School of Civil, Environmental and Mining Engineering

CEME coastal engineer detects tsunami during Rottnest swim

ChariRottness

Professor Chari Pattiaratchi

Professor of Coastal Oceanography

23 March 2016

Professor Chari Pattiaratchi had the opportunity to mix two of his great loves—science and swimming—last weekend, but with some unintended results.

He took part in the 20-kilometre Port to Pub swim to Rottnest Island and had used ocean current modelling software to help chart the best course to follow. However, the modelling also predicted something else: a weather-induced meteotsunami striking while the swimmers were on their way to the island.

While tsunamis are usually caused by earthquakes or subsea landslides, a meteotsunami is caused by meteorological conditions. Though not as deadly as normal tsunamis, they occur occasionally off WA and around the world.

Prof. Pattiaratchi is the head of Coastal Oceanography within the School of Civil, Environmental and Mining Engineering (CEME) at UWA.

“The CEME Coastal Oceanography group had been predicting currents for the race using the operational ocean current models that have been developed at UWA,” Prof. Pattiaratchi says.

“The model predictions were used to chart the most efficient course to Rottnest Island using the swim tool developed by CSIRO.”
He says the weather was quite good when the swim got underway, with easterly winds pushing swimmers towards Rottnest Island. That soon changed.

“Between 11am and midday, the sea became quite rough for a period of about 20-30 mins with a lot of white caps—winds were from the north-east and there were a few droplets of rain, obviously part of a squall,” explains Prof. Pattiaratchi.

“The passage of the squall from north to south created a meteotsunami which was recorded at Hillarys Boat Harbour tide gauge as predicted in the models.”

Prof. Pattiaratchi has already been dubbed ‘Dr Tsunami’ for his expertise involving tsunamis and he was in Sri Lanka when the 2004 Boxing Day tsunami struck, killing an estimated 250,000 people. He now has another tsunami claim to fame.

“I think I can now claim the unique distinction that I have first-hand experienced a seismic tsunami (the 2004 Boxing Day tsunami) and a meteotsunami, the 2016 meteotsunami off Rottnest!” he says.

Prof. Pattiaratchi’s love of swimming stretches back decades and he is a former Welsh and English universities swimming champion.
“It was just over 41 years ago, as a fit and lean 17-year-old that I completed my previous ocean race, the annual two-mile sea swim in Sri Lanka, in around 40 minutes,” he says.

“I think I swam the same distance for the Rottnest swim.”

For the record, his team completed the 20-kilometre swim to Rottnest in six hours and 35 minutes.

—Tony Malkovic

RottnestChannelSwim 

Image (Click image to enlarge): The best route to Rottnest. The UWA/CSIRO modelling shows predicted waypoints (red markers) and the actual swim course (white squares) for Professor Pattiaratchi’s team.


 

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Wednesday, 23 March, 2016 3:03 PM

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