Subglacial volcanic activity above a lateral dyke path during the 2014–2015 Bárdarbunga-Holuhraun rifting episode, Iceland

Reynolds, Hannah I.; Guðmundsson, M. T.; Högnadóttir, Þórdís; Magnússon, Eyjólfur

doi:10.1007/s00445-017-1122-z

Cited by 26 publications

(46 citation statements)

References 39 publications

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“…Three of the cauldrons have been infilling with ice since then, with the exception being SE‐01, which was reactivated in July 2016 (Figure ). These cauldrons are thought to have formed during small subglacial eruptions due to the initially large thermal signal, which gradually decreased within months, similar to those observed at Dyngjujökull (Reynolds et al, ). The dates of eruption are not known; the earliest possible date is 16 August 2014 (when seismicity at Bárdarbunga increased), but it may have occurred a few days later.…”

Section: Resultssupporting

confidence: 60%

“…(a) The northwestern part of Vatnajökull ice cap, showing the Bárdarbunga, Grímsvötn, and Kverkfjöll central volcanoes, and the path of the dike, which produced the 2014‐2015 eruption at Holuhraun (Sigmundsson et al, ). Red circles show the locations of cauldrons formed during small subglacial eruptions, which took place during the dike propagation (Reynolds et al, ). The green circles denote ice cauldrons, which formed to the southeast of the Bárdarbunga caldera rim after the period of unrest began in August 2014, and the blue circles show the locations of cauldrons, which formed around the caldera rim.…”

Section: Introductionmentioning

confidence: 99%

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Changes in Geothermal Activity at Bárdarbunga, Iceland, Following the 2014–2015 Caldera Collapse, Investigated Using Geothermal System Modeling

et al. 2019

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The gradual collapse of the subglacial Bárdarbunga caldera in 2014–2015 provided an opportunity to explore the geothermal signals produced by large‐scale volcanic events. In August 2014, four ice cauldrons (shallow depressions on the ice surface) formed on the caldera flank. These cauldrons reached their maximum volume rapidly and then shrank, indicating that they were created during minor subglacial eruptions. Several weeks after the start of the collapse, three cauldrons on the caldera rim grew in volume, with four smaller cauldrons forming in 2015–2017. The cauldrons reached volumes in the range of 1.0 ± 0.2 to 27 ± 3 million m3. HYDROTHERM numerical simulations of fluid flow and heat transport in the uppermost 1 km of the crust were performed to explore possible causes for these thermal signals and in particular assess the role of shallow magmatic intrusions. The heat transfer required to create the more rapidly formed caldera‐rim cauldrons can be reproduced with shallow intrusions into high‐permeability pathways, which greatly enhance the surface thermal signal. The preintrusion temperature of the surrounding bedrock has a major effect on heat transfer to the surface, with cold bedrock causing a buffering effect, whereas temperature conditions close to the boiling point of water produce far more efficient heat transfer due to the formation of steam plumes. Not all observed behavior is reproduced by our models, suggesting that geothermal reservoirs below 1‐km depth may play a significant role in the observed thermal anomalies.

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Section: Resultssupporting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Changes in Geothermal Activity at Bárdarbunga, Iceland, Following the 2014–2015 Caldera Collapse, Investigated Using Geothermal System Modeling

et al. 2019

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“…Then, re-arranged for ∆h: (12) where ∆h is the crust thickness (m), M rad and M conv are radiative and convective flux densities (W m −2 ), respectively, k is the thermal conductivity, where we use 2.5 Wm −1 K −1 [14,31], and T i is the temperature of the lava flow interior. In this study, we use an interior temperature of 1128 • C (for lava outside vent) and 1200 • C (for lava surrounding vent); these values were selected according to thermocouple measurements for freshly exposed patches of lava in Holuhraun on the 19 and 20 November 2014 [3].…”

Section: Crust Thickness Modelmentioning

confidence: 99%

New Insights for Detecting and Deriving Thermal Properties of Lava Flow Using Infrared Satellite during 2014–2015 Effusive Eruption at Holuhraun, Iceland

et al. 2018

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Abstract:A new lava field was formed at Holuhraun in the Icelandic Highlands, north of Vatnajökull glacier, in 2014Vatnajökull glacier, in -2015. It was the largest effusive eruption in Iceland for 230 years, with an estimated lava bulk volume of~1.44 km 3 covering an area of~84 km 2 . Satellite-based remote sensing is commonly used as preliminary assessment of large scale eruptions since it is relatively efficient for collecting and processing the data. Landsat-8 infrared datasets were used in this study, and we used dual-band technique to determine the subpixel temperature (T h ) of the lava. We developed a new spectral index called the thermal eruption index (TEI) based on the shortwave infrared (SWIR) and thermal infrared (TIR) bands allowing us to differentiate thermal domain within the lava flow field. Lava surface roughness effects are accounted by using the Hurst coefficient (H) for deriving the radiant flux (Φ rad ) and the crust thickness (∆h). Here, we compare the results derived from satellite images with field measurements. The result from 2 December 2014 shows that a temperature estimate (1096 • C; occupying area of 3.05 m 2 ) from a lava breakout has a close correspondence with a thermal camera measurement (1047 • C; occupying area of 4.52 m 2 ). We also found that the crust thickness estimate in the lava channel during 6 September 2014 (~3.4-7.7 m) compares closely with the lava height measurement from the field (~2.6-6.6 m); meanwhile, the total radiant flux peak is underestimated (~8 GW) compared to other studies (~25 GW), although the trend shows good agreement with both field observation and other studies. This study provides new insights for monitoring future effusive eruption using infrared satellite images.

