Conclusions from Surveillance Flight over Eruption

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Eruption

Conclusions from Surveillance Flight over Eruption

Holuhraun eruption

The lava fountains stretch as high as 50 meters up into the air. Photo: Insitute of Earth Sciences.

The Icelandic Met Office reports that TF-SIF, the Icelandic Coast Guard's aircraft, was used for a surveillance flight over the Holuhraun eruption site this afternoon, 1:45-4:30 pm. Scientists from the Icelandic Met Office and the Institute of Earth Sciences and a representative of the Civil Protection Department in Iceland were onboard. Conditions were somewhat cloudy, but visibility was fair in low flight and radar images were retrieved at higher altitudes.

Main conclusions:

  • The fissure is 1.5 km long. Continuous eruption takes place on a 600-800-m long central section. A single crater has been active at its southern end, but little or no lava extrudes from it now. Lava plumes rise to a height of a few tens of meters where the activity is greatest, centrally on the fissure.
     
  • The lava stretches 3.5 km ANA from the center of the fissure. It is max 1.6 km wide but narrower further from the craters. The edge of the lava is a tongue 500-m wide. A continuous lava stream flows along the center of the lava field, almost to the edge. The edges are glowing. Apparently, none of the tributaries of river Jökulsá á Fjöllum touches the lava edge.
     
  • The area of the lava is now 4 km2. At 16:00, a rough estimate gives 20-30 million cubic meters of lava. This means that 5-10 million cubic meters have been added in 18-19 hours. Therefore, average flow is of the order of degree 100 m3/s.
     
  • Two small cauldrons in Dyngjujökull, aligned in the direction of the fissure, seemed unchanged since Friday 29 August.
     
  • Radar revealed no changes in Bárðarbunga or in the depressions to the southeast of it.

Plume:

A white plume (cloud), with a blue tint below, rose from the eruptive site, and drifted ENE. Maximum height is 15,000 feet (4.5 km a.s.l.), ca. 10 km from the eruptive site. The plume forms a cloud with very sharp edges at the top and below. The lower edge is in 6,500 feet (2.0 km a.s.l.). This cloud reaches at least 60 km NNE. The southern edge of it is over Báruvatn, Laugarvalladalur and the southernmost part of Lake Lögurinn. The cloud is about 10 km wide, 30 km northeast of the eruptive site. A dust cloud, originating from the Flæður, lies below the plume and its cloud. It didn‘t seem that any ash came from the cloud. The white color of the plume does not suggest any ash. 

Here are plume photos with explanations from Halldór Björnsson.