New 3D model reveals geophysical structures beneath Britain

Fountain: Geophysical Research Journal: Solid Earth

Magnetotelluric (MT) data, which contain measurements of electric and magnetic field variations at the Earth’s surface, provide information about the electrical resistivity of the Earth’s crust and upper mantle. Changes in resistivityor the ability to conduct an electric current, may indicate the presence of geological features such as igneous intrusions or sedimentary basins, meaning MT studies can complement other types of geophysical studies to help reveal the Earth’s subsurface. Additionally, these studies can play an important role in improving understanding of the risks that space weather poses to human infrastructure.

Montiel-Álvarez et al. To present Britain’s first 3D electrical resistivity model, based on long-period MT data (using measurements collected every second for 4 to 6 weeks straight) from across the island. Their model, called BERM-2024, points to previously recognized and probably new tectonic and geological structures. The authors also model the effects of a recent solar storm on Earth’s geoelectric field, validating the utility of MT-based approaches for space weather impact prediction.

The BERM-2024 electrical resistivity model is based on MT data from 69 sites in Great Britain, including new and legacy data sets. Creating the final model involved processing the raw time series data and taking into account the “coastal effect” caused by the conductivity of ocean water when reversing the data—or calculate the causes based on observations.

Sensitivity tests of the new model indicate that it resolves features at depths of 200 kilometers (125 miles), including many known from other geophysical studies and geological observations. It also reveals new anomalies, including highly conductive areas beneath the terrain of the Southern Highlands of Scotland and a resistive anomaly beneath the island of Anglesey. What is more intriguing is that a previously unknown large conductive anomaly appears in their model between 85 and 140 kilometers (52 to 87 miles) below the West Midlands region.

The authors tested the usefulness of their resistivity model for estimating the electric field at the Earth’s surface, which is key to forecasting the effects of geomagnetically induced currents caused by space weather. To do this, they obtained a time series of the horizontal electric field in Great Britain during a solar storm that occurred from October 10 to 11, 2024, which caused brilliant displays of northern lights across the northern hemisphere. They found good agreement between their modeled time series and those measured at observatories, indicating that electrical resistivity models are a tool that can provide accurate information for space weather impact planning. (Geophysical Research Magazine: Solid Earth, https://doi.org/10.1029/2025JB0318132025)

—Nathaniel Scharping (@nathanielscharp), scientific writer

Citation: Scharping, N. (2025), New 3D model reveals geophysical structures beneath Britain, Éos, 106, https://doi.org/10.1029/2025EO250381. Published on October 10, 2025.

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