Subsidence is the downward movement of the ground and is widespread across Europe. Its causes and effects vary greatly depending on location, creating issues such as home and infrastructure damage, increased susceptibility to flooding and loss of groundwater storage capacity. Climate change could increase these pressures in certain areas through more frequent droughts and heatwaves and changing groundwater recharge patterns.

Satellite radar has changed the way researchers study land movement. Europe Copernicus Land Monitoring Service, particularly the European Ground Motion Service, provides open-access information on ground motion across most of the European landmass. It helps researchers identify areas of subsidence and compare developments across countries. However, to understand why some land is sinking, satellite measurements need to be combined with subsurface knowledge: geology, groundwater levels, soil properties and human activities both above and below ground.

An international group of researchers, led by the Geological Survey of the Netherlands and including experts from BGS, has authored a new paper, , exploring the insights Europe has gathered from decades of studying land subsidence. The paper highlights the fact that such subsidence is not only a scientific concern but also a societal one, which needs a multi-system approach to ensure it is properly managed.

What causes subsidence?

The study describes a wide range of natural and human-induced processes that can contribute to land subsidence, including:

• tectonic movements
• groundwater extraction
• mining
• hydrocarbon extraction
• soft soils
• natural ground compaction

The researchers also point to possible new causes linked to the energy transition. Technologies such as geothermal energy, carbon capture and storage, underground gas storage and hydrogen storage all make use of the subsurface. Depending on local conditions and how these systems are operated, such activities may influence ground motion. This makes careful monitoring and integrated assessment essential.

Land subsidence is common across Europe. In the UK, we have measured subsidence up to 2 cm per year in some coastal areas. This has important implications for coastal erosion and long-term impacts from sea level change.

Ekbal Hussain, remote sensing geoscientist.

Better decisions need better data

Better subsurface insight helps governments, industry and society make more informed decisions about water, infrastructure, climate adaptation and the energy transition.

Europe already has an important foundation for this: open data infrastructures, national monitoring programmes and cooperation between geological surveys, research institutes and policymakers. The challenge now is to bring this data together more effectively. By combining satellite observations with subsurface data and physics-based models, governments and industry can better distinguish between possible causes of land subsidence, assess future risks and weigh appropriate measures. It is hoped that this knowledge will support future risk assessment and decision-making across Europe.

The origin of the Kinnekulle tephra, a huge volcanic ash layer spread across Norway, Sweden, the Baltic region, Belarus and Poland, has long been a mystery but new evidence may have uncovered the source of the ash for the first time.

Scientists at the 51���� (BGS) and the University of Oslo have studied tiny crystals, smaller than the diameter of a human hair, extracted from boreholes 65 km apart in Lincolnshire and Norfolk. The analysis uncovered evidence of a 454 million year old supervolcano, now concealed beneath The Wash on the east coast of England.

Volcanic rocks of comparable age comprise the rugged topography of Eryri (Snowdonia) and the Lake District. A belt of arc volcanism extended from the Lake District towards Belgium in late Ordovician times, when England was separated from Scandinavia by an oceanic basin. The geography was probably comparable to the West Pacific region (Korea–Japan–Indonesia) today.

Using cutting-edge analytical techniques at ���ҳ� laboratories, scientists have been able to examine zircon crystals, which form within molten magma before a volcano erupts. Over time, uranium within the zircon slowly decays into lead isotopes, analysis of which enables the age of eruption to be precisely determined. The research reveals that the zircon crystals at both sites were formed at approximately the same time, about 454.4 million years ago. Researchers at the University of Oslo had previously obtained an almost identical age for the Kinnekulle tephra in the Oslo region.

The scientists believe that the near‑identical ages suggest that ash from the eruption plume in what is now eastern England was blown across the Tornquist Sea, which separated England and Scandinavia, and settled on the sea floor of ancient Scandinavia. Further support for this hypothesis is provided by chemical analysis of apatite crystals in both the proposed source and the tephra. During the highly explosive ‘super-Plinian’-type eruption, hundreds of cubic kilometres of rock were launched into the stratosphere by the force of the blast. One of the samples also contained younger zircon grains, dated to 453.70 million years, reflecting a further eruption associated with the collapse of the volcanic caldera.

