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Volcanic Hazard from Iceland:

Analysis and Implications of the Eyjafjallajökull eruption

Executive Summary

compilation of Iceland report figures

The explosive eruption on the 14th April 2010 of the Eyjafjallajökull volcano, Iceland, caused an unprecedented closure of UK, European and North Atlantic air space, which must be understood if similar situations are to be better managed in the future. This report examines the Eyjafjallajökull eruption, its impact on aviation and implications for the future, in the expectation of further activity in Iceland. By bringing together expertise from across the University, the UCL Institute for Risk and Disaster Reduction provides an integrated analysis covering volcanology, geophysics, rock and ice physics, meteorology, statistics, mechanical engineering, systems engineering, transport engineering, hazard and risk communication, law and ethics. 

We find: 

  • The current volcanic activity in Iceland is not unusual. Explosive eruptions, comparable to the 2010 Eyjafjallajökull event, occur in Iceland every 20 to 40 years on average. The 1821-23 Eyjafjallajökull eruption lasted 14 months.
  • Volcanic activity at Eyjafjallajökull only becomes a major problem over Europe if this activity is coincident with north to north westerly air flow between Iceland and North West Europe, which prevails for only 6% of the time. The implication, however, is that the most recent disruption of air transport in mid-May may not be the last, despite the current (24th May) cessation of ash production.
  • The impact of the eruption on regional air space could have been predicted and better prepared for as the growing problem of aircraft-ash cloud encounters has been recognised for decades. Similarly, the potential for ash clouds, specifically from Icelandic volcanoes, to interfere with air traffic in UK, European and North Atlantic air-space was appreciated by the aviation industry well before the start of the Eyjafjallajökull eruption.
  • The response to the ash cloud’s arrival in UK and adjacent air space was entirely reactive and therefore less effective than it should have been. This was primarily a function of the failure to recognise in advance the potential threat presented by volcanic ash clouds from Iceland. The situation was made worse by the inflexible nature of existing aviation protocols and by the absence of any pre-existing agreement on safe ash levels.
  • Volcanic ash in the atmosphere can be highly damaging to the airframes, avionics and engines of civil jet aircraft: ingestion by engines of 2 gm-3 of ash has caused loss of power and near-crashes. The newly defined safe limits of ash are ad hoc and arbitrary and cannot be scientifically justified. Determining a range of robust best-estimate safe levels of ash for a wide range of situations, aircraft, engine types and pilot responses will cost time and money and will require the commitment of the aviation industry.
  • Since the start of the Eyjafjallajökull eruption there has been much speculation about an eruption of the larger neighbouring Katla volcano. With the high frequency of eruptions of Katla, an eruption in the short term is a strong possibility. It is likely to be preceded by new earthquake activity. Presently there is no unusual seismicity under Katla.
  • There is no doubt that future explosive eruptions in Iceland and elsewhere, coupled with appropriate meteorological conditions, have the potential to cause further disruption to air transport. It is not possible, however, to predict either when this will occur, or at what scale. The Eyjafjallajökull eruption demonstrated the limits of a precautionary approach. This then raises ethical issues, over who is to articulate the values to be taken into account when managing risk.


The air travel infrastructure comprises a complex system that was very significantly disrupted by the Eyjafjallajökull eruption. With foresight and investment, it would not be difficult to reduce disruption significantly. Critically, it has to be recognised that:

- For whatever reason, air travel across the UK and Europe may again be disrupted for a prolonged period (e.g., following a series of terrorist incidents) and contingency plans for this should be established.

- Ways need to be established to maximise safe air travel during such disruption.

In relation to the hazard associated with volcanic ash, the report makes the following recommendations:

  • Recognition - The potential threat to aviation presented by all sources of volcanic ash and sulphur dioxide should be added to the National Risk Register.
  • Characterisation - National capabilities for measuring and predicting the extent and character of volcanic ash over UK and European air space should be enhanced. Modelling of scenarios for future eruptions and ash plume dispersion should be undertaken.
  • Analysis - While the 200 and 4000 μgm-3 thresholds of ash concentrations are useful, they are not explicitly based on empirical experience other than that they appear to be ‘safe’. These levels need to be reviewed. Such analysis should take into account the type of aircraft, age of aircraft, engine make, flight path, frequency of service, ground maintenance capabilities, pilot behaviour and other characteristics, so that a clear and consistent picture of risk is obtained. Although this makes a clear ‘no fly’ message more convoluted it would prevent the necessity of a highly disruptive blanket ban. Acknowledging the emotive nature of the issue and the vested interests and commercial pressures involved, and to balance precaution and pragmatism, the report proposes establishing an independent review panel with appropriate expertise to set robust best-estimate safe levels for volcanic ash.
  • Regulation - To minimise chaos, ill-feeling and exploitation, regulation should be considered to manage the actions of organisations such as airlines at times of emergency. These might include approval of night operations at airports; insistence that no plane flies with empty seats if passengers with valid tickets are stranded; and fixing fares during the affected period.
  • Communication - A communications centre should be established that advises the public and which all affected bodies are required to support. This would avoid the huge expense to individuals trying without success to contact airlines and other transport bodies. Such a communications plan should use the resources available to the media in communicating advice objectively.
  • Planning - At a national level plans should be developed to deal with the long term grounding of aircraft, including consideration given to the financial impact on stakeholders as well as arrangements for repatriation of travellers. At an international level, the report reiterates the principal recommendation of the UK Government Natural Hazards Working Group (2005), vis-à-vis the establishment of an international science panel to catalogue, evaluate and raise awareness of regional natural hazards with the potential to affect more than one nation.
iceland report

If you would like to comment on this report, please email the Institute Administrator. All comments will be addressed. We are happy to make available our data and details of the methodologies we employed.

This report was produced by members of the IRDR and internally reviewed.

To cite:

Sammonds, P., McGuire, W., & Edwards, S. (Eds.). 2010. Volcanic Hazard from Iceland: Analysis and Implications of the Eyjafjallajökull Eruption. UCL Institute for Risk and Disaster Reduction, London