Environmental pressure from the 2014–15 eruption of Bárðarbunga volcano, Iceland

The effusive six months long 2014-2015 Bárðarbunga eruption (31 August-27 February) was the largest in Iceland for more than 200 years, producing 1.6 ± 0.3 km3 of lava. The total SO2 emission was 11 ± 5 Mt, more than the amount emitted from Europe in 2011. The ground level concentration of SO2 exceeded the 350 μg m−3 hourly average health limit over much of Iceland for days to weeks. Anomalously high SO2 concentrations were also measured at several locations in Europe in September. The lowest pH of fresh snowmelt at the eruption site was 3.3, and 3.2 in precipitation 105 km away from the source. Elevated dissolved H2SO4, HCl, HF, and metal concentrations were measured in snow and precipitation. Environmental pressures from the eruption and impacts on populated areas were reduced by its remoteness, timing, and the weather. The anticipated primary environmental pressure is on the surface waters, soils, and vegetation of Iceland

Gradual caldera collapse at Bárdarbunga volcano, Iceland, regulated by lateral magma outflow

Large volcanic eruptions on Earth commonly occur with a collapse of the roof of a crustal magma reservoir, forming a caldera. Only a few such collapses occur per century, and the lack of detailed observations has obscured insight into the mechanical interplay between collapse and eruption.We usemultiparameter geophysical and geochemical data to show that the 110-squarekilometer and 65-meter-deep collapse of Bárdarbunga caldera in 2014-2015 was initiated through withdrawal of magma, and lateral migration through a 48-kilometers-long dike, from a 12-kilometers deep reservoir. Interaction between the pressure exerted by the subsiding reservoir roof and the physical properties of the subsurface flow path explain the gradual, nearexponential decline of both collapse rate and the intensity of the 180-day-long eruption

Gradual caldera collapse at Bárdarbunga volcano, Iceland, regulated by lateral magma outflow

Large volcanic eruptions on Earth commonly occur with a collapse of the roof of a crustal magma reservoir, forming a caldera. Only a few such collapses occur per century, and the lack of detailed observations has obscured insight into the mechanical interplay between collapse and eruption.We usemultiparameter geophysical and geochemical data to show that the 110-squarekilometer and 65-meter-deep collapse of Bárdarbunga caldera in 2014-2015 was initiated through withdrawal of magma, and lateral migration through a 48-kilometers-long dike, from a 12-kilometers deep reservoir. Interaction between the pressure exerted by the subsiding reservoir roof and the physical properties of the subsurface flow path explain the gradual, nearexponential decline of both collapse rate and the intensity of the 180-day-long eruption.</p

High northern geomagnetic field behavior and new constraints on the Gilsá event: Paleomagnetic and 40Ar/39Ar results of ∼0.5–3.1 Ma basalts from Jökuldalur, Iceland

Recent paleomagnetic results of extrusive rocks from high southern latitudes (&gt; 60°S) and high northern latitudes (&gt; 60°N) have been suggested to reflect a hemispheric asymmetry of the geomagnetic field on time-scales of 105 to 106 years, with higher and more stable fields in the north. This interpretation, however, is based on only a few modern-standard paleodirectional data sets and on high northern stable field paleointensity data of rocks that are mainly younger than 100 kyr. The sparsity of modern-standard data questions the validity (and age range) of this potential geomagnetic asymmetry. In 2013 and 2014, we sampled basaltic lava ows in Jokuldalur, north-eastern Iceland,to obtain high-standard paleodirectional and paleointensity data at relatively high-northern latitudes (65.2°N). On average, we sampled &gt;15 cores per site at 51 sites of predominantly Matuyama age. Complete demagnetization was carried out on all samples using AF or thermal demagnetization. We present 45 distinct paleomagnetic directions based on overall N &gt; 10 ChRMs per site and α95 &lt; 3:5°. We obtain a mean direction of D =355.7°, I =76.3°,and α95 =3.2 for N =45 sites that is not significantly different from a GAD field. The resulting 45 VGPs distribute around the North Pole, and the global mean paleomagnetic pole (λ = 87:8°, Φ = 224:3°) is coincident with the North Pole within the α95 confidence limit. We calculate a VGP dispersion for our 38 Matuyama age sites of 20:523:3 17:8 , which is ~1-4° lower than estimates from published Iceland data (from surveys that sampled 2-5 cores per site) but still supports the interpretation of a dependence of VGP dispersion on latitude during the Matuyama. Based on relatively strict cut-off criteria we also present six new field strength estimates from the time interval ~1.2-1.83 Ma, thus filling a large data gap of the high-northern stable field behaviour. We obtain a median VADM of 57±3 ZAm2 (VDM of 60±5 Am2), which is higher than the median VADM of 16 intensity estimates from Antarctica (39±7 ZAm2) from the same period. A higher northern field is also found when using less strict cut-off criteria resulting in 14 field estimates from Jokuldalur, i.e. we find support for higher field strength in the northern hemisphere as compared to the southern hemisphere during the Matuyama. Finally, we deliver a revised magneto-chronostratigraphic model of Jokuldalur and conduct an investigation of the type sections of the so called Gilsa normal polarity event around 1.62 Ma. Our revised model is based on 11 new 40Ar/39Ar ages. No evidence is found of the existence of the Gilsa event in Jokuldalur. Instead we find that the normal polarity intervals in the type sections can both be correlated to Olduvai subchron

Environmental pressure from the 2014-15 eruption of B\ue1r\uf0arbunga volcano, Iceland

The effusive six months long 2014-2015 B\ue1roarbunga eruption (31 August-27 February) was the largest in Iceland for more than 200 years, producing 1.6 + 0.3 km3of lava. The total S02emission was 11 \ub1 5 Mt, more than the amount emitted from Europe in 2011. The ground level concentration of SO2exceeded the 350 μg m-3hourly average health limit over much of Iceland for days to weeks. Anomalously high SO2concentrations were also measured at several locations in Europe in September. The lowest pH of fresh snowmelt at the eruption site was 3.3, and 3.2 in precipitation 105 km away from the source. Elevated dissolved H2SO4, HCl, HF, and metal concentrations were measured in snow and precipitation. Environmental pressures from the eruption and impacts on populated areas were reduced by its remoteness, timing, and the weather. The anticipated primary environmental pressure is on the surface waters, soils, and vegetation of Iceland