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Secrets in the Peat

Written into an approximately 30-meter-long (100-foot-long) core sample drilled from the seafloor near West Antarctica is a history that might seem impossible if it weren’t so clearly documented. From fossilized pollen grains and preserved plant roots in the core sample, scientists found that during the Cretaceous period around 90 million years ago, Antarctica was a humid, swampy rainforest. When scientists published the results in 2020, it became the southernmost forest ever recorded.

Now, in a new study published in Communications Earth and Environment, the same scientists report that the original core sample, drilled roughly 900 kilometers (560 miles) from the South Pole, also holds evidence of the southernmost wildfires ever recorded. Those wildfires likely facilitated the transition of the landscape from rainforest into a sphagnum moss–dominated peat bog that experienced low-level fires. According to the scientists, the discovery reveals a fire regime that is remarkably similar to that of modern-day peat bogs.

A Changing Landscape

When the scientists were studying the core sediment for traces of ancient forests, they used strong acids that dissolve away everything except organic material. At first, they were interested in the pollen and spores that remained, aiming to get an idea of the flora that grew on the landscape, but they also noticed another interesting organic material in the mix.

“We spotted these tiny pieces of charcoal,” evidence of burnt material, said Johann Klages, a sedimentologist at the Alfred Wegener Institute.

“It’s the southernmost evidence for wildfires on the planet so far.”

For the new study, the scientists took a variety of approaches to confirm they were looking at remnants of ancient blazes. First, they examined the charcoal fragments using high-powered microscopes and saw plant cell walls, indicating the fragments were burnt plant material. Partially burnt plants also leave behind specific chemical residues, which the scientists identified in the core sediment using spectrometry. The presence of amber, which is fossilized tree resin, was another clue.

“We saw, in some instances, that the amber was covering the bark of a former tree,” Klages said. “That usually happens when the tree gets injured by some kind of external force,” such as a fire. On the basis of the way that light reflected off the burnt particles in the sediment core, the scientists were even able to determine that the fires were lower-temperature surface fires, as opposed to underground fires that can occur in peatlands or crown fires that burn the tree canopy.

Taken together, “it’s the southernmost evidence for wildfires on the planet so far,” Klages said.

Scientists examined a sediment core under a microscope to learn more about Antarctica’s past. Top, left to right: a moss spore, charcoal, and amber. Bottom, left to right: a scanning electron micrograph (SEM) of cell walls that appear to be homogenized, indicating that charcoal burned at high temperatures; an SEM of radial wood, with arrows pointing to gaps that indicate coniferous wood; and a similar image highlighting similarities between a modern-day conifer and the fossil image. Credit: Salzmann et al., 2026, https://doi.org/10.1038/s43247-026-03959-1

The story broadened when the scientists tracked changes to the fire history and ecosystem over time. By investigating the chemical signatures further and assessing the different types of fossilized pollen and spores, the researchers recorded a landscape full of conifers representative of a temperate rainforest in the lower, earlier sections of the Cretaceous. Higher up in the sample, later in the Cretaceous, they saw a sharp increase in ferns and sphagnum moss, commonly found in peat bogs. Peat bogs are also acidic environments, and the scientists saw in tests that the pH in the core dropped during the transition.

“It was just spectacular to have slightly different ways of looking at the geologic record and looking at fire histories. And by putting them all together, you understand more than you would with just one proxy.”

The transition from rainforest to peat bog paralleled an increase in fire occurrence. “We see an evolution of fire going on,” said Ulrich Salzmann, a paleoecologist at Northumbria University. The scientists speculate that more frequent fires helped sustain the shift to peat bogs by keeping the landscape more open. “You basically see the peat spores increasing at the same time that fire goes up,” Salzmann said. He noted that similar links between fire and peat bogs are seen in the high Arctic today.

“It was just spectacular to have slightly different ways of looking at the geologic record and looking at fire histories. And by putting them all together, you understand more than you would with just one proxy,” said Ellen Currano, a paleoecologist at the University of Wyoming who wasn’t involved in the study.

