The official height of New Zealand's tallest peak, Mt Cook,
will soon fall by 30m, after updated measurements by
University of Otago researchers.
The peak is still officially listed as 3754m above sea level,
but analysis of high-accuracy GPS data gained during an
Otago-led climbing expedition last November shows the
mountain is, in fact, only 3724m tall.
The readings confirm new calculations, based on aerial
photography, made by Otago National School of Surveying
researcher Dr Pascal Sirguey and master's student Sebastian
Vivero, with support from GNS Science and New Zealand Aerial
This is believed to be the first time the height of a major
New Zealand mountain has been adjusted after a study
conducted by university researchers.
And this is also understood to be the first time a modern,
relatively light-weight, survey-grade GPS device has been
carried close to the summit of a New Zealand mountain to
measure its height, officials said.
Dr Sirguey, the research project leader, said the old height
had been estimated from aerial photography immediately after
a massive rock-ice collapse on the mountain on December 14,
The discrepancy between the old and new heights could be
explained by a subsequent two-decades-long erosion and
reshaping process affecting the remnant of the originally
thick ice cap.
Despite being taken down a peg or two, Mt Cook still towers
above its close neighbour Mt Tasman, which, at 3497m high,
remains New Zealand's second highest mountain.
The four-person Otago expedition that obtained the GPS data
took place on November 23 last year and was led by Dr Nicolas
Cullen, a senior lecturer in geography.
To observe Mt Cook's tapu status, and as agreed with Ngai
Tahu, the climbers did not step on the summit, but instead
took GPS measurements while at the top of the ice cap, a few
metres below the true summit.
"Dr Sirguey said it had been ''very exciting'' to see that
the team's GPS data ''closely matched our photogrammetric
calculations from a 2008 aerial survey''.
''From early on in this work we suspected that Aoraki was
tens of metres lower that the official height,'' he said.
There had then been ''a bit of a jump into the unknown'' to
investigate the actual height.
Second-year surveying student Tyler Hager also undertook a
related ''tribute'' trigonometric survey of the peak, as part
of his summer scholarship work.