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Nov. 17th, 2006 01:21 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
stellar_muddleKiwi Crater 'Sign Of Mega Tsunami'
7/11/2006
NZPA
A meteorite-impact crater south of Stewart Island is being held by Australian researchers as evidence that enormous meteorite impacts may have relatively often caused tsunamis that dwarf ones seen.
Australian geomorphologist, associate Professor Ted Bryant of the University of Wollongong, said today that evidence of a mega-tsunami as recently as 500 years ago has been found on the eastern coast of Australia.
He and Assistant Professor Dallas Abbott from the Lamont-Doherty Earth Observatory at Columbia University in the USA have linked this to the impact crater south of Stewart Island.
The scientists have been seeking what they say is evidence of massive 1km-wide objects slamming into the Earth's oceans as recently as 500 years ago.
Prof Bryant told the ABC today there had been up to 10 such impacts in the past 10,000 years.
None of the research has been published but some of it will be presented at an American Geophysical Union meeting in San Francisco next month.
Earth scientist Professor Richard Arculus of the Australian National University said he accepted Prof Bryant's evidence of mega-tsunamis, but working out what caused them and when will require more evidence.
New Zealand-based tsunami expert Dr Mauri McSaveney of GNS Science said there was is pretty good evidence that there are more large craters on our planet than mainstream scientists think there should be.
But while Prof Bryant's claims were "perfectly plausible" and the best available evidence suggested the New Zealand crater was one from the Holocene period, this could still be wrong.
"He has yet to convince me and a lot of others," Dr McSaveney said.
Most critics are yet to be convinced there is evidence to back claims about such recent, frequent mega-impacts. Conventional wisdom has it that the Earth suffered such violent hits from space only twice every million years.
Prof Bryant said these would have caused mega-tsunamis 10 times bigger than the 2004 Asian tsunami, one of the largest earthquake-generated tsunamis the world has ever seen.
"Aceh was a dimple compared to what we're looking at," said Professor Bryant, who is associate dean of science at the university.
Prof Bryant used satellite images from Google Earth to identify inland dunes in the shape of arrowheads that he says are signs of mega-tsunamis.
He said the tsunamis would have displaced marine deposits containing marine fossils, dumping them inland as `chevron' dunes.
"We've found that chevrons are everywhere, everywhere around the world's coasts," he said.
Prof Abbot used sea surface altimetry, which measures the height of the sea surface to get an image of the seabed, to identify possible underwater craters, which could be evidence of the impact that caused the tsunamis.
Prof Bryant said Prof Abbot also looked for melted material in cores from the seabed around the craters to confirm impacts caused them.
The chevrons and craters were linked by the direction the chevrons were pointing.
Two chevrons identified 6km inland from the Gulf of Carpentaria in Australia both pointed north in the direction of two craters found in the Gulf of Carpentaria itself, Prof Bryant told the ABC.
Dating of sediments to the north of the craters suggested the impact happened 1500 years ago, and the well-preserved chevrons also dated to around the same time.
At least they are no longer arguing for it wiping out Chinese fleets in the 1500s...
Afraid I am with Dad on this. Especially given they have been working on this for a while now and have yet to publish. Publish then publicise is generally good practice.
7/11/2006
NZPA
A meteorite-impact crater south of Stewart Island is being held by Australian researchers as evidence that enormous meteorite impacts may have relatively often caused tsunamis that dwarf ones seen.
Australian geomorphologist, associate Professor Ted Bryant of the University of Wollongong, said today that evidence of a mega-tsunami as recently as 500 years ago has been found on the eastern coast of Australia.
He and Assistant Professor Dallas Abbott from the Lamont-Doherty Earth Observatory at Columbia University in the USA have linked this to the impact crater south of Stewart Island.
The scientists have been seeking what they say is evidence of massive 1km-wide objects slamming into the Earth's oceans as recently as 500 years ago.
Prof Bryant told the ABC today there had been up to 10 such impacts in the past 10,000 years.
None of the research has been published but some of it will be presented at an American Geophysical Union meeting in San Francisco next month.
Earth scientist Professor Richard Arculus of the Australian National University said he accepted Prof Bryant's evidence of mega-tsunamis, but working out what caused them and when will require more evidence.
New Zealand-based tsunami expert Dr Mauri McSaveney of GNS Science said there was is pretty good evidence that there are more large craters on our planet than mainstream scientists think there should be.
But while Prof Bryant's claims were "perfectly plausible" and the best available evidence suggested the New Zealand crater was one from the Holocene period, this could still be wrong.
"He has yet to convince me and a lot of others," Dr McSaveney said.
Most critics are yet to be convinced there is evidence to back claims about such recent, frequent mega-impacts. Conventional wisdom has it that the Earth suffered such violent hits from space only twice every million years.
Prof Bryant said these would have caused mega-tsunamis 10 times bigger than the 2004 Asian tsunami, one of the largest earthquake-generated tsunamis the world has ever seen.
"Aceh was a dimple compared to what we're looking at," said Professor Bryant, who is associate dean of science at the university.
Prof Bryant used satellite images from Google Earth to identify inland dunes in the shape of arrowheads that he says are signs of mega-tsunamis.
He said the tsunamis would have displaced marine deposits containing marine fossils, dumping them inland as `chevron' dunes.
"We've found that chevrons are everywhere, everywhere around the world's coasts," he said.
Prof Abbot used sea surface altimetry, which measures the height of the sea surface to get an image of the seabed, to identify possible underwater craters, which could be evidence of the impact that caused the tsunamis.
Prof Bryant said Prof Abbot also looked for melted material in cores from the seabed around the craters to confirm impacts caused them.
The chevrons and craters were linked by the direction the chevrons were pointing.
Two chevrons identified 6km inland from the Gulf of Carpentaria in Australia both pointed north in the direction of two craters found in the Gulf of Carpentaria itself, Prof Bryant told the ABC.
Dating of sediments to the north of the craters suggested the impact happened 1500 years ago, and the well-preserved chevrons also dated to around the same time.
At least they are no longer arguing for it wiping out Chinese fleets in the 1500s...
Afraid I am with Dad on this. Especially given they have been working on this for a while now and have yet to publish. Publish then publicise is generally good practice.
