Jökull - 01.01.2014, Page 83

Erratum in; Removing the ice cap of Öræfajökull central volcano,
SE-Iceland: Mapping and interpretation of bedrock topography, ice volumes,
subglacial troughs and implications for hazards assessments
Eyjólfur Magnússon1,2, Finnur Pálsson2, Helgi Björnsson2 and Snævarr Guðmundsson2
1Nordic Volcanological Center, Institute of Earth Sciences, University of Iceland
2Institute of Earth Sciences, University of Iceland, Askja, Sturlugata 7, IS-101 Reykjavík, Iceland
Corresponding author: eyjolfm@hi.is
In the paper Removing the ice cap of Öræfajökull
central volcano, SE-Iceland: Mapping and interpre-
tation of bedrock topography, ice volumes, subglacial
troughs and implications for hazards assessments
by Magnússon et al. (2012) published in vol. 62 of
Jökull, a small part of the Radio Echo Sounding
(RES) data used to constrain the subglacial topogra-
phy included a scaling error resulting in 20% under-
estimate of the ice thickness. This only applies to data
acquired in 2012 but not data acquired in 2009 or ear-
lier (see Figure 1). The receiver used in 2009 recorded
at 100 MHz, whereas in 2012 an upgraded receiver
was used sampling at 80 MHz. Unfortunately the
MATLAB code used for post-processing of the data
was inadequately updated to read the data from the
upgraded receiver resulting in this scaling error.
The scaling error only affects the bedrock Digi-
tal Elevation Model (DEM) at the two main passes
cutting the rim of the Öræfajökull caldera, east, to-
wards the Kvíárjökull outlet glacier, and west, to-
wards Virkis- and Falljökull outlet glaciers (Figure
1). Correcting the erroneous RES data, leads to lo-
calized changes in the bedrock DEM of the Öræ-
fajökull caldera (Figure 1) and consequently some
minor changes in some of the figures presented in
Magnússon et al. (2012). This does however not
change the main results and the conclusions of the pa-
per. The corrected bedrock elevation of the passes out
of the caldera is ∼1525 m a.s.l. and ∼1575 m a.s.l.
for Kvíárjökul and Virkis- and Falljökull respectively
instead of ∼1570 m a.s.l. and ∼1610 m a.s.l. This
changes the total amount of water that can be stored
within the caldera, in the extreme case of an eruption
melting all the ice stored within it, from 1.3 km3 in
Magnússon et al. (2012) to 1.0 km3. A version of the
paper where figures and numerical results have been
updated based on the corrected data may be obtained
from the corresponding author.
Í greininni Removing the ice cap of Öræfajökull
central volcano, SE-Iceland: Mapping and interpre-
tation of bedrock topography, ice volumes, subglacial
troughs and implications for hazards assessments eftir
Eyjólf Magnússon o.fl. (2012) sem birtist í 62. hefti
Jökuls, var lítill hluti íssjármæligagna sem notast
var við með kvörðunarvillu sem olli 20% vanmati á
ísþykkt. Vegna þessa var hæð lægstu skarða út úr
Öræfajökulsöskjunni rangt metin. Rétt túlkun mæl-
inganna gefur um ∼1525 m hæð yfir sjó á skarðinu þar
sem Kvíárjökull fellur austur úr Öræfajökli (var sögð
∼1570 m í greininni) meðan hæðin á skarðinu ves-
tur úr honum, undir Fall- og Virkisjökli, er ∼1575 m
y.s. (var sögð ∼1610 m í greininni). Þeim sem
vilja nálgast greinina uppfærða, þar sem myndir og
tölulegar niðurstöður hafa verið leiðréttar, er bent á
að senda Eyjólfi Magnússyni tölvupóst á póstfangið
eyjolfm@hi.is.
JÖKULL No. 64, 2014 83