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In NW Europe (including Iceland), what could be the environmental impacts of a large Icelandic plinian eruption and a large effusive eruption? How might they differ?

Introduction

The eruption of Eyjafjallajkull in 2010 was followed by widespread disruption across much of Europe to both air travel and to those sectors of the economy impacted by the loss of trade. The International Air Transport Association stated that the disruption caused by the ash cloud cost the global airline industry 130 million per day (The Guardian Online, 2010). Industries trading in fresh produce and pharmaceuticals also reported losses of several millions of pounds daily (BBC Online, 2010). Eyjafjallajkulls connection to the (historically) much more volatile Katla has led the Icelandic government to devise precautionary measures for an eruption which is expected in the near future (BBC Newsnight, 2010). What will be the impacts of another eruption on northwestern Europe? In this project I aim to discuss the various potential environmental impacts that both a large plinian eruption and a large effusive eruption might have across NW Europe today. I intend to do this by detailing the causes and effects of previous plinian eruptions from Icelandic volcanoes, namely Hekla, rfajkull, Askja, and Eyjafjallajkull, as well as effusive eruptions, namely Eldgj, Laki, and Katla. Examples are drawn solely from Iceland as it is the only volcanic region in NW Europe (and the world) where eruptions of this type and scale are occurring on repeat intervals of 100s to 1000s of years (Thordarson and Self, 2003). Assumptions must be made about the environmental impacts of past eruptions and the similarities between them and the impacts of future eruptions.

Past examples of the effects of Icelandic plinian eruptions on NW Europe

In the past, the effects brought about by large plinian eruptions in Iceland have been both localised and extensive. The earliest known plinian eruptions happened on Iceland in prehistoric, pre-Landnm times. The tephra layers laid down by the volcano Hekla in the mid-late Holocene are referred to as H3 and H4, and have been detected in Europe as far afield as Lake Furskogstjrnet in Sweden (Tephrabase, 2012). However, the H4 deposit pre-dates settlement on Iceland by over two millennia, and the volcano is unlikely to have had a significant effect on NW Europe until the earliest recorded eruption of Hekla in 1104AD. Even so, it has been suggested that Hekla had limited impact on the local farms and communities in the jrsrdalur valley during the 1104 eruption, merely exacerbating the environmental degradation brought about by grazing and leading to the abandonment of several farms and settlements in the area (Dugmore et al., 2007). The 1875 Askja eruption was likely considerably more damaging to the local Icelandic communities: assigned a Volcanic Explosivity Index (VEI) of 5, over the course of approximately ten months Askja ejected 1.8 km3 of tephra and 0.3 km3 of lava. The eruption resulted in damage to land and property and the evacuation of settlements (Sigurdsson and Sparks, 1978). The explosive eruption of rfajkull in 1362 was largely restricted to widespread ash fall across Eastern Iceland and parts of northern Europe (Sharma et al., 2008). One model of the rfajkull 1362 eruption estimates the height of the eruption column at 30 km high, which identifies the eruption as plinian-type. Similarly, the 2010 Eyjafjallajkull eruption was one of the most notable eruptions of the 21st century due to its ash ejecta and the heavy impact that it had on air travel and the economy.

