Gas changes in the Krafla geothermal system, Iceland

Ármannsson, Halldór; Benjamínsson, Jón; Jeffrey, A.W.A.

doi:10.1016/0009-2541(89)90089-2

Cited by 50 publications

(36 citation statements)

References 22 publications

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“…Meltwater pH and temperature were determined in the laboratory on filtered samples using a portable pH meter calibrated by pH 4 and pH 7 buffers. The H2S concentration was measured on 50-ml samples by titration to a red endpoint with 0-001 M mercury (11) acetate solution, aHg(CH3C00)2, using dithizone as indicator (Olafsson, 1988: 16-17;Armannsson et al, 1989). Precision was f 5 % and the detection limit was 0.6 pmol I-'.…”

Section: Hydrochemistry: Sampling and Analytical Methodsmentioning

confidence: 99%

“…Arnorsson, 1974;Armannsson et al, 1989). H2S is a volcanic gas and increased concentrations of dissolved H2S and C 0 2 in geothermal fluids are commonly taken to represent enhanced magmatic activity (Armannsson et al, 1989). The pronounced H2S spike ( Figure 8C) is thus likely to represent degassing of a magma reservoir (e.g.…”

Section: Interpretation Of' Water Quality Perturbationsmentioning

confidence: 99%

“…Sigvaldason, 1963), with a magma body assumed to provide the source of sulphur (e.g. Arnorsson, 1974;Armannsson et al, 1989). H2S is a volcanic gas and increased concentrations of dissolved H2S and C 0 2 in geothermal fluids are commonly taken to represent enhanced magmatic activity (Armannsson et al, 1989).…”

Section: Interpretation Of' Water Quality Perturbationsmentioning

confidence: 99%

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Impact of Subglacial Geothermal Activity on Meltwater Quality in the Jökulsá Á Sólheimasandi System, Southern Iceland

Lawler

Björnsson

Dolan³

1996

Hydrol. Process.

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The influence of subglacial geothermal activity on the hydrochemistry of the Jokulsa a Solheimasandi glacial meltwater river, south Iceland, is discussed. A radio echosounding and Global Positioning System survey of south-west Myrdalsjokull, the parent ice-cap of the valley glacier S6lheimajokul1, establishes the geometry and position of a subglacial caldera. A cauldron in the ice-cap surface at the basin head is also defined, signifying one location of geothermally driven ablation processes. Background H2S concentrations for the Jokulsa meltwaters in summer 1989 show that leakage of geothermal fluids into the glacial drainage network takes place throughout the melt season. Chemical geothermometry (Na+/K+ ratio) applied to the bulk meltwaters tentatively suggests that the subglacial geothermal area is a high-temperature field with a reservoir temperature of =289-304"C. A major event of enhanced geothermal fluid injection was also detected. Against a background of an apparently warming geothermal reservoir, the event began on Julian day 205 (24 July) with a burst of subglacial seismic activity. Meltwater hydrochemical perturbations followed on day 209 and peaked on day 213, finally leading to a sudden and significant increase in flow on day 214. The hydrochemical excursions were characterized by strong peaks in meltwater H2S, SO:-and total carbonate concentrations, transient decreases in pH, small increases in Ca2+ and Mg2+ and sustained increases in electrical conductivity. The event may relate to temporary invigoration of the subglacial convective hydrothermal circulation, seismic disturbance of patterns of groundwater flow and geothermal fluid recruitment to the subglacial drainage network, or a cyclic 'sweeping out' of the geothermal zone by the annual wave of descending groundwater. Time lags between seismic events and meltwater electrical conductivity responses suggest mean and maximum intraglacial throughflow velocities of 0.032-0.132 m s-l, respectively, consistent with a distributed drainage system beneath Solheimajokull. Because increases in flow follow hydrochemical perturbations, the potential exists to use meltwater hydrochemistry to forecast geothermally driven flood events in such environments.

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Section: Hydrochemistry: Sampling and Analytical Methodsmentioning

confidence: 99%

Section: Interpretation Of' Water Quality Perturbationsmentioning

confidence: 99%

Section: Interpretation Of' Water Quality Perturbationsmentioning

confidence: 99%

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Impact of Subglacial Geothermal Activity on Meltwater Quality in the Jökulsá Á Sólheimasandi System, Southern Iceland

Lawler

Björnsson

Dolan³

1996

Hydrol. Process.

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“…Only data on chloride and fluoride concentrations (246 and 56 samples respectively) are presented here, however, because they are likely to reflect magma-water interaction, signifying upstream volcanic disturbance. HCl and HF gases often degas from magma (Sigurdsson et al, 1985) and may condense into overlying meteoric water (Ármannsson et al, 1989;Nicholson, 1993). The duplicate samples were filtered through 0·45 µm cellulose nitrate filter circles to minimize post-sampling sediment dissolution and stored untreated in plastic bottles according to guidelines on water quality analysis (e.g.…”

Section: Hydrochemistrymentioning

confidence: 97%

“…Both these anions may be derived from the volcanic gases HCl and HF (e.g. Ármannsson et al, 1989;Nicholson, 1993;Sigurdsson et al, 1985). Furthermore, an earthquake also occurred below or close to the eastern cauldron (<2 km) from where Jökulhlaup 1 is believed to have originated (Table III and Figure 7).…”

Section: Suspended Sediment Concentration (Ssc) Dynamics During the Jmentioning

confidence: 98%

Discharge and suspended sediment dynamics during two jökulhlaups in the Skaftá river, Iceland

Old

Lawler

Snorrason³

2005

Earth Surf Processes Landf

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This paper investigates the dynamics and significance of discharge and suspended sediment transport (SST) during two jökulhlaups (glacier outburst floods) in the Skaftá River, south Iceland. Jökulhlaups occur frequently in many glacial environments and are highly significant in the geomorphological evolution of river basins and coastal environments. However, direct high-resolution monitoring of jökulhlaups has rarely been accomplished and hardly ever at more than one station in a downstream sequence. Here we present detailed data on jökulhlaup discharge and water quality from an intensive monitoring and sampling programme at two sites in summer 1997 when two jökulhlaups occurred. Evidence is discussed that supports the origin of both jökulhlaups being subglacial reservoirs, produced over several months by subglacial geothermal activity. At the downstream site, Ása-Eldvatn, the larger jökulhlaup (1)

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Volcanology

Luhr¹,

Williams

1991

Reviews of Geophysics

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Gas changes in the Krafla geothermal system, Iceland

Cited by 50 publications

References 22 publications

Impact of Subglacial Geothermal Activity on Meltwater Quality in the Jökulsá Á Sólheimasandi System, Southern Iceland

Impact of Subglacial Geothermal Activity on Meltwater Quality in the Jökulsá Á Sólheimasandi System, Southern Iceland

Discharge and suspended sediment dynamics during two jökulhlaups in the Skaftá river, Iceland

Volcanology

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