Sunday, November 9, 2014

Mahuika Crater

In 2003, a member of the Holocene Impact Group named Dallas Abbott and her colleagues from the Lamont-Doherty Earth Observatory of the Columbia University published a paper that identified the location of a submarine crater on the southern edge of the New Zealand continental shelf, just south of the Snares Islands, 120km southwest of Stewart Island. It was given the name Mahuika crater. The crater is 20 ± 2 kilometers wide and over 153 meters (501 feet) deep. Based on elemental anomalies, fossils, and minerals, Abbott argues that an impact event occurred around 1443 AD. (568 years ago). A later study by Edward Bryant placed the impact date on February 13, 1491.

Around the year 1400, the natives of New Zealand abandoned their southern coastal settlements and moved inland. A large number of volcanic eruptions occurred in New Zealand during the 15th century. Rangitoto Island was formed in the Hauraki Gulf near Auckland. A collection of animal species became extinct in New Zealand towards the end of the 15th century, including the moa, which were eleven species of flightless birds, the giant Haast’s Eagle, and the flightless predatory Adzebills.

Researchers were attracted to the area after it was discovered that a large collection of beach sand is present on Stewart Island 220 meters (721 feet) above sea level at Hellfire Hut and 150 meters (492 feet) above sea level at Mason Bay. In eastern Australia, there are megatsunami deposits with maximum run-ups of over 130 meters (426 feet) and a C-14 age of 1500 AD. Megatsunami deposits also occur on the eastern side of Lord Howe Island in the middle of the Tasman Sea, implying a source crater further east, which is towards the Mahuika crater.

The largest historical earthquakes on record have produced a maximum tsunami range of 40 to 60 meters (131-196 feet). Abbott et al. has suggested that a bolide impact, including the collision of a large meteorite, asteroid, comet, or other celestial object, would explain both the geological and anthropological evidence better than an earthquake. The most reliable and widespread evidence found at the site are natural glass rocks called tektites. Tektites form when a massive impact liquefies its target and sends melt into the atmosphere. The Mahuika tektite field contains glassy tektites that appear orange, light green, and clear in visible light. Tektites have been found over 220 km from the crater.

Wollongong University geographer Ted Bryant believes the tsunami may have reached the 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 that a mega-tsunami could have caused the destruction of all but one of 100 ships he says were dispatched by China to circumnavigate the globe in AD 1421. The New Zealand tsunami expert Dr James Goff disagrees with the claims and says there is no evidence that an impact event occurred so recently. The discovery of the Mahuika crater remains a controversial subject.

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