Jökull - 01.12.2003, Blaðsíða 34

Thordarson et al.
e)
f)
rp
1 km
internal lava pathway
(filled tube)
1 m
Figure 7. cont. e) An internal lava pathway (i.e., filled tube) in a Laki sheet lobe; f) a large frontal breakout
(large black arrows) near the edge of the Laki flow field (rough textured area, labelled rp). This breakout burst
out from the active flow front on 1 July 1783 and formed a ∼5 km long pahoehoe sheet lobe in six days. It is
crowned by numerous smaller breakouts along the lobe margins (the speckle-textured areas). At the southern
margin of the lobe these smaller breakouts are mingled with breakouts from the main flow field (small arrows
point in direction of flow), indicating that lava was transported through both the main flow field and the sheet
lobe at this time. The main flow field is rubbly pahoehoe covered by thick flow top rubble that was piled up into
concentric ridges oriented perpendicular to flow. The interior of this flow was well insulated and hot because
it fed numerous frontal breakouts of pahoehoe morphology (e.g. large white arrow and small black arrows).
–Flæðistrúktúrar í Skaftáreldahrauni sem bera vitni um einangrað flæði undir samfelldri skorpu og hraunris.
32 JÖKULL No. 53, 2003