Jökull - 01.01.2016, Side 29

First documented surge of Kverkjökull, central Iceland
Table 1. A summary of the quantified geometry changes during surges or extended quiescence periods of land-
terminating glaciers. For interest and comparison, King et al. (2015) tabulate similar parameters of surges of
ocean-terminating glaciers. ++ note that elevation changes occur over different time periods, * note that the
elevation changes took place over 46 years during a period of quiescence and indicate the magnitude of elvation
changes resulting from a surge. – Yfirlit um breytingar á þykkt og lögun framhlaupsjökla sem stöðvast á landi.
Til samanburðar gefa King o.fl. (2015) svipað yfirlit um framhlaupsjökla sem ganga fram í sjó. ++ athugið að
breytingar í hæð eiga sér stað yfir mismunandi tímabil. * athugið að breytingar í hæð taka til 46 ára tímabils
milli framhlaupa og gefa til kynna umfang breytinga sem eiga sér stað af völdum framhlaups.
Glacier Timing / Terminus Max. elev. Volume Max. Surge Refs.
duration pos. change changes (m) displ. surface mechanism
(km) in receiving and (km3) velocity
reservoir zones++ (m day−1)
Variegated glacier, 1982 to NA +110 ≈5 x 108 65 hydrological Kamb et al., 1985;
Alaska 1983 −60 Raymond, 1987.
Metvezhiy glacier, 1963 and NA 120 NA 100 hydrological? Dolgushi and
Pamir 1973 Osipova, 1975.
Horcones Inferior gl., 2002 to +3.1 +36 −1.1 x 108 14 hydrological Pitte et al., 2016.
Argentina 2006 −72 +1 x 108
8 Karakorum various up to NA NA 5.5 thermal Quincey et al.,
glaciers +2.4 [from max. of] 2011, 2015.
[2000 m yr−1]
Karakorum NA NA +16 m yr−1 NA NA NA Gardelle et al.,
−16 m yr−1 2013.
Black Rapids gl., between 1949 NA −249 m∗ NA NA NA Shugar et al.,
Alaska and 1995 +63 m∗ 2010.
central Yulinchuan 2008 to 0.59 Not NA 13 NA Guo et al.,
glacier, Tibet 2009 studied 2013.
36 of 50 glaciers various NA e.g. +40 m for NA NA NA Sund et al.,
on Svalbard Kroppbreen 2009.
3 of 50 land-terminat- NA NA NA NA NA NA Arendt et al.,
ing glaciers in Alaska 2002.
31 glaciers various 0.1 to >100 m NA >0.5 hydrological 2003
in Iceland 10 2003.
Kverkjökull 2009?– ? +20 5 x 107 1? hydrological this paper.
2013 ? −20?
surging glaciers, finding equal thinning and thicken-
ing rates of ∼16 m yr−1 in reservoir and receiving
zones. In Iceland, all the 26 surging glaciers that have
been identified (Björnsson et al., 2003; Björnsson and
Pálsson, 2008) are land-terminating, although some
of them end in pro-glacial lakes along a part of the
terminus, and spatially-distributed elevation changes
during several surges of the lobate type Vatnajökull
outlet glaciers have been mapped (Björnsson et al.,
2003; Aðalgeirsdóttir et al., 2005).
The aims of this study are therefore to (i) analyse
in unprecedented spatial detail the surface elevation
changes of a land-terminating glacier during an active
surge and (ii) use these measurements, in conjunc-
tion with terminus position, surface morphology and
surface velocity observations, to interpret the likely
timing and duration of the surge, and to speculate on
the surge mechanism(s).
STUDY SITE
The Kverkfjöll central volcano on the northern mar-
gin of the Vatnajökull ice cap is a mountain massif
with a relief of ∼1200 m in central Iceland (Figure 1).
The southern part of the Kverkfjöll Volcanic System is
mostly ice covered and includes two calderas and ex-
tensive geothermal areas around the northern caldera
rim, particularly at Hveradalur (Ármannsson et al.,
2000; Ólafsson et al., 2000; Cousins et al., 2013).
JÖKULL No. 66, 2016 29