By SIMON COLLINS, science reporter
An international scientific expedition will fly to Stewart Island next week on a quest to track down a meteor that may have sparked a tsunami that possibly wiped out a legendary Chinese fleet 500 years ago.
Expedition leader New York oceanographer Dallas Abbott has found survey evidence of a huge undersea crater caused by a meteor impact 20km wide and more than 153m deep just south of the Snares Islands, 120km southwest of Stewart Island.
The expedition is going to remote Mason Bay on the west coast of Stewart Island to look for evidence of a "mega-tsunami", sparked by the meteor, which may have dumped sand up to 150m above the present sea level.
Wollongong University geographer Ted Bryant, who will join the party, believes the tsunami may have swept as far as the east coast of New South Wales, where he has found evidence of waves up to 130m high that hit about AD 1500.
Australian author Gavin Menzies has claimed the mega-tsunami as a possible cause of the destruction of all but one of more than 100 ships which he says were dispatched by China to circumnavigate the globe in AD 1421.
However, New Zealand tsunami expert Dr James Goff visited Mason Bay in December and said there was no evidence either that the tsunami occurred there as recently as 1500, or that it was caused by a meteor.
Dr Goff, who came here from Britain 10 years ago, recruited Maori novelist Keri Hulme and former Conservation Department archaeologist Bruce McFadgen to co-author a devastating attack on Professor Bryant's previous research in the December issue of the Journal of the Royal Society of New Zealand.
The trio said that in a controversial 2001 book on tsunamis, Dr Bryant created a "geo-fantasy" about a meteor that he said exploded in the sky above Tapanui, west of Dunedin, around 1500.
They alleged that he misinterpreted a Maori legend about the "fires of Tamatea", misunderstood Maori place names, and identified a "meteor impact crater" at Tapanui which was in fact debris from a landslide.
Dr Goff said Dr Bryant had now latched on to Dr Abbott's evidence of an undersea meteor crater near the Snares Islands "because unfortunately his meteor exploding above Tapanui didn't work".
"He is desperately searching for some evidence for his possible events, which are incorrectly dated anyway," Dr Goff said.
Dr Abbott told the Geological Society of America in November that the Snares Islands meteor appeared to have hit only about 500 years ago because glassy rocks called tektites that were scattered around the ocean after the impact were still sitting on the seafloor - not covered by mud as expected if they were any older.
She said she was now seeking radiocarbon dating to prove the tektites' age.
But Dr Goff said the tektites around the Snares were "more likely to be 100,000 years old", and the sand Dr Abbott was investigating high up at Mason Bay had not yet been dated.
"There is undoubtedly a deposit there. Stewart Island gets incredibly big storms and yes, it's had a tsunami hit in the past," he said. "It's the dating of the event that is unproven, and I don't know that there is enough proof yet that there was a meteor impact at the site that she suggests."
Dr Bryant told the Herald from Wollongong that he agreed that the date was uncertain, but he said Dr Abbott found the Snares Islands crater in exactly one of the areas where he told her to look in order to account for the New South Wales mega-tsunami around 1500.
He said the words that he interpreted from the "fires of Tamatea" legend were not in Maori, but in the language of a "pre-Maori" people called Waitaha.
When they arrive at Mason Bay next Saturday, he and Dr Abbott plan to inspect piles of logs that have been observed 60m to 80m above the present sea level.
They will also look for a 20cm dust layer which Dr Abbott believes would have been dropped over the island if the meteor theory is correct.
Dr Mauri McSaveney, of the Institute of Geological and Nuclear Sciences in Lower Hutt, said he planned to take 10 days' annual leave to join the expedition because of its extraordinary goals.
"I'm interested enough that I'm not going to let the opportunity go," he said. "A lot of evidence for a lot of Ted Bryant's things are not valid. But some of it is. Occasionally people have been right for the wrong reasons."
Huge waves in history
* Tsunamis are high sea waves usually sparked by earthquakes, volcanic eruptions or other geological disturbances - and sometimes by meteors.
* More than half (53.3 per cent) of the Earth's tsunamis occur in its biggest ocean, the Pacific.
* Scientists agree that both New Zealand and eastern Australia were hit by unusually large tsunamis in the mid-15th century.
* NZ scientists James Goff and Bruce McFadgen say known earthquakes and the eruption of Rangitoto Island were enough to explain these tsunamis.
* But Australian Ted Bryant and American Dallas Abbott believe one "mega-tsunami" may have been caused by a giant meteor south of Stewart Island.
By SIMON COLLINS, science reporter