EOS

Source: Journal of Geophysical Research: Planets

Like Earth, Mars is surrounded by an ionosphere—the part of its upper atmosphere where radiation from the Sun knocks electrons off of atoms and molecules, creating charged particles. The Martian ionosphere is complex and continuously changes over the course of the day, but its role in atmospheric dynamics and radio communication signals means understanding it is key for Mars exploration.

One way to study the Martian ionosphere is with radio occultation, in which a spacecraft orbiting Mars sends a radio signal to a receiver on Earth. When it skims across the Martian ionosphere, the signal bends slightly. Researchers can measure this refraction to learn about Martian ionospheric properties such as electron density and temperature. However, the relative positions of Mars, Earth, and the Sun mean conventional radio occultation cannot measure the middle of the Martian day.

Now, Parrot et al. deepen our understanding of the Martian ionosphere using an approach called mutual radio occultation, in which the radio signal is sent not from an orbiter to Earth but between two Mars orbiters. As one orbiter rises or sets behind Mars from the other’s perspective, the signal passes through the ionosphere and refracts according to the ionosphere’s properties.

The researchers analyzed 71 mutual radio occultation measurements between two European Space Agency satellites orbiting Mars: Mars Express and the ExoMars Trace Gas Orbiter. Thirty-five of these measurements were taken closer to midday than was ever previously achievable, in effect allowing scientists to see a new part of the Martian ionosphere.

The new data enabled the research team to calculate how the ionosphere’s electron density changes throughout the day. They were also able to learn more about how the altitudes of the upper and lower layers of the ionosphere—called M2 and M1, respectively—vary daily. The new data suggest that the peak electron density of the M2 layer changes less dramatically during the day than has been suggested by prior research. The data also show that the M1 does, indeed, still exist during the midday, contradicting previous assumptions.

The researchers also used the new data to calculate ionospheric temperatures. They found that instead of being hottest at midday, temperatures in the ionosphere rise as the Sun reaches Martian sunset. Simulations using a Mars climate model suggest that it is likely winds transporting air, rather than the Sun’s direct heat, that control these temperature dynamics. (Journal of Geophysical Research: Planets, https://doi.org/10.1029/2024JE008854, 2025)

—Sarah Stanley, Science Writer

Citation: Stanley, S. (2025), Orbiter pair expands view of Martian ionosphere, Eos, 106, https://doi.org/10.1029/2025EO250228. Published on 20 June 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.

Coral reefs are vital ecosystems supporting marine life, ecotourism, and coastal protection. They also hold something valuable under their surface: records of the ocean’s past. Beneath the living outer layer of massive corals are dense, rocklike skeletal structures containing annual bands, similar to tree rings. Scientists can study the conditions at the time these bands formed by drilling, retrieving, and analyzing cores, some of which represent centuries of coral growth.

Daren Coker (left) and Thomas DeCarlo drill for a coral core in the Red Sea. Credit: Morgan Bennett-Smith

Since the 1970s, studies of coral cores to determine past growth patterns, a field known as coral sclerochronology, have produced notable scientific discoveries. Knutson et al. [1972] found that annual bands comprise alternating high- and low-density bands that reflect seasonal growth patterns. Hudson [1981] found that typically, high-density bands form during slower winter growth and low-density bands form during faster summer growth and that long-term coral growth variations are influenced by water quality and the effects of coastal development. Some cores also contain high-density “stress bands” formed because of coral bleaching events or other environmental challenges [Lough, 2008]. Together, this banding provides insights into coral growth history, enabling scientists to construct reliable age models of past oceanic and climatic conditions.

Today, methods used to investigate coral cores have advanced considerably. Alongside other methods such as stable isotope and elemental ratio analyses, computed tomography (CT) scanning plays a major role in yielding data that help to reveal coral growth parameters. Scientists can use 2D X-ray and 3D CT scanning to examine the internal structure of coral cores, including their annual density bands [Knutson et al., 1972; Hudson, 1981; Lough, 2008; DeCarlo et al., 2025]. In some cases, such analysis even involves a scientist visiting a local hospital to use its CT machine—an unexpected patient for the radiology technician.

This animation of a CT scan shows a cross section of a coral core. The small circles within the core are corallites, the individual skeletal structures formed by coral polyps. Credit: USGS, Public Domain A coral core sits on the exam table of a CT machine at a hospital before being scanned. Credit: Thomas DeCarlo

However, there has been no systematic archiving of coral core imagery data, partly because of the lack of a suitable repository. This gap presents risks of losing valuable images and prevents streamlined, transparent sharing of scientific interpretations from these images. Therefore, a centralized, virtual, open-access repository of coral core imagery is crucial for fostering transparent science and preserving these resources for future research.

An App for Organizing an Archive

The CoralCT application was developed to consolidate and organize coral core scans in a virtual repository that enables digital archiving and image analysis [DeCarlo et al., 2025]. The repository currently contains scans of more than 1,000 cores collected from a wide range of coral reef regions, including the Great Barrier Reef, the Caribbean, and the Red Sea. These core scans have been contributed by individuals and agencies, including the U.S. Geological Survey (USGS) and NOAA.

Coral researchers upload X-ray or CT scans to CoralCT and, when they are ready, can make their data publicly available to anyone with a computer and internet connection. This approach to transparency fosters collaborations among coral core researchers, who can view the app’s core directory and see who else has collected cores from their areas of interest. It also helps avoid unnecessary duplication of research efforts, which is especially important given the need to reduce sampling impacts on corals, many of which are endangered species.

Using the application’s analytical tools, observers can map annual density bands in coral cores to extract data on growth rates and skeletal density. As in tree ring studies, this sort of analysis offers insights into past environmental conditions because coral growth can respond sensitively to climate variability.

