Jökull - 01.01.2016, Side 41

First documented surge of Kverkjökull, central Iceland
Figure 8. Analysis of surface horizontal motion by manual feature-tracking of selected points. Annotations
denote most major horizontal shifts only for clarity and have units of metres since previous image. The lo-
cation of these panels is indicated in Figure 1. Panels in A focus on the western part of the terminus where
manual feature tracking worked well, whereas panels in B focus on a part of the western flank margin that is
too chaotic and apparently moving too fast for confidence in finding the same features in successive images. –
Mæling á íshreyfingu með handvirkri greiningu á hliðrun yfirborðsauðkenna. Merkingar sýna lárétta hliðrun
helstu auðkenna í metrum miðað við fyrri mynd á nokkrum stöðum. Staðsetning myndanna er sýnd á 1. mynd.
Myndir A eru frá vesturhluta jökulsins nærri sporðinum þar sem handvirk greining tókst vel en myndir B eru
frá svæði nærri vesturjaðrinum þar sem yfirborðið var of úfið og hreyfing of mikil til þess að greina sömu
yfirborðsauðkenni í myndum frá mismunandi tímum.
of up to 79 m, suggesting that the surge was not com-
pletely over. No manual feature tracking could be
performed on images one year apart for the margins
of the glacier due to horizontal shifts in surface fea-
tures being too large and too variable in orientation to
confidently detect the same feature in successive im-
ages (Figure 8B). On the eastern margin of the glacier
in its mid-section, near the Kverk or gap, ice surface
features in images with an annual interval could not
be manually tracked, but images at monthly intervals
illustrated surface displacements of up to 21 m over
30 days (tentatively extrapolated to 250 m yr−1) in the
horizontal (Figure 9).
JÖKULL No. 66, 2016 41