Residents from hundreds of Illawarra streets would be required to flee in the event of a tsunami, new evacuation mapping released by the State Emergency Service shows.
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Until now the SES’s projections were based on the idea that a land-threat tsunami would affect properties 10 metres above sea level and one kilometre from Australia’s coast.
The new mapping factors in the inundation likely to occur around rivers and other waterways, said Illawarra South Coast SES region controller Greg Murphy.
“What these new maps do is they take into account the attenuation of the wave up river streams and bays,” he said.
“The best science available to us would suggest that the land-based tsunami would peter out by about 10kms upstream.”
The modelling shows a tsunami would pose scant threat to the high-lying neighbourhoods north of Austinmer.
From Thirroul to Wollongong, the evacuation zone spreads further in, cutting as far as the railway at several points, covering the stretch of tracks between Campbell Street, Woonona, and Bellambi Lane at Russell Vale.
The evacuation zone extends from the Northern Distributor to the coast for a 3.5km stretch between Fairy Meadow and Gwynneville.
It covers Campus East, Beaton Park, Keira High School and the steelworks at Port Kembla, where the water line extends inland to the Princes Highway.
All of Windang would be inundated, along with large sections of Lake Illawarra, Warilla, Yallah, Koonawarra, Kanahooka, Shellharbour, Dunmore, Minnamurra and Jamberoo.
Marine-threat tsunamis pose a risk to swimmers and boater about every six years, but no land-threat tsunami has been recorded in Australia since European settlement.
Stanwell Park surf scientist Dr Rob Brander said this was due to the steep and narrow continental shelf on the eastern Australian margin
“Tsunamis like to hit a big, wide and shallow continental shelf that slows them down and [allows them] to get bigger and bigger and bigger,” said Dr Brander, a coastal geomorphologist and Associate Professor at the University of New South Wales in Sydney.
“We haven’t got that. It’s not like we’re immune, but [Australia] is at the very, very low end of [tsunami risk].”
Dr Brander said the value of the SES’s mapping lay in awakening people to the need to get to higher ground quickly if the unlikely should happen.
“If there’s a tsunami warning and it’s severe, people need to heed that warning,” he said.
“Too often people are a bit complacent and they don’t take it seriously.”
