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A weak spot in Earth’s protective magnetic field is growing larger and exposing orbiting satellites and astronauts to more solar radiation, according to more than a decade of measurements by three orbiting observatories.

“The region of weak magnetic field in the South Atlantic has continued to increase in size over the past 11 years.”

The observations by the European Space Agency’s Swarm trio of satellites found that Earth’s already weak magnetic field over the South Atlantic Ocean—a region known as the South Atlantic Anomaly (SAA)—is getting worse and that it has grown by an area half the size of continental Europe since 2014. At the same time, a region over Canada where the field is particularly strong has shrunk, while another strong field region in Siberia has grown, the measurements show.

“The region of weak magnetic field in the South Atlantic has continued to increase in size over the past 11 years since the launch of the Swarm satellite constellation,” explained Chris Finlay, a geomagnetism researcher at the Danmarks Tekniske Universitet. “Although its growth was expected based on early observations, it is important to confirm this change in Earth’s magnetic field is continuing.” Finlay is the lead author of a new study published in the journal Physics of the Earth and Planetary Interiors that analyzes data from the Swarm satellites.

Geomagnetic Field

The three satellites were launched in 2014 to precisely monitor magnetic signals from Earth’s core and mantle, as well as from the ionosphere and magnetosphere. Earth’s magnetic field (technically, the “geomagnetic field”) is thought to be generated by a rotating core of molten iron, roughly 2,900 kilometers, or 1,800 miles, beneath our feet. But the strength of the field changes continuously, and scientists are still learning about its exact mechanisms.

“Satellites experience higher rates of charged particles when they pass through the weak field region…astronauts will also experience these charged particles.”

The geomagnetic field protects life on Earth’s surface from harmful charged particles in solar radiation. We can see the effects of charged particles from the Sun interacting with the geomagnetic field in the upper atmosphere during aurorae such as the northern lights.

And because it extends into space, the geomagnetic field also protects orbiting spacecraft, including most satellites and the International Space Station (ISS). However, the study authors warn that spacecraft—and spacefarers—that enter the South Atlantic weak spot during their orbits of our planet could now be exposed to more radiation.

For spacecraft hardware, this radiation could cause more malfunctions, damage, or even blackouts. “The main consequence is for our low-Earth-orbit satellite infrastructure,” Finlay said. “These satellites experience higher rates of charged particles when they pass through the weak field region, which can cause problems for the electronics.”

Danger to Astronauts

People in orbit will also face higher risks from radiation, including a greater chance of DNA damage and of suffering cancer during their lifetimes. “Astronauts will also experience these charged particles, but their times in orbit are shorter than the lifetime of most low-Earth-orbit satellites,” Finlay said. (On average, astronauts on the ISS spend about 6 months in low Earth orbit, but satellites typically spend more than 5 years there—about 10 times as long.)

The geomagnetic field is relatively weak compared with more familiar forms of magnetism: Its intensity ranges from about 22,000 to 67,000 nanoteslas. In comparison, a typical refrigerator magnet has an intensity of about 10 million nanoteslas.

In the SAA, the geomagnetic field’s intensity is lower than 26,000 nanoteslas. According to the study, the region’s area has grown by almost 1% of the area of Earth’s surface since 2014. The weakest point in the SAA now measures 22,094 nanoteslas—a decrease of 336 nanoteslas since 2014.

In the region of strong geomagnetic field over northern Canada, the intensity is greater than 57,000 nanoteslas. The study found that the area has shrunk by 0.65% of the area of Earth’s surface, while its strongest spot has fallen to 58,031 nanoteslas, a drop of 801 nanoteslas since 2014. In contrast, a strong field region in Siberia has grown in size, increasing in area by 0.42% of Earth’s surface area, with the maximum field intensity increasing by 260 nanoteslas since 2014 to 61,619 nanoteslas today.

Scientists have discovered that the weak region in Earth’s magnetic field over the South Atlantic—known as the South Atlantic Anomaly—has expanded by an area nearly half the size of continental Europe since 2014. Credit: ESA (Data source: Finlay, C.C. et al., 2025)

These changes in the Northern Hemisphere were unexpected, Finlay said. “It is related to the circulation patterns of the liquid metal in the core, but we are not certain of the exact cause,” he said.

The study did not, however, find any sign of an impending magnetic field reversal. Earth’s magnetic field has already reversed hundreds of times, but “we know from paleomagnetic records that Earth’s magnetic field has weakened many times in the past, displaying weak field regions like the South Atlantic Anomaly, without reversing,” Finlay said. “We are more likely seeing a decade to century timescale fluctuation in the field.”

