VS02 Lava Flows

IAVCEI (Volcanology, Geochemistry)



01-Jul-2015, 13:30 - 15:00


 
Abstract content:

Nornahraun lava morphology and mode of emplacement

The ongoing Nornahraun eruption is the largest effusive eruption in Iceland in ~260 years, with an estimated lava volume of ~1.15 km3 covering an area of ~83.9 km2 (as of 15 JAN 2015). The flow field provides an unprecedented opportunity to study a continuum of morphologies from pahoehoe to ‘a‘a, which have been monitored in the field and from remote sensing platforms. At the onset of the eruption 31 AUG, lava flows advanced rapidly (400–800 m/hr) from the 1.5 km long fissure as large slabby pahoehoe sheet lobes. By 1 SEPT, a central open channel developed, feeding a 1–2 km wide active ‘a‘a frontal lobe that advanced 1–2 km/day towards the NE. In addition to its own caterpillar motion, the frontal lobe advanced in a series of breakouts, predominantly slabby and rubbly pahoehoe. The flow front came to halt on 12 SEPT 18 km from the source vent. Subsequently, a new lobe broke out S of the first lobe and migrated eastward until it also came to arrest at a slightly shorter distance from the fissure. This mode of gradual clockwise propagation of new frontal lobes continued from mid-SEPT to end-NOV. At this time the main lava channel partly crusted over and a series of insulated flows overrode the previous emplaced flows, changing transport system to include closed/insulated (and inflating) pathways in addition to open channels. Resultantly, the area now covered by the flow field has undergone several topographic inversions due to stacking of lava lobes.

 
Author(s):
G.B.M. Pedersen1, A. Höskuldsson1, M. Riishuus1, I. Jónsdóttir1, M.T. Gudmundsson1, F. Sigmundsson1, T. Thórdarson1, F. IES Eruption team1.
1NORDVULK, Institute of Earth Sciences, Reykjavik, Iceland.

 

Keywords:
Nornahraun     Iceland     Lava emplacement     Lava morphology