Jökull - 01.01.2019, Blaðsíða 144

Breiðamerkurjökull og Hoffellsjökull 2010–2019
5. Mynd/Figure 5. Breytingar á Hoffellsjökli 2002–2019. a) Fyrir jökulhlaupið 2015 hopaði jökullinn við Gjá-
vatn og ísstíflan veiktist. Græna línan er dreginn umhverfis ísgljúfrið, eins og það var árið 2015. b) Eftir hlaupið
2015 hvarf Gjávatn og ísgljúfrið við Stórahnaus breyttist í mjóan dal. c) 2017 og 2018 brotnuðu stórir geirar úr
jaðri jökulsins (sjá texta). d) Á árunum 2010–2019 hefur Hoffellsjökull hopað > 450 m frá Stórahnaus og mun
áin frá Gjávatni hafa átt mikinn þátt í því. Árið 2019 lá jökuljaðarinn að Efstafellsnesi við lónið, á um 400 m
löngum kafla. Þar fyrir innan er orðið gengt inn að Gjánúpstanga. – Retreat of Hoffellsjökull 2002–2019. a)
Prior to the 2015 jökulhlaup, the glacier margin near lake Gjávatn had retreated 450 m and the ice dam had
weakened. The ice-dammed lake Gjávatn was visible in 2002 (yellow broken line depicts the glacier margin
that year), 2010 (red broken line) and 2015 (green line along the glacier margin and the then newly formed ice
canyon). b) 2010–2017. The Gjávatn lake disappeared permanently after the 2015 jökulhlaup and a narrow
valley was eventually formed by its river. c) 2017–2019. Huge ice blocks collapsed in two events in 2017 and
2018. As a result, a horseshoe-like bay has formed in the glacier and continues to expand. d) In 2010–2019
Hoffellsjökull retreated >450 m from Stórihnaus, mainly because the glacial river from the now vanished Gjá-
vatn contributed to the melting of ice. In 2019, the glacier margin touched the slopes of Efstafellsnes over a
distance of 400 m, adjacent to the Hoffellslón terminus lake (Figure 1). On its north side, it is possible to walk
on a ice-free ground along the glacier margin.
JÖKULL No. 69, 2019 143