Peat Bogs, Then and Now

Antarctica’s peat bogs show similarities to peat bogs throughout history all the way up to present day. Salzmann said that when he looks at the 90-million-year-old sphagnum spores from the study and compares them to ones from the past 10,000 years in Scotland, they look remarkably similar. “I find it so amazing,” he said. Peat bogs today also experience low-intensity, surface fires like those they documented in ancient Antarctica. Though the Cretaceous had a climate dramatically different from today’s, with warmer temperatures and higher carbon dioxide and oxygen levels, the findings reflect that fire can be a part of healthy peatlands as long as they aren’t drained or dried.

“One of the greatest powers of the fossil record is it teaches us that the present is just one data point for how Earth works,” Currano said. “By looking at the Late Cretaceous and seeing a time period when you have much warmer temperatures, we can see other ways that Earth works, and maybe even a little bit about where we might be heading in the future.”

—Andrew Chapman (@andrewgchapman.bsky.social), Science Writer

Citation: Chapman, A. (2026), Wildfires burned in Antarctica 90 million years ago, Eos, 107, https://doi.org/10.1029/2026EO260312. Published on 1 October 2026. Text © 2026. 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.

Secrets in the Peat

Peat bogs are weird repositories of Earth science, history, and ecology.

“Peatlands have taught us perhaps more about human history than any other” ecosystem, says ecologist Merritt Turetsky, author of Bogland: The Secret World That Defies Death and Protects Life. “They’re storytellers about Earth’s history. They’re storytellers about early human societies.”

“Bog bodies,” unearthed hundreds and even thousands of years after their burial, are one example of the preservative power of peatlands. “Natural Mummies Hold Memories of Life and Land” is a fascinating introduction to bog bodies, icemen, and other human remains that are naturally, if unintentionally, preserved by the intersecting idiosyncrasies of temperature, moisture, aridity, pressure, and microbiomes. This feature also reminds us that these mummies are not only scientific specimens—they are the remains of human beings and touchpoints for the rights of Indigenous peoples long overlooked in Western-dominated research.

Peatlands record stories far older than humanity, of course. “Wildfires Burned in Antarctica 90 Million Years Ago” explores how Antarctic sediment cores are revealing the White Continent’s evolution from a temperate rainforest to a peatland during the Cretaceous.

History is still being written in peat, and it might even help predict the future. Recent research revealed that bird biodiversity is soaring in a solar park built on degraded peatland. (That story is one of many Eos articles available in audio.) Rewetted bogs offer an additional reason for cautious optimism, as detailed in “Restored Peatlands Could Become Carbon Sinks Within Decades.”

In addition to being Turetsky’s storytellers, peat bogs and other wetlands “are actually unsung heroes,” says Annie Proulx in Fen, Bog and Swamp: A Short History of Peatland Destruction and Its Role in the Climate Crisis.

We hope this issue of Eos reacquaints you with wetlands and ushers in a hopeful approach to October.

—Caryl-Sue Micalizio, Editor in Chief

Citation: Micalizio, C.-S. (2026), Science on repeat, peat, peat, Eos, 107, https://doi.org/10.1029/2026EO260311. Published on 1 October 2026. Text © 2026. 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.

body {background-color: #D2D1D5;} Research & Developments is a blog for brief updates that provide context for the flurry of news regarding law and policy changes that impact science and scientists today.

Last week, FEMA administrator Cameron Hamilton issued a memorandum outlining the agency’s scope and essentially redefining “emergency management.”

 
Related

•  We Must Return to the Basics: A Definition of Emergency Management and Professional Framework
•  He Got Fired From FEMA. His Return Could Mark a New Era for Disasters.
•  The President’s Council to Assess the Federal Emergency Management Agency
 

“Effective immediately, FEMA defines emergency management as the strategic coordination of emergency services to protect life, property, and continuity of operations,” Hamilton said in a video announcement.

A previous definition on the FEMA website defined the phrase as “the managerial function charged with creating the framework within which communities reduce vulnerability to hazards and cope with hazards.” Samantha Montano, an associate professor at the Massachusetts Maritime Academy who researches emergency management, explained that this previous definition was developed by a focus group of emergency management researchers and practitioners.

It’s unclear whether any experts were involved in developing the new definition.