More than 454million years ago, a supervolcano now hidden beneath some of England flattest landscapes, produced some of the biggest eruptions in recorded Earth history. We believe that, thanks to cutting edge-analysis, we have been able to provide evidence that the source of the ash layer in Scandinavia originated from this supervolcano, reshaping our understanding of England deep geological past.

Tim Pharaoh, BGS, principal author of the paper.

The research paper, ‘, is now available to read.

The analytical work for the the supervolcano project was funded by The  is an integrated analytical platform funded by the , part of UK Research and Innovation ().

Across Europe, the subsurface is increasingly being recognised as a strategic asset that is critical for energy transition, resource security and environmental resilience. At the heart of efforts to harness this potential is the (GSEU), a major pan-European initiative working closely with national geological surveys such as BGS. Together, we are reshaping how geological knowledge is generated, shared and applied for societal benefit.

A shared European vision beneath our feet

Launched in 2022 under Horizon Europe, GSEU aims to establish a permanent geological service for Europe. Its core premise is simple yet transformative: geological challenges do not stop at national borders and therefore must be addressed through harmonised data and collaboration.

Through a partnership of nearly 50 organisations across more than 35 countries, GSEU is developing integrated pan-European datasets and services that address Europe most pressing challenges, such as:

• securing the critical raw materials needed for green technologies
• managing groundwater resources under increasing climate pressure
• expanding renewable energy solutions, including geothermal
• planning subsurface use
• coastal management to avoid conflicts between infrastructure, storage and environmental protection

Rather than treating these domains separately, GSEU recognises that they interact within a complex and interconnected subsurface system that requires a holistic and coordinated approach to support policymaking, environmental protection and the transition to a low-carbon economy. Through shared standards, interoperable data models and coordinated research agendas, GSEU aims to create a unified geological knowledge base capable of supporting these goals.

From data to knowledge: the power of publications

One of the most tangible outputs of GSEU is its growing body of open-access publications that translate complex geoscientific work into actionable knowledge. The showcases a diverse range of outputs, such as scientific papers, factsheets and strategic position papers.

Recent highlights include:

• a , emphasising the need for coordinated approaches to achieve resilience and strategic autonomy
• scientific studies advancing the understanding of , including deposit mapping and predictive modelling approaches
• practical factsheets on and , supporting evidence-based environmental management
• the , a strategic roadmap outlining the long-term vision for a sustainable geological service across Europe
• the Geo-Assessment Matrix, a pan-European catalogue of key parameters for offshore wind farm siting

These publications form part of a broader effort to move beyond isolated datasets and towards the integrated (EGDI), a platform that makes harmonised geological data accessible for research, policy and industry.

The role of BGS

As the UK national geological survey, BGS is a key contributor to GSEU. Our involvement reflects a longstanding commitment to international collaboration and data sharing. Through GSEU, our scientists contribute expertise in areas such as:

• critical raw materials and resource assessment
• groundwater systems, including leadership in groundwater drought and trend analysis
• geothermal energy and geoenergy systems
• subsurface storage
• coastal vulnerability assessment
• offshore renewable energy, including task leadership in developing pan-European geological datasets and methodologies for offshore windfarm siting, stability assessment and marine spatial planning
• geological data harmonisation and modelling

This breadth of involvement ensures that UK expertise is embedded within the development of interoperable, pan-European datasets and services.

Another example of BGS’s contribution is the European CO₂ Storage Atlas, which was developed through GSEU and launched in May 2025. By integrating geological datasets and subsurface characterisation from across Europe, the atlas provides a harmonised assessment of carbon dioxide (CO₂) storage capacity and injectivity potential, demonstrating how detailed national expertise, including petrophysical and rock physics insights, can be translated into a coherent framework to support carbon capture and storage deployment at European scale.

51���� played a key role through its leadership in UK storage assessments and is continuing this work through the recently launched , funded by the European Union. Over the next three years, CO2SITE will develop an open-access atlas of CO₂ storage opportunities across Europe, bringing together the geological, regulatory and other data needed to help advance projects towards implementation. As a key project partner, BGS will develop the database underpinning the CO2SITE atlas, providing an important resource for researchers, policymakers and investors to support informed decision making on geological CO₂ storage.

