In this explainer series, 9news.com.au is examining the concerns and fears around natural disasters, examining potential impacts on Australia.
For thousands of years, myths and legends have swirled around large destructives waves that have crashed onshore, claiming lives and destroying homes.
The civilizations at the time believed these waves were sent from higher powers, but science now tells us they could have been tsunamis; a Japanese term comprised of two words,"tsu", which means harbour, and "nami", which means "wave".
Here we break down what we know about tsunamis, including where in Australia they are most likely to occur, and where they have hit in the past.
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What is a tsunami?
The National Oceanic and Atmospheric Administration (NOAA) defines a tsunami as "a series of waves caused by earthquakes or undersea volcanic eruptions."
"As the waves travel inland, they build up to higher and higher heights as the depth of the ocean decreases," it explains.
"The speed of tsunami waves depends on ocean depth rather than the distance from the source of the wave."
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Professor Phil Cummins, a senior seismologist at Geoscience Australia, told 9news.com.au it's important to understand a tsunami isn't just one wave.
Instead he prefers using the analogy of ripples in an ocean.
"I define a tsunami as an ocean disturbance, caused by a rapid displacement of a large body of water," he said.
"If you threw a stone into a pond there would be a single disturbance, but there would be many ripples that go through the pond.
"Those ripples, are part of that disturbance."
There are two types of tsunamis; local and Far Field, or distant tsunamis, which are generated from a long way away.
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What was the largest tsunami in history?
The largest recorded tsunami occurred in a place called Lituya Bay in Alaska on July 9, 1958.
An 8.3 magnitude earthquake occurred along the Fairweather Fault and triggered a debris avalanche.
The rushing fall of rocks and debris created a colossal wall of water measuring more than 500 metres tall.
Five people died in the disaster, but Howard Ulrich, a father who was out fishing with his son, managed to survive.
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"They had the anchor out, and he couldn't pull it in in time," Cummins said.
"The father turned to his son and told him to pray, and somehow they lived.
"A boat can survive a tsunami, as it can just float over it."
When was the last tsunami in Australia?
According to the Bureau of Meteorology's (BoM's) records, the last tsunami waves to hit Australia arrived on March 11, 2011.
These were linked to the TÅhoku earthquake in Japan, which triggered destructive tsunami waves up to 40-metres high in the Asian country.
It's estimated more than 18,000 people died in the natural disaster, which also sparked the Fukushima nuclear meltdown.
The effects in Australia were far less severe.
A 56 centimetre wave was observed at Norfolk Island, a 35 centimetre one at Port Kembla in New South Wales, and a 23 centimetre wave at Spring Bay in Tasmania.
"Unusual currents were noted at Port Kembla and Sydney Harbour," BoM said.
"(And) several swimmers were washed into a lagoon at Merimbula, NSW".
Also of note, is an eight-metre tsunami observed in Steep Point, Western Australia in 2006.
This occurred after a earthquake in Java, Indonesia.
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"That was the largest run-up ever measured in Australia," Cummins explained.
"The run-up, is the maximum height the wave measured on land.
"It was somewhere around seven to eight metres."
The wave destroyed "several campsites" and there was evidence of inundation up to 200 metres inland.
And on May 23, 1960 small tsunami waves were also observed across Queensland, NSW, South Australia, Victoria and Tasmania.
This was linked to an earthquake in Chile.
"It was certainly observable in Sydney Harbour without instruments," Cummins said.
"I think it was about a metre on the tide gauge. It tore boats from their moorings and caused strong currents."
Where in Australia is a tsunami more likely to occur?
Cummins said there are two areas around the country's coast deemed most at risk of tsunamis.
"The one that worries me most is the south-east coast, that urban area around Sydney," he said.
"That could potentially be affected if there was a large earthquake south of New Zealand, which could also affect the eastern coast of Tasmania.
"Sydney is more vulnerable, simply because there's more people, a lot close to the beach, and the density of construction."
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Cummins added that the north-western coast of Australia has experienced the most frequent tsunami waves in the past, but two factors minimise the impact.
"As it so happens that coast is also affected strongly by tropical cyclones," Cummins said.
"First of all there aren't that many big cities, but secondly, the settlements tend to have moved up the beach a bit to avoid storm surges associated with cyclones.
"So, I don't think the risk is so high on the north-west coast even though it does experience the most frequent tsunamis."
How vulnerable is Australia to tsunamis?
While Australia is at risk of tsunamis, Cummins said the country is in a relatively safe position due to its distance from neighbouring countries and subduction zones, which are where two plates collide.
"The main sources are south of New Zealand, because normally it's a subduction zone that causes the very large thrust earthquakes, which causes very large tsunamis.
"There's subduction south of New Zealand and north."
How long would it take for a tsunami to hit Australia?
Should the worst case scenario occur and a strong earthquake hit off the coast of New Zealand, Cummins said the mainland would have about two hours warning before the waves started to arrive.
"That's a pretty quick time for it to hit," he said, before adding some good news.
"But so far we haven't recorded a really large earthquake, even historically, in those areas."
The other potential tsunami source would be South America.
"You do have a lot of warning for that particular source," Cummins said.
"These days we would be well aware it's on its way, and a pretty good idea of even the height.
"You'd have at least 12-hours warning. That's plenty."
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Is there a warning before a tsunami?
The short answer to this is yes, at least in Australia.
Local tsunamis, which are experienced in countries like Japan, Indonesia and New Zealand, can arrive in as up to as little as 30-minutes, but Australia doesn't face this threat.
Our country is also protected by the "world class" Joint Australian Tsunami Warning Centre (JATWC), which provides 24 hour tsunami monitoring, assessment and warnings.
https://twitter.com/BOM_au/status/1588704954474459141"For us, another thing that can be done is to use the GPS satellites," Cummins explained.
"As it turns out a tsunami, even though it may only be a metre or so high in the open ocean, disturbs the atmosphere."
"As that disturbance propagates upwards it gets to be quite large and affects the ionosphere, and that affects the signals of the GPS satellites.
"That may be helpful for Australia, as we have more time to deal with it."
Cummins added earthquakes themselves can serve as warnings for local tsunamis.
"There are rules for various countries," Cummins explained.
"But 'strong, long, and get gone', is what New Zealand says.
"If there's strong shaking that lasts for a long time, get up hill."
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