2,400 homes and over 1,000 farms); 18,000 cattle; 340,000 sheep; 20,000km of fencing; and huge areas of forest and bushland. Their insured loss was A$320 million and total estimated costs reached A$950 million (in Dec 1998 values)

Floods in north-eastern Victoria caused widespread, severe damage in October 1993 when intense rainfall in mountain catchments caused a total of 12 river systems to rapidly flood many towns and the surrounding rich agricultural regions, some with very little warning. The worst-affected large towns were Benalla, Shepparton, Wangaratta and Euroa where most of the total of over 4,000 homes and businesses were inundated for several days. Approximately 5,500 people were evacuated and huge losses were inflicted on fruit and vegetable crops, dairy cattle herds and other livestock. Roads, bridges and other infrastructure items suffered massive damage. Insurance payouts were very small but total estimated costs (including lost agricultural production) were A$400 million (in Dec 1998 values).

A severe hailstorm struck many of Sydney's eastern and inner suburbs without warning on the evening of 14 April 1999. Huge hailstones averaging the size of tennis balls in many areas caused widespread devastation to the roofs and windows of tens of thousands of homes, factories, businesses, and motor vehicles and even damaged a number of large aircraft at Sydney Airport. Fierce lightning and rain caused fire and water damage adding to the destruction. Although only one death resulted, there were numerous injuries and several hundred people left homeless. The homeless figure would have been much higher except for a massive effort by emergency service volunteers who worked for weeks to secure and temporarily seal roofs with approx' 200,000 huge tarpaulins. In all, 22,000 homes, 2,800 commercial buildings and 63,000 cars were damaged creating Australia's most expensive insurance loss from a natural disaster. The resulting payout figure to June 1999 was A$1.5 billion and total estimated costs exceed A$2 billion.

GEOLOGICAL AND EXTRA-TERRESTRIAL HAZARDS - OVERVIEW

Compared with regional neighbours such as New Zealand, Papua New Guinea and Indonesia, the Australian continent is relatively geologically-stable and is less prone to geological hazards such as earthquakes, tsunamis, landslides and volcanoes.

Moderate-sized earthquakes, however, have caused substantial losses. In December 1989, an earthquake resulted in 13 deaths and 160 injuries at Newcastle, 'shaking' over an area of more than 250,000 sq km of the State of New South Wales, reported building damage across an area of about 20,000 sq km and total estimated property/infrastructure and recovery costs of over A$4 billion, of which only $1.145 billion was insured.

Tsunamis (seismic seawaves), despite being rare in Australia, have impacted on our coastlines. Serious damage was caused in 1960 along the eastern seaboard and in 1977 and 1994 along the north-west coast from distant earthquakes.

Landslides in Australia are usually the result of soil saturation and human activity. In 1996 and 1997 they began to be viewed more seriously when lives were lost in a cliff collapse at a beach near Gracetown in Western Australia (9 dead) and a landslide on a steep site at the Thredbo ski resort in New South Wales (18 dead).

Volcanoes are extremely unlikely to seriously impact directly on Australia, although scientists believe further minor volcanic activity is possible from long-dormant ones in South Australia and Victoria.

Although presenting a very low risk, a comet or asteroid impact on Earth could cause a major regional disaster or even a world-wide catastrophe. There are many past impact sites throughout the world, including Australia.

 

BIOLOGICAL HAZARDS - OVERVIEW AND SELECTED CASE STUDIES

Biological hazards with potential for causing disaster in Australia include: human disease epidemics (such as influenza, Ross River fever, Hepatitis, AIDS); vermin and insect plagues (eg rabbits, mice, locusts); exotic animal diseases (eg 'foot-and-mouth', Anthrax); and food-crop diseases. These and other similar hazards have dramatically and suddenly affected both the health and wealth of our nation in the past, particularly in rural areas.

In late January 1997, Australia's most serious outbreak of Anthrax this century occurred on dairy farms in northern Victoria. The emergency was brought under control by late February after approximately 200 cattle & some sheep had died on over 80 properties. More than 60,000 cattle & 2,000 sheep were immunised to contain the disease. The estimated cost of control measures and lost exports and other impacts was approximately A$15 million. A knackery worker required hospital treatment after becoming infected via a small wound.

HUMAN-CAUSED HAZARDS - OVERVIEW AND SELECTED CASE STUDIES

Human error or deliberate acts sometimes take on disastrous proportions. These may include: terrorist bombings; riots; wars; crowd-crushes at mass gatherings; shooting massacres (eg Port Arthur); and even sabotage of essential services (eg water or power supplies).

On Sunday 28 April 1996 the peaceful serenity of Port Arthur in Tasmania was shattered by a tragic and shocking event that left 35 people dead and 19 injured. A military-style weapon was used to kill 20 people in the Broad Arrow Cafe at the Port Arthur Historic Site. The shooting rampage continued outside, leaving behind more dead and injured before the offender left the historic site in a commandeered motor vehicle and drove to the Port Arthur Store. There he took a hostage, securing him in the boot of the vehicle and shooting dead the hostage's female companion. He then drove to a nearby guest-house, firing upon large numbers of people along the way and flagging down and shooting the occupants of a four-wheel-drive vehicle. Taking refuge in the guest-house, the offender kept police at bay until the early hours of the following morning before setting fire to the building. He later emerged from the building and was taken into police custody. The fire destroyed the building and site examination revealed three more bodies.

TECHNOLOGICAL HAZARDS - OVERVIEW AND SELECTED CASE STUDIES

Australia is an industrialised and resource-rich nation which has suffered from, or is at risk from, technological hazards and accidents which sometimes become disasters. These include: major transport, mining and hazardous materials accidents (eg oil or chemical spills); as well as industrial explosions; urban fire and occasional structural collapses (eg 'Westgate', Melbourne and 'Tasman', Hobart). This category also includes dam failures, nuclear accidents and re-entry of space debris to Earth (eg Skylab, WA 1979).

Accidental damage to essential services also has the potential to cause loss of life and significant economic and social disruption, as evidenced by recent disruptions to gas and water supplies in major urban centres.

In early July 1998, some sections of Sydney's water supply became contaminated by harmful bacteria necessitating the boiling of drinking water by tens of thousands of residents in the affected areas. The crisis continued for over two months until the source of the problem was identified. Although only isolated illness cases occurred, a total cost of approximately A$75 million resulted.

On 25 September 1998, following a gas refinery explosion at Longford in Victoria (which killed 2 and injured 8 other workers), the State was left without its major domestic and industrial energy source for a period of two weeks at a relatively cool time of the year. Massive disruption to commerce and industry resulted which has been estimated to total A$1.3 billion in lost production and revenue.


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