Volcanic eruption
| Impact | 5 |
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| 3 |
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| 2 |
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| ID | 43 |
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| Risk theme | Natural and environmental hazards |
Impact & Likelihood
| 5 | Catastrophic |
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| 4 | Significant |
| 3 | Moderate |
| 2 | Limited |
| 1 | Minor |
| 5 | >25% |
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| 4 | 5-25% |
| 3 | 1-5% |
| 2 | 0.2-1% |
| 1 | <0.2% |
Background
There are a number of volcanoes across Europe that could affect the UK, such as Santorini in the Aegean Sea and Vesuvius in Italy. However, volcanoes in Iceland (such as Bárðarbunga and Eyjafjallajökull) are of most concern because they are close to the UK, and the high volume of air traffic across Europe that could be impacted.
Scenario
The reasonable worst-case scenario is based on an ash-rich volcanic eruption into UK airspace that results in sporadic and temporary severe disruption to flights in parts of UK or international airspace. Severe disruption could occur for up to 15 days (potentially non-consecutive), with moderate disruption over an additional 10 days during a 3-month eruption period. The duration of severe disruption would be heavily influenced by eruption characteristics, meteorological conditions, concentration of ash and level of aviation activity. Disruption could include severe flight delays, diversions and cancellations, impacting passenger and freight flow. The greatest risk to the UK from volcanic eruptions comes from Iceland. British nationals may be stranded abroad, while foreign nationals in the UK (including those diverted to the UK) may find themselves being forced to delay their return home.
Key assumptions
Volcanic eruptions are unpredictable in nature and the severity of volcanic eruptions can be vastly different depending on the type of volcanic eruption. Disruption to aviation services is also dependent on the meteorological conditions, which are also variable.
There are no assumptions about the specific locations. It is assumed that the eruption produces a large ash cloud rising to high altitude in conjunction with meteorological conditions causing major disruption to aviation in the UK and Europe. Some early warning signs may be observed, including volcanic earthquakes, seismic tremor (vibration), ground deformation (changes in elevation), gas emissions or meltwater from glaciers.
Variations
A lower impact, higher probability scenario could see a volcanic eruption with explosive phases over a 2-week period with smaller ash plumes or winds that carry the ash further north/away from the UK. This would result in ash concentrations in the UK not being sufficient to cause significant travel disruption, but there is some anxiety and people could postpone travel resulting in an economic impact on the airline industry and wider UK. There could be disruption to aviation in Iceland and/or Scandinavia.
A higher impact, lower probability variation involves a large eruption (volcanic explosivity index 7, VEI7+) generating ash and gas that is carried across the northern hemisphere, causing widespread devastation. Aviation could experience significant disruption across several countries in this period. The eruption could lead to an international humanitarian crisis and include major disruption to supply chains, international displacement, and hazardous weather.
Response capability requirements
The London Volcanic Ash Advisory Centre (Met Office) would produce volcanic ash forecasts and guidance to the relevant agencies and airlines. Consular support would be required for British nationals stranded abroad.
Recovery
Eruptions can last several months to a year with different explosive phases, with disruption to aviation services also being dependent on meteorological patterns. There could be a period of days before air services return to normal as the backlog is managed.