“Hardened” Spacecraft

The heightened danger from solar radiation to satellites and astronauts passing over the SAA could be mitigated by ensuring that spacecraft are “hardened” to withstand it, Finlay said: “Since the weakness is growing, the satellites will experience such effects over a larger area, [so] this should be taken into account when designing future missions.”

Geophysicist Hagay Amit of Nantes Université in France, who wasn’t involved in the latest study but who has studied the SAA, noted that several scientists have proposed possible reasons for the observed changes in the geomagnetic field, but the actual mechanisms remain unknown. “Overall, [the authors] convincingly demonstrated that continuous high-quality geomagnetic measurements are crucial for providing vital insights into the dynamics in the deep Earth,” he told Eos in an email.

—Tom Metcalfe (@HHAspasia), Science Writer

Citation: Metcalfe, T. (2025), A weak spot in Earth’s magnetic field is going from bad to worse, Eos, 106, https://doi.org/10.1029/2025EO250417. Published on 10 November 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Source: Geophysical Research Letters

The way clusters of differently sized water droplet populations are distributed within clouds affects larger-scale cloud properties, such as how light is scattered and how quickly precipitation forms. Studying and simulating cloud droplet microphysical structure is difficult. But recent field observations have provided crucial, centimeter-scale data on cloud droplet size distributions in stratocumulus clouds, giving researchers an opportunity to better match their models to reality.

The simulations of characteristic droplet size distributions that those models are providing are likely too uniform, say Allwayin et al. This muddled microphysical structure could be leading cloud simulations, and the climate models that use them, astray.

The authors compare the new observed data on cloud microphysical structure with results from large-eddy simulations (LES) of stratocumulus clouds. At convective scales, the model showed intriguing correlations between droplet cluster characteristics and overall cloud physics. For example, regions of the clouds dominated by drizzle tended to have larger drops but not necessarily more total water content, and the updraft regions of clouds tended to have smaller drops and a narrower distribution of droplet size.

However, across larger spatial scales, the characteristic droplet size distributions in the model looked very similar across different parts of a cloud. This diverges sharply from the observations, which show that the size distributions vary across large-eddy scales within the cloud.

One explanation could be that the process of entrainment—in which drier air is introduced into a cloud and causes evaporation—is not well resolved in these models, the authors say, noting a relationship between observations of characteristic droplet size distributions and local entrainment rates. In addition, models often assume that boundary layer properties such as surface fluxes and aerosol types are uniform across clouds.

The authors argue that a better understanding of cloud microphysics and its link to entrainment and boundary fluxes is needed to advance atmospheric modeling. The LES runs in this study are idealized cases, the researchers add, which should be kept in mind when interpreting their results. Future work should focus on understanding the role of horizontal gradients in aerosol concentrations, as well as on improving model entrainment layers, the authors suggest. Lagrangian schemes in LES models could hold more promise for this work. (Geophysical Research Letters, https://doi.org/10.1029/2025GL116021, 2025)

—Nathaniel Scharping (@nathanielscharp), Science Writer

Citation: Scharping, N. (2025), Understanding cloud droplets could improve climate modeling, Eos, 106, https://doi.org/10.1029/2025EO250420. Published on 10 November 2025. Text © 2025. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Lake Turkana in northern Kenya is often called the cradle of humankind. Home to some of the earliest hominids, its fossil-rich basin has helped scientists piece together the story of human evolution. Now, researchers from Syracuse University and the University of Auckland are revealing that the lake's geologic history may be just as significant as its anthropological one.

The Landslide Blog is written by Dave Petley, who is widely recognized as a world leader in the study and management of landslides.

According to Wikipedia, Pikillaqta is a large archaeological site located 20 km to the east of Cusco in Peru. Inhabited by the Wari people, it was abandoned at about 900 AD for reasons that have not been clear. At the point of abandonment, the site was incomplete, with several key buildings still being under construction. Thus, there has been considerable speculation as to why the site was left by the Wari people.

This area of Peru has a high level of seismic hazard. In the historical record, major earthquakes occurred in 1650, 1950 and 1986 in the immediate area. In a paper just published in the journal Geoarchaeology, Garcia et al. (2025), explore the hypothesis that the abandonment of Pikillaqta might be associated with earthquakes and a landslide at the site. Note that, although the paper is behind a paywall, the link should provide access for all.

