The first practical electric telegraph networks were deployed during the 1840s and, as solar activity increased during the following years, Victorian telegraph operators began to experience unexplained electrical effects caused by geomagnetic disturbances.

An international group of researchers, led by Lancaster University and including BGS, has re-examined a widely cited account of a train delay in Exeter that was reportedly caused by geomagnetic disturbance from the Sun interfering with railway telegraph systems. The event has previously been cited as potentially the earliest recorded example of space weather affecting human technology, but the team research contradicts this assumption.

The original account described how the 22:05 train departing Exeter in Devon on 18 October 1841 was delayed by 16 minutes when a ‘very intense magnetic disturbance’ interfered with the electric signalling telegraph equipment used to determine whether the railway line ahead was clear. However, the researchers found a critical problem: the railway line referenced in the account did not open until 1846, almost five years after the alleged 1841 incident.

To discover what really happened, the team combined evidence from railway timetables, historical newspapers, solar observations, aurora reports and digitised geomagnetic records. The BGS magnetogram archive shows a strong geomagnetic disturbance on 18 October 1848, alongside reports of sunspots and aurorae seen across the UK and Europe, providing compelling evidence that the date in the original account was a typographical error.

The findings show that, while the Exeter incident remains one of the earliest documented examples of space weather disrupting technology, it was not the first. The earliest credible report currently known to be due to interference with telegraph systems was actually on the Midland Railway in March 1847.

Using BGS historic archive of magnetic records from Greenwich Observatory in London, we were able to confirm that 18 October 1848 experienced very large auroral disturbances. Preserving long-term records is vital for informing research on the vulnerabilities of modern technology.

Dr Ciarán Beggan, geophysicist, BGS.

Space weather is often discussed as a modern challenge because of our dependence on technologies such as satellites, communications systems and electricity networks. What this study shows is that society has been experiencing the effects of space weather on technology for almost as long as electrical technologies have existed.

Prof Jim Wild, Lancaster University School of Physics and Astronomy and lead author of the study.

The research paper is available to read on the .

‘True north’ is the direction to the geographic north pole; ‘grid north’ is where the vertical blue lines shown on Ordnance Survey (OS) maps converge, and ‘magnetic north’ is the direction that a compass needle points as it aligns with the Earth magnetic field.

In November 2022, as all three ‘norths’ aligned and met at a point in Langton Matravers in Dorset, England, for the first time. Now, after three historic years together, new magnetic field data collected by the 51ÁÔÆæ (BGS) and calculations made by OS have shown that the triple alignment is set to leave England at Berwick-upon-Tweed on 13 December 2025 and move into the North Sea. It predicted that the triple alignment will hit land again at the end of October 2026 in Drums, just south of Newburgh in Scotland. After passing through Mintlaw, its last stop in Scotland will be Fraserburgh around mid-December 2026, before it returns to the North Sea.

Once over the North Sea, the three norths are expected to continue northwards before leaving the British national grid. They will also stay in alignment for another couple of years before magnetic north separates from true north and grid north. Magnetic north moves slowly, so it may be several hundred years before this alignment comes around again., when magnetic north became east of grid north for some locations in Great Britain for the first time in more than 350 years. This affected navigators using a compass, who needed to adjust their bearing by subtracting instead of adding the difference between magnetic and grid north.

During the three norths’ time in England, they moved northwards through Poole near the end of 2022, then through Chippenham and Birmingham before reaching Hebden Bridge, West Yorkshire, in October 2024. The triple alignment then passed though the Pennines and will leave England at Berwick-upon-Tweed.

Due to refinement of the underlying models and the prediction data, the alignment progress has slowed slightly since the initial predictions back in 2022. When it crosses the coast at Berwick-upon-Tweed it will have travelled 576km (about 358 miles) in 1127 days so that about 511m per day (or about 5.9 mm per second or about 0.013 miles per hour). It will likely be a very long time before the alignment comes around again.

Mark Greaves, Earth measurement expert at OS.

The three norths combining in Great Britain has been a once-in-a-lifetime occurrence. Although part of geospatial history, there is no impact for navigators, pilots and captains once the alignment leaves, and people will still need to continue to take account of the variation between magnetic north from a compass and grid (or true) north on a map.

It been a privilege to be able to observe this phenomenon over the past few years. The magnetic field is not predictable in the long term, so we don’t know how many hundreds of years it will take for this historic alignment to occur again.

Dr Ciarán Beggan, geophysicist at BGS.