For example, Barkley et al. [2018] used CoralCT to visualize high-density stress bands and reconstruct the history of coral bleaching over 6 decades on a remote reef in the equatorial Pacific Ocean where monitoring data were sparse. Rodgers et al. [2021] measured annual growth rates in CoralCT to track the recovery of corals off Kaua‘i, Hawaii, in the 15 years after a damaging flood event. More recently, DeCarlo et al. [2024] leveraged the breadth of cores in CoralCT to reconstruct coral growth trends over recent decades to centuries across thousands of kilometers of the Indo-Pacific.

Rescuing Old Records and Gathering New Ones

Archiving valuable data that might otherwise be lost is a foundational purpose of CoralCT. A standout example of how it’s serving this purpose involves the rescue and digitization of X-ray images of more than 20 cores collected across the Pacific Ocean between the 1980s and early 2000s. The X-ray films, previously stored by a retiring scientist, are now archived and available for analysis on CoralCT.

Older collections like these can provide valuable insights into coral growth before environmental disturbances, such as mass bleaching from heat stress, began to affect them.

In a similar effort, USGS recently CT scanned coral cores dating back to the late 1960s, some of the earliest cores ever collected [Hudson et al., 1976]. These scans are being added to the repository so they can be reanalyzed by researchers now and into the future. Older collections like these can provide valuable insights into coral growth before environmental disturbances, such as mass bleaching from heat stress, began to affect them.

Alongside these historical contributions, CoralCT’s repository continues to grow with the addition of new data. One such recent contribution includes scans of reef cores collected from offshore Hawai‘i in 2023 during the International Ocean Discovery Program’s Expedition 389. Reef cores differ from coral cores in composition and structure but are also critical for understanding ocean history and environmental change. During Expedition 389, cores were collected from drowned reefs that once grew near the ocean surface but stopped calcifying as they were submerged in deeper water. These reef cores contain fragmented coral, coralline algae, microbialites, and other reef-building materials whose compositions enable scientists to look millennia into the past and uncover valuable records of sea level and climate change.

Repeatable Analyses, Verifiable Results

When raw, unprocessed coral core images are not archived, the value of growth measurements and other analyses is limited because other scientists cannot readily and independently verify them. This is problematic because science fundamentally relies on the ability to repeat experiments and verify results, especially considering individual researchers can introduce subjectivity and potential biases into even highly systematic and rigorous interpretations of data. As datasets grow larger, more intricate, and more numerous, maintaining transparency is increasingly important but also increasingly difficult.

In this screenshot of a coral core being analyzed in the CoralCT application, the orange lines on the core image indicate where an observer has mapped the annual density bands. Credit: Avi Strange

CoralCT addresses these challenges by ensuring that all information and context about a core is fully documented, accessible, and downloadable. This information includes essential metadata such as the core’s origin, ownership details, collection date, depth, and species identifications. Most important, CoralCT archives the user-defined maps of annual banding used to derive growth rate data [DeCarlo et al., 2025], ensuring that these data and interpretations are fully reproducible and open to verification by others.

This transparency is also shared among observers within the application. When a user is mapping the bands of a core, they can add notes and screenshots that other users can view when they’re analyzing that core. Furthermore, when a user finishes mapping the bands of a core and processes the data, this information is saved and made downloadable for other scientists to view. This ability enables scientists to conduct multiobserver studies, which can reduce potential biases introduced by individual observation.

A challenge encountered in our efforts to broaden CoralCT has been the hesitancy of some researchers and programs to share data.

Despite these advantages, a challenge encountered in our efforts to broaden CoralCT has been the hesitancy of some researchers and programs to share data because of concerns about intellectual property infringements and the “scooping” of prepublication data. This hesitancy, which is understandable considering the lack of transparency and protections for data owners in prior data management practices, can unfortunately limit scientific advancements and collaborations that might help address climate change, coral reef degradation, and other complex challenges.

To address these concerns, CoralCT offers privacy controls to core owners that they can use to restrict access to their scans and the derived output data. These controls are particularly useful when cores are part of ongoing research that has not yet been published or are subject to a postcruise moratorium, ensuring that sensitive data remain protected until the research is ready to be shared. In addition, each core is tagged with a data owner, acknowledgments, and relevant citations.

Advancing Accessibility and Collaboration

CoralCT also represents a path to making science more inclusive and accessible. The application is designed with an easy-to-use interface and includes resources such as video tutorials and a step-by-step user guide to help introduce its features to a wide audience. K–12 lesson plans that guide students through mapping coral core bands in the app were also recently created, offering approachable ways to explore marine science.

A middle school student visiting the Sclerochronology Lab at Tulane University uses a virtual reality headset to interact with coral cores in 3D during the university’s 2025 Boys at Tulane in STEM event. Credit: Danielle Scanlon Middle school students learn about coral cores from a hologram at a workshop at Hawai‘i Pacific University. Credit: Thomas DeCarlo

The app’s educational potential was demonstrated during recent outreach events. Using virtual reality technology, middle school students in New Orleans viewed 3D coral core scans from CoralCT and practiced identifying annual density bands. At a similar event, sixth grade students in Hawaii interacted with 3D holographic coral cores, learning how scientists retrieve and study them to understand growth patterns over time. The positive experiences of students and teachers during these events demonstrated how CoralCT provides an opportunity to engage hands-on with real scientific data.

Integration of AI could also, importantly, make it easier for all users to contribute to coral core analysis, regardless of their academic background or field experience.

Looking forward, there is potential to integrate artificial intelligence (AI) into CoralCT for automated identification of coral banding patterns. If an AI system were trained on existing human interpretations, it could automatically suggest band markings that users could review and verify. This advancement offers the potential for more accurate and efficient coral core analyses while maintaining human oversight. Integration of AI could also, importantly, make it easier for all users to contribute to coral core analysis, regardless of their academic background or field experience. Each new contribution or analysis of a core enhances the CoralCT database and extends our knowledge of coral reefs and past ocean conditions.

Coral sclerochronology is vital for understanding environmental changes in coral reef ecosystems and the impacts these changes have wrought. Through this research, we gain insights into the ocean’s past and advance our understanding of coral reefs today. As threats to reefs intensify, large open-access datasets are increasingly essential for monitoring reef health and predicting future impacts.