The image below shows the site in 2017 – note the scarp to the northeast of the site:-

Google Earth image from 2017 showing Pikillaqta (note the different spelling on Google Earth), and the projected source of the debris flow.

A large part of Garcia et al. (2025) focuses on documenting so-called Earthquake Archaeological Effects at Pikillaqta – these are pieces of evidence in the archaeological record of past earthquake events. They have found 149 pieces of evidence, such as collapsed walls, and they infer from the orientations of these that they record the impacts of two large earthquakes (one between 856 and 988 CalAD and one between 770 and 900 CalAD) that have been identified from palaeoseismological studies of local faults.

But interestingly, Garcia et al. (2025) have also investigated a geological deposit, up to 3 m deep, in and around some of the buildings. This has the sedimentological characteristics of a debris flow, and it contains a fragment of an animal bone that has been dated to 766–898 cal AD. They have then used a high resolution digital elevation model to map the debris flow deposit. They have concluded that it initiated from the scarp to the northeast (see the label on the the Google Earth image) and then flowed through parts of Pikillaqta.

Radiocarbon dating is not precise, so this debris flow could have been triggered by an earthquake, or it could have been associated with exceptional rainfall (or a combination of the two, of course). But there is little doubt that the earthquakes and the landslide caused substantial damage to the site at about the time of abandonment, even when construction was ongoing.

The authors recognise that this is an unproven hypothesis, and encourage further research. But it is deeply fascinating to see how earthquakes and landslides may have shaped the events at this key archaeological site.

Reference

García, B., C. Benavente, M. Á. Rodriguez-Pascua, et al. 2025. Prehistoric Evidence of Crustal Earthquakes and Debris Flow in Archaeological Site of Pikillaqta in Cusco: Archaeological Implications. Geoarchaeology  40: 1-14. https://doi.org/10.1002/gea.70033.

Return to The Landslide Blog homepage Text © 2023. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

New Zealand—particularly the South Island/Te Waipounamu—is one of the most seismically active regions in the world. For this reason, the country has acknowledged the importance of building awareness and preparedness.

SummaryWe efficiently extract high-quality Pn wave arrival times from seismograms recorded at recently deployed 120 portable seismic stations of TanluArrays and 317 stations of the Chinese provincial seismic network for 7231 local earthquakes (M >2.0) using the PickNet automatic picking method. Then we use the Pn data to determine 2-D P-wave velocity and anisotropic tomography of the uppermost mantle in and around the Tanlu Fault Zone. Our Pn tomography reveals segmented features of the fault zone, which are well consistent with geological structural features. A continuous low-velocity anomaly parallel to the fault zone is revealed along the Bohai Bay-Weifang, Weifang-Tancheng, and Tancheng-Mingguang segments, whereas the Mingguang-Wuxue segment exhibits a bead-like alternating high and low velocity belt. A similar segmented characteristic also appears in the Pn wave anisotropy in and around the fault zone. A majority of strong earthquakes are located in transitional zones between high and low Pn velocities, suggesting that structural heterogeneities in the uppermost mantle may affect crustal seismogenesis. The low Pn velocities may reflect upwelling of hot and wet upwelling flows in the big mantle wedge due to mantle convection and dehydration of the flat Pacific slab in the mantle transition zone, which cause seismic anisotropy in the upper mantle in and around the Tanlu fault zone.

SummaryEarthquake monitoring plays a critical role in disaster warning and geophysical research, including earthquake phase picking and source parameter estimation. However, traditional methods suffer from cumbersome workflow and challenges in parameter selection during multi-parameter joint estimation. Here, we propose a multitask network for earthquake monitoring that reduces computational complexity by replacing the self-attention mechanism with fast Fourier transform. Through the integration of a fusion module and an enhancement module, the interaction between tasks is strengthened to optimize network performance. Additionally, a dynamic adaptive weight allocation strategy is introduced to achieve a balance among different tasks. The proposed method was trained and tested on the STEAD and INSTANCE datasets and compared with advanced approaches. The results demonstrate that this method outperforms other deep learning methods in earthquake phase picking and source parameter estimation, achieving lower errors and higher evaluation metrics, thus showing potential for practical application in earthquake monitoring.

Online map reveals link between deforestation and rises in tropical temperatures Deforestation is leading to temperature increases of up to 5°C in some tropical regions, according to data revealed in a new interactive map created by researchers at the University of Leeds.

