An intense seismic swarm is currently taking place under the eastern part of Bárðarbunga. Between 03:04 and 13:00 on August 16th a total of 189 earthquakes occurred (max. M2.9). The seismic swarm continues and continuous GPS stations have detected deformation that confirm magma movements associated with intrusive activity. No indications of surface magma extrusion beneath the ice cap have been observed. If the activity progresses towards an eruption, a scenario could involve a subglacial, or partly subglacial eruption, at the northwestern part or edge of Vatnajökull, with a jökulhlaup in the Jökulsá á Fjöllum river towards the north.
This is the largest seismic swarm seen in Bárðarbunga since the end of September 1996, in the days leading to the Gjálp eruption. The area is covered by Vatnajökull and the ice thickness varies from 100-200 at the caldera rims of Bárðarbunga to over 800 m within the Bárðarbunga caldera. IMO, IES and Civil Protection are monitoring the situation – the seismic activity can be observed at www.vedur.is.
A direct link to the Vatnajökull seismic map is: http://www.vedur.is/skjalftar-og-eldgos/jardskjalftar/vatnajokull/#view=map
Publications:
M. T. Gudmundsson, G. Larsen, Á. Höskuldsson and Á. G. Gylfason, 2008. Volcanic hazards in Iceland, Jökull (58), 251-268.
Óladóttir, B.A., Larsen G. & Sigmarsson, O. Holocene volcanic activity at Grímsvötn, Bárdarbunga and Kverkfjöll subglacial centres beneath Vatnajökull, Iceland. Bulletin of Volcanology, 73, 1187-1208. doi: 10.1007/s00445-011-0461-4
Björnsdóttir, Þ. & Einarsson, P., 2013. Evidence of recent fault movements in the Tungnafellsjökull fissure swarm in the Central Volcanic Zone, Iceland. Jökull (63), 17-32.
Björnsson, H. & Einarsson, P., 1990. Volcanoes beneath Vatnajökull, Iceland: Evidence from radio echo-sounding, earthquakes and jökulhlaups. Jökull (40), 147-168.
Einarsson, P., 1991. Earthquakes and present-day tectonism in Iceland. Tectonophysics, 189, 261-279.
Thordarson, T., and G. Larsen, 2007. Volcanism in Iceland in historical time: Volcano types, eruption styles and eruptive history. Journal of Geodynamics, 43, p. 118-152.
Pagli, C., and F. Sigmundsson, 2008. Will present day glacier retreat increase volcanic activity? Stress induced by recent glacier retreat and its effect on magmatism at the Vatnajökull ice cap, Iceland. Geophys. Res. Lett., 35, L09304, doi:10.1029/2008GL033510.