Past examples of the effects of large effusive eruptions on NW Europe

With regard to effusive eruptions, the Laki flood lava eruption was one of the most destructive and well-documented eruptions in Icelandic and NW European history. In 1783, the Laki fissure opened (a fissure which contains 130 craters, including the Grmsvtn volcano which erupted in the spring of 2011) and ejected approximately 122 Mt of SO2 over a period of eight months (Global Volcanism Program, 2012). An estimated 14 km3 of lava and 0.95 km3 of tephra flowed from the fissure and covered over 8,000 km2 in ash (Thordarson and Self, 2003). 175 Mt of H2SO4 (sulphuric acid) was washed or rained out of the atmosphere as a direct result of Lakis emissions. Over 500 mg of fluorine per km2 was deposited on Icelandic farmland and grazing land. This resulted in dental and skeletal fluorosis in the livestock which led to a further 9,300 famine-related deaths approximately 20% of Icelands population at the time. It was not until 1824 that the population had recovered, some fifty years later. In England there were approximately 23,000 excess deaths due to cardiopulmonary disease resulting from sulphur dioxide in the atmosphere (Grattan et al., 2003). The sheer volume of dust particles meant that there was upwards of 16 times the average amount of cloud condensation nuclei (CCN) in the upper troposphere (Schmidt et al., 2010). This led to heavy fog and extreme weather across NW Europe in the months that followed the winter of 1783 was one of the coldest on record in Europe and North America (Thordarson and Self, 2003) and the summers of 1783-84 were noted as being unusually hot.Effects were felt as far afield as Egypt (Oman et al., 2006), where famine struck, and in Brazil, which was subjected to heavy fogs, most likely due to the increased concentration of CCNs (Schmidt et al., 2010).Eldgj, part of the volcanic system which also includes Katla, erupted to devastating effect in 934-938 approximately (Stothers, 1998). An estimated 19.5 km3 of lava poured out of a 75 km long fissure system and injected 219 Mt of SO2 into the atmosphere the largest volume of gas emitted by a volcano in historic time (Stothers, 1998). Because Eldgj erupted during the European Dark Ages, there is no written account or description of the eruption available. However, it would be reasonable to assume that the effects of the Eldgj eruption were similar to those of the Laki flood lava eruption of 1783. Exposed lava and tephra deposits in Iceland and tephra fallout deposition in Greenland have been studied and have shown the Eldgj eruption to have had an even greater influence on climate than Laki 1783, in both volume of aerosols injected into the atmosphere and duration of effects where the effects of the Laki flood lava eruption were still apparent after 2-3 years, the climate remained affected by Eldgjs input for 5-8 years (Stothers, 1998). However, large flood lava eruptions such as these occur on repeat intervals of 300-1000 years (Thordarson and Self, 2003).

Discussion

Do the described environmental impacts have the potential to affect the greater part of NW Europe? In future, the result of a large eruption may be that affected settlements are evacuated/displaced, similarly to the 2010 Eyjaffjallajkull eruption, when the Icelandic Civil Protection Agency ordered the evacuation of up to 800 people in the vicinity of the ice-covered Eyjafjll volcano (Davies et al., 2010). Whether or not a settlement is evacuated is largely dependent on the type of eruption and the direction of lava flow. There may also be a considerable risk to property, primarily from the lava flow and tephra, but also from secondary hazards such as jkulhlaups and lahars. For instance, Eldgj 934 and Laki 1783 buried 781 km2 and 599 km2 of land by lava flow, respectively. These risks would generally be localised to within tens of kilometres and almost exclusively threaten Icelandic settlements. The threat to life is very small however, due to the local knowledge of the Icelandic Government and NW Europe in general. Evacuation procedures are readily-conceived and well-implemented when an eruption is predicted or expected.

Damage to livestock and crops however could very likely reach far beyond NW Europe as has been observed in the past, where Eldgj 934 and Laki 1783 produced so much sulphur dioxide that a volcanic haze affected as far as 20S of the equator and as far east as Egypt (Oman et al., 2006).One of the greatest risks from a large effusive volcano is typically the poisonous gases ejected from it HF (hydrogen fluoride) has been attributed to the death of approximately 50% of livestock in Iceland following the flood lava eruption of Laki in 1783 as the cause of fluorosis. The airborne transport of HF may lead to the disease or death of livestock and crops in NW Europe. SO2 was also a significant contributor to the deaths of 23,000 in England following the Laki 1783 eruption, and still holds the potential for widespread damage in terms of respiratory illness and acid rain across modern Europe. Perhaps the greatest threat is more indicative of the time we live in, where the greatest impact that Icelandic volcanoes can have on NW Europe is economic: the primary threat to Scotland from the tephra is economic in nature. Airborne ash, even from small eruptions such as the ongoing Eyjafjallajkull eruption, causes the redirection or cancellation of transatlantic flights (Whitham et al., 2007). The dangers that volcanic ash poses to aviation are well understood and were fully realised in the disruption brought about by Eyjafjallajkull 2010.

Conclusions

While the most significant Icelandic eruptions occur over timescales of 100s to 1000s of years, smaller eruptions like that of Eyjafjallajkull in 2010 tend to occur much more frequently, and so the risk they pose to the environment is considerable. The potential impacts that another eruption comparable to Askja 1875 or Laki 1783 might have on NW Europe are more than likely to be similar to the effects observed in the past. Thordarson and Self state: eeruptions of Laki magnitude have occurred in the recent past in Iceland and will occur again. If such an eruption were to occur today, one of the most likely immediate consequences would be disruption to air traffic over large portions of the Northern Hemisphere (Thordarson and Self, 2003). Disruption to air traffic will of course require an eruption of an explosive nature so that it generates an eruption column and tephra capable of being carried across Europe and North America, but a large effusive eruption has the potential to heavily impact the environment for much of the Northern Hemisphere, not just in NW Europe.

