BARDARBUNGA FIELD TRIP 2015

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In August 2014 unrest began at one of the major volcanic systems in Iceland, Bardarbunga volcanic system. Bardarbunga system is situated right above the presumed Icelandic mantle plume in the centre of Iceland. The central volcano of the system is mostly covered by the Vatnajökull glacier (Fig 1). Volcanic fissures and faults extend north and south from the main central volcano, such that its length is about 190 km and with about 25 km. The Bardarbunga volcanic system connects Iceland’s Eastern Volcanic zone to Iceland´s Northern Volcanic zone. For the past 11 centuries in Iceland the system has been active 26 times. It´s most resent eruption, prior to the 2014 unrest, being the one of Tröllahraun (1862-64) in the southern half of the system. The Bardarbunga central volcano marks the point of shallow magma accumulation in the crust and build-up of a major mountain massive. Within the summit region of Bardarbunga massif there is a 65 km2 ice filled caldera. 

The central part of the fissure during the first day of the eruption, near continuous fire fountaining. Fountains reaching as high as 90 m.

On the 16th of August 2014 seismicity increased within the caldera of the central volcano and warning was given of a possible eruption. Already during the first day seismic epicentres began moving from within the Bardarbunga caldera towards east. In the subsequent days seismic epicentres where focused along relatively narrow path east and then north along the Bardarbunga volcanic systems faults and fissures. First eruption began in the eastern slopes of Bardarbunga on the 23rd of August, it was small and entirely subglacial. Second eruption began on the 29th of August on the sandur outwash plains north of the glacier. The eruption lasted for about a day. On the 31st of August a major eruption began that lasted until 27th of February 2015. During the main eruption two other eruptions occurred, on the 3rd of September a small eruption underneath the glacier snout just south of the main eruption. From 5th to 7th of September a small eruption took place between the main eruption and the glacier snout. 

Lava spreading on the sandur plain. It’s front is about 20 cm, but quickly stiffens and builds higher as the lava front starts to cool. Average flow front throughout the eruption proofed to be about 6 to 8 m after which it broke and lava continued to gush forward.

The main eruption lasting from 31st of August 2014 to 27th of February 2015 is the largest eruption in Iceland since the great Laki eruption in 1783. Although the eruptive fissure was only 2 km long huge masses of lave where expelled out of it. Maximum effusion rate measured during the first week are 350 to 400 m3/s. Through the six months of activity some 1.2 to 1.7 km3 of magma was erupted to surface. The total area cover of the eruption is about 85 km2. The average thickness of the lava is about 15 to 20 m. 

Volcanic gas turned out to be the biggest environmental and health threat during the eruption. A total of some 10-15 Mtons of sulphur was released into the atmosphere during the eruption. Highest emission rates where in the order of some 160 ktons per day.

The area in which the lava was erupted is low topography sandur plain. The activity and the prelude to the eruptions are extremely well recorded. Seismic and continuous gps network constantly monitoring the changes in the crust. Further during the eruption constant monitoring of vent activity and growth of the lava field was conducted by scientists in the field and satellite network. Thus the eruption is ideal for modelling with VeTools. 

A combination of a satellite image and field based measurements, denoting the lava evolution during the first 6 days of the eruption. 

Graph showing the area coverage with time during the eruption. High rate of coverage during the first days of the eruption coincide with high effusion rate. But as effusion rate declines so does the rate of area coverage.

Principal investigator and co-PI´s thus planned a field trip into the area during the period of 1st of March to the 8th, 2015. Since the area is remote access is difficult and needs specialised vehicles. During the trip cooling processes where analysed and the vent area to gain understanding of the changing nature of the lava field growth. All the data collected will help to calibrate the different simulation models for lava flow invasion included in VeTOOLS, thus allowing to conduct a sensitivity analysis of all them and to characterise their main similarities and differences. This is an important task of VeTOOLS as it will facilitate potential users choosing the more appropriate model depending on the characteristics of the area and of the lavas in each particular case. 

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© GVB-CSIC 2015