Montano said she was disturbed by the new definition’s emphasis on “emergency services.”

“I know it looks like a really small change, but that term ‘emergency services’ is a total, total recalibration of what emergency management is, does, and who we work with, in a way that is deeply concerning,” she told Eos.

In the field of emergency management, “emergency services” refers to fire, police, and emergency medical services—what people typically mean when they refer to first responders, she explained. This means the new definition does not involve emergency managers coordinating with other government agencies, nonprofits such as the Red Cross, or private entities—including utility companies. The new definition also seems to preclude providing funding for disaster mitigation or recovery.

By this definition emergency management has no role in mitigation and recovery and also excludes from response groups like the Red Cross, utility companies, public health, hospital/ university emergency management, etc.

— Dr. Samantha Montano (@samlmontano.bsky.social) 2026-09-30T16:14:52.032Z

Montano also noted that the new definition seemed to be in line with suggestions made in the right-wing policy initiative Project 2025 as well as the FEMA Review Council report released in May. Those documents proposed a shift of many current FEMA responsibilities to states and localities.

What’s In a Name?

Hamilton was ousted as acting head of FEMA in May 2025 after suggesting that the agency should continue to exist, but was confirmed as the agency’s new leader in August 2026.

His new memo, titled in part “We Must Return to Basics,” frames the redefinition as an effort to clarify FEMA’s mission. It argues that the field of emergency management has expanded beyond its original scope, “which has diluted our credibility, capability, and professional development.”

Montano agreed that there is value in clarifying the definition of some terms within the field of emergency management, and that she has been involved with such efforts herself. However, this redefinition struck her as “bizarre.” Hamilton himself doesn’t have a background in emergency management, and the new definition doesn’t engage with the decades of work experts have put into developing a definition of the field, she said.

It’s unclear exactly what implications the new definition carries, but the memo seems to imply changes could be sweeping, noting that all “doctrine, policies, guidance, training, websites, workforce materials, planning and exercise products, publications, presentations, and other internal and public-facing materials” will be updated to align with the new definition.

The memo also identifies 12 core areas for the agency to focus on, some of which seem to contradict the new definition of emergency management—including risk analysis and hazard vulnerability assessments, planning and plan development, and cross-functional coordination.

“If, as the memo implies, [Hamilton] is expecting FEMA to start operating under this definition, then everything at FEMA would change,” Montano said. “There’s a real potential here for a complete overturning of what we think of as being emergency management.”

—Emily Gardner, Deputy Editor (@emfurd.bsky.social)

These updates are made possible through information from the scientific community. Do you have a story about how changes in law or policy are affecting scientists or research? Send us a tip at eos@agu.org. Text © 2026. 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.

Author(s): Z. H. Chen, Z. Q. Zhao, X. H. Yang, L. R. Li, B. Zeng, Z. Li, B. H. Xu, G. B. Zhang, H. H. Ma, M. Tang, Y. Y. Ma, H. Xu, F. Q. Shao, and J. Zhang

Distortions in the electron distribution function driven by intense temperature gradients critically influence the heat transport and the generation and evolution of magnetic fields in plasmas under the condition of inertial confinement fusion. Describing such kinetic behaviors at large spatiotempor…

[Phys. Rev. E 114, 045201] Published Thu Oct 01, 2026

Examination of Planet Labs satellite imagery before the collapse of the slope suggests that there were surprisingly few signs of incipient failure.

The catastrophic landslide – debris flow – flood that swept through Tibet and Nepal on 26 August originated with very large rock slope failure on the flanks of Langtang Lirung, a massif located within Langtang National Park in Nepal. Good satellite imagery is available via Planet Labs from two days (12 and 25 August 2026) leading up to the failure.

Given the discussion about the potential for protecting the population through early warning systems (loyal readers will know that I have my doubts about this), thought it would be interesting to see what changed in the days leading up to the failure.

A caveat is of course that the Planet Labs imagery is of moderate spatial resolution – but that is likely to be imagery upon which this sort of system is based if an optical approach is used.