More broadly, BGS continues to deliver high-impact science that feeds into international initiatives, such as new findings on the formation timeline of the Giant Causeway, and developments in national geothermal data resources. Together, these contributions reinforce ���ҳ� role as a trusted provider of high-quality geoscientific knowledge.

Initiatives like GSEU are essential, because geology does not stop at borders. By understanding that continuity is key to tackling shared challenges and building a common knowledge base, we can support decisions that balance energy needs, environmental protection and long-term sustainability across Europe.

Audrey Ougier-Simonin, project lead at BGS.

Collaboration in action

Beyond data integration, the project is actively strengthening professional networks, firstly by bringing together all Europe national geological surveys through and now enabling new forms of collaboration.

These include:

• research exchanges and short-term visits, such as collaboration with TNO (Netherlands) researchers
• student placements, including visiting researchers from organisations such as IGME (Spain)
• development of joint proposals and future research initiatives, building on new relationships formed through GSEU

Looking ahead

As Europe navigates the complexities of the energy transition and environmental change, initiatives like GSEU will be indispensable. By transforming fragmented geological data into a coherent, accessible and actionable resource, they are enabling better decisions at every level, from local land-use planning to EU-wide policy.

The message emerging from both GSEU publications and community engagement is clear: understanding the subsurface is key to building a resilient and sustainable future. Through continued collaboration, innovation and knowledge sharing, Europe is steadily bringing that future into focus.

51���� is to create a Memorandum of Understanding (MoU) in partnership with the State Service of Geology and Mineral Resources of Ukraine, after a meeting between BGS Director Karen Hanghøj and Yehor Perelyhin, Ukraine Deputy Minister of Economy, Environment and Agriculture. The document will establish a framework through which geological projects can be pursed.

Karen Hanghøj welcomed the agreement and the opportunities it brings with it.

51���� is built upon a history of strong collaborations that centralise the vital role of the subsurface in shaping resilient economies, sustainable environments and thriving societies.

I am excited by the potential to deliver innovative solutions and make a meaningful, positive impact on some of the most pressing challenges facing the world today, which will be unlocked through joint research and data exchange opportunities with Ukraine.

Dr Karen Hanghøj, BGS Director.

The talks with BGS took place as part of a visit to London that saw the Ukrainian delegation meet with the UK Government to explore the development of the critical minerals sector. Also on the agenda for the meeting was the creation of targeted training and professional development programmes for Ukrainian geologists and specialists, as investment in skills and scientific expertise are essential for the growth of strategic sectors.

Work will now focus on finalising the MoU, which will involve identifying priority projects related to the critical minerals sector and preparing the joint training programmes for Ukrainian geologists and specialists.

Chalk: a shared geology

The Upper Cretaceous-aged (commonly known as ‘the Chalk’) is perhaps Europe most iconic geological unit. Besides forming the famous white cliffs, the Chalk:

• is a major aquifer, supplying millions of people with drinking water and sustaining rare ecological habitats
• is important for energy as it hosts oil and gas reservoirs in the North Sea, provides the foundation for offshore wind farms and hosts numerous shallow geothermal-energy schemes
• has the potential act as storage for hydrogen and CO2
• is a raw material for cement
• hosts many major civil engineering and infrastructure schemes across northern Europe including, in the UK alone, the recently approved Lower Thames Crossing, HS2, the Channel Tunnel and the new ‘super sewer’, the Thames Tideway Tunnel in London

Yet the Chalk is also one of the most misunderstood geological units. It is a common misconception that it is a uniform rock unit with very little structure or faulting. In reality, it has significant variations in physical properties and is often faulted.

Recent geological mapping in the Chilterns and Yorkshire Wolds, undertaken by BGS in collaboration with the Environment Agency and water companies, has shown how geological discontinuities in the Chalk affect groundwater flow. These discontinuities facilitate the development of dissolutional conduits and rapid flow pathways, creating a very heterogenous aquifer. This heterogeneity generates major challenges for the water industry, civil engineers and planners.

As an aquifer, the Chalk is under pressure, both in terms of water quality and resource. The demand for water, especially in more populated areas of southeast England is increasing, but there is also a need to protect rare chalk stream habitats and maintain river flows. Climate change, drought and contaminants such as nitrate exacerbate the problem. Addressing these issues require a greater geological understanding of the aquifer and how groundwater flows it.

