Educational Resources

Tsunami

Tsunamis are infrequent but inevitable, and can be devastating. They cannot be prevented, however the impacts can be mitigated by effective warning systems and a better informed public.

Large tsunamis, like that of the Indian Ocean 2004 Boxing Day tsunami, occur on average about every 50 years, and can cluster closely in time. Smaller tsunami occur on average yearly. On average, a tsunami is recorded in Australia every two years, but most are small. The tsunami threat to Australia varies from 'low' for most of our coastline to 'medium' along the northern half of Western Australia. A small tsunami struck Western Australia in 1994.

Since 1990, other tsunami have caused severe local destruction including (in the Australian region) Indonesia (1992, 1994, 1996), Japan (1992), Papua New Guinea (1998) and Vanuatu (1999).

Tropical Cyclones

Tropical Cyclones are dangerous because they produce destructive winds, heavy rainfall with flooding and damaging storm surges that can cause inundation of low-Iying coastal areas.

Cyclones have wind gusts in excess of 90 km/h around their centres and, in the most severe cyclones, gusts can exceed 280 km/h. These very destructive winds can cause extensive property damage and turn airborne debris into potentially lethal missiles.

While Cyclone Tracy is probably the most well known tropical cyclone in Australia's history, Cyclone Mahina (Queensland, 1899) and Cyclone Ada (Queensland, 1970) also caused much devastation. Over 400 people lost their lives in Cyclone Mahina, and 14 people lost their lives in Cyclone Ada, which also caused severe damage to resorts on the Whitsunday Islands.

Bushfires

The nature of the Australian environment - long periods of dry, hot weather and volatile natural vegetation - makes many parts of the country particularly vulnerable to fire. Southeastern Australia has the reputation of being one of the three most fire-prone areas in the world, along with southern California and southern France. The Black Friday fires in 1939 in Victoria, Ash Wednesday (1983) in Victoria and South Australia, and the 1967 fires in Tasmania, have each killed in excess of 60 Australians.

Very little of the Australian continent is free from fires - scrub-fires may sweep even the arid regions in years when good wet season rains are followed by a long dry spell. In the spring of 1974, 15 percent of the land area of Australia burned after prolific growth during the preceding wet summer dried off and ignited. More generally, fire tends to follow a seasonal cycle: the dry summer months are the danger time for southern Australia, as are the winter months over northern Australia. Most loss of life and property damage occurs around the fringes of the cities where homes are sometimes surrounded by flammable vegetation.

More information about Bushfires and Bushfire Weather

Severe Weather

Severe thunderstorms are very localised events that don't usually affect as wide an area as tropical cyclones and floods. Often, their devastating impact in Australia is under-estimated. According to Emergency Management Australia, severe thunderstorms cause more damage in Australia each year than any other natural hazard, and the damage bill in individual cases has gone into the hundreds of millions of dollars. Hail causes the greatest proportion of the damage, accounting for nearly half the total losses from severe storms.

Flooding

Few parts of Australia are immune from flooding, whether it be localized flash flooding from intense thunderstorms, or more widespread and longer-lived inundations resulting from heavy rain over the catchments of established river systems. During significant floods lives can be lost, stock losses may be in the tens of thousands, and damage to homes, businesses, roads, etc can run into hundreds of millions of dollars. Lost production can add considerably to the costs, as can the intangible costs, such as effects on health.

Overall, flooding is Australia's costliest form of natural disaster, with losses estimated at over $400 million a year. On the positive side, floods have some beneficial aspects, such as cleansing excess salt from the soil and recharging underground aquifers.

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