Australia is a vast nation, comprising the Australasian mainland, the island of Tasmania, and several smaller archipelagos. Surrounded by the Pacific, Indian and Southern Oceans, and bordering the Timor, Tasman, and Coral Seas, Australia’s waters are notorious for their surfing appeal and spectacular reefs. Still, you might be wondering, are there tsunami danger zones in Australia?
The Land Down Under is one of diverse wildlife, spectacular landscapes, stunning coral reefs, and notoriously welcoming natives. Close to 10 million tourists visit Australia every year and the nation boasts over 25,000 kilometers of vibrant coastline. Australia might not sit on any plate boundaries, but the east coast faces the ‘Pacific Ring of Fire’ and the northwest is bounded by tectonic activity. So what does this mean for Australia’s tsunami risk?
Our guide takes a closer look at the tsunami dangers zones in Australia to find out what would happen if a tsunami hit Australia’s shores and what you should do if you’re there. Let’s go.
Tsunami Danger Zones in Australia
Tsunamis, meaning “harbor waves” in Japanese, are freak waves caused by movements in the Earth’s outer layer or crust, which are forced out in all directions from their source. They’re usually the result of undersea earthquakes, but landslides and volcanic eruptions can also displace ocean water and send waves speeding as fast as jet planes across entire ocean basins.
Tsunamis are difficult to predict as they do not have a season or an advanced cause. The Pacific Basin, where Australasia joins South Asia, North America, and Japan, sees an average of two destructive tsunamis a year. Pacific-wide tsunamis, namely those that originate in the Ring of Fire but are so severe they have an effect on continents beyond the region, are a 10-12 year phenomenon.
The northwest, northeast, and east coasts of Australia are bounded by 8,000 kilometers of active tectonic plate boundaries which could send a tsunami hurtling towards Australia’s coastline in two to four hours. One in three global earthquakes happen along these boundaries, so there are several tsunami danger zones in Australia to look out for.
- New South Wales – The east coast state, bordering Queensland and best known for its coastal cities like Sydney and scenic national parks, has the highest number of recorded tsunamis in the country thanks to its Pacific coastline. Outlying islands face a higher risk of severe destruction from tsunamis waves. Earthquakes on the Kermadec-Tonga trench, New Hebrides Trench, Solomon trench, and even in South America, could generate tsunami waves to reach Australia’s east coast shores in three to 15 hours.
- Tasmania – Tasmania comes in close second for the number of tsunami events by state in Australia. Entirely surrounded by the Pacific Ocean, Tasmania, like NSW, is exposed to freak waves caused by earthquakes in the Ring of Fire. As an island state, Tasmania faces the risk of widespread damage as a result of a tsunami.
- Western Australia – It might not beat NSW on record numbers, but the northwest coast of WA is now believed to face a greater risk of a tsunami than the rest of the country, due to its close proximity to the Indonesian tectonic plate boundary and its long, seismically active fault line.
- Queensland – Also facing the Ring of Fire, Queensland has experienced around half as many tsunamis as its southern neighbor, but border cities like Brisbane and the Gold Coast are not completely safe from the threat of underwater seismic events.
The Australian Tsunami Warning System, along with Geoscience Australia and the Bureau of Meteorology is currently able to issue a tsunami warning to all Australians at least 90 minutes ahead of impact. That’s thanks to 24/7 monitoring using technology like deep-ocean tsunami detection buoys. However, this time frame is usually even bigger as it can take hours for high waves to reach Australia’s shores after a distant earthquake.
What is a likelihood of a tsunami in Australia?
The threat of tsunamis in New South Wales, Western Australia, Tasmania, Queensland, and even the Northern Territory and Victoria, means major cities like Sydney, Brisbane, Melbourne, Darwin, and Perth are all at risk of being hit with devastating waves. But you’re probably wondering just how likely these events are.
A total of 145 tsunamis have been recorded in Australia since records began – that includes 125 since European settlement in the late 18th century and 20 ‘paleo tsunamis’ before that time, detected from sediment deposits. New South Wales has experienced the highest number of tsunamis with 57 on record. This might sound like a lot, but most of these have been too small to cause any noticeable effects.
In New South Wales, a tsunami with a maximum offshore height of 40 cm will only occur once every 100 years. This means the average Australian has a 55 percent chance of being around to experience an event of this scale.
New South Wales has received its fair share of tsunami-category waves, but the largest tsunami impacts have been recorded along the northwest coast of Western Australia. In 2006, a magnitude 7.7 earthquake that happened off the coast of Java in Indonesia inundated a coastal campsite at Steep Point, WA. It caused localized damage and erosion and the run-up height reached 7.9 meters. Vehicles and debris were carried up to 10 meters inland, but no one was hurt.
The last significant tsunami to reach Australia’s shores was the 2011 Tohoku tsunami that caused widespread destruction in Japan. Strong currents were observed in Sydney Harbor and Port Kembla, and swimmers were even washed into the Merimbula lagoon in southern NSW, but no one was seriously injured in the country.