OS and the BGS Geomagnetism team collect detailed measurements of the magnetic field at more than 40 sites around the UK. These enable scientists to create high-resolution maps and make accurate forecasts of the .

Several factors, including changes in the flow of the Earth liquid outer core, the iron content of the local rocks and the variations in the magnetic field that are caused by the Sun, mean these predictions have some uncertainty and are a rough estimation of when the three norths are due to leave British soil.

The 51ÁÔÆæ (BGS) has upgraded its geomagnetic forecast today (12 November 2025) to the highest intensity level amid an ongoing solar storm, which prompted the aurora displays that entertained stargazers across the UK overnight.

Current predictions suggest that a second storm, feeding off the first, will result in potentially the largest solar storm to hit our planet in over two decades. Scientists believe that it has the potential to achieve the maximum level of G5 on the . Dubbed a ‘cannibal storm’, the first event has already disrupted communications and global positioning system (GPS) satellite accuracy. At ground level, it created the biggest measured geoelectric field since BGS records began in 2012.

The increase in activity from the coming storm could have further, significant impacts on space and ground-based technologies, including communication systems, global positioning systems (GPS) and satellite orbits.

Geomagnetic storms are caused by solar activity interacting with the Earth magnetic field, which has implications for national energy infrastructure and navigation. For this reason, it is listed as one of the primary hazards on the UK .

Space weather can have a real impact on the lives of people across the planet. BGS records real-time data of geomagnetic conditions, underpinning the national forecast service. Our data suggests that this event could be one of the biggest storms we’ve seen in 20 years.

Dr Gemma Richardson, BGS Geomagnetic Hazard Specialist.

Like any forecast, it is not possible to say with certainty exactly how big the storm will be. Solar storms travel from the Sun and can reach Earth in as little as 17 hours, although they can also take significantly longer. Based on satellite observations, we anticipate this event will be significant; early indications such as ground measurements of solar energetic particles are some of the largest recorded since 2005.

Assuming clear, dark skies, there is an increased chance of seeing the aurora borealis from the UK tonight. Observers in Scotland, northern England and Northern Ireland have the best chance if the weather is favourable.

Further information

Volcán de Fuego in Guatemala is one of the most active volcanoes in the world. Its frequent eruptions are spectacular to watch, but they also gradually build steep deposits of ash and lava fragments on its flanks. From time to time, this material becomes unstable and collapses, sending hot flows known as pyroclastic density currents (PDCs) often 5 to 10km, sometimes more than 10km, down the slopes of the volcano.

While eruptions at Fuego are closely monitored, these collapse-generated flows remain less understood. Our project, funded through a NERC Urgency Grant, is a collaboration between Guatemalan scientists, local institutions and international partners to investigate the timing and monitoring of these collapses.

Fieldwork in the rainy season

This project focuses on the 9 to10 March 2025 eruption, which generated PDCs with runouts exceeding 6km. In August 2025, we travelled to Fuego to study the deposits left behind. Our work combined field mapping and sampling with drone surveys and satellite imagery, but this was a race against time: Guatemala rainy season quickly erodes the evidence.

Our main study site was the Ceniza ravine, a valley that channels many of Fuego flows. Using satellite images, we identified deposits from the March 2025 eruption. On the ground, we confirmed a few intact outcrops, which were unconsolidated and, months after the eruption, still hot.

Reading magnetic fingerprints

To understand these deposits better, we collected samples for particle-size analysis and geomagnetic thermal proxy analysis. This technique uses tiny magnetic minerals that are naturally present in rocks. When heated, their magnetic orientation resets to align with the Earth magnetic field and, once cooled, the orientation becomes locked in, like a tiny compass needle frozen in place. By measuring the magnetism of our samples, we can tell whether particles were hot when they came to rest. If they all point the same way, the deposits came directly from the eruption column. If the directions are random, the material had cooled long before and was likely part of older piles that later collapsed.

Geomagnetism therefore lets us trace the provenance of the material — whether it was born in the eruption or destabilised from older accumulations. This is crucial for hazard assessment, since collapses of stored flank material can generate larger flows than those expected from eruption size alone.

Drones and 3D models

Another key part of our work involved flying high-resolution drones along the flanks of the volcano to produce detailed 3D models of the ravines. Together with satellite imagery, these allow us to measure how much material is stored on the volcano and how this material changes over time. By repeating the surveys, we will be able to build a timeline of how volcanic material accumulates and when it becomes unstable.

Next steps

Back in the UK and with our partners abroad, we are now analysing the samples and drone data. Geomagnetic measurements and remote sensing data will allow us to extend our observations back in time. Together, these results will help us understand how much material can safely accumulate on Fuego flanks before it becomes unstable.