So this is the Planet Labs image from 12 August 2026 for the site of the landslide, draped onto the Google Earth DEM:-

Satellite image draped onto the Google Earth DEM for the Langtung Lirung landslide. Image copyright Planet Labs, used with permission, collected on 12 August 2026.

Here is the same location with an image from 25 August 2026:-

Satellite image draped onto the Google Earth DEM for the Langtung Lirung landslide. Image copyright Planet Labs, used with permission, collected on 25 August 2026.

And here is a slider to allow comparison:-

Images copyright Planet Labs, used with permission.

Two things jump out – first, there is comparatively little change on first inspection between the two images bar the obvious (and irrelevant) shadows, clouds and suchlike. And second, the 25 August 2026 image – collected the day before the massive landslide – shows no real signs of instability. There is no obvious dust being generated for example, and there are no obvious dust deposits around the landslide.

In more detail, there are a couple of things that have changed. First, it does appear that the ice near the crown of the landslide has moved – this is the change that was picked up in the pixel tracking research that I highlighted previously. Care is needed here because of the shadows, but there is probably change in this area.

Second, there are signs of increased rockfall activity in the midslope area – this can be seen in the image below:-

Satellite image draped onto the Google Earth DEM for the middle section of the Langtung Lirung landslide. Image copyright Planet Labs, used with permission, collected on 25 August 2026.

The area in the centre of the image has seen substantial change. It appears that several areas parts of the rock slope have detached, with large boulders collecting immediately below (still in the midslope area).

This indicates debuttressing of the upper part of the slope, and this was probably part of the failure process. But these are really minor changes that are probably very difficult to differentiate from the background level of activity.

It is quite interesting that this slope generated so little obvious precursory signs of failure. Other large landslides behave very differently. This needs more detailed investigation, but the signs are not good in terms of being able to use these sorts of precursory signals as a reliable indicator of incipient failure.

Acknowledgement

Many thanks to the wonderful people at Planet Labs for allowing me to use their imagery.

Return to The Landslide Blog homepage Text © 2026. The authors. CC BY-NC-ND 3.0
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SummaryLow-frequency tremors provide important constraints on the mechanical and hydrological conditions of subduction plate interfaces, yet their focal depth distributions remain challenging to be resolved compared to those of fast earthquakes. In this study, low-frequency tremors in the Hyuga-nada region are independently relocated using earthquake location techniques with travel-times by converting cross-correlation-derived arrival-time delays into pseudo-arrival times for each single station, without imposing a priori depth constraints. The resulting hypocenter distribution reveals systematic spatial patterns that are robust across multiple observation periods. Hypocenter locations are determined through a multi-stage relocation procedure, in which an initial maximum-likelihood location incorporating station correction terms is followed by a double-difference relocation using a three-dimensional velocity model. Only events meeting stringent quality thresholds on converted arrival counts, azimuthal gap, and initial hypocentral depth uncertainty are retained. Location uncertainties are quantified at each stage using a Bayesian framework and jackknife resampling, which respectively characterize the probabilistic confidence of the solution and its robustness against the influence of individual stations and potentially biased converted arrival times. These steps are iteratively applied to refine source parameters, thereby improving depth resolution and overall location stability. The relocated low-frequency tremors are predominantly concentrated at shallower depths than fast earthquakes and are distributed along the plate interface. Comparison with seismic reflection profiles indicates that low-frequency tremors are generally distributed in the vicinity of strong reflective interfaces along the plate boundary, supporting previous interpretations that associate low-frequency tremors with mechanically weak, fluid-rich layers. The relocated tremor locations further show a clear spatial correspondence with a subducted seamount inferred from magnetic anomaly data, consistent with mechanical and hydrological contrasts associated with seamount subduction, particularly along the downdip flank, which may reflect stronger compression and enhanced fluid drainage. These results demonstrate that low-frequency tremors in the Hyuga-nada region are strongly controlled by the plate interface and structural heterogeneity. The relocation framework presented here provides a unified basis for integrated analyses of fast and slow earthquake processes in subduction zones.

