TerraSAR-X view of Bardarbunga on Iceland
Bardarbunga, (Bárðarbunga) in Iceland, one of the largest volcanoes in Europe and located beneath the biggest glacier in Europe, became active again in mid-August. For several years now, German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) researchers have been keeping a close eye on Bardarbunga and the system of volcanoes associated with it - an enormous network of subterranean magma channels, vents and craters. The German Earth observation satellite TerraSAR-X has now provided important data on the volcano's latest activity.
The image shown here covers an area of approximately 30 by 50 kilometres, and the recently ejected lava covers an area of roughly 10 square kilometres. The brighter areas, which are also highlighted in red for better visibility, indicate changes in amplitude (the intensity of the radar signals returned to the satellite). Since the rough surface of freshly-cooled lava reflects the radar signals back very strongly, it appears bright and is easily visible on the lava flow at the lower right in the image or on the two arcs at the right edge of the image (the northern edge of Vatnajökull). Smooth surfaces, such as water, reflect the incoming radar signals away from the satellite and so appear dark on the images.
In the bottom half of the image, the lake in the caldera of the Askja volcano is visible as a black area. A landslide occurred recently on this volcano, triggering a tsunami in the lake - with a wave height of up to 30 metres. From this image, it is clear that the area adjacent to the water is darker in colour than the more elevated regions. This is very probably due to flooding associated with the tsunami.
Activity in the Bardarbunga volcano system began with earthquakes having magnitudes of up to of 5.7 in the Richter scale, indicating that magma beneath the surface was moving and rising. On 27 August, volcanologists discovered several new depressions in the ice to the south of the caldera of Bardarbunga, with depths of up to 15 metres. This is another indication that a heat source lies beneath the ice sheet of the glacier. On 29 August, a lava flow escaped from a breach in the Holuhraun lava field to the north of the glacier - an ice-free area. On 31 August, a second eruption occurred there. The Holuhraun lava field has now grown to cover an area of over 19 square kilometres. If the lava had escaped directly beneath the ice and forced its way to the surface, there would have been a large steam explosion, reducing the lava to tiny particles of ash and forming an ash cloud. This is exactly what happened in 2010 with the eruption of Eyjafjallajökull, another subglacial volcano in this region, which lead to significant disruption for air traffic.
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Credit: German Aerospace Center (DLR)