Tsunami warnings are categorized into three levels by the Joint Australian Tsunami Warning Center (JATWC), these are no threat, marine threat, and land threat. The vast majority of tsunamis that have hit or are likely to Australia, come with a purely marine threat. This means that dangerous rips, waves, strong currents, and localized overflow would be likely to occur on the immediate foreshore and create possible danger for surfers, swimmers, water-users, and beachside dwellers.
Tsunamis with a real land threat, which means causing major inundation, flooding, and destruction, have only happened around three times in Australian history and remain unlikely.
What should you do in case of a tsunami in Australia?
In the unlikely event of a land inundation level tsunami hitting Australia, knowing what to do could save your life. Because the tectonic plate boundaries that could prove detrimental to Australia’s shores are located in other territories, it’s important that Australia has its own systems for monitoring fault line activity.
Luckily, the nation now has a world-class tsunami detection and warning system which is able to monitor underwater seismic activity 24/7 and alert citizens at least 90 minutes before an event, and much longer in normal cases. The Bureau of Meteorology will intercept regular television and radio channels to warn residents of an incoming tsunami, but in case you’re in a remote area, try to keep up to date with weather reports and news alerts as often as you can.
Coastal areas most at risk will likely sound continuous sirens if the damage is expected to be high before initiating evacuation procedures. If you’re too far from the coast the hear this, chances are, the tsunami won’t reach you.
More than 50 percent of Australians live within seven kilometers of the coast, and although Australia has never experienced a catastrophic tsunami, a considerable proportion of the population is vulnerable to the hazard.
Australia uses a nationally recognized, five stages of the evacuation process in its tsunami response planning. These can be found in the Australia Disaster Resilience Tsunami Emergency Planning Handbook. It is a good idea to familiarise yourself with local protocol in the case of a tsunami, but here are some extra things you can do to keep safe:
- First of all, don’t panic – The Australian authorities are well-prepared for a tsunami, and listening to official instructions is the best thing you can do.
- Familiarize yourself with evacuation routes – If the tsunami warning is only a precaution, you don’t have to evacuate, but it doesn’t hurt to know where your nearest yellow zone is and how to get there.
- Don’t head to the beach – This might sound obvious but a surprising amount of people need to see before they believe and you don’t want to be in the direct line of impact for a big wave.
- Respond to earthquakes – Tsunamis often follow seismic activity. While a tsunami in Australia could be caused by earthquakes many hundreds of miles away that you wouldn’t feel, if you’re on the coast and feel a big tremor, it’s worth moving to a yellow zone when it’s safe to do so, even if there hasn’t been an official warning. Still, don’t panic – most earthquakes don’t result in tsunamis.
- Get to high land – If there isn’t time for yellow zones and evacuation routes, the best thing to do when a tsunami is imminent is to get high up. If there are no maps and signs, you want to try and get two miles inland, and if you can’t, aim for 100 feet above sea level.
If you’re really off the grid, there are some signs from mother nature that you can look out for that might suggest that a tsunami is incoming:
- Severe ground shaking – It can be hard to decipher what an earthquake is if you’ve never experienced one, but if you feel severe ground shaking and you’re far away from train lines and airplanes, chances are it’s an earthquake.
- Receding shoreline – Just like the tide draws back before big waves crash, an approaching tsunami can cause the ocean to recede from the coast abnormally far, sometimes exposing reefs, fish, and fishing nets.
- Other abnormal marine activity – The sound of an approaching tsunami has been likened to that of a train or jet aircraft, often called an “ocean roar”. There’s a chance you could hear a tsunami before you see it, especially at night or if you’re inside.
If you experience any of these phenomena, don’t wait for official instruction and leave low-lying coastal areas for higher ground that’s further inland as soon as you can.
When was the last tsunami in Australia?
The 2011 Tohoku tsunami, originating from a 9.1 magnitude earthquake that struck off the northeast coast of Honshu on the Japan trench, was the last serious tsunami to reach Australia’s shores. The event produced 40-meter waves, devastating Japan and leaving more than 450,000 people without homes. Despite being almost 8,000 km from the activity site, effects were felt as far as Sydney where unusual currents were observed in the harbor and several swimmers were washed from the sea into the Merimbula lagoon in New South Wales.
Is Melbourne safe from a tsunami?
Melbourne might be flanked by the large Australian landmass from tsunamis originating in the Pacific Ring of Fire, but the coastal metropolis is not completely safe from freak waves. In fact, the effects of a 9.5 magnitude earthquake in Chile in 1960 were felt on Melbourne’s shores, where a number of boats were broken from their moorings by strong waves. Still, Victoria faces less tsunami risk than the northwest and eastern coasts of Australia, but the Cascadia Subduction Zone, the Alaska-Aleutian Subduction Zone, and local shallow crustal faults are all potential sources.
Did the 2004 Indian Ocean tsunami hit Australia?
The Boxing Day tsunami of 2004 was one of the world’s deadliest natural disasters, killing more than 230,000 people across 14 countries. It began when a 9.1 magnitude earthquake struck off the northern tip of Indonesian Sumatra and traveled as far as Tanzania and Australia. Australia didn’t experience devastation like that in Thailand, India, Indonesia, and Sri Lanka, but localized inundation swept through Western Australian towns and more than 30 swimmers had to be rescued. A total of 26 Australians lost their lives, but none of them were in Australia at the time.