No-show tsunami proved a good test

THE effect of Wednesday night's earthquake off New Zealand's south-west coast was recorded as a jagged line on Newcastle Port Corporation's tidal graph.

The graph, which uses data taken from a floating gauge at the Newcastle pilot station, shows the tide dipped about 10 centimetres below what was expected just after 9pm.

The sawtooth tidal pattern can be seen on the Newcastle graph for the next 11 hours, but no practical implications were seen along the coast.

The weather bureau said Australia's tsunami warning system had passed its biggest test yet and that the nation was well placed to meet any future threat.

Coast guards, police and fire services along Australia's east coast were on tsunami alert on Wednesday night after the quake.

People were told to get out of the water and keep away from harbours, rock platforms and beaches as the threat of tidal waves loomed.

Six hours later, the warnings were cancelled but head of weather services Ray Canterford, who helps manage the country's tsunami offensive, said the marine warnings proved Australia's tsunami technology was on track.

"I would say we were probably 90 per cent successful, but there's always room for improvement," he said.

Coastal monitoring group Coastalwatch plans to install a network of shore-mounted videos within the next 12 months, which will allow real time monitoring of tidal fluctuations in the case of a tsunami alert. with AAP