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“…Caldera subsidence at Bárðarbunga is likely related to magma draining from a shallow (2-3 kbar) magma reservoir into a lateral dyke. Three ice cauldrons along the dyke path most probably indicate the sites of small subglacial eruptions (Reynolds et al 2017). Coloured symbols indicate the possible origins of melt inclusion-and embayment-bearing macrocrysts at the relevant pressures of crystallization.…”

Section: Comparison Of Petrological and Geophysical Datasetsmentioning

confidence: 99%

“…The total volume of caldera subsidence, 1.8 ± 0.2 km 3 , is comparable with a combination of the intruded magma volume (0.5 ± 0.1 km 3 ) and the total erupted magma output from the Holuhraun vents (~ 1.44 km 3 ; Pedersen et al 2017). Three small ice cauldrons formed along the dyke path probably indicate the sites of small subglacial eruptions (Reynolds et al 2017), which are not included in this erupted volume estimate. Both seismic and geodetic observations are consistent with the magma erupted at Holuhraun being fed by a lateral dyke extending over 45 km from Bárðarbunga central volcano (Sigmundsson et al 2015;Ágústsdóttir et al 2016;Gudmundsson et al 2016).…”

Section: Geophysical Observations Of the Holuhraun Volcano-tectonic Ementioning

confidence: 99%

Melt inclusion constraints on petrogenesis of the 2014–2015 Holuhraun eruption, Iceland

Hartley

Bali

Maclennan

et al. 2018

Contrib Mineral Petrol

129

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The 2014-2015 Holuhraun eruption, on the Bárðarbunga volcanic system in central Iceland, was one of the best-monitored basaltic fissure eruptions that has ever occurred, and presents a unique opportunity to link petrological and geochemical data with geophysical observations during a major rifting episode. We present major and trace element analyses of melt inclusions and matrix glasses from a suite of ten samples collected over the course of the Holuhraun eruption. The diversity of trace element ratios such as La/Yb in Holuhraun melt inclusions reveals that the magma evolved via concurrent mixing and crystallization of diverse primary melts in the mid-crust. Using olivine-plagioclase-augite-melt (OPAM) barometry, we calculate that the Holuhraun carrier melt equilibrated at 2.1 ± 0.7 kbar (7.5 ± 2.5 km), which is in agreement with the depths of earthquakes (6 ± 1 km) between Bárðarbunga central volcano and the eruption site in the days preceding eruption onset. Using the same approach, melt inclusions equilibrated at pressures between 0.5 and 8.0 kbar, with the most probable pressure being 3.2 kbar. Diffusion chronometry reveals minimum residence timescales of 1-12 days for melt inclusionbearing macrocrysts in the Holuhraun carrier melt. By combining timescales of diffusive dehydration of melt inclusions with the calculated pressure of H 2 O saturation for the Holuhraun magma, we calculate indicative magma ascent rates of 0.12-0.29 m s −1 . Our petrological and geochemical data are consistent with lateral magma transport from Bárðarbunga volcano to the eruption site in a shallow-to mid-crustal dyke, as has been suggested on the basis of seismic and geodetic datasets. This result is a significant step forward in reconciling petrological and geophysical interpretations of magma transport during volcano-tectonic episodes, and provides a critical framework for the interpretation of premonitory seismic and geodetic data in volcanically active regions.

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Subglacial volcanic activity above a lateral dyke path during the 2014–2015 Bárdarbunga-Holuhraun rifting episode, Iceland

Cited by 26 publications

References 39 publications

Changes in Geothermal Activity at Bárdarbunga, Iceland, Following the 2014–2015 Caldera Collapse, Investigated Using Geothermal System Modeling

Changes in Geothermal Activity at Bárdarbunga, Iceland, Following the 2014–2015 Caldera Collapse, Investigated Using Geothermal System Modeling

New Insights for Detecting and Deriving Thermal Properties of Lava Flow Using Infrared Satellite during 2014–2015 Effusive Eruption at Holuhraun, Iceland

Melt inclusion constraints on petrogenesis of the 2014–2015 Holuhraun eruption, Iceland

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