CoralCT thus plays an important role in preserving valuable records of coral growth and environmental history while promoting collaborative, accessible, and transparent data sharing. In making coral reef science available to researchers and the public alike, it is connecting data, ideas, and people to address critical questions about our changing world.

Acknowledgments

CoralCT was developed with support from National Science Foundation award OCE-2444864. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. government. We thank the IODP 389 Expedition Science Party, ECORD Science Operator (ESO) support staff, benthic drilling team, MMA surveyors, and the captain and crew of the MMA Valour. International Ocean Discovery Program (IODP) Expedition 389 was supported by funding from the various national funding agencies of the participating IODP countries. We also thank all data contributors to date, including Giulia Braz, Jessica Carilli, Leticia Cavole, Ben Chomitz, Travis Courtney, Ian Enochs, Thomas Felis, Ke Lin, Malcolm McCulloch, Haojia Ren, Riccardo Rodolfo-Metalpa, Natan Pereira, and the U.S. Geological Survey Coastal and Marine Hazards Resources Program.

References

Barkley, H. C., et al. (2018), Repeat bleaching of a central Pacific coral reef over the past six decades (1960–2016), Commun. Biol., 1, 177, https://doi.org/10.1038/s42003-018-0183-7.

DeCarlo, T. M., et al. (2024), Calcification trends in long-lived corals across the Indo-Pacific during the industrial era, Commun. Earth Environ., 5, 756, https://doi.org/10.1038/s43247-024-01904-8.

DeCarlo, T. M., et al. (2025), CoralCT: A platform for transparent and collaborative analyses of growth parameters in coral skeletal cores, Limnol. Oceanogr. Methods, 23(2), 97–116, https://doi.org/10.1002/lom3.10661.

Hudson, J. H. (1981), Growth rates in Montastraea annularis: A record of environmental change in Key Largo Coral Reef Marine Sanctuary, Florida, Bull. Mar. Sci., 31(2), 444–459, www.ingentaconnect.com/content/umrsmas/bullmar/1981/00000031/00000002/art00014.

Hudson, J. H., et al. (1976), Sclerochronology: A tool for interpreting past environments, Geology, 4(6), 361–364, https://doi.org/10.1130/0091-7613(1976)4<361:SATFIP>2.0.CO;2.

Knutson, D. W., et al. (1972), Coral chronometers: Seasonal growth bands in reef corals, Science, 177(4045), 270–272, https://doi.org/10.1126/science.177.4045.270.

Lough, J. M. (2008), Coral calcification from skeletal records revisited, Mar. Ecol. Prog. Ser., 373, 257–264, https://doi.org/10.3354/meps07398.

Rodgers, K. S., et al. (2021), Rebounds, regresses, and recovery: A 15-year study of the coral reef community at Pila‘a, Kaua‘i after decades of natural and anthropogenic stress events, Mar. Pollut. Bull., 171, 112306, https://doi.org/10.1016/j.marpolbul.2021.112306.

Author Information

Avi Strange and Oliwia Jasnos, Tulane University, New Orleans, La.; Lauren T. Toth, St. Petersburg Coastal and Marine Science Center, U.S. Geological Survey, Fla.; Nancy G. Prouty, Pacific Coastal and Marine Science Center, U.S. Geological Survey, Santa Cruz, Calif.; and Thomas M. DeCarlo (tdecarlo@tulane.edu), Tulane University, New Orleans, La.

Citation: Strange, A., O. Jasnos, L. T. Toth, N. G. Prouty, and T. M. DeCarlo (2025), A coral core archive designed for transparency and accessibility, Eos, 106, https://doi.org/10.1029/2025EO250226. Published on 20 June 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.

A community in China had a narrow escape when a landslide, triggered by Typhoon Wutip, occurred on the slopes above the village. Fortunately, the population had been evacuated when a local woman noted signs that a failure might be imminent.

At about 4 am on 15 June 2025, rainfall associated with the remnants of Typhoon Wutip triggered a landslide at Zhonghe village in western Guangdong province in China. At present I am unable to give a precise location for this event, which is listed in the Chinese media as having occurred at Lian’er Natural Village, Zhonghe village, located in Guizi Town, Xinyi City, Maoming. Guizi town is located at [22.6397, 111.1113], so it is in this general area.

China Daily has a photographic feature on this landslide, which includes this image:-

The 15 June 2025 landslide at Zhonghe village in western Guangdong province, China. Image via China Daily.

There is also a view from the crown of the failure looking along the landslide track:-

View from the crown of the 15 June 2025 landslide at Zhonghe village in western Guangdong province, China. Image via China Daily.

This failure affected 25 households and 57 people, but all were evacuated in the hours prior to the event (see below). The landslide itself appears to have been a large, shallow failure that has channelised before striking the village. Note also at least two other shallow failures in the same area – these landslides are characteristic of landslides triggered by very high rainfall intensities that drive saturation and a loss of suction forces.

It is fortunate that the material involved in the failure was comparatively fine-grained, which has meant that the damage to the village appears to be modest. XKB has this image of the aftermath of the landslide:-

The aftermath of the 15 June 2025 landslide at Zhonghe village in western Guangdong province, China. Image via XKB.

There is an article in nfnews (in Mandarin) that describes the sequence of events that led to the evacuation of the community. The key person is Liu Mingfang, a member of the Zhonghe Village Committee. This is a description of the events (using Google Translate):-

In the rain, her vision was blurred, and Liu Mingfang used a flashlight to patrol along the muddy village road. At 0:42 on the 15th, she suddenly discovered: “Why is this water yellow and muddy, and it still carries sediment?”

Red flags! She immediately dialed the phone number of Cao Musheng, the village party secretary: “Secretary, there is an abnormality in the water, something may happen!” ”

In less than 5 minutes, Liu Chunhua and Cao Musheng, deputy mayors of the village, arrived at the scene. After research and judgment, Liu Chunhua decisively reported to the town’s three prevention offices and received instructions: transfer immediately!