These challenges aren’t just restricted to the UK: France has similar problems in the extensive chalk outcrops across the north of the country, as do the Netherlands, Denmark and Belgium.

Current research

A good understanding of the Chalk Group is needed to better predict groundwater flow and engineering ground conditions. This requires good quality geological maps and 3D models fit for the 21st century, using all the available information including field data, geophysical borehole logs, geophysical surveys and biostratigraphical data. In the UK, geological maps used to show the Chalk Group with just three subdivisions; we now divide the chalk into nine individual mappable formations, reflecting their differing engineering and hydrogeological properties. These more detailed maps are able to show much more geological structure, and are more relavent to engineers and hydrogeologists.

Recent groundwater modelling in BGS work has focused on building the national scale British Groundwater Model, simulating groundwater flooding, and projecting the impact of climate change on chalk streams and public water supplies. Other geological surveys are also modelling groundwater, for example, to investigate the impacts of nitrate and other contaminants on the chalk aquifer.

Likewise, more detailed understanding of the Chalk Group has helped civil engineers better predict ground conditions on major infrastructure projects. For example, BGS maps and models help identify zones of weak faulted ground that might be an issue for tunnelling or road cuttings. Similarly, BGS helped characterise flint content in the Chalk in the Thames Estuary to help design cutting heads for the Lower Thames Crossing tunnel-boring machines. Lessons learned from major projects in the UK can be equally applied in northern France and vice versa.

Common problems: common solutions

A key remit of geological surveys and research institutions is to work to find solutions to geological problems. BGS has teamed up with other northern European geological surveys and research institutes to discuss common interests in the Upper Cretaceous Chalk. Twenty-eight participants from 13 different research institutions and geological surveys, including geologists, hydrogeologists, biostratigraphers and engineering geologists, gathered for the inaugural in the town of Étretat on the French coast. Étretat hosts spectacular chalk cliffs and rock arches made famous by the painter Claude Monet. These amazing outcrops admirably demonstrate how variations in the Chalk influence the local hydrogeology and cliff stability.

Outcomes

Exactly how does the Chalk vary across northern Europe? Many productive discussions were had during the workshop and several common themes were identified. Key to understanding the variability of the chalk is the application of a unified Chalk Group stratigraphy, so variations and changes in rock properties across the Anglo–Paris basin can be better understood and predicted.

Another area of common interest is the development of karst features in the chalk such as sinkholes, dissolution pipes, caves and dissolutional conduits. These are important not only from a hydrogeological perspective, but also as an engineering hazard. The French geological survey, BRGM, has been leading the way here, undertaking numerous tracer tests and identifying sinkholes across Normandy. A similar approach is being taken by BGS, learning from the French.

A third area of interest is incorporating lithological variability and karst into groundwater models. At present, many groundwater models treat the Chalk as a single porous medium, often modelled as just one or two layers. This ignores much of the complexity within the group. Much discussion was had on how to best approach modelling groundwater in the Chalk at a range of scales.

Next steps

This first meeting generated a huge amount of interest and enthusiasm. The next steps are to translate this into concrete actions. Essential to this is identifying potential funding sources for common projects, such as stratigraphical correlations across the Anglo–Paris basin. A special issue on Chalk Group stratigraphy in a relevant journal is another possibility.

Another workshop is being planned for 2026, either in Maastricht or in south-east England.

Thanks

Thanks to Ophélie Faÿ (University of Mons) and Eric Lasseur (BRGM) for organising the event.

About the author

Dr Andrew Farrant is a geologist and karst geomorphologist based at the BGS. He is the Regional Geologist for Southeast England and has extensive experience mapping the Chalk across southern and eastern England.

As a state of emergency is declared on the Greek island of Santorini, seismologists are increasingly turning to artificial intelligence technology to provide high-resolution images of the ongoing seismic activity, in a bid to enhance short-term forecasting accuracy.

Since the start of the crisis, a team from BGS comprising Margarita Segou, Brian Baptie, Rajat Choudhary, Wayne Shelley and Foteini Dervisi, has been employing machine learning algorithms to detect ten times as many earthquakes as standard techniques, with over 20000 tremors accurately predicted in the Santorini area alone since 1 December 2024. This approach is allowing geologists to identify for the first time small magnitude earthquakes that were previously undetected using standard approaches.

