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Seismic Investigations on the Nordaustlandet Ice Caps

1971; Taylor & Francis; Volume: 53; Issue: 1 Linguagem: Inglês

10.1080/04353676.1971.11879830

1468-0459

Stig-Rune Ekman,

Landslides and related hazards

Seismic refraction and reflection measurements made on Nordaustlandet, Spitsbergen, during the Swedish Glaciological Expedition in 1958 are reported. A standard six-channel refraction instrument was used and one refraction profile and 76 refraction stations were shot on the two main ice caps.Previously the Nordaustlandet ice caps were thought to be very thin and more or less stagnant. The seismic profiles, however, show ice thicknesses of more than 500 m on Austfonna and more than 300 m on Vestfonna. The ice seems to rest in large depressions, partly surrounded by marked ridges. The partly subglacial ridges damming up the eastern side of Vestfonna and the western side of Austfonna give a likely explanation of the existence of Rijpdalen, the ice-free valley separating the two ice caps. A maximum ice thickness of 576 m was recorded in the central part of Austfonna; the lowest bed elevation recorded was 3 m above sea-level in the northeastern part.The refraction profile on Vestfonna gave a longitudinal-wave velocity of 3750 ms-1 and a transverse-wave velocity of 1870 ms-1. The thickness of the from in the central part of Vestfonna was computed from the seismic data to be 28 m, where the total ice thickness was 375 m.Symbols and units are listed at the end of the paper.