SummaryWave-induced fluid flow (WIFF) across multiple scales causes significant seismic wave dispersion and attenuation over a broad frequency range in partially saturated rocks. Accurately characterizing these effects is crucial for improving hydrocarbon reservoir detection. In this study, we develop a model that integrates mesoscopic Rayleigh bubble oscillation with an extended microscopic squirt-flow mechanism (with varying microcrack aspect ratios), including capillarity effects. Plane-wave analysis indicates that both P1 (fast P) and S waves are strongly influenced by multiscale fluid flow, with the extended squirt-flow mechanism producing a broader range of wave attenuation and dispersion at high-frequency. Numerical analysis shows that the pore structure controls wave-velocity dispersion and attenuation at different scales. The inclusion radius determines the mesoscopic relaxation characteristic frequency, and the microcrack porosity governs squirt flow. Furthermore, the model predictions agree reasonably well with two independent sets of experimental data, validating the applicability of the theory. This study provides valuable insights for understanding seismic wave dispersion and attenuation in partially saturated rocks.

Switzerland's glaciers lost more than 5% of their ice volume in 2026. Although melt rates did not quite reach the record levels of 2022, glacier thickness decreased by an average of 2.5 to 4 meters (8 to 13 feet) this year, and some glacier tongues lost up to 10 meters (33 feet) of ice. The research is published in the journal GLAMOS—Glacier Monitoring Switzerland.

Ice cores recovered from an ice cap in northwestern Tibet appear to preserve fragments of ancient ice from the last ice age, extending Earth's glacial record by more than 100,000 years and making them the oldest ice cores ever recovered from the region, according to a new study.

A few days of rain do not change low groundwater levels after a long drought. To better determine how groundwater systems recover after a drought and which groundwater reserves are most vulnerable, hydrologist Sandra Hauswirth developed a method to classify groundwater systems based on their ability to recover from prolonged drought.

Irrigation canals form a sort of circulatory system for global agriculture. Across the world, millions of kilometers of human-made canals carry water from lakes, rivers and reservoirs downhill to farmland. Canals are vitally important to human food production, yet many agricultural areas lack the means to monitor the ebb and flow of water through these waterways. This forces farmers and water managers to rely on scattered gauges, inspections and local reports to make decisions about water use.

Sea-level rise is one of the most visible signs of climate change, one that is threatening low-lying coastal communities around the world. Today, about 1 billion people live in coastal areas; about 100 million live within 1 meter (3.3 feet) of sea level, highly exposed to coastal flooding.

Editors’ Vox is a blog from AGU’s Publications Department.

As wildfire activity and severity continue to amplify across the globe, it is increasingly important to understand and have the ability to forecast wildfire emissions, which can affect air quality, climate, and public health.

A new article in Reviews of Geophysics explores our current understanding of the chemical reactions within wildfire smoke plumes. Here, we asked the lead author to give an overview of fire plumes, how scientists study them, and future directions for research.

In simple terms, what are fire plumes?

Fire plumes are rising masses of hot air, gaseous chemical species and particles produced as vegetation and other material burn. We commonly see them as smoke columns above the fire source, but their chemical constituents are not visible. Depending on the fire intensity and meteorological conditions, a plume may disperse near the source or rise high into the atmosphere and travel further away from the source. Its composition also depends on the fuel type. For example, a forest, a grassland, and a building can release different pollutants and chemicals. A plume is not chemically uniform or static. Close to the flames, newly emitted compounds can react rapidly, while downwind in-plume species mix with surrounding gases and form new secondary species. This is commonly called plume aging, meaning that smoke can alter significantly between the fire source and the areas it reaches.

Why is it important to understand the chemistry inside fire plumes?

Understanding the chemistry inside fire plumes helps us answer the question that smoke concentration alone cannot: “What are people and ecosystems actually exposed to as smoke travels?”

Fires release pollutants directly, but reactions inside the plume can result in the formation of new pollutants.

Fires release pollutants directly, but reactions inside the plume can result in the formation of new pollutants. Specific compounds get consumed, while others become more abundant or change their properties as the plume moves downwind. Our review brings together these chemical pathways to explain why smoke from different fuels, locations, and meteorological conditions present different behaviors. Combining this knowledge, in-plume chemistry helps improve air-quality forecast and estimates of downwind exposure. In addition, it provides necessary evidence and information to investigate health and climate impacts, inform health guidelines, and fire management decisions. It is important to understand that smoke that reaches a community may be chemically different from the smoke emitted near the fire source.