51���� Seismologist Margarita Segou, who is leading the development of the groundbreaking research, says it has revolutionised the way scientists can learn from seismic activity and predict patterns.

This machine learning technique results in far richer data feeding into short-term forecasts, which can allow experts to track the evolution of events and better advise emergency services and at-risk communities.

Dr Margarita Segou, BGS Seismologist.

These algorithms allowed researchers to first note increased seismic activity across the Santorini region on 26 January 2025. In comparison, standard detection schemes did not register the same increase until 31 January and only picked up around 2000 seismic events in the Santorini area; ten times less than the new approach has detected.

Dr Segou says it is the ability to combine different sources of information more quickly that is at the heart of the advancement.

Through strong international partnerships, we can reprocess past and present data through machine learning and gain a new and priceless insight into the seismic activity in Santorini in previous phases of unrest and its links to the volcanic system.

Dr Margarita Segou.

Santorini is located on the Hellenic volcanic arc at the convergence of the African plate and the Eurasian plate, at a complex tectonic boundary. Currently, seismic events around the island show that seismicity bursts occur almost twice a day, with the tremors lasting for one to two hours.

Dr Segou adds the data is revealing some unique features.

We have evidence that this is fluid-driven, swarm-type seismicity that comes in pulses. This is not unheard of in other volcanic regions; however, this time it is evolving on top of active faults that complicate the expression of seismicity.

It is easy to get a disconnected story when we just look at moderate magnitude seismic events. It is only when we investigate the smaller magnitude events that occur between that we learn of the hidden mechanisms that take place between the large earthquakes.

It is critical that we track whether those pulses become more frequent and how they migrate in space and depth. So far, the largest quake in this swarm has been a 5.2 magnitude.

Dr Margarita Segou.

Contact

For more information, please contact 51���� press (bgspress@bgs.ac.uk) or call 07790 607 010.

51���� and the Icelandic Geological Survey (ÍSOR) have been awarded an to assess Iceland offshore geological and geomorphological landscapes for the suitability of windfarms. The grant enables BGS scientists to share their experience in , as well as working with wind developments.��

Iceland fulfils its primary energy consumption with around 100 per cent renewable energy, via geothermal and hydro energy. Nowadays, there is a strong motivation to increase the country energy mix and energy security via wind power. Geology underpins the appropriate placement and foundation design for wind turbine structures. The NERC grant, which is supported by the Foreign, Commonwealth & Development Office, aims to facilitate knowledge sharing between BGS and ÍSOR about the geological classification of the seabed and subsurface, as well as the potential impacts on foundation design. 

To help facilitate this partnership, Anett Blischke, a senior geoscientist at ÍSOR, led a week-long field trip in Iceland. Participants from BGS included Nicola Dakin, Andrew Finlayson, Dayton Dove and Duncan Stevens, who were joined by ISOR Árni Magnússon, Steinunn Hauksdóttir and Ögmundur Erlendsson, alongside Sigurður Friðleifsson from the National Energy Authority of Iceland (Orkustofnun).  

Visiting Iceland presented a fantastic opportunity to see excellent analogue sites onshore that are often present in the UK offshore environment, such as glacial landforms and deposits. The field visits allowed us to discuss these sites, including the glacial moraine complex of �����ð����á�������Ի�ܰ�, how geoscience fits into the offshore wind development process in Iceland and its opportunities and challenges. 

Visit to the British Embassy 

The team was also invited to the British Embassy in Reykjavk to discuss the goals of the project. Embassy staff were eager to hear about the project goals and future collaborations around geology and renewables. During the visit and in her role as task lead of the Geological Service for Europe ‘Optimised windfarm siting’ work package, Nicola Dakin highlighted the benefits of the first deliverable to the European Commission: using the new ‘Geo-Assessment Matrix’, which will develop the first draft geological complexity maps offshore Iceland and European waters. Utilising existing datasets, such as , the maps aim to serve as a first-pass assessment showing areas that have low to high geological complexity. The maps will also highlight areas that require new data acquisition where the geology is unknown. 

