Saturday, May 21, 2016

[Geology2] Tennant Creek 1988 earthquake now Australia's biggest after Geoscience revises list

Tennant Creek 1988 earthquake now Australia's biggest after Geoscience revises list

Updated 12 May 2016, 5:12pm

An earthquake recorded near Tennant Creek in the Northern Territory in 1988 is now considered Australia's largest ever, snatching the title from Western Australia.

Key points:

  • 1941 WA quake slips from biggest to fifth biggest
  • Historic quake severity revised using new methods
  • No magnitude 7 quakes in Australia since records began in late 1800s

Geoscience Australia has revised the magnitudes of the country's biggest earthquakes as part of an international project using new technology to more accurately reflect their sizes.

Senior seismologist Spiro Spiliopoulos said the magnitude 6.6 earthquake, recorded south of Tennant Creek, was one of three in the area on the same day, with thousands of aftershocks felt throughout the Northern Territory.

"Under the current revision, the Tennant Creek earthquake from 1988 is now the largest earthquake in our historical database," Mr Spiliopoulos said.

"Previous to that the largest earthquake that we thought had occurred in Australia was one in Western Australia called the Meeberrie earthquake which had a magnitude of about 7.2 or 7.3 in 1941."

The data revision has seen the Meeberrie event downgraded from 7.2 to 6.3, which sees it slip from first to fifth on the list of severity.

"The shaking at Meeberrie homestead was very severe; all the walls of the homestead were cracked, several rainwater tanks burst, and widespread cracking of the ground occurred," Geoscience Australia said.

"Minor non-structural damage was reported in Perth more than 500 kilometres away from the epicentre."

The Tennant Creek series of three quakes in 1988 now come in at number one, four and seven on the list of severity.

Geoscience Australia said the country had not experienced a magnitude 7 earthquake since record keeping began in the late 1800s.

While there was evidence of earthquakes above magnitude 7 occurring in Australia over the past 100,000 years, Geoscience described them as "very rare and thousands of years apart".

'I've had a good innings, if I go I go'

Nigel Skelton said he was working in the Tennant Creek library at the time the 1988 quake struck and said the noise was "terrifying".

"An elderly lady who regularly came in on Friday mornings had arrived at the door, as we opened the doors," Mr Skelton told the ABC.

"And then when this rumbling starts, of course I'm trying very hard to get her out the door ... ceiling tiles were falling on us."

"As she's shuffling her way out the front door she says 'Oh, I've had a good innings, if I go I go", and I'm behind her thinking 'I haven't had mine yet, hurry up!'"

Noel Marsh, who has lived in Tennant Creek for 33 years with wife Andrea, said he can remember when the shaking started.

"There was a very loud rumbling noise, like a train passing. It lasted for about 10 or 15 seconds," Mr Marsh said.

Baby almost left behind

While the older Marsh children were at school, their baby was in the cot and was almost left behind as the frightened family fled the house.

"We all panicked a little bit, tried to get out ... somebody remembered where the baby was. We retrieved the baby and all left the house," he said.

Mr Marsh said the earthquake was the talk of the town.

"It was a major event. We went out and saw where the centre of it was ... it opened up the ground for about five k's, about two metres wide and about three metres deep.

"The strength of the earthquake must have been fantastic because it also passed underneath the gas pipeline and twisted the pipe up pretty badly, too."

Mr Marsh said the quake was an important part of Tennant Creek's history.

"It was an experience and I don't want that experience again."

"We had one [an earthquake] about three weeks ago, it was only minor though."

Magnitude post-2016 revisionsMagnitude pre-2016 revisionsLocationDate
6.66.7Tennant Creek, NT1988
6.56.9Meckering, WA1968
6.45.6Simpson Desert, NT1941
6.36.4Tennant Creek, NT1988
6.37.2Meeberrie, WA1941
6.26.3Collier Bay, WA.1997
6.26.3Tennant Creek, NT1988
6.16.2Cadoux, WA1979
6.06.0West of Lake Mackay, WA1970
6.06.0Warooka, SA1902

Source: Geoscience

Despite not making the top ten, the 1989 Newcastle earthquake in New South Wales is widely regarded as Australia's most devastating earthquake, in terms of damage and cost.

The magnitude 5.6 quake killed 13 people, injured 160 and caused damage to more than 35,000 homes, 147 schools, and 3000 commercial and other buildings.

The damage bill of the Newcastle earthquake has been estimated at $4 billion, including an insured loss of more than $1 billion.



Posted by: Lin Kerns <>


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