How do scientists observe and measure chemical reactions in fire plumes?

Scientists usually investigate plume chemistry by utilizing a combination of complementary approaches. Ground stations continuously measure gases and particles as smoke passes, while research aircrafts can collect samples within and around a plume at different distances from the fire source. These approaches are characterized as online methods. Comparing these measurements helps see which compounds are emitted, reduced, and formed as the smoke ages.

Air filters collected during fire events can later be analyzed to identify additional particle components and constitute an offline method. Additionally, controlled in-lab combustion experiments allow scientists to burn selected fuels and examine reactions under known conditions. Moreover, satellites provide a wider view of plume dispersion and select, typically long-lived, species. However, they cannot detect reactions. Finally, atmospheric models combine these observations to test possible chemical pathways and investigate changes that cannot be measured directly. Each method reveals different pieces of the same evolving chemical system.

What are the main chemical components of fire plumes explored in your review?

Fire plumes contain a complex mixture of gases and particles, rather than a single compound we simply call smoke. Major gases emitted during a fire include carbon dioxide and monoxide, methane, nitrogen oxides and volatile organic compounds, usually referenced as VOCs. Depending on the fuel, plumes can also contain ammonia and sulfur species. The particle fraction includes soot, organic material, ash, and trace metals.

In our review, we pay particular attention to black and brown carbon, which are light-absorbing species, and organic particles that can change as the smoke ages. It is important to note that not all the species existing inside a plume were emitted directly by the fire. Chemical reactions can generate ozone and secondary organic aerosols, resulting in the formation of new pollutants in the original mixture. Understanding both the initial emissions and the secondary formed products is essential for assessing air quality, climate effects, and potential exposure.

Simple schematic representation of selected in-plume chemical species and processes. Credit: Dovrou et al. [2026], Figure 1

What factors influence the chemistry inside fire plumes?

The chemistry of a fire plume begins with what is burning and how it burns. Different vegetation types and anthropogenic materials release different compounds, while intense flaming and slower, smoldering combustion produce release emissions. Temperature and oxygen availability also affect the in-plume chemistry. In addition, plume size and injection height play a key role. Specifically, a dense plume rising high above the surface encounters different conditions from a smoke remaining close to the ground. As the plume dilutes and ages, gases can react or dilute into particles, altering both pollutant concentrations and particulate properties. All these factors interact; thus, two fires of similar size will produce chemically different smoke plumes.

How do fire plumes impact cloud formation?

Fire smoke can influence clouds, as small smoke particles can act as cloud condensation nuclei, meaning surfaces on which water vapor condenses to from droplets. When smoke adds large numbers of these particles, a cloud may contain more droplets that are individually smaller, potentially changing its lifetime and precipitation. Some fire-related mineral particles can also assist ice crystals to form colder clouds. In-plume chemistry is important because the particles continue to change as plume ages, altering their size, composition, and ability to take up water. There is also a competing effect. Black and brown carbon absorb sunlight and warm the surrounding air, occasionally reducing humidity and making cloud formation less favorable. The overall outcome depends on the plume and cloud types as well as the atmospheric conditions.

What are some of the remaining knowledge gaps where additional research efforts are needed?

Ultimately, the goal is to predict not only where the plume travels, but how its composition and impacts evolve along the way.

One major challenge is capturing the fastest reactions in fresh smoke and following the same plume as it ages, especially under dark conditions or after it passes through clouds. We also need to understand why models sometimes struggle to reproduce ozone, and the formation or loss of organic particles when simulating fire events. Other uncertainties include the mechanism of smoke rise, its mixture with surrounding air, and the way that biological particles change during plume transport. Our review highlights the value of combining controlled laboratory experiments with aircraft, ground-based and satellite observations, supported by higher-detailed chemical models. Improved sensors and drones could also help fill important gaps. Ultimately, the goal is to predict not only where the plume travels, but how its composition and impacts evolve along the way.