Fieldwork 

The team then travelled east to Landsvirkjun, the state-owned energy utility company, at ��ú���ڱ����, which is an onshore wind turbine test site consisting of two turbines that have been in situ since 2012. Here, Landsvirkjun has been testing the development of onshore wind potential, using the powerful and persistent winds in the Icelandic highlands. Environmental impact assessments have been important to ensure that the effects on the area are minimised and a 200 MW windfarm has received development approval. 

The field trip continued along south Iceland coastal ribbon, where the team observed active volcanic, tectonic, sedimentary and glacial processes, the effects of sea level changes, and geohazards. Such onshore analogues are critical to understanding the geological processes found in offshore environments. Starting in the west, at Stokkseyri, and travelling to Jökulsárlón (‘Diamond Beach’) in the east, the team visited a range of geological outcrops and sites highlighting the variety of tectonic, sedimentary and volcanic challenges.  

South Iceland offers a variety of geological features that can be studied to better understand the offshore environment: variable topography, ancient lava flows and glacial landforms tens of metres high. Understanding depositional environments, such as those around �����Բ��ڱ��������ö��ܱ���, is key to understanding their effects on sedimentology and any possible engineering implications in advance of foundation design and installation. 

The final study location of Melasveit consists of an outcrop near Akranes, north-west of Reykjavk. The locality exposes ancient glaciotectonised sediments in a cliff section along the beach (Sigfúsdóttir et al., 2018). This cross-section is an excellent analogue to the lateral and vertical heterogeneity, and possible geotechnical impacts, of glaciotectonised sediments, which are also observed in windfarm sites the North Sea. 

The final, fortuitous and (naturally) most spectacular geological phenomenon was a visit to the fissure eruption that began during our visit on 22 August 2024 near the Blue Lagoon and the Svartsengi geothermal energy plant. Icelandic authorities closed the roads to protect people; however, the eruption and lava flows can be observed safely from the roadside.  

Future collaboration 

Iceland is a country full of opportunity regarding offshore wind potential. The geohazards and geological constraints in the offshore environment require a full assessment to better understand the influence on foundation types and design. BGS openly welcomes ÍSOR and Orkustofnun for further workshops and continuing our collaboration in the future. 

More information 

Field guide 

A summarising the visited sites is available online. 

References 

Sigfúsdóttir, T, Benediktsson, Í Ö, and Phillips, E. 2018. . Boreas, Vol. 47(3), 813–836. DOI: https://doi.org/10.1111/bor.12306;

As part of our NERC ‘Exploring the frontiers’ grant, Dr Peter Wynn of Lancaster University and I have been out undertaking fieldwork in the Matienzo valley in northern Spain. The Matienzo valley is a fantastic karstic depression; it over two million years old and contains hundreds of kilometres of natural cave systems. Beyond its fantastic history of use as a repository for scientific data, the region is also heavily used by recreational cavers and cave explorers.��

Our current work is focused on a small cave system called Llanio, just outside the main Matienzo karst depression. The work aims to develop a novel method for extracting cave speleothem (stalagmite) formation temperatures.

Cave temperatures

Caves have stable annual temperatures, only fluctuating within one degree over the annual cycle. This stable temperature reflects the average external annual temperature very accurately. For this reason, the development of a palaeothermometer from speleothem carbonate has been something of a ‘holy grail’ for palaeoclimate scientists over the last 50 or more years.��

The entrance to Llanio involves a flat-out crawl for several metres before some more small passages lead into the larger sections of the cave, where our water and speleothem sampling takes place. This spring, the crawl was made even worse than normal as the entrance had numerous large spiders in residence and the remains of some unidentifiable animal that we had to crawl over on both the way in and way out of the cave!

Inside the caves

Once we entered the cave, we had an excellent and productive research trip. We were able to collect numerous water samples and extract the phosphate from them using an in-cave chemical extraction method. The data from these samples will be compared to what we would expect at the known cave temperature. We also collected some already-broken calcite, which we will dissolve later back in the BGS Stable Isotope Facility.��

Further work

All these samples will be collated with samples that have been sent to us from collaborators from around the world, to see if we can use our new method to develop a reliable cave palaeothermometer in the BGS laboratories.

About the author

Dr Andrew Smith