At 0:58, a total of 10 village cadres and village cadres rushed from all directions to the entrance of Lian’er Natural Village. Immediately afterwards, the sound of gongs, knocks on the door, and shouts instantly tore apart the rainy night.

The entire community was relocated before the slope failed.

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.

Boreal peatlands in Canada provide crucial ecosystem services, from flood mitigation and water purification to storing colossal amounts of carbon and providing a habitat for species such as caribou.

Over the past several decades, more than 36,000 hectares of well pads have been constructed to house oil and gas drilling platforms in these landscapes, destroying the underlying vegetation and disrupting the flow of water through the ground.

“We want to get as close to the original state as is possible and realistic.”

Once drilling operations are finished, operators are required to return pads to a state similar to that before construction. Though restoration efforts have historically focused on tree planting, reintroducing the right mosses is crucial for restoring functional peatlands. A study in Ecological Engineering outlines a new approach to reintroduce these keystone plant species, tested for the first time at the scale of a full well pad in Alberta, Canada.

“We want to get as close to the original state as is possible and realistic, given the very long time scales that peatlands develop over,” said Murdoch McKinnon, a graduate student at the University of Waterloo and lead author of the study.

The challenge is providing the right hydrological conditions for mosses to thrive.

Removing Fill

Well pads are constructed by heaping crushed mineral fill onto a section of peat to create a harder level surface.

Traditionally, researchers in the region have reintroduced moss by first completely removing the fill, which lowers the surface so that it is closer to the water table. In some cases, they would bury some of the fill under the newly exposed peat, a technique referred to as inversion.

This process has been successful in establishing the Sphagnum mosses typical of bogs, which have acidic soil that is low in nutrients. It’s been less successful in reintroducing the Bryopsida mosses characteristic of fens, the nutrient-rich wetlands that make up almost two thirds of peatlands in Canada’s Western Boreal Plain.

“I think it’s a good approach, but maybe the surface of the pad was not low enough to have flowing water, which you need in a fen.”

To reestablish a moss community that could eventually turn into a fen, the team left some of the fill on the surface, which provided the minerals that Bryopsida mosses rely on for growth. The team then roughed up the surface with an excavator to create different microsites, which promotes species diversity.

After introducing mosses from a nearby donor fen and closely monitoring the site for two growing seasons, researchers found that conditions for the reestablishment of Bryopsida mosses were best when the water table was within 6 centimeters (2 inches) of the surface. That was often the case along the edges of the pad that received water from the adjacent peatland, whereas the mosses in the interior of the pad struggled with drier conditions.

“I think it’s a good approach, but maybe the surface of the pad was not low enough to have flowing water, which you need in a fen,” said Line Rochefort, an expert in peatland restoration at Université Laval in Quebec who was not involved in the study.

“Without addressing that, it’s hard to introduce and establish peatland vegetation on mineral substrate,” said Bin Xu, a peatland ecologist at the Northern Alberta Institute of Technology (NAIT) who worked on the project. “On the flip side, when you do have good hydrobiological conditions, it’s really easy to support peat-forming vegetation, which is encouraging.”

A well pad located near the town of Slave Lake, Alberta, was still brown immediately after researchers introduced the moss, before it started to become established. Credit: University of Waterloo

An important takeaway from the study is the importance of decompacting the surface by roughing it up to allow for not only hydrological flow across the pad but also the natural vertical fluctuation of the water table, Xu said.

He and colleagues at NAIT have now applied these lessons to three additional well pads in Alberta, and industry experts have used a similar approach on around a dozen more, Xu said. “Through informing policy and sharing the learnings with industry, we can together address the need to reclaim well pads built in peatland across the province.”

—Kaja Šeruga, Science Writer

Citation: Šeruga, K. (2025), Surface conditions affect how mosses take to former well pads in Canada’s boreal fens, Eos, 106, https://doi.org/10.1029/2025EO250227. Published on 18 June 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: Journal of Geophysical Research: Oceans

Submarine canyons around Antarctica tend to have less sea ice, higher sea surface temperatures, and more biomass such as phytoplankton blooms than the shelves they cut into. Phytoplankton blooms feed Antarctic krill, making these canyons an attractive feeding ground for larger predators such as penguins, who make permanent homes for foraging and breeding on the shores surrounding submarine canyons.

Previous studies suggested that, as on a farm, the phytoplankton blooms that attract predators were locally grown, supported by the upwelling of nutrient-rich water. But newer research shows that water moves through the canyon more quickly than phytoplankton can accumulate, so it is likely that currents transport most of the surface biomass into the canyon from other parts of the ocean. Canyons therefore act more like biomass supermarkets, to which food is delivered, than like farms.

McKee et al. examined to what degree phytoplankton grow locally in Palmer Deep canyon on the western Antarctic Peninsula versus being transported in by ocean currents. To do so, they used high-frequency radar to measure ocean currents and satellite imagery taken hours to days apart to measure levels of surface chlorophyll, a proxy for phytoplankton.

The results showed that both processes were occurring. Ocean currents appeared to bring in much of the phytoplankton that flowed on the western side of the canyon, making it more like a supermarket, the researchers write. In contrast, more phytoplankton seem to be growing in place on the eastern flank, making it more like a farm.

The authors also examined how the movement of water correlated to plankton growth, by tracking chlorophyll levels in moving parcels of water. In general, they found that water parcels that saw an increase in phytoplankton levels as they moved through the canyon tended to exhibit more clockwise motion, whereas parcels that saw decreasing phytoplankton levels showed more counterclockwise rotation. (Journal of Geophysical Research: Oceans, https://doi.org/10.1029/2024JC022101, 2025)

—Rebecca Owen (@beccapox.bsky.social), Science Writer

Citation: Owen, R. (2025), Where do Antarctic submarine canyons get their marine life?, Eos, 106, https://doi.org/10.1029/2025EO250224. Published on 18 June 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.