Ultimately, our aim is to develop a monitoring framework for these deposits, so that future collapses and the potential runout of associated PDCs can be anticipated more effectively. Although our focus is Volcán de Fuego, the same processes occur at other active volcanoes around the world, from Etna in Italy to Fuji in Japan.

While in Guatemala…

Guatemala is a spectacular country with volcanoes always on the horizon. We spent our nights after work at the Fuego observatory, where we could watch the volcano — and it put a show up for us! Playing football on the local pitch with the volcano in the background was also a highlight of our evenings.

It was a privilege to spend time with our Guatemalan colleagues and learn from their experiences of living alongside active volcanoes. Field days were demanding, often cut short by weather, but what more could a volcanologist want than to discuss volcanic processes as they unfold in front of you, with delicious food and the country famously strong coffee to end the day?

A collaborative project

The fieldwork was a collaboration between:

• 51ÁÔÆæ
• University of Edinburgh
• University of South Florida (USA)
• Institute for Scientific and Technological Research of San Luis Potos (Mexico)
• National Institute for Seismology, Vulcanology, Meteorology and Hydrology (INSIVUMEH, Guatemala national monitoring institute)
• Coordinating Agency for Disaster Reduction (CONRED, the national civil protection agency)

The project also includes colleagues from the University of Liverpool and Michigan Technological University (USA).

The monitoring carried out by INSIVUMEH was essential for managing risks during our campaign, especially afternoon rainstorms that often trigger lahars (volcanic mudflows) in our study area. Their expertise and guidance, based on daily experience working on Fuego, allowed the team operate safely in the field.

About the author

Five UK-made quantum magnetometers are being installed across the UK to provide complete national coverage of the magnetic field for the first time.

Quantum magnetometers are highly sensitive instruments that can detect variations in the Earth’s magnetic field with extreme precision. These new sensors will provide data to BGS that will give scientists a more comprehensive understanding of how the magnetic field changes during extreme magnetic storms. These are the same storms that trigger aurorae like those the UK experienced during May 2024.

During these storms, variations of the geomagnetic field can be large enough to cause localised effects on grounded technology such as power grids, Global Navigation Satellite System (GNSS) receivers and railway signals. Until now, it has not been possible to study these regional variations using the three existing UK geomagnetic observatories. The new quantum magnetometers have been strategically placed around the country to fill in gaps in the national coverage and allow small-scale, local variations to be monitored.

The more that is known about the nature of magnetic storms — how often they occur, how big they can be and how they interact with our natural and artificial environments — the better scientists can advise Government, the public and industry on where the risks are to the technologies we rely on. This allows organisations such as the UK’s power distribution companies to take measures to protect supplies and services against the effects of space weather.

The quantum magnetometers have been developed and optimised by the University of Strathclyde and the Science and Technology Facilities Council (STFC) RAL Space. The sites of these new sensors have been carefully selected across the UK and have been picked for their suitability for detecting magnetic signals with minimal interference. They are installed at:

• Aberystwyth, Ceredigion
• Boulby, Noth Yorkshire
• Blickling, Norfolk
• Chilbolton Observatory, Hampshire
• Thurso, Caithness

We are incredibly excited to be able to study the magnetic field around the UK in greater detail than ever before. The installation of the five new quantum magnetometers will help to fill in the gaps between the existing observatories and will improve our vision of the changes taking place during extreme magnetic storms.

These new measurements will greatly enhance our understanding of how extreme magnetic storms impact different parts of the country. This means that society in general will have access to the advice and information needed to understand where we are vulnerable to magnetic storms and to make informed decisions on how to mitigate against them.

Dr Ciarán Beggan, geophysicist at BGS.

The quantum magnetometers were developed through the , specifically the Quantum Technology Hub in Sensors and Timing. The funding to build and deploy the sensors comes from UK Research and Innovation (51ÁÔÆæ).

A new space weather variation hazard index, developed by BGS researchers using data from the European Space Agency (ESA) Swarm satellite constellation, provides a near-real time, global picture of geomagnetic variations to spot the local effects of space weather.

Space weather can pose significant hazards to satellites and Earth-based technologies. Infrastructure and technology, including global navigation satellite systems, telecommunications and power grids can be disrupted by strong geomagnetic activity.

ESA three Swarm satellites, which measure changes in Earth magnetic field from space, can capture geomagnetic anomalies related to space weather all over the world. Whilst they do not offer the continuous time coverage at a single location that a ground station can offer, the trio global coverage provides our best-ever survey of Earth magnetic field.