—Eleni Dovrou (edovrou@uoc.gr; 0000-0003-0564-9573), Assistant Professor at the University of Crete, Department of Chemistry, Greece, Visiting Fellow Honorary Appointment at the HEAL Research Institute, University of Canberra, Australia, Alumni Affiliate at the Leverhulme Research Center, Imperial College, UK, Alumni Affiliate at the Technical University of Crete, School of Chemical and Environmental Engineering, Greece

Citation: Dovrou, E. (2026), Where fire ends, chemistry begins, Eos, 107, https://doi.org/10.1029/2026EO265038. Published on 30 September 2026. This article does not represent the opinion of AGU, Eos, or any of its affiliates. It is solely the opinion of the author(s). Text © 2026. 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.

Many cities around the world are sinking because too much water is extracted from the groundwater reservoirs beneath them. This sinking makes these coastal cities more exposed to rising seas as the climate warms. But as our new research shows, this process can work in reverse: When groundwater is replenished, cities can rise.

Over a century ago, Australian geologist Sir Douglas Mawson led a sledding expedition over hundreds of kilometers of ice into a remote part of East Antarctica. The party turned back after the tragic death of a party member. Fellow Australian Cecil Madigan led another group across sea ice into the region before also turning back.

In 2025, along parts of Kamchatka's coast in Russia, a magnitude 8.8 earthquake caused a tsunami to surge nearly 20 meters (65 feet) above sea level. Yet across the Pacific, its waves were much smaller than those produced by the region's great 9.0 earthquake in 1952. How could the tsunami climb so high near the source yet have a comparatively modest impact far away?

On 6 August 2025, the Dayuan landslide in Guangzhou, China killed 7 people. It was triggered by rainfall onto an area affected by a wildfire.

In recent decades, China has built substantial capacity for investigating landslides. One result of this is that most significant landslides there are now analysed with the results published. This is a welcome development.

One example is the 6 August 2025 Dayuan landslide in Guangzhou, China, which killed seven people. An analysis of this event (Che et al. 2026) has been published in the journal Landslides – it is a very interesting story.

The location of this landslide is [23.24560, 113.33723] (Che et al. (2026) provide a location that appears slightly incorrect, but mapping in China is an issue in its own right). This is a Google Earth image of the site:-

Google Earth image of the location of the 6 August 2025 Dayuan landslide.

The Dayuan landslide had a volume of about 15,000 m3, travelling about 80 metres to impact eleven houses at the toe of the slope. The event, which was triggered by an intense burst of rainfall (peak intensity = 32.8 mm/h) that followed a prolonged period of rainfall. The landslide had unusually high mobility, which was a major factor in its lethality.

The really interesting aspect of this event is that the slope had suffered a substantial wildfire in January 2025, a few months before the landslide. Che et al. (2026) conclude that this wildfire created an ash layer that initially impeded infiltration until it was eroded away, which then exposed a layer of highly permeable soil. When the rains arrived, the topography channelled water into this part of the slope, generating high pore water pressures that triggered the failure.

It is not clear as to why the landslide had unusually high mobility – perhaps static liquefaction was a factor?

Wildfire occurrence is rising, and the link to landslides in places such as California is well established. That even small wildfires are promoting fatal landslides in Asia is very interesting, especially ahead of the unpredictable global weather that will accompany the peak of the 2026-27 El Nino event.

Reference

Che, F., Zou, J., Qiu, Y. et al. 2026. Coupled effects of wildfire, rainfall, terrain, and lithology on the failure of the Dayuan landslide. Landslides. https://doi.org/10.1007/s10346-026-02854-2

