The United Nations’ World Tsunami Awareness Day is 5 November, presenting an annual opportunity to raise tsunami awareness globally and share innovative approaches to tsunami risk reduction.
Historically, tsunami impact on Australian communities has been relatively small compared to impacts from other natural hazards such as bushfires, floods and storms. However, research shows that tsunamis still undoubtedly pose a risk and that a large tsunami could impact our shores resulting in severe damage.
Most tsunamis are generated by large undersea earthquakes that occur at subduction zones where one tectonic plate slips under another. When earthquakes occur here, a column of water can be displaced resulting in a series of waves, often crossing ocean basins and impacting multiple countries. Such disasters can occur with little warning, emphasising the need for people and emergency services to be adequately prepared.
Though Australia is not located on a subduction zone, our coastline faces almost 8,000km of active tectonic plate boundary, meaning that large undersea earthquakes can occur at subduction zones in our region that could result in a damaging tsunami. Such regions include the Java (Sunda) and Timor trenches to Australia’s north-west, the New Hebrides trench to our east and the Puysegur trench to the south-east.
Records suggest that many tsunamis have affected our coastline in the last 200 years, often resulting in strong currents and rips in bays, harbours and beaches. A tsunami in 1960, resulting from a large earthquake offshore of Chile, caused damage to boats in harbours along the NSW coast. On the Western Australian coast, there have been episodes of localised coastal inundation resulting from tsunamis in 1977, 1994 and 2006. In December 2004, off the south-west coast of Indonesia’s Northern Sumatra, a 9.2 magnitude earthquake caused a tsunami to hit 1,200km of coastline around the Indian Ocean, including Australia, prompting the Australian Government to begin work on a suitable Australian warning system. As recent as January this year, beaches were closed along the east coast when a tsunami warning was issued after the eruption of the Hunga Tonga-Hunga Ha’apai volcano in Tonga.
To detect tsunami threats, Geoscience Australia, the Bureau of Meteorology and the Department of Home Affairs operate the Australian Tsunami Warning System. It is important that when people receive a warning, they promptly follow advice. If someone is in a low-lying coastal area and feels a large earthquake, they should immediately seek higher ground. Australians can also be at risk when travelling to coastal areas overseas, especially countries with higher tsunami risks than Australia – another great reason
Research undertaken through the Bushfire and Natural Hazards CRC in 2017 found that Australians have a low awareness of tsunami risk. Results highlight the need to engage with communities to enhance the effectiveness of our Australian Tsunami Warning System. Natural Hazards Research Australia will be actively exploring options for future research to strengthen community resilience to natural hazards. To stay up to date with our research, subscribe to our newsletter or keep an eye on our website at www.naturalhazards.com.au.