References cited:

Davies, S.M., Larsen, G., Wastegard, S., Turney, C.S.M., Hall, V.A., Coyle, L., and Thordarson, T. (2010). Widespread dispersal of Icelandic tephra: how does the Eyjafjll eruption of 2010 compare to past Icelandic events?. Journal of Quaternary Science, 25, 605-611.

Dugmore, A.J., Church, M.J., Mairs, K., McGovern, T.H., Perdikaris, S., and Vsteinsson, O. (2007). Abandoned Farms, Volcanic Impacts, and Woodland Management: Revisiting jrsrdalur, the Pompeii Of Iceland. Arctic Anthropology, 44(1), 1-11.

Grattan, J.P., Durand, M., and Taylor, S. (2003). Geological Society Special Publication, 213, 401414.

Oman, L., Robock, A., Stenchikov, G.L., and Thordarson, T. (2006). High-latitude eruptions cast shadow over the African monsoon and the flow of the Nile. Geophysical Research Letters, 33, L18711.

Schmidt, A., Carslaw, K.S., Mann, G.W., Wilson, M., Breider, T.J., Pickering, S.J. and Thordarson, T. (2010). The impact of the 1783-1784 AD Laki eruption on global aerosol formation processes and cloud condensation nuclei. Atmospheric Chemistry and Physics, 10, 6025-6041.

Sharma, K., Self, S., Blake, S., Thordarson, T., and Larsen, G. (2008). The AD 1362 rfajkull eruption, S.E. Iceland: Physical volcanology and volatile release. Journal of Volcanology and Geothermal Research, 178(4), 719-739.

Sigurdsson, H., and Sparks, R.S.J. (1978). Rifting episode in North Iceland in 1874-1875 and the eruptions of Askja and Sveinagja. Bulletin of Volcanology, 41, 149-167.

Stothers, R.B. (2008). Far reach of the Tenth Century Eldgj Eruption, Iceland. Climatic Change, 39, 715-726.

Thordarson, T., and Self, S. (2003). Atmospheric and environmental effects of the 1783-1784 Laki eruption: A review and reassessment. Journal of Geophysical Research, 108(D1), 4011.

Witham, C. S., Hort, M. C., Potts, R., Servranckx, R., Husson, P., and Bonnardot, F. (2007). Comparison of VAAC atmospheric dispersion models using the 1 November 2004 Grimsvtn eruption. Meteorological Applications, 14(1), 27-38.

Websites:

BBC News (2010). Iceland volcano cloud: The economic impact. Available at http://news.bbc.co.uk/1/hi/business/8629623.stm" http://news.bbc.co.uk/1/hi/business/8629623.stm [Accessed 13/03/2012]

Wearden, G. (2010). Ash cloud costing airlines 130m a day. Available at http://www.guardian.co.uk/business/2010/apr/16/iceland-volcano-airline-industry-iata" http://www.guardian.co.uk/business/2010/apr/16/iceland-volcano-airline-industry-iata [Accessed 13/03/2012]

United States Geological Survey (2008). Laki and Eldgj two good reasons to live in Hawaii. Available at http://hvo.wr.usgs.gov/volcanowatch/2008/08_11_26.html" http://hvo.wr.usgs.gov/volcanowatch/2008/08_11_26.html [Accessed 13/03/2012]

BBC Newsnight (2010). Olafur Grimsson: Eruption is only small rehearsal. Available at http://news.bbc.co.uk/1/hi/programmes/newsnight/8631343.stm" http://news.bbc.co.uk/1/hi/programmes/newsnight/8631343.stm [Accessed 13/03/2012]

Tephrabase (2011). A Tephrochronological Database. Available at http://www.tephrabase.org/" http://www.tephrabase.org/ [Accessed 13/03/2012]Global Volcanism Program (2011). Worldwide Holocene Volcano and Eruption Information. Available at ttp://www.volcano.si.edu/world/volcano.cfm?vnum=1703-05=&volpage=sources" http://www.volcano.si.edu/world/volcano.cfm?vnum=1703-05=&volpage=sources [Accessed 13/03/2012]