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SummaryInterferometric Synthetic Aperture Radar (InSAR) deformation measurements are susceptible to long wavelength errors, yet existing geometric and strain models for estimating three-dimensional (3D) deformation from combined Global Navigation Satellite System (GNSS) and InSAR observations do not explicitly account for these errors. Neglecting long wavelength errors can substantially bias 3D deformation estimates for large earthquakes. We therefore develop a combined adjustment model that introduces additional systematic parameters to represent InSAR long wavelength errors, defines these parameters using GNSS minimum constraints, and optimizes the stochastic model of the heterogeneous observations through least-squares variance component estimation (LS-VCE). We evaluate the model using synthetic tests and observations of the 2011 Tohoku-Oki earthquake. In the synthetic tests, the proposed model constrained the datum deviation to below 1 mm, whereas the corresponding mean datum deviations obtained using the geometric and strain models were 5.40 and 3.80 m, respectively. Relative to the design values, compared with the geometric and strain models, the proposed model reduces the mean absolute error (MAE) for the East (E) and North (N) components by 98.63% and 98.84%, 93.65% and 96.45%, respectively. This indicates that the proposed model can effectively eliminate the interference of long wavelength errors on the 3D deformation parameter estimation. We further applied the proposed model to the 2011 Tohoku-Oki earthquake and compared the resulting deformation with the Jet Propulsion Laboratory (JPL) co-seismic displacement solution. Compared with the geometric and strain models, the proposed model reduces the MAE for the E, N and U components by 89.32% and 89.27%, 83.33% and 85.25%, 37.50% and 82.14%, respectively. Under the adopted fault geometric parameters, the proposed model also recovered candidate strike-slip components that were not resolved by the conventional models. Compared with the geometric and strain models, the proposed model reduces the MAE between forward modeled and JPL co seismic displacements for the E and N components by 98.36% and 98.01%, 95.45% and 94.59%, respectively. Overall, explicitly estimating InSAR long wavelength errors within a combined adjustment framework improves the numerical and physical reliability of GNSS-InSAR 3D deformation estimation.

SummarySeismic velocity profiles are crucial for exploring subsurface features and monitoring seismicity. The depth sensitivity of seismic surface waves depends on frequency and, therefore, dispersion curves, routinely obtained from frequency-wavenumber methods, are used to invert subsurface velocity structures. However, an optimal, scalable array design concept suitable for various target depths and applications remains under discussion. We propose an array design, optimised for passive seismic surveys, based on circular arrays using only the target depth range as input. Exploiting the impact of the array layout on wavenumber resolution and aliasing, we derive new relations for optimized arrays requiring only the target depth range. The concept accounts for different modes and wave types by considering penetration depth in terms of wavelength. For fundamental-mode Rayleigh waves, the maximum inter-station distance should be at least five times the maximum target depth, and the minimum distance smaller than twice the minimum target depth to avoid aliasing.

SummaryGlobal Navigation Satellite System (GNSS) and Gravity Recovery and Climate Experiment (GRACE)/GRACE Follow-On (GFO) observations provide complementary geodetic constraints on terrestrial water storage (TWS) changes, but either data source alone is often insufficient for interpreting water storage response in small humid coastal monsoon regions. We integrated vertical displacements from 49 GNSS stations with GRACE/GFO mascon solutions to estimate monthly TWS changes in Guangdong, China, from 2017 to 2024. An objective-space weighting strategy was used to balance local detail constrained mainly by GNSS with regional mass signals stabilized by GRACE/GFO. The joint solution retains GNSS-supported spatial detail not resolved by GRACE/GFO and reduces boundary artifacts relative to the GNSS-only inversion. It also shows the highest consistency with hydroclimatic water-balance estimates among the geodetic solutions, with a maximum correlation coefficient of 0.85 (95 per cent CI: 0.72–0.93). We further combined the joint solution with hydroclimatic data to interpret water storage response under different moisture conditions. At the seasonal scale, soil moisture storage (SMS) responds nearly synchronously to precipitation, whereas TWS changes peak about one month later. Both responses show weaker amplitudes and shorter lags along the coast, with the opposite pattern inland. For storage anomalies, TWS shows state-dependent memory, mainly 3–7 months under normal and wet conditions but 11–12 months during the prolonged 2021 drought, while SMS remains tied to a much shorter timescale. The joint TWS record also captures three hydrological droughts and two regional flood episodes from 2017 to 2024, including an extreme drought that persisted from December 2020 to January 2022. Together, these results show that joint inversion of GNSS and GRACE/GFO observations provides observation-based constraints on integrated TWS for interpreting storage adjustment, state-dependent storage memory and major hydrological extremes in humid coastal monsoon regions, beyond what can be inferred from meteorological indicators or model-based analyses alone.