Tsunami warning passes its test

Chris Ryan, the chief meteorologist in the joint Australian Tsunami Warning Centre, says the new system passed its first real test with flying colours.

SYDNEY // Australia's new tsunami warning system has been heralded a success after a major undersea earthquake off southern New Zealand triggered a full-scale alert. The sophisticated network of deep ocean sensors and sea-level gauges was built in response to the devastating Indian Ocean tsunami in December 2004. It estimates the approximate arrival time and size of unusual wave patterns. The recent emergency in July was the first real test for the Australian mechanism, where an alert was issued within 20 minutes of the seismic shocks in the Pacific Ocean near New Zealand. "We coped extremely well. The tsunami warning system we have here in Australia is world class," said Daniel Jaksa, the project's leader at Geoscience Australia, which runs the scheme in partnership with the Bureau of Meteorology. Australia's defensive shield grades tsunamis in a similar way to earthquakes, where some are more powerful and menacing than others. The quake off New Zealand generated what scientists called a marine threat, where there was no risk of damage to life or property on the coast. A land threat is far more ominous and would indicate that large waves were surging towards the shoreline. While mainland coastal regions and parts of Tasmania were issued with the less severe warning, Lord Howe Island, a remote Australian territory, was told to prepare for a potentially ferocious onslaught of wild waves. "We activated our tsunami response plan. We were advised to evacuate people in low-lying areas to higher ground," said Greg Pierce, a senior administrator on the island, a remnant of an ancient volcano that is perched in the Pacific, 600km east of Australia. About a third of the population of 400 people were urged to leave their homes on a cold evening in the middle of winter, with anxious residents wondering what might be coming their way through the darkness. "We had most people up onto the evacuation site by 9.45pm. The tsunami was predicted to arrive at Lord Howe Island around 10pm," Mr Pierce added. "We're pretty confident we can react appropriately and don't forget in this particular alert we only had a reasonably short time - only an hour-and-a-half maximum - between the first notification and the predicted arrival time." In the event, the crescent-shaped island was spared a serious pounding and, although a tsunami did strike, it was only minor, but it did send an abnormally large swell rolling onto Australia's eastern seaboard. "Our deep-ocean buoy recorded a small tsunami going past in the southern Tasman Sea," said Chris Ryan, the chief meteorologist in the joint Australian Tsunami Warning Centre. "On the Australian coast our tide gauges definitely recorded a tsunami arriving around about 10pm. "Many people associate the word tsunami with huge, destructive waves. "That is the most extreme form of the threat but you can also get relatively small tsunami waves which can be dangerous for people on the beach or in small boats." His colleague Mr Jaksa agreed: "You can be standing in water 30cm high when a tsunami comes through and it'll drag you tens of kilometres out to sea and that has happened many times in Australia's history." While experts have applauded the system's performance, there are those who believe it has fundamental flaws because some exposed settlements remained oblivious to the danger. "A large number of people who weren't watching television or listening to the radio didn't know that there was any threat until the following morning," Craig Ingram, an independent MP in the Victorian state parliament, said. "There is a large number of communities along that section of coast where there was really no information about the threat." While Australia does not face the same risk of major tsunamis as Indonesia, the Philippines, Vanuatu or Japan, potential dangers still lurk beneath the ocean. "If a magnitude nine earthquake occurred north or south of New Zealand, in the Solomon Islands or even south of Sumbawa Island in Indonesia, there would be some pretty interesting and decent-sized waves hitting the coast of Australia," Mr Jaksa warned. [e-mail]