Publication date: Available online 5 November 2025

Source: Advances in Space Research

Author(s): Zhen Lyu, Ningbo Wang, Zishen Li, Zhiyu Wang, Liang Wang, Bingcheng Liu

EU researchers are exploring how undersea communication cables can double-up as environmental and seismic sensors—a potential game-changer for early warning systems.

AbstractMeasurements of the propagation of teleseismic fundamental-mode surface waves are essential for studies of Earth structure and earthquake source processes. Understanding sources of noise and error in these measurements can help improve the accuracy and precision of analyses that use these measurements. One prominent source of noise is interference of overtones with the fundamental mode, which is well-studied in the context of surface wave phase observations. In this work, we show that overtone interference also has a substantial impact on group measurements and has uniquely different characteristics when compared with the analogous interference in phase measurements. We illustrate these characteristics using measurements on both synthetic and real data. Importantly, our experiments suggest that group measurements are more vulnerable than phase measurements to interference from overtones; both synthetic data and published datasets show larger and more variable interference in group measurements than in phase measurements. This interference leads to significant errors in group velocity estimates made using regional or array-based approaches. We show that some quality control measures designed to eliminate overtone interference in phase measurements may not be applicable for group measurements. Our results emphasize the need for careful monitoring of group velocity overtone interference in tomographic imaging, as well as the need for accurate uncertainty quantification when group velocity maps are used in further studies.

AbstractCompared to first-arrival traveltime tomography (FATT), first-arrival traveltime and slope tomography (FASTT) integrates both traveltimes and local slopes of first arrivals at sources and/or receivers to construct more accurate subsurface velocity models. Local slopes serve as additional constraints, helping to mitigate the ill-posedness of tomography by better constraining ray directions. This is particularly beneficial in regions with complex topography, where shadow zones arise due to strong velocity contrasts. However, representing complex topography or bathymetry can be less accurate when using classical rectangular grid discretization. To address these complexities with greater versatility and accuracy, we compute traveltimes of locally coherent events using a factored topography-dependent eikonal solver on curvilinear grids. Slopes are then estimated by finite differences in the traveltime maps after a back-and-forth coordinate transform from the curvilinear grid to a rectangular computational grid. Additionally, we solve the inverse problem with the matrix-free approach, where the data misfit gradient is computed with the adjoint-state method. This adjoint—state formulation avoids the explicit construction and storage of large Fréchet derivative matrices and does not require a tedious posterior ray tracing on curvilinear grids. A land synthetic example first illustrates the sensitivity of slopes to topography and the more accurate velocity models with FASTT than with FATT in the presence of topography. We then perform a first application of the topography-dependent FASTT method on a real redatumed ocean-bottom node dataset, where the bathymetry exhibits a steep scarp. We show that the topography-dependent FASTT generates a velocity model that matches more closely a legacy reflection tomography model than conventional FATT. We conclude that the topography-dependent FASTT provides a versatile approach for handling complex surfaces during velocity model building in both marine and land environments.

In the dense forests of northwestern Pennsylvania, hundreds of thousands of retired oil and gas wells—some dating back to the mid-1800s, long before modern construction standards—dot the landscape, according to geochemists in Penn State's College of Earth and Mineral Sciences who recently led a study in the region. Left uncapped and exposed to air and erosion, they break down, leaching harmful chemicals into the atmosphere and, the researchers reported, into the groundwater.

Publication date: Available online 5 November 2025

Source: Advances in Space Research

Author(s): Yuhao Zheng, Chao Xiong, Gaofang Mi, Yuanqiang Zhao, Ziyuan Zhu, Artem Smirnov, Rui Yan

Publication date: Available online 5 November 2025

Source: Advances in Space Research

Author(s): Dongling Ma, Zhenxin Lin, Qian Wang, Yifan Yu, Guoqiang Yu

Publication date: Available online 5 November 2025

Source: Advances in Space Research

Author(s): Kamyar FULADLU

A team led by LMU researchers shows why CO₂ fluxes from land use are so difficult to quantify—and how they can be estimated more accurately in the future.

Satellite scatterometers play a crucial role in monitoring ocean surface winds, with their accuracy directly impacting weather forecasting and climate research. However, rainfall has consistently challenged precise wind measurements, as Ku-band radar signals are much affected by rain clouds.

Thwaites Glacier in West Antarctica—often called the "Doomsday Glacier"—is one of the fastest-changing ice–ocean systems on Earth, and its future remains a major uncertainty in global sea-level rise projections. One of its floating extensions, the Thwaites Eastern Ice Shelf (TEIS), is partially confined and anchored by a pinning point at its northern terminus.

