A computer graphic shows the possible path of tsunami waves from an earthquake in Chile while Dr. Charles McCreery speaks on the phone at the Pacific Tsunami Warning Center on Feb. 27, 2010 in Ewa Beach, Hawaii. Hawaii was among the areas under a tsunami warning after an 8.8 magnitude earthquake hit Chile. (Marco Garcia, Associated Press)

People who defied beach warnings in Australia over the weekend may not understand the danger posed by tsunamis, says an expert who has called for more research into risk behaviour and public education.

Associate Professor Dale Dominey-Howes, of the Australian Tsunami Research Centre and Natural Hazards Research Laboratory in Sydney, has made the call in the wake of the tsunami that sped across the Pacific after the weekend's devastating Chilean earthquake.

While this particular tsunami did not inundate Australia's coast, Dominey-Howes said extra-strong currents caused by the tsunami could have swept swimmers out to sea.

"The speed of flow in a tsunami as it goes in and goes out is significantly higher than a rip," Dominey-Howes said. "We've had notable, awful tragedies of people drowning in rips."

Warnings defied

Hundreds of people continued swimming at Australia's most famous beach, Bondi, after the tsunami warning had been issued, says Phil Campbell from the NSW Government State Emergency Services.

"Those people who did go in the water were very much a minority," says Campbell, adding that a normal hot summer's day could see as many as 50,000 people at the Sydney beach.

But while generally pleased with the public response, Campbell says the emergency service is concerned about those who did not heed the warnings.

Research by Dominey-Howes and colleagues shows there is some evidence that people don't understand the true risk of tsunamis.

"Where we don't have these events very often, there's a general low public awareness of the hazard," says Dominey-Howes.

"Unless you actually have personal experience, you generally don't really appreciate the risk very highly."

Feeling of invincibility

Even when there are warnings of a tsunami that will inundate the land, people tend to overestimate their capacity to react and respond, says Dominey-Howes.

"Video footage from the 2004 Indian Ocean disaster shows people standing on beaches in Phuket in Thailand, watching the ocean withdraw and being frozen, mesmerized," he says.

"They're not running away, saying 'oh gosh this could be terrible'. They are transfixed by this process that they have no experience of."

"By the time they realize that the ocean is surging back towards them as this frightening wall of water, it's too late. Because that wall of water is moving at 40-60 kilometres an hour."

Marine warning

Australia's Bureau of Meteorology's Joint Tsunami Warning Centre issued a marine warning. The warning is designed to warn against strong currents that can be a threat to people and boats.

Dominey-Howes says surveys after previous tsunami alerts suggest another possible reason for a lack of action is that people don't believe the authorities' claim there is a risk.

Still another possible reason is people accept the risk or are fatalistic — they believe "what will be, will be."

Dominey-Howes says more socially oriented research is needed to probe the reasons people defy warnings.

"Are the communication messages working? If not, what would the public like to see that would make them say 'okay, I believe that message, and I would react'," he says.

But there will only be so much that authorities can do to understand people's behaviour and develop risk communication strategies to influence as many people as possible, says Dominey-Howes.

"Ultimately there's a degree of personal responsibility."

Flawless warning system

While the anticipated surge did not happen, the detection, monitoring and early warning methods of Australia's tsunami warning system itself "worked flawlessly," says Dominey-Howes.

"The issue that arose this weekend is with regard to what we refer to as 'the last mile,'" he says. "That's the bit where the emergency service agencies … communicate that warning message to the public."

Campbell agrees more work is needed to ensure people understand what a marine warning is and the particular threat it poses.

"People were expecting to see large waves down at the beach," says Campbell, adding that it is a challenge to communicate risks from currents that are under the waterline.

"Just because you can't see the effects that are there, it doesn't mean the area is safe," he says.