Significant earthquakes in the UK are rare, and an earthquake powerful enough to inflict severe damage is unlikely. Each year, the UK experiences around 200 to 300 earthquakes but only 10% of these are powerful enough to be noticed by people. There is an increased chance of damage occurring and of that damage being severe, in historical buildings. The risk of damage would be greatest closest to the epicentre and decrease with distance. In 2007, a very shallow earthquake occurred near Folkestone in Kent, resulting in power outages, transport disruption and widespread superficial damage. The most damaging UK earthquake in terms of intensity occurred in 1884 in Colchester, Essex. Approximately 1,200 buildings required repairs to collapsed walls, chimneys and roofs. The maximum observed intensity for the earthquake was 8 on the European Macroseismic Scale (EMS).
EMS is an assessment tool and scale of an earthquake’s impact, incorporating the magnitude, local geology, and vulnerability of buildings as part of its measurements. This is preferred to the Richter scale, which only measures the energy of an earthquake, as it provides more information to practitioners and media.
The British Geological Survey (BGS) operates a network of seismometers throughout the UK to acquire seismic data on a long-term basis and to help coordinate an appropriate emergency response, plan for future events and improve confidence in seismic hazard assessments. BGS also collates information on historic earthquakes, to improve estimates of earthquake activity rates, a key part of hazard assessment. These activities are part of its Seismic Monitoring and Information Service.
Scenario
The reasonable worst-case scenario is based on earthquake activity in the UK that results in the ground shaking with an intensity up to 8 on the EMS, which causes damage to buildings and infrastructure. This could result in a small number of fatalities and casualties due to falling masonry or interior damage. Damage to buildings would range from moderate to severe, for example from extensive cracks in walls to complete collapse of chimneys. More substantial damage could occur to more vulnerable structures. Such an earthquake may cause short-term but significant disruption to infrastructure, transport and communications, even if the physical damage is comparatively minor. There is a low likelihood of power outages caused by vibration of apparatus at electrical substations. There is also a low likelihood of disruption to transport and communications networks. Safety inspections of high consequence structures and installations including nuclear power plants, dams and reservoirs, bridges and tunnels would be required.
Key assumptions for this scenario
The risk assumes that no critical infrastructure is damaged to an extent that overwhelms existing emergency plans. It assumes one EMS 8 earthquake, with further related earthquakes having only minor impacts.
Variations of this scenario
A higher magnitude earthquake, or one that affects more critical infrastructure or built-up areas would have higher impacts.
Response capability requirements
Capabilities required to deal with the aftermath from an earthquake are largely covered by plans put in place by government departments and Local Resilience Forums (LRFs). This includes the restoration of essential services (gas, water, electricity, communications) due to pipes or cables being disrupted. Damage to infrastructure such as power or communications networks will require specialist intervention. Additional support could be provided via mutual aid agreements with neighbouring local authorities or LRFs – supplemented as necessary by national support (for example specialist Fire and Rescue equipment held as national assets).
Recovery
Temporary or permanent rehousing may be necessary where residential properties are unsafe or uninhabitable (due to a lack of access or a lack of services), and while clearance and assessment is carried out. Temporary relocation of commercial premises or other infrastructure such as schools might be necessary where the properties have been damaged and are considered unsafe or unusable.Short-term closures of bridges, roads, and rail lines may be necessary to carry out safety inspections and repairs. There are unlikely to be any significant long-term implications from an earthquake, although there may be a spike in numbers of people seeking access to mental health services for psychological support in the months after the incident. Vulnerable persons and children in particular are more likely to require support.
Aftershocks may be experienced following magnitude 5 and 6 earthquakes, which could last weeks or months. These aftershocks may cause further disruption and damage, delaying recovery efforts.
Key assumptions for this scenario
Wildfires typically occur between February and October. There are differences in nature, scale and timing of the risk across the UK. Responsibility for fire and rescue services is devolved.
Variations of this scenario
Multiple wildfires could take place at the same time as a result of a prolonged period of heat and dry spells. This would impact multiple Fire and Rescue Services (FRS) which would impact mutual aid support.
Response capability requirements
Fire and Rescue services would lead on the response; putting out the fire and emergency evacuation and rescue of residents. This would include utilisation of national capabilities, for example high-volume pumps for water, and urban search and rescue assets to help move equipment. Mutual aid from unaffected Fire and Rescue Services would be requested.
Recovery
Recovery would be dependent on the location of fire and the vegetation/soil types impacted. Vegetation can take years to recover, with a sustained impact on local wildlife. If the location of the fire features peat in the soil there would be additional longer-term environmental implications due to the release of carbon from the burning.
