Tomorrow, 5 November is the United Nations World Tsunami Awareness Day, an annual event to raise awareness of the risks posed by tsunamis and encourage preparedness. The theme this year focuses on passing on lessons learnt from the Indian Ocean Tsunami on Boxing Day 2004, twenty years ago, to the next generation.
The 2004 Indian Ocean tsunami was triggered by a very large earthquake off northern Indonesia that uplifted the sea floor, causing destructive waves that raced across the Indian Ocean, taking lives as far away as Africa. At their worst, in Indonesia’s Aceh province in northern Sumatra, wave heights reached tens of metres, without warning, flooding low-lying communities for kilometres inland.
Australia escaped the worst of the impacts but did record strong currents along beaches and harbours. Two people had to be rescued after a strong rip current swept them out to sea at Busselton, Western Australia.
Without an early warning system to alert people, it is estimated that some 275,000 people lost their lives, including 26 Australians whilst overseas, making it one of the most significant disasters in living memory.
The Indian Ocean Tsunami triggered significant efforts in Australia to enhance preparedness. The Australian Tsunami Warning System was established, providing an early warning capability for Australian communities that previously did not exist, and emergency services developed specific plans to evacuate low-lying communities.
Since European settlement, tsunamis in Australia have been limited in their damage, largely only impacting areas such as beaches, harbours and ports, with some coastal inundation reported in isolated circumstances. For example, the 1960 tsunami which resulted from a large undersea earthquake off the coast of Chile, resulted in strong rips and damage in ports and harbours along parts of our east coast. This risk remains, and while there is a low chance that future tsunami impact in Australia would result in widespread fatalities and destruction, we must be aware of the risk posed and have systems in place to prepare, respond and recover, particularly for coastal infrastructure like our ports and marinas, as well as coastal suburbs and towns.
Most tsunamis are generated by large undersea earthquakes that occur at tectonic plate boundaries, however, they can also result from undersea or coastal landslides, volcanic eruptions or meteors. Australia is exposed to tsunamis generated from earthquake faults in south east Asia and the Pacific. Tsunamis travel around 800 kilometres per hour meaning that they can arrive from these regions within a couple of hours providing some limited time to warn and evacuate communities.
Natural Hazards Research Australia research has demonstrated that there is a low awareness of tsunami risk amongst the Australian population reinforcing the need for engagement programs.
People living and working in coastal areas should:
- Research their local risk, develop an understanding of tsunami warnings and where they would evacuate to if needed
- If they hear a tsunami warning indicating a threat to coastal communities, they should head to high ground immediately.