A new medical study simulated an avalanche in the Italian Alps, demonstrating the life-saving power of a new portable fan system.

The Safeback SBX device weighs 18 ounces, fits into a backpack or vest, and draws oxygen from snowpack’s natural porosity to extend survival. While other safety tools—like emergency beacons and airbags—can make it easier to find someone in an avalanche, the Safeback SBX extends the time a person can survive while waiting for rescue.

“This is the biggest innovation in avalanche safety devices in 25 years.”

In a recent study in the Journal of the American Medical Association (JAMA), the Safeback SBX helped buried victims breathe under the snow for at least 35 minutes. That’s a critically important window. Roughly two thirds of people asphyxiate within 30 minutes of avalanche burial.

“This is the biggest innovation in avalanche safety devices in 25 years,” said Giacomo Strapazzon, an adjunct professor of emergency medicine at the Università degli Studi di Padova and lead author of the study.

Simulating an Avalanche

Strapazzon led the study for the Institute of Mountain Emergency Medicine at the private research center Eurac Research. While the makers of Safeback SBX proposed the study, the research team maintained independence.

To study the efficacy of the device, researchers first needed to bury willing victims. They put out a call for volunteers, screening potential participants for claustrophobia before bringing them to the mountains. They recruited 36 participants, ultimately using 12 men and 12 women, a gender balance celebrated in a separate JAMA editorial for addressing the “severe underrepresentation of females” in high-altitude physiology tests.

The test took place in a mountain pass, 2,000 meters above sea level in the Dolomite range in northeastern Italy. Participants were buried face down under 50 centimeters of high-density snow (500 kilograms per cubic meter) while wearing a Safeback SBX.

In an avalanche, the main cause of death is asphyxiation from lack of oxygen. But snow is naturally porous, up to 67% air even at a density of 300 kilograms per cubic meter. The Safeback SBX uses a large fan to suck oxygen-rich air from the snow behind a victim. It delivers up to 150 liters of air per minute toward the user’s face via shoulder strap tubes. The device works with the company’s backpacks and vests and can be activated before entering avalanche terrains. The equipment is cold weather tested, with a battery lasting at least 60 minutes even at −30°C.

During the test, half the participants received a functioning device that switched off after 35 minutes. The other half received a sham device. Participants were buried one at a time, while a gang of puffy-coat-clad medical professionals monitored their vital statistics from the surface.

The Safeback SBX successfully extended survival time. Of the 12 participants buried with a sham device, only one lasted 35 minutes. Seven had to be rescued after their pulse oximetry, or the level of oxygen in the blood, dipped below the study threshold of 80%. The other four requested an early rescue by radio. Average burial time was 6.4 minutes under the snow.

Of the 12 people buried with a functioning device, 11 lasted the full 35 minutes. Only one requested an early rescue. When the functioning devices were switched off after 35 minutes, participants lasted an average of 7.2 minutes. Five requested rescue, and six required it after their pulse oximetry dropped below 80%.

Winter Work

The device could be valuable for anyone who works and recreates in avalanche terrain, including Earth scientists.

Peter Veals is an atmospheric scientist at the University of Utah. His lab group deploys atmospheric gauges in the Wasatch Mountains each year before the snow falls. But winters are long, and equipment needs maintenance. His team may ski 30 minutes over 4.5 meters (15 feet) of snow to knock icicles off a heated radar dish before a storm starts.

His lab group uses a detailed safety plan, but it’s difficult to avoid avalanche terrain completely, he said. By extending the rescue time, the Safeback SBX has clear value in the mountains.

“Those are some brave volunteers.”

“There’s probably a lot of people that get there a minute too late,” Veals said of avalanche rescues. “Extending [survival time] by 20 minutes plus is a huge deal.”

Other factors affect survivability. People in an avalanche may strike a tree or boulder. Deeper, denser snow would delay a rescue. Preventive measures like avalanche training and education are still essential.

“All those factors mean this isn’t a silver bullet, but I think it is still a huge step forward,” Veals said of the device.

The study did a great job mimicking the conditions of an avalanche, he noted.

“I thought it was as applicable as you could get to the actual situation,” Veals said. “Those are some brave volunteers.”

—J. Besl (@jbesl.bsky.social), Science Writer

Citation: Besl, J. (2025), Safety device supplies life-saving air in an avalanche, Eos, 106, https://doi.org/10.1029/2025EO250418. Published on 7 November 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.