Jökull - 01.01.2019, Side 13

Guðmundsson et al.
Figure 8. The development of terminus lakes by Morsárjökull. For explanations and credits see Figures 3 and
7. – Þróun sporðlóna við Morsárjökul (sjá nánari skýringar við 3. mynd og 7. mynd).
before that time, but later than 1904, a small and shal-
low lake was formed in dead ice in the depression
where the glaciers had merged, and lasted for a few
decades (Figure 10). The AMS maps (1951) show this
small lake in 1945–1946 and four other small lakes by
the terminus of Svínafellsjökull that were formed be-
fore the middle of the 20th century. These lakes had a
total area of 0.09 km2 at this time. The largest of them
still survives as an isolated pond. None of these lakes
is connected to the current ice-marginal lakes that are
forming in an area recently evacuated by Svínafells-
jökull (Figures 5 and 10).
Svínafellsjökull has retreated rapidly since
∼2000, and lakes have formed by the northern and
southern ends of the terminus. The lowest part of the
terminus appears to be afloat in the lakes. The size of
the lakes has grown sporadically from approximately
0.01 km2 in 2000 to 0.38 km2 in 2018, or on average
by ∼0.02 km2 a−1. The area was slightly reduced in
2017 by a temporary advance of the terminus (Figure
10).
Radio-echo sounding measurements (Magnússon
and others, 2012) and soundings of water depth show
that the northern lake is 60–70 m deep at its deepest
point near the ice margin at present and that the vol-
ume of the lakes in 2018 was ∼10×106 m3. If the
glacier eventually retreats out of the ∼6 km long sub-
glacial trough shown by the radio-echo sounding, a
> 300 m deep lake with an area of ∼5 km2 will be
formed in the depression.
12 JÖKULL No. 69, 2019