Until recently, the data processing pipeline meant that Swarm data was only made available after four days, preventing its use in space weather hazard monitoring. That all changed in 2024 with the introduction of a FAST data processing chain, which makes a lot of the mission data available in close to near-real time – as quickly as three hours after measurement.

The new space weather hazard variation index developed by Lauren and colleagues at the BGS draws on over ten years of Swarm data. Using the mission long-term record of Earth geomagnetic field as a baseline, it is possible to spot sudden variations that depart strongly from the normal or expected level of variation.

All space weather scientists want real-time, global geomagnetic field data. Swarm data isn’t quite real time yet, but it getting closer. We wanted to make sure the techniques were available to make use of the FAST data so that it would be available to space weather scientists in the future.

A big geomagnetic storm might be obvious, but if there was just a little blip over the Atlantic Ocean, and perhaps some aircraft was struggling to communicate, we could use this index to check if there was something more localised that could explain the drop in communications.

Lauren Orr, space weather scientist at BGS.

Space weather monitoring is precisely the sort of application we had in mind for Swarm FAST data, and it is wonderful to see it being used so effectively. It another great example of the applications and benefits the Earth Explorer satellites bring to Europe and the rest of the world.

Anja Strømme, Swarm Mission Manager.

To read the full update on the new hazard index, please visit the .

Every five years since 1990, the international science community teams up to update the International Geomagnetic Reference Field (IGRF), a standard reference set of maps of the Earth magnetic field created for the public good. This year, BGS led the coordination and evaluation for .

True north and magnetic north

Unlike ‘true north’, which is the fixed point around which the rotation axis of the Earth spins, ‘magnetic north’ is constantly moving due to the motion of liquid iron in the Earth outer core. As the liquid iron is conductive, the entire magnetic field moves slowly with it, dragged along in an unpredictable way. Compass needles point towards the magnetic pole in the northern hemisphere, so forecasting its movement is crucial for accurate navigation and for other applications. Due to the unpredictability of the flow of the outer core, the maps are updated every five years to remain accurate.

This is where the IGRF comes in. The IGRF can be used for many purposes, particularly those requiring very accurate magnetic field values, including:

• aeromagnetic studies
• mining
• oil and gas exploration
• ionospheric modelling
• space weather forecasting
• spacecraft orientation
• magnetic correction for compass users

Tracking the movement of magnetic north

Magnetic north is estimated to have moved at about 10 km a year from 1600 to 1990. In the 2000s, it accelerated at a record speed up to 55 km a year. The 2019 IGRF update showed magnetic north was moving by around 50 km per year, continuing on its path towards Russia, having been in Canada for the last 400 years.

Newly released maps have shown that the movement of magnetic north has slowed down over the past five years to about 35 km a year, a deceleration that has not been seen before. In comparison, the magnetic south pole has moved very little in the past decade.

The current behaviour of magnetic north is something that we have never observed before.

With the release of the fourteenth update to the International Geomagnetic Reference Field, we have captured this unprecedented change, ensuring that scientists across the world can continue with their forecasts and explorations.

Ciarán Beggan, BGS Geophysicist.

Measurements of the magnetic field are made at geomagnetic observatories on the ground and by dedicated satellites that orbit around 500 km above the planet surface. Data from hundreds of absolute magnetic observatories were used, including nine operated by BGS. To make the maps, tens of millions of measurements are collected and checked for errors, before sophisticated computer programs crunch through the data to extract the core field signals.

As part of the measurements, the geomagnetic community also estimates how the magnetic field will change between 2025 and 2030.

We predict that the magnetic north pole will continue to slow down its movement over the next five years, although still travelling towards Siberia. Interestingly, in early 2026, both the north and south pole will have the same longitude (135°W), which has not happened in many centuries.

We also noticed there is a new weak region of the field developing offshore South Africa along with the existing weak area known as the South Atlantic Anomaly, which is currently passing over Argentina.

Ciarán Beggan, BGS Geophysicist.

IGRF-14 was created in collaboration with 18 other institutes from four continents and represents the global consensus from international scientists about the Earth magnetic field. In 2030, this process will be repeated, in order to update the maps to 2035.

The is now available for download.

The World Magnetic Model

In conjunction with the US National Oceanic and Atmospheric Administration, BGS has also updated the World Magnetic Model (WMM). The WMM is a series of magnetic field maps that help underpin commercial navigation systems in aircraft and electronic devices including mobile phones, which is also updated every five years.

The are available for download.

Contact

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