Jökull - 01.01.2015, Side 2

Einarsson and Hjartardóttir
Figure 1. Map of topography and volcano-tectonic structures in Iceland. Volcanic systems (central volcano
shown with red contour, fissure swarm in yellow) are from Einarsson and Saemundsson (1987). WVZ, EVZ
and NVZ are the Western, Eastern and Northern Volcanic Rift Zones, respectively, SISZ is the South Iceland
Seismic Zone. The Hreppar Microplate, HM, is bounded by the two parallel rifts, EVZ and WVZ, and the trans-
form zone, SISZ (e.g. Einarsson, 2008). The volcanic flank zone of South Iceland is located south of the main
plate boundary marked by the SISZ and the EVZ. – Yfirlitskort af landslagi og tektóník Íslands. Eldstöðvakerfi
(Einarsson and Sæmundsson, 1987) eru sýnd með rauðum útlínum megineldstöðva og gulum lit sprungusveima.
WVZ, EVZ og NVZ tákna Vestur-, Austur-, og Norðurgosbeltin, SISZ er skjálftabelti Suðurlands, HM er Hreppa-
flekinn (sjá t.d. Einarsson, 2008) sem afmarkast af Vestur- og Austurgosbeltunum og skjálftabelti Suðurlands.
Suðurlandseldfjöllin sitja á Evrasíuflekanum, sunnan flekaskilanna sem markast af skjálftabelti Suðurlands og
Austurgosbeltinu.
uldsson, 2008; Sturkell et al., 2006). Added com-
plexity is provided by the relative motion of the plate
boundary with respect to the deeper roots of the Ice-
land hotspot. This leads to instability and repeated
jumps of the ridge segments achieved by rift propa-
gation away from the center of the hotspot (e.g. Sae-
mundsson, 1978; Einarsson, 1991; Sigmundsson et
al., 1995; Sigmundsson, 2006). Microplates are tem-
porarily created between the propagating and reced-
ing rifts. This is the present situation in South Ice-
land. The propagating Eastern Volcanic Zone (EVZ)
and the receding Western Volcanic Zone (WVZ) de-
markate the Hreppar Microplate that is in the pro-
cess of being transferred from the Eurasia Plate to the
N-America Plate (Einarsson, 2008). Latitude depen-
dent variations in spreading rate are observed along
2 JÖKULL No. 65, 2015