Derek Cronmiller of the Yukon Geological Survey has provided a stunning set of the images of the fascinating recent failure that partially blocked the Yukon River.

Following my post yesterday about the May 2025 landslide on the Yukon River, Derek Cronmiller, who is head of Surficial Geology at the Yukon Geological Survey kindly made contact to provide further information about this most interesting failure. He has also provided an amazing set of images of the landslide.

Derek noted the following about the landslide:-

“The slide is a 9 km above Lake Laberge and happed sometime between May 14th and 18th as constrained by Sentinel imagery and river user reports.“

“The slide is 950 m wide and up to 250m long from crown to toe. It blocked ~ 45% of the active channel which is no small feat on the Yukon River! The material is finely bedded glaciolacustrine silt and clay at river level (and below) grading up to massive medium to coarse sand at the top of the main scarp with variable thickness of aeolian dune cover at the surface.  Perhaps the most interesting part of the slide is that the rupture surface daylighted somewhere in the river and thrust river bottom sediments (and vegetation) several metres above the river level. There are some great spreading structures on the slide reminiscent of sensitive clay slides in Quebec. We observed seeps daylighting at the bottom of the adjacent slopes just above river level at the transition from sands to silt and clay. Slides have occurred here in the past but an order of magnitude smaller.”

And so to the images. This image shows the landslide from a drone, looking from the crown towards the river:-

The May 2025 Yukon River landslide, viewed from a drone. Image copyright the Yukon Geological Survey, used with permission.

The very beautiful morphology of this landslide is visible with rows of back-tilted trees, with upright trees in between. Note also the uplifted toe of the landslide, including river gravels.

Let’s take a look at the toe – here is the uplifted portion, located almost half way across the former channel. The scale of the uplift here is really impressive:-

The uplifted toe of the May 2025 Yukon River landslide. Image copyright the Yukon Geological Survey, used with permission.

For those who are unfamilar with rational landslides, and who may be wondering how this is possible, I provided a sketch of this mechanism back in 2013 at the time of the Hatfield Stainforth landslide:-

Sketch of the rotational landslide mechanism of the 2013 Hatfield Stainforth landslide. The Yukon River landslide had a similar mechanism.

This rotational generates some complex structures in the landslide, including horst and graben phenomenon:-

Horst and graben structures in the toe of the May 2025 Yukon River landslide. Image copyright the Yukon Geological Survey, used with permission.

And this image shows the uplifted river gravels in more detail:-

Uplifted river gravels in the toe of the May 2025 Yukon River landslide. Image copyright the Yukon Geological Survey, used with permission.

Moving up into the main body of the landslide, there are some extremely impressive back-tilted blocks:-

Back-tilted blocks in the May 2025 Yukon River landslide. Image copyright the Yukon Geological Survey, used with permission.

And also some horst and graben structures:-

Back-tilted trees in the May 2025 Yukon River landslide. Image copyright the Yukon Geological Survey, used with permission.

Finally, there are areas of seepage as Derek noted above, which probably gives an indication of one of the drivers of this landslide:-

Seepage in the May 2025 Yukon River landslide. Image copyright the Yukon Geological Survey, used with permission.

This is a really interesting landslide – in many ways, a textbook example of a complex rotational failure. If I was still teaching, I would use this landslide to illustrate the mechanisms of rotational landslides.

Many thanks to Derek Cronmiller and his colleagues at the Yukon Geological Survey for providing these amazing images and the detailed commentary. I hope that they will write the landslide up for publication in due course.

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.

Source: Radio Science

Between 50 and 1,000 kilometers above our heads is the ionosphere, a layer of Earth’s upper atmosphere consisting of charged particles: ions (atoms that have gained or lost a negatively charged electron) and loose electrons. The ionosphere alters the path of electromagnetic waves that reach it, including radio and GPS signals, so studying it is helpful for understanding communication and navigation systems.

One way to study the ionosphere is to “nudge” it with powerful radio waves sent from the ground to see how it reacts. Where the waves hit the ionosphere, they temporarily heat it, changing the density of charged particles into irregular patterns that can be detected from the way they scatter radio signals. By studying these irregularities, known as artificial periodic inhomogeneities (APIs), scientists can learn more about the ionosphere’s composition and behavior.

However, factors such as space weather and solar activity can inhibit both the formation and detection of APIs. La Rosa and Hysell sought to enhance the reliability and utility of the API research technique by examining API formation in all three main regions of the ionosphere, the D, E, and F regions. Past techniques focused only on API formation in the E region.

To do so, the researchers revisited data from research conducted in April 2014 at the High-frequency Active Auroral Research Program (HAARP) facility in Alaska. HAARP’s radio transmitters created small perturbations in the ionosphere, and the facility’s receivers captured the resulting scattered radio signals.

Initial analysis of the 2014 data revealed some APIs in the E region, but this team of researchers reprocessed the data at higher resolution. This reanalysis allowed them to document, for the first time, simultaneous APIs across all three regions, all triggered by a single radio nudge.

API formation in each of the three regions is dictated by a different set of mechanisms, including chemical interactions, heating effects, and forces that change the density of charged particles; this variability has made it difficult to develop a stand-alone model of API formation across the ionosphere.

To address that challenge, the researchers extended a model previously created to capture API formation in the E region by incorporating the relevant mechanisms for the D and F regions. In simulation tests, the model successfully reproduced the behavior observed in all three regions. This model could help deepen understanding of the physics at play in the ionosphere. (Radio Science, https://doi.org/10.1029/2025RS008226, 2025)

—Sarah Stanley, Science Writer

Citation: Stanley, S. (2025), Nudging Earth’s ionosphere helps us learn more about it, Eos, 106, https://doi.org/10.1029/2025EO250222. Published on 17 June 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.

