New Zealand tremor causes tsunami warnings

by BW Media on 16 Jul 2009 Alarm bells rang for the South East Australian coast weather forecasters yesterday when a New Zealand earthquake centred near Invercargill sent shock waves across the Tasman, and coastguard services quickly issued tsunami warnings.

The 7.8-magnitude earthquake struck off New Zealand's western coast Wednesday generating a small tsunami. No injuries or major damage were reported.

The Pacific Tsunami Warning Center in Hawaii warned that a tsunami was generated, but it later said the waves were less than 8 inches (20 centimeters) in height and the warning was canceled after about an hour.

'All available New Zealand and international data about the earthquake and sea levels showed that there is no tsunami threat to New Zealand,' said John Hamilton, director of the Ministry of Civil Defense and Emergency Management.

The quake's epicentre was 100 miles (161 kilometers) west of Invercargill, off the west coast of New Zealand's South Island at a depth of 21 miles (33 kilometers), the U.S. Geological Survey said. It hit at 0922 GMT on Wednesday.

There were two aftershocks, the first 6.1 magnitude around 20 minutes later, and the another 5.9 magnitude another four hours later.

However the Joint Australian Tsunami Warning Centre also issued a tsunami alert for eastern Australia that was still in effect late Wednesday.

With memories of the lack of warnings that accompanied the devastating tsunami which hit Asia on Boxing Day 2004, the authorities were quick to act, and even after the tsunami warning was cancelled within hours, the weather bureau says east coast beaches may experience abnormal wave conditions today.

On the mainland, people were advised to get out of the water and move away from the edge of harbours, rock platforms and beaches.

People on low-lying areas of Lord Howe Island were evacuated to higher ground, and the population of locals and tourists waited for five hours to see if there was was any out of the ordinary wave activity.

All warnings by authorities were cancelled at 1.00am Sydney time, Tony Leggett from the Bureau of Meteorology told the ABC it was better to be safe than sorry.

'From our perspective, the gauges that we've installed over the last four years worked, the software that we've installed was pretty good,' he said.

'We didn't really get a significant impact on Lord Howe that we thought we'd get, but you know that's unlikely that we'll ever really know why that is.'

Mr Leggett says the east coast can still expect unusual wave patterns throughout the day.

Editor's Note for Sailors: Sailors who experienced sudden inexplicable and dramatic shallowing of the water where they were anchored in Thailand at the onset of the 2004 tsunami, set to sea immediately to get into deep water. They then experienced hardly any wave motion as the tsunami passed under them. All were gravely shocked when they returned to the shore and saw the damage and loss of life.