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The Himalayas K2

How high is K2 really ?
Mountaineer Mario Panzeri measuring the depth of snow on the peak of Mount K2.
Background

After the initial measurements of the Himalayan peaks carried out by the British India Survey in the middle of the XIX century other measurements followed for Mt. Everest (1904, 1954, 1975, 1992), Kanchenjunga and Dhawlagiri.

Another team followed in 1998. This article is the first in the REPORTER to describe the major international Mt. Everest measurement campaign of 1992, and the remeasuring of K2 in 1996. On this 150th anniversary, the comprehensive results achieved by the original surveyors under George Everest and Andrew Waugh still remain impressive.

However, a completely different situation surrounds K2, the second-highest mountain on earth: it was only in 1986, some 120 years later, that George Wallerstein rekindled interest in the height of K2. His claim that K2 might be even higher than Mt. Everest triggered fascination among his peers, and a storm of sensationalism in the international press. Subsequent remeasurement by Alessandro Caporali and Ardito Desio already disproved the claim. Reports by the research expedition described here under professor Giorgio Poretti, scientific leader of the major Mt. Everest and K2 remeasurements, again revealed that the assumption was no longer tenable. K2 remains in the shadow of Mt. Everest.

Latest measurements

When Alessandro Caporali and Ardito Desio remeasured K2 in 1986 a global positioning system (WM 101) and laser distance meters for the measurement of the base lines were employed for the first time. Leica TC2000 total stations were aimed at the snow covering of the summit of the mountains. The measurement of Caporali was performed from Concordia at a distance of about 15 km. The ellipsoidal height GPS turned out to be 8579 metres. The geoid-ellipsoid separation deduced from the global geoid was of -37 metres and therefore the geoidal height of K2 turned out to be 8616 metres.

In 1996, a research expedition led by the author set out to verify this height using a combination of modern equipment, and concepts tried out during the remeasurement of Mt. Everest. The base network for the measurement of K2 was formed by a triangle with two points (C and E) located on bedrock and one (G) on the glacier’s moraine. To define the movements of the Godwin Austen Glacier, a special measuring project was carried out. The point G was linked to a point located at the "K2 Motel" in Skardu at a distance of about 98 km. This point was later linked to a fundamental trigonometric point (TR) of the triangulation network of Pakistan located on the rock above the Fort of Skardu.

The Geological Survey of Pakistan provided the coordinates of the trigonometric point from which the ellipsoidal height of the point at the K2 Motel was computed at 2222.583 metres. A 30 hour GPS session linked the K2 Motel to the G point at K2 Base Camp establishing an elevation of 4934.338 metres for it. The average height difference between the Base Camp network and the summit was 3656.920 metres, giving for the summit the ellipsoidal height of 8591.258 metres at snow level.

Taking into account the depth of the snow of 2.22 metres and the ellipsoid-geoid separation 25.23 m derived from the NASA/DMA 1996 Global Geoid the elevation of the rock top of Mount K2 was computed as 8614.27 ±0.6 m a.s.l.

Results for K2 from 1996 measuring campaign

Skardu K2 Motel                                       2222.583 ± 0.3
Base Camp-G point                                   2711.755
G point-summit                                         3656.920
K2 ellipsoidal height                                   8591.258 (at snow level)
Ellipsoid-geoid separation                           25.23
Depth of snow                                           2.22
Height                                                      8614.27 ± 0.6 a.s.l.

All heights in meters