Editors’ Highlights are summaries of recent papers by AGU’s journal editors. Source: Geochemistry, Geophysics, Geosystems

Geologists are responding to increasing demand for a variety of rare metals by focusing attention on the origins of high silica leucogranites that often host high concentrations of valuable metals such as niobium (Nb), tantalum (Ta), zirconium (Zr), hafnium (Hf), tin (Sn), and lanthanides. Many of these rocks have anomalous trace-element signatures (distinctively low ratios of Zr/Hf, Nb/Ta, and europium (Eu)/(gadolinium (Gd) + samarium (Sm)) that have long been thought to indicate extensive fractional crystallization or interaction with large volumes of fluid. They may also have unradiogenic Hf isotope ratios suggestive of input from depleted mantle sources despite their presence in thick crustal orogenic belts.

Huang et al. [2025] contribute measurements of the stable isotope ratio of boron (B) and the radiogenic neodymium (Nd) system from a belt of Paleozoic leucogranites in the Qilian orogenic belt in central China. The results show decoupling of Nd and Hf isotope signatures, not consistent with simple crust/mantle mixing, but correlation of Hf and B isotope signatures with trace element ratios that fingerprint mixing of various sedimentary rocks in the sources of the granites. The authors conclude that these are pure S-type (sediment-derived) magmas, whose budget of valuable metals was scavenged from the Paleozoic crust rather than concentrated by extreme fractionation of mantle-derived magma, overturning the common interpretation based on Hf isotope data alone. 

Citation: Huang, H., Niu, Y., Romer, R. L., Zhang, Y., He, M., & Li, W. (2025). High silica leucogranites result from sedimentary rock melting—Evidence from trace elements and Nd-Hf-B isotopes. Geochemistry, Geophysics, Geosystems, 26, e2024GC012024. https://doi.org/10.1029/2024GC012024

—Paul Asimow, Editor, G-Cubed

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.

In May 2025, a 950 m wide landslide occurred on the banks of the Yukon River in Canada.

A few days ago, the Yukon Geological Survey posted some information to its Facebook site regarding a large landslide that has occurred on the banks of the Yukon River close to Burma Road. This was the information that they posted:-

GS staff visited the landslide on the east bank of the Yukon River near Burma Road on June 4th. The landslide is 950 m wide, up to 250 m long and approximately 20 ha in area.

Based on satellite imagery and river user reports, the slide occurred between May 14–18. It’s a compound landslide of clay, silt & sand from Glacial Lake Laberge sediments deposited at the end of the last glaciation. The slide moved through translation, rotational sliding and spreading.

The slide extended below the riverbed, thrusting sediments and vegetation several metres above river level—creating spectacular classic landslide landforms.

The photo is an oblique view of slide looking north. Several minor scarps can be seen in front of the main headscarp.

And this is the rather amazing image of the landslide:-

The May 2025 landslide on the Burma River in Yukon. Image posted to Facebook by the Yukon Geological Survey.

The location of this landslide is [60.89369, -135.13024]. This is a Planet Labs image from 11 May 2025 showing the site of the failure:-

Satellite image of the site of the May 2025 landslide on the Yukon River. Image copyright Planet Labs, collected on 11 May 2025.

I have placed a white target marker on the site of the rear scarp of the landslide. This is an image after the failure:-

Satellite image of the aftermath of the May 2025 landslide on the Yukon River. Image copyright Planet Labs, collected on 5 June 2025.

And here is a slider to compare the two images:-

Images Copyright Planet Labs, used with permission.

Whilst the river has been narrowed significantly by this landslide, it is likely to be eroded away quite quickly given the fine grained materials involved. Landslides of this type are part of the functioning of the natural system, providing the mechanism through which the river can meander across the plain.

Reference and acknowledgement

Thanks to loyal reader Maurice Lamontagne for highlighting this landslide to me.

Planet Team 2025. Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://www.planet.com/

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.

Canada is home to more than 400,000 nonproducing oil and gas wells. These abandoned facilities still emit methane, which can contaminate water supplies and pollute the atmosphere with a greenhouse gas more potent than carbon dioxide. The scope of these emissions may be greater than previously understood, according to a new study.

“There’s a range of engineering, geological, and policy-related factors that are all playing a role in what emissions rates are observed.”

In 2023, nonproducing wells may have leaked 230 kilotons of methane, about 7 times more than the official estimates published in the government’s annual National Inventory Report (NIR). The NIR, compiled by Environment and Climate Change Canada (ECCC), informs the country’s greenhouse gas mitigation efforts and is submitted as part of Canada’s reporting obligations to the United Nations Framework Convention on Climate Change.

Methane estimates are calculated by multiplying the total number of nonproducing wells by emissions factors determined by well characteristics, such as the type of well (oil, gas, or unknown), depth, and whether it is plugged with concrete. These emissions factors offer only a rough idea of methane leakage, however.

“It’s really hard to predict emissions,” said Mary Kang, a study coauthor and associate professor of civil engineering at McGill University in Montreal. “There’s a range of engineering, geological, and policy-related factors that are all playing a role in what emissions rates are observed.”

Surprising Discoveries

To address this ambiguity, Kang and her colleagues measured methane flow rates at 494 nonproducing wells throughout Canada between 2018 and 2023 to define new emissions factors. While these sites account for only a fraction of the country’s abandoned wells, making uncertainty inevitable, the authors describe their data as the largest set of direct methane emissions figures collected through consistent methods.

They reported that the amount of methane leaked from the nonproducing wells was 1.5–16 times greater than NIR estimates.

Most of the departure from the NIR figures was driven by leaks from surface casing vents, narrow slits that ring the outermost steel layer surrounding the wellbore itself. Kang explained that emissions from surface casing vents indicate issues with a mine’s structural integrity and are trickier to manage than wellhead leaks, which may require only minor adjustments at the surface.

“The geology doesn’t care if you’re in one province or another….So what’s going on?”

The researchers analyzed their measurements to gauge how different well attributes contribute to methane flow rates. Whether a well is more prone to leakage than others, they found, isn’t determined by a single emissions factor such as its age or operating company.

