EGU Earth Magnetism & Rock Physics Division

EGU Earth Magnetism & Rock Physics Division Earth Magnetism & Rock Physics (EMRP) Division of the European Geosciences Union (EGU)

💡 February paper (2/2): “The First Archaeomagnetic Age at Tiwanaku and Implications for Dating Andean Metallurgic...
27/02/2026

💡 February paper (2/2):

“The First Archaeomagnetic Age at Tiwanaku and Implications for Dating Andean Metallurgical Furnaces” — Judit del Río, Pablo Cruz, Miriam Gómez-Paccard, Alicia Palencia-Ortas, Marina Puente-Borque, F. Javier Pavón-Carrasco, Erik Marsh

👉 https://doi.org/10.1111/arcm.70046

This paper delivers the first archaeomagnetic age estimate from Tiwanaku—one of the most important pre-Hispanic sites in the Andean Altiplano—by dating a metallurgical furnace using magnetic field recordings preserved in fired materials.

What they did:
The authors compared the geomagnetic field values recorded in fragments of a metallurgical furnace at Tiwanaku with both an updated global geomagnetic field model (including new Southern Hemisphere data) and a regional intensity curve. This combination allowed them to derive a robust age range tied to the magnetic signal preserved in the furnace.

Key takeaways:
🔹 First archaeomagnetic age at Tiwanaku: The last use of the metallurgical furnace is dated to roughly 450–740 CE, with ceramic evidence further constraining the most likely age range to 570–740 CE (mid-late 600s).

🔹 Methodological advance: This work highlights archaeomagnetic dating as a powerful alternative where radiocarbon and thermoluminescence methods face limitations, especially in the Andes.

🔹 Broad implications: By improving chronological control at key archaeological sites and for metallurgical activities, archaeomagnetism can significantly enhance our understanding of cultural timelines and technological developments in pre-Hispanic South America.

If you work on archaeological dating methods, geomagnetic field variation, or Andean pre-Hispanic technologies, this paper is worth a read.



European Geosciences Union - EGU

💡 February paper (1/2): “Permeability Enhancement by Slow Faulting Under High Pore Fluid Pressure” — Tommaso Man...
27/02/2026

💡 February paper (1/2):

“Permeability Enhancement by Slow Faulting Under High Pore Fluid Pressure” — Tommaso Mandolini, Zachary Zega, Mark Rivers, Wenlu Zhu

👉 https://doi.org/10.1029/2025GL119145

We talk a lot about faults as barriers to flow — especially the fault core. This paper flips that intuition (at least for slow faulting): under high pore-fluid pressure, the fault core can become the most permeable part of the system.

What they did:
They compared two faulted sandstone samples formed under low Pf (brittle faulting) vs high Pf (slow faulting), then used synchrotron X-ray microtomography + digital rock physics to quantify 3D porosity and permeability across fault core, damage zone, and wall rock.

Key takeaways:
🔹 Slow faulting under high Pf produces a fault core that’s much more porous and permeable than the surrounding damage zone/wall rock.

🔹 The fault core permeability is strongly anisotropic (flow is easiest along the fault-core plane).

🔹 Bigger picture: because slow slip is common below the seismogenic zone, this kind of permeability enhancement could help explain how mantle-derived fluids find pathways upward over time.

If you work on slow slip, fault zone architecture, or deep fluids, this one is worth a read.



European Geosciences Union - EGU

💡 December paper (2/2): Excited to highlight the new study “Frictional healing and induced earthquakes on conventiona...
01/12/2025

💡 December paper (2/2):

Excited to highlight the new study “Frictional healing and induced earthquakes on conventionally stable faults” by Meng Li (Utrecht University) and colleagues, recently published in Nature Communications.

👉https://www.nature.com/articles/s41467-025-63482-3

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division!

Challenge:

Velocity-strengthening (VS) faults are traditionally regarded as stable and incapable of generating earthquakes. However, field observations reveal that these faults frequently host induced seismicity linked to subsurface exploitation (e.g. gas production and fluid injection), challenging fundamental assumptions in seismic hazard assessment.

Approach:

Li and co-authors use rate-and-state friction numerical models to investigate fault behaviour across geological and earthquake timescales, explicitly accounting for long-term frictional healing on both velocity-strengthening and velocity-weakening faults under human-induced stress perturbations.

Key Findings:

🔹 Velocity-strengthening faults can nucleate earthquakes if they have undergone sufficient long-term healing.
🔹 Fault strength may increase by Δμ ≈ 0.25 over millions of years, enabling significant stress drops upon reactivation.
🔹 The first induced earthquake is the most hazardous; subsequent slip becomes stable on VS faults.



European Geosciences Union - EGU
Nature Portfolio

💡 December paper (1/2): Thrilled to highlight the study “Unlocking planetesimal magnetic field histories: A refined, ...
01/12/2025

💡 December paper (1/2):

Thrilled to highlight the study “Unlocking planetesimal magnetic field histories: A refined, versatile model for thermal evolution and dynamo generation” by Hannah R. Sanderson (University of Oxford) and colleagues, published early this year in Icarus.

👉 https://www.sciencedirect.com/science/article/pii/S001910352400383X

✨ Follow us for more updates from the community of our division!

Challenge:

The thermal and magnetic histories of planetesimals offer critical insight into the formation and evolution of Earth’s earliest building blocks. Yet existing models have not been able to simultaneously capture realistic mantle convection, sub-eutectic core solidification, and magnetic field generation, limiting interpretations of meteorite-derived constraints on early planetary evolution.

Approach:

Sanderson and co-authors developed a new 1D planetesimal thermal evolution and dynamo generation model that couples mantle convection with sub-eutectic core solidification in a differentiated, mantled body. The model improves mantle heat transport through updated viscosity formulations and stagnant lid convection parameterizations consistent with internal heating, includes radiogenic heating from 6060Fe in the metallic core, and implements combined thermal and compositional buoyancy fluxes alongside modern magnetic field scaling laws.

Key findings:

🔹 Our model can predict a complete magnetic field generation history for a planetesimal.
🔹 We can model dynamo generation by inward sub-eutectic core solidification.
🔹 We have refined the description of planetesimal mantle convection and viscosity.



European Geosciences Union - EGU

💡 September paper: Thrilled to highlight the study “East side story of Gondwana: the last frontier of the Arabian Nu...
01/10/2025

💡 September paper:

Thrilled to highlight the study “East side story of Gondwana: the last frontier of the Arabian Nubian Shield at 720 Ma based on new high-quality paleomagnetic pole” by Paul Yves Jean Antonio (Montpellier University) and colleagues, recently published in Gondwana Research.

👉 https://doi.org/10.1016/j.gr.2025.08.005

✨ Follow us for more updates from the community of our division!

Challenge:
The Cryogenian (~720 Ma) was a turning point in Earth history, marked by global “Snowball Earth” glaciations and the transition from Rodinia breakup to Gondwana assembly. Yet the paleogeographic position of the Arabian Nubian Shield—especially the Oman block—remained poorly constrained due to scarce reliable paleomagnetic data.

Approach:
Antonio and co-authors combined paleomagnetic, structural, and geochronologic analyses of the Shaat d**e swarm (~722 Ma) intruding the Mirbat basement (SW Oman). Rigorous field tests and rock magnetic analyses isolated stable magnetizations carried by single- to pseudo-single-domain magnetite, yielding a robust new paleomagnetic pole.

Key Findings:
🔹 First reliable paleomagnetic pole for the Omani block at 720 Ma (25.9°N, 104.9°E).
🔹 Confirms paleogeographic linkage of Oman to the Indian Shield, also tied to Madagascar and Seychelles.
🔹 Places Oman at a moderate paleolatitude (~42°), challenging earlier low-latitude reconstructions.
🔹 Implies India–Madagascar–Seychelles rotation into Gondwanan position occurred after 720 Ma.



European Geosciences Union - EGU

💡 September paper: Thrilled to highlight the study “The Role of Grain Size on Shear Localization Illuminated by Acou...
01/10/2025

💡 September paper:

Thrilled to highlight the study “The Role of Grain Size on Shear Localization Illuminated by Acoustic Emissions” by Nathalie Casas (Sapienza Università di Roma) and colleagues, recently published in Journal of Geophysical Research: Solid Earth.

👉 https://doi.org/10.1029/2024JB030448

✨ Follow us for more updates from the community of our division!

Challenge:
Fault gouges—fine rock powders produced during fault slip—govern how faults localize strain and may control earthquake nucleation. Yet, the role of initial grain size in these processes remains poorly constrained.

Approach:
Casas and co-authors conducted double-direct shear experiments on quartz gouges of varying grain sizes, continuously monitoring Acoustic Emissions (AEs) alongside mechanical behavior and microstructural evolution.

Key Findings:
🔹 Steady-state friction is largely independent of grain size, but early-stage deformation strongly depends on it.
🔹 Coarse and mixed gouges show strain-hardening before localization, while fine gouges tend to strain-weakening.
🔹 Acoustic emissions scale with grain size: larger grains produce stronger AE signals, providing a window into grain-scale processes.
🔹 AE b-values track the transition from distributed deformation to localized shear, making them a sensitive proxy for evolving micro-mechanics.



European Geosciences Union - EGU

💡July paper: Did you know the equatorial ionosphere can get heated up and cooled down by thousands of degrees within ...
10/07/2025

💡July paper:

Did you know the equatorial ionosphere can get heated up and cooled down by thousands of degrees within a few hours during magnetic storms?
Artem Smirnov and co-authors (Yuri Shprits, Hermann Lühr, Alessio Pignalberi, Elena Kronberg, Fabricio Prol, Chao Xiong) reveal a surprising two-stage response of the morning electron temperature overshoot to geomagnetic activity — initial heating followed by extreme cooling — in Scientific Reports (Nature Portfolio):

👉 https://doi.org/10.1038/s41598-025-89602-z

✨ Follow us for more insights from the community of our division

🔬 Challenge:
An intense surge in the equatorial electron temperature at sunrise, known as the morning overshoot, is one of the defining ionospheric features, yet its behavior during magnetic storms has not been well understood.

⚙️ Approach:
The team developed a neural network–based model to simulate electron temperatures globally during geomagnetic storms based on CHAMP satellite data. This model accounts for external drivers like solar wind and geomagnetic indices, with a 12-hour history input.

📌 Key Findings:
• Two-phase storm response: The morning temperature overshoot first intensifies, then vanishesdropping by >1000 K on average within a few hours.
• Electric field drivers: This pattern is linked to an early westward prompt pe*******on electric field, followed by a delayed eastward disturbance dynamo driven by the neutral thermospheric winds.
• Model performance: This is the first global electron temperature model that includes geomagnetic activity driving. The model accurately reproduces both satellite and ground-based radar observations and offers valuable insights into the ionospheric dynamics.


European Geosciences Union - EGU

💡July paper (1/2): Excited to share a field motivated laboratory study “Frictional and microstructural evidence for ...
10/07/2025

💡July paper (1/2):

Excited to share a field motivated laboratory study “Frictional and microstructural evidence for a weak Wasatch fault zone” by Srisharan Shreedharan, Alexis K. Ault; Jordan Jensen (Utah State University University), published in Geology!

👉https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G52606.1/653895/Frictional-and-microstructural-evidence-for-a-weak

✨ Follow us for more updates from the community of our division!

Challenge:
- The Wasatch Fault Zone (WFZ) in Utah—home to ~80% of the state’s population—is one of the world’s longest active normal faults. Yet, it dips at angles

🔥Re-thinking Fieldwork: Current Challenges and Future PerspectivesOur online event is tomorrow! Don’t forget to register...
26/03/2025

🔥Re-thinking Fieldwork: Current Challenges and Future Perspectives
Our online event is tomorrow! Don’t forget to register if you’d like to join:

🔗 Register here: https://us02web.zoom.us/meeting/register/cDFp0ecQRm2o8hrGYsyAAw #/registration

🔨 Are you an Early Career Scientist preparing for fieldwork and wondering how to plan it effectively? Or looking for ways to make it more inclusive and sustainable?

Join our interactive Q&A online Campfire—a space for early career scientists to discuss and exchange ideas.

Dr. Natalie Farrell (Manchester University) and Dr. Dan Palcu (Utrecht University) will share their insights and experiences in and .

📅 When? Thursday, March 27, at 2pm CET
ℹ️ More info: https://www.egu.eu/webinars/403/re-thinking-fieldwork-current-challenges-and-future-perspectives/

💡March paper (2/2): Did you know the intensity of the Earth’s magnetic field can be estimated from Beryllium record...
03/03/2025

💡March paper (2/2):

Did you know the intensity of the Earth’s magnetic field can be estimated from Beryllium records?

✨ Savranskaia and co-authors developed a new method to improve this estimation by removing climatic overprints.

👉 https://doi.org/10.1029/2024GC011761



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