Jökull - 01.01.2012, Page 100

S. Guðmundsson et al.
Figure 1. Kotárjökull glacier flows southwest from Öræfajökull ice cap. The eastern branch of the glacier is
named Rótarfjallsjökull. The white area delineates the glacier’s extent in 2011, whereas the middle-gray area
indicates the glacier outline at the LIA maximum. Crevasse areas (black triangles) are used to calculate glacier
surface changes between 1891 and 2011. Black dots represent lateral moraines used to reconstruct the maxi-
mum glacial extent in the gorge, and white circles and boxes indicate sites where surface changes are estimated
from geomorphological and photographic evidence. Line B-B’ is a longitudinal profile for later discussion. –
Kotárjökull skríður suðvestur úr Öræfajökulsöskjunni en eystri armurinn er nefndur Rótarfjallsjökull. Hvítt
svæði sýnir útlínur jökulsins árið 2011 en milli-grátt markar hámarksútbreiðslu á litlu ísöld. Ísaskil liggja
innan við öskjubrúnina í um 1800 m hæð. Yfirborðslækkun milli 1891 og 2011 var metin út frá gömlum ljós-
myndum af sprungukollum (svartir þríhyrningar). Svartar punktraðir sýna jaðarurðir og hvítir hringir ásamt
hvítum kössum sýna staði sem voru notaðir til þykktarútreikninga í Kotárgili út frá ljósmyndum Howells og
rofmörkum. Línan B-B’ sýnir hvar langskurðarsnið af jöklinum liggur. Howellssteinn og Howellsnöf eru ekki
örnefni heldur heiti á kennileitum á Sandfelli.
glacier mass change over the last 120 years. We also
compare the 1904 map of the Danish General Staff
(Herforingjaráðið, 1905) of Öræfajökull’s plateau, at
an altitudinal range of 1700–2100 m, with a recent
DEM, to get an estimate of glacier surface changes
during this time period.
RESEARCH AREA
Öræfajökull is a 2000 m high ice-covered central vol-
cano. The ice-filled caldera is 5 km wide and 500
m deep, with an ice volume of 4.6 km3 (Björnsson,
1988; Magnússon et al., 2012). Ice flows over the
caldera rim and forms several outlet glaciers. The ice
thickness of Kotárjökull is on average 90 m, approx-
98 JÖKULL No. 62, 2012