Still, Kang was surprised to discover how much flow rates varied by province, even between wells operated by the same company in similar locations. The highest rates were observed in Alberta, where 74% of Canada’s known nonproducing wells are located.

“The geology doesn’t care if you’re in one province or another,” she said. “It’s the same formation. So what’s going on?”

Kang noted that each province and territory has its own emissions regulations, and policy factors might explain the differences in methane flow rates, though other geological differences such as seismic activity could also be at play.

Continuous Improvement

Complicating any study of methane emissions from nonproducing wells is the large number of sites abandoned before contemporary recordkeeping practices were established, said Maurice Dusseault, professor emeritus of engineering geology at the University of Waterloo in Ontario, who was not involved in the research.

A history of well abandonment practices in Ontario illustrates how hard it is to identify older wells throughout Canada. The first oil well in Ontario was drilled in 1858, but records were not mandatory in the province for another 60 years. Surface casings were often removed when a well closed so that the steel could be reused in other mines. This means some legacy wells cannot be detected with conventional magnetic techniques.

Still, Dusseault praised the researchers for their rigorous pursuit of better emissions estimates.

Kang and her colleagues returned to the field this year and last year, measuring methane flow at additional known well sites and revisiting previous sites to observe how leakage changes over time.

Meanwhile, their work is already affecting how the country approaches methane emissions. “Continuous improvement is a key principle of Canada’s NIR,” wrote ECCC spokesperson Cecelia Parsons in an email, noting that the improvement plan in the 2025 NIR draws from the new research.

—Lauren Schneider (@laur_insider), Science Writer

Citation: Schneider, L. (2025), Nonproducing oil wells may be emitting 7 times more methane than we thought, Eos, 106, https://doi.org/10.1029/2025EO250225. Published on 16 June 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.

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

During explosive eruptions, tephra particles are injected into the atmosphere and undergo different fates: while larger particles settle close to the volcano, smaller ones remain suspended, forming volcanic clouds. In all cases, tephra poses significant hazards to human activities both near the volcano and hundreds of kilometers away.

A new article in Reviews of Geophysics explores our current understanding of tephra plumes and clouds, including their generation, characteristics, and monitoring strategies. Here, we asked the lead author to give an overview of tephra plumes, recent advances in modeling them, and what questions remain.

How does tephra form and spread?

Tephra forms through a process called fragmentation within volcanic conduits and is then expelled into the atmosphere by volcanic plumes. These fragments are classified based on their size: blocks and bombs (greater than 16 mm in diameter), lapilli (ranging from 2 mm to 16 mm), and ash (less than 2 mm in diameter). Once airborne, larger tephra particles typically settle near the volcanic vent, while finer particles (ash) can be carried by the wind over vast distances, forming what are known as volcanic clouds.

What kinds of hazards does tephra pose both in the air and on the ground?

Volcanic clouds pose a significant threat to aviation safety. When aircraft encounter these clouds, tephra particles can be ingested by jet engines, leading to performance degradation and, in severe cases, catastrophic engine failure. In addition, airborne tephra poses serious risks to public health. Studies on populations exposed to volcanic ash have documented increases in both acute and chronic respiratory conditions. The most dangerous particles are those smaller than 4 micrometers in diameter as they can penetrate deep into the lungs’ alveolar region, potentially triggering toxic reactions.

Tephra fallout can cause extensive damage to critical infrastructure, leading to substantial economic losses across multiple sectors.

On the ground, tephra fallout can cause extensive damage to critical infrastructure, leading to substantial economic losses across multiple sectors. These include energy systems, water and wastewater services, transportation networks (aviation, land, and maritime), food and agriculture, manufacturing, and communications. Rural communities, particularly those reliant on agriculture and livestock, are especially vulnerable. Tephra fallout can disrupt livelihoods not only in the immediate aftermath of an eruption but also over the long term. This is because tephra deposits can be remobilized by wind, generating ash storms that resemble the effects of the original eruption. These recurring events can persist for years, hindering economic recovery and prolonging hardship for affected communities.

What factors influence how far tephra spreads?

Tephra can be dispersed over vast distances, and in some cases, it may even travel around the globe. The extent of tephra dispersal is influenced by several factors, including the magnitude of the eruption, the size of the tephra particles (with smaller fragments remaining suspended in the atmosphere for longer periods), the volcano’s geographic location, and atmospheric conditions (particularly wind strength and direction). For example, the 1991 eruption of Mount Pinatubo in the Philippines, one of the major eruptions of the 20th century, injected massive amounts of volcanic ash into the stratosphere, which were carried by high-altitude winds and circled the globe in just 22 days.

Even relatively small eruptions can have major impacts when atmospheric and geographic conditions are unfavorable.

Similarly, the 2010 eruption of Eyjafjallajökull in Iceland, although moderate in size, caused significant disruption to European air travel. The fine-grained ash particles were carried thousands of kilometers by the jet stream, grounding flights across much of Europe for several days. This highlights how even relatively small eruptions can have major impacts when atmospheric and geographic conditions are unfavorable.

How do scientists monitor tephra plumes and clouds?

Scientists monitor tephra plumes and volcanic ash clouds using a combination of ground-based instruments and satellite observations. These data are essential for characterizing key aspects of volcanic activity, including plume extent, eruption column height, umbrella cloud spread, ash cloud altitude and thickness, tephra particle properties (such as size, shape, and settling velocity), mass eruption rate, sedimentation rate, and eruption duration. Ground-based tools include visible and thermal cameras, lidar, radar, infrasound microphones, and lightning detection antennas, each optimized for specific types of observations and deployed at varying distances from the volcanic vent.

Satellite sensors support global monitoring efforts through both active and passive remote sensing across a wide range of wavelengths, from ultraviolet to microwave. Modern ash cloud detection relies heavily on geostationary satellites, which provide high-temporal-resolution imagery (every 1 to 10 minutes), ideal for continuous real-time observation. However, these systems have trade-offs, such as coarse spatial resolution (approximately 4 km² at nadir) and limited coverage at high latitudes due to their equatorial orbital positioning.

Visible (a and c) and thermal (b and d) images of Mount Etna (Italy) plumes, acquired by the monitoring network of the Italian Institute of Geophysics and Volcanology, Osservatorio Etneo (INGV-OE). Courtesy of INGV-OE. Credit: Pardini et al. [2024], Figure 9

What are some recent advances in modeling tephra dispersal?

The movement of volcanic clouds and the deposition of tephra on the ground can be simulated using specialized numerical tools known as Tephra Transport and Dispersal Models (TTDMs). These models first emerged in the 1980s and have since undergone significant advancements in model physics, numerical solvers, and computational efficiency.

TTDMs require two main types of input data: meteorological information (such as wind speed, temperature, and pressure) and volcanic source parameters, which define what is emitted, how much is emitted, how particles are injected into the atmosphere (including their height and distribution), and the duration of the emission (start and end times). These models produce outputs that describe both the distribution of tephra suspended in the atmosphere and the patterns of tephra deposition on the ground. Modern TTDMs are capable of simulating complex atmospheric processes affecting tephra transport, such as particle aggregation and wet deposition (removal of ash particles by precipitation).

A recent development in the field is the emergence of in-line modeling approaches, which couple TTDMs directly with numerical weather prediction (NWP) models. In this integrated setup, the atmospheric evolution and tephra transport are computed simultaneously, eliminating the need to interpolate meteorological data between separate models. This approach improves the accuracy of tephra dispersal simulations, particularly under rapidly changing weather conditions. However, it comes at the cost of increased computational demand and is currently used primarily in research settings rather than for operational forecasting.

How have models contributed to improved forecasting and risk mitigation?

TTDMs play a crucial role in volcanic risk mitigation by providing forecasts of volcanic cloud movement and tephra deposition during eruptions. These models are especially valuable for early warning systems, enabling timely decisions to protect public health, aviation safety, and critical infrastructure.

One of the key operational users of TTDMs are the Volcanic Ash Advisory Centers (VAACs), which are a network of nine specialized agencies distributed globally under the mandate of the International Civil Aviation Organization (ICAO). VAACs are responsible for monitoring volcanic ash clouds and issuing advisories to aviation authorities. To do so, they routinely run TTDMs to predict the spatial and temporal extent of ash clouds, helping to prevent aircraft encounters with hazardous volcanic plumes. In addition, TTDMs are used by national meteorological and civil protection agencies to forecast and manage the ground-level impacts of tephra fallout. For example, the Japan Meteorological Agency (JMA) issues real-time forecasts of tephra dispersal and deposition following eruptions to support public safety measures. Similar practices are implemented in other volcanically active countries, such as Iceland and Italy.

Example output from the TTDM Ash3d, used at the Alaska Volcano Observatory to forecast the movement of volcanic clouds during periods of unrest. The example shown simulates a hypothetical volcanic cloud from Shishaldin volcano on 7 August 2024, using eruption source parameters that are considered realistic for that volcano. Results are publicly available at the Alaska Volcano Observatory website. Credit: Pardini et al. [2024], Figure 18

What are some of the remaining questions where additional modeling, data, or research efforts are needed?

In recent decades, there has been significant progress in our conceptual understanding of the processes that drive tephra plumes and the behavior of volcanic clouds. However, the inherent variability of explosive eruptions (ranging in style, location, and unique characteristics) continues to pose major challenges for both comprehensive understanding and effective monitoring.

Improving observational capabilities represents a critical frontier in volcanology.

One persistent difficulty lies in connecting model predictions with real-world observations. Large eruption plumes are rare, and even smaller events are difficult to characterize due to the limitations of current satellite systems, ground-based instruments, and visual data. As a result, improving observational capabilities represents a critical frontier in volcanology. Integrating these improved observations into modeling frameworks is essential, also to better understand underexplored processes such as particle aggregation and in-plume phase-change of water. 

The emerging potential of artificial intelligence in the detection and forecasting of tephra is increasingly recognized, although its current application remains limited, primarily to a few ash retrieval algorithms. In contrast, the use of large synthetic datasets generated by TTDMs to train data-driven models remains largely unexplored, despite the encouraging results achieved in other atmospheric dispersion contexts, where machine learning models have demonstrated strong generalization capabilities even under previously unseen conditions not represented in the training data.

—Federica Pardini (federica.pardini@ingv.it; 0000-0001-6049-5920), Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione di Pisa, Pisa, Italy

Editor’s Note: It is the policy of AGU Publications to invite the authors of articles published in Reviews of Geophysics to write a summary for Eos Editors’ Vox.

Citation: Pardini, F. (2025), Inside volcanic clouds: where tephra goes and why it matters, Eos, 106, https://doi.org/10.1029/2025EO255020. Published on 16 June 2025. 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 © 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.

Between 4 and 6 August 2023, intense rainfall triggered at least 346 landslides in the area around Ho Bon commune in Mu Cang Chai district, Yen Bai province in Vietnam

I have written frequently on this blog about clusters of rainfall-induced landslides. Another really interesting example has been highlighted in a paper (Toan et al. 2025) in the journal Landslides. Between 4 and 6 August 2023, intense rainfall triggered at least 346 landslides in the area around Ho Bon commune in Mu Cang Chai district, Yen Bai province in Vietnam.

Frustratingly, the paper does not give a lat / long location for this event (it continues to amaze me that this is not mandatory), but I believe the location is: [21.87657, 103.91738]. The exact nature of the rainfall event that triggered these landslides is uncertain as the loacl rain gauge was destroyed during the event. However, in the hour before the loss of data (6-7 pm on 5 August 2023), the rain gauge recorded 62.6 mm of precipitation.

The two Planet Labs images below show the outcome. The first was collected on 22 May 2023, before this event:-

Satellite image of the area that was affected by the August 2023 landslides around Ho Bon commune in Vietnam. Image copyright Planet Labