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- Magnusson, E., et al.
(författare)
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Development of a subglacial lake monitored with radio-echo sounding: case study from the eastern Skafta cauldron in the Vatnajokull ice cap, Iceland
- 2021
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Ingår i: Cryosphere. - : Copernicus GmbH. - 1994-0416. ; 15:8, s. 3731-3749
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Tidskriftsartikel (refereegranskat)abstract
- We present repeated radio-echo sounding (RES, 5 MHz) on a profile grid over the eastern Skafta cauldron (ESC) in Vatnajokull ice cap, Iceland. The ESC is a similar to 3 km wide and 50-150 m deep ice cauldron created and maintained by subglacial geothermal activity of similar to 1GW. Beneath the cauldron and 200-400 m thick ice, water accumulates in a subglacial lake and is released semi-regularly in jokulhlaups. The RES record consists of annual surveys conducted at the beginning of every summer during the period 2014-2020. Comparison of the RES surveys reveals variable lake area (0.5-4.1 km(2)) and enables traced reflections from the lake roof to be distinguished from bedrock reflections. This allows construction of a digital elevation model (DEM) of the bedrock in the area, further constrained by two borehole measurements at the cauldron centre. It also allows creation of lake thickness maps and an estimate of lake volume at the time of each survey, which we compare with lowering patterns and released water volumes obtained from pre- and post-jokulhlaup surface DEMs. The estimated lake volume was 250 GL (gigalitres = 10(6) m(3)) in June 2015, but 320 +/- 20 GL drained from the ESC in October 2015. In June 2018, RES profiles revealed a lake volume of 185 GL, while 220 +/- 30 GL were released in a jokulhlaup in August 2018. Considering the water accumulation over the periods between RES surveys and jokulhlaups, this indicates 10 %-20% uncertainty in the RES-derived volumes at times when significant jokulhlaups may be expected.
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| 2. |
- Guðmundsdóttir, R. B., et al.
(författare)
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Medication use in populations exposed to the 2010 Eyjafjallajökull eruption: an interrupted time series analysis
- 2022
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Ingår i: Bmj Open. - : BMJ. - 2044-6055. ; 12:5
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To assess the trends in medication use indicative of physical and psychological morbidity following the 2010 volcanic eruption in Eyjafjallajökull immediately after and during a 3-year period following the eruption. DESIGN: Population-based register study. SETTING: Eyjafjallajökull eruption in Iceland, 2007-2013. PARTICIPANTS: All residents in Iceland who received at least one medication dispensing were identified. Residents of exposed areas were classified into exposure groups (individual-level data) and residents in other parts of Iceland were included as a non-exposed group (aggregated data). INTERVENTION/EXPOSURE: Eyjafjallajökull erupted on 14 April 2010 and continued for 39 days, producing heavy ash fall in South Iceland. MAIN OUTCOME MEASURES: Using interrupted time series analysis, we examined annual and quarterly changes in medicine use, measured as number of dispensed defined daily dose (DDD) per 1000 individuals. We calculated the level shift (immediate change) and change in slope from pre-eruption to post-eruption (long-term change) in medication dispensing. RESULTS: Among exposed residents, there was a 6% decrease (95%CI -7% to -4%) in the annual number of dispensed DDDs 1-year post-eruption in the overall medication class, including analgesics (-5%, 95%CI -6% to -3%), hypnotics and sedatives (-9%, 95%CI -11% to -7%) and respiratory medications (-7%, 95%CI -9% to -5%; -8%, 95%CI -11% to -4%). Simultaneously, there was a 9% decrease (95%CI -14% to -4%) in the overall medication class among non-exposed residents. Moreover, among exposed residents, we observed change in slope of -4% (95%CI -7% to -1%) in the overall medication class, including for analgesics (-6%, 95%CI -8% to -3%) and other respiratory drugs (-10%, 95%CI -16% to -4%). CONCLUSION: Our findings indicate that the eruption did not lead to increases in medication dispensing among residents of exposed areas, rather decreases for some medicine classes. The results should be interpreted with caution since the content of each eruption differs.
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