Monitoring Magmatism and Intrusion from the Bardabunga Volcano, Iceland

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An eruption in Iceland has presented a unique opportunity to monitor the lateral movement and eventual eruption of melt using a network of seismometers deployed directly above and around the volcanic system. An intense earthquake swarm began on 2014 August 16 at Bardarbunga central volcano in Central Iceland under the Vatnajokull ice cap, which has continued to be very active. It then produced a dyke which travelled northwards over 45 km towards the Askja volcanic system at aproximate depths of 6-12 km and produced a small fissure eruption near its tip on 2014 August 29. GPS measurements show continued movement of the rift and suggest that about 400 million cubic metres of magma has already been injected into the dyke and that melt continues to flow into it. So continued activity is likely, probably for many months.This is a significant magmatic and tectonic event. In terms of seismicity, volumes of melt and displacements involved only two events in Iceland during recent decades are comparable to this one. These are the Gjálp eruption in the Bárdarbunga area in 1996 and the Krafla rifting episode of 1975-1989. The presently propagating dyke is equalled only by the initial dyke in the Krafla sequence of dykes. Possibly we are witnessing the intial phase of a major rifting episode on the scale of the Krafla volvcanism and the similar episode that began in Afar in 2005.The Cambridge research group is uniquely well placed to monitor this tectono-magmatic event. We already have a wide array of 50 broad-band seismometers operating around Vatnajokull and the Askja volcanic system and had 15 SEIS-UK seismometers sitting in Reykjavik. For good depth control and constraint on the cracking and failures causing microseismicity it is important to have seismic sensors directly above the activity. Unusually and importantly we are in a superb position to monitor simultaneously both the source of the melt in the Bardabunga volcano and its transit and emergence along the lateral dyke flowing northwards along the rift system.We don't know how this magmatic-rifting event will develop, but it is likely to continue for many months because there is so much molten rock sitting at a shallow crustal level. We will run 15 extra seismometers through the next 12 months to obtain a continuous record throughout the entire tectono-magmatic episode.