Jökull - 01.01.2021, Síða 115

Ljósmyndir Þorláks Sverrissonar
Five photographs (Figures 10–13) show the melt-
water, icebergs and sediments that accompanied the
1918 Katla eruption. These were taken while the
eruption was ongoing and are the only such pho-
tographs known to the authors. Two (Figures 10–
11) show flood routes and deposits, two show the ice
canyon through which the main phase of the jökulh-
laup emerged (Figures 12a, b), and one a colossal ice-
berg (Figure 13). The photographs of Kjartan Guð-
mundsson of icebergs and sediments were taken in
mid-November, after the eruption had ceased.
None of the photographs were dated by Sverris-
son, except that he claimed to have photographed the
eruption from the beginning to the end. However, de-
tailed day to day descriptions exist of the eruption
cloud when the glacier was visible, of the weather
conditions, and the tephra fall in Vík village and vicin-
ity (Jóhannsson 1919; Sveinsson 1919). This infor-
mation has been crucial for constraining the most
likely dates for the photographs.
Figures 2 and 3, showing the Katla eruption cloud
on October 12, may be the first photographs ever
taken of a subglacial volcanic eruption, and are almost
certainly the first of an explosive basaltic eruption
through a glacier. Search for older photographs has
not revealed any photos of eruptions through glacier
ice prior to the 1918 eruption. An undated photograph
from Reykjavík by Magnús Ólafsson showing a sunlit
Katla eruption cloud may have been taken in the late
afternoon on October 12, 1918.
In addition to the historical value, the scientific
value of Sverrisson’s photos is considerable and the
examples detailed here are only a part of the informa-
tion they contain. The height of the eruption cloud
at various times can be calculated, the location of
source vents can be constrained, the photos contain
information on the response of the Kötlujökull outlet
glacier to the flood and the maximum flood level at
Hafursey can be estimated. Although peak discharge
for the 1918 main phase has been estimated (Tómas-
son 1993; Karlsson 1994) the additional information
may help to refine these estimates.
HEIMILDIR
Eiríkur Þ. Einarsson 2021. Þorlákur Sverrisson og Kötlu-
myndir hans. Jökull 71, 91–94.
Geodætisk Institut 1905. Hjörleifshöfði 69 NV, 1:50 000.
Generalstabens topografiske Afdeling, Kjöbenhavn.
Gísli Sveinsson 1919. Kötlugosið 1918 og afleiðingar
þess. Prentsmiðjan Gutenberg, Reykjavík, 61 bls.
Guðgeir Jóhannsson 1919. Kötlugosið 1918. Bókaverslun
Ársæls Árnasonar, Reykjavík, 72 bls.
Haukur Tómasson 1996. The Jökulhlaup from Katla in
1918. Ann. Glaciology 22, 249–254.
Helgi Björnsson, Finnur Pálsson og Magnús T. Guð-
mundsson 2000. Surface and bedrock topography of
the Mýrdalsjökull ice cap, Iceland: The Katla caldera,
eruption sites and routes of jökulhlaups. Jökull 49, 29–
46.
Kristín U. Sigurðardóttir 2019. Vesturhluti Víkur í Mýr-
dal. Húsakönnun. Unnið af Landmótun fyrir Mýrdals-
hrepp. 56 bls.
Magnús T. Guðmundsson og Þórdís Högnadóttir 2001.
Gögn um Kötlugosið 1918: Ljósmyndir Kjartans Guð-
mundssonar úr ferðum á Mýrdalsjökul í júní og sept-
ember 1919. Raunvísindastofnun Háskólans RH-08-
2001. 19 bls.
Morgunblaðið 18. mars 1919, bls. 3.
Morgunblaðið 19. maí 1919, bls. 2.
Porter, C., P. Morin, I. Howat, M.-J. Noh, B. Bates,
K. Peterman, S. Keesey, M. Schlenk, J. Gardiner,
K. Tomko, M. Willis, C. Kelleher, M. Cloutier,
E. Husby, S. Foga, H. Nakamura, M. Platson, M.
Wethington, C. Williamson, G. Bauer, J. Enos,
G. Arnold, W. Kramer, P. Becker, A. Doshi, C.
D’Souza, P. Cummens, F. Laurier and M. Boj-
esen 2018. „ArcticDEM“, https://doi.org/10.7910/-
DVN/OHHUKH, Harvard Dataverse, V1.
Tómas Jóhannesson, Helgi Björnsson, Eyjólfur Magnús-
son, Sverrir Guðmundsson, Finnur Pálsson, Odd-
ur Sigurðsson, o.fl. 2013. Ice-volume changes, bi-
as estimation of mass-balance measurements and
changes in subglacial lakes derived by lidar mapping
of the surface of Icelandic glaciers. Ann. Glaciology
54, 63–74. doi:10.3189/2013AoG63A422
Þorbjörn Karlsson 1994. Kötluhlaup 1918 – vangaveltur
um eðli hlaupsins og hámarksrennsli. Kötlustefna 26.
febrúar 1994, Jarðfræðafélag Íslands, 10–12.
Þjóðminjasafn Íslands, Ljósmyndasafn Íslands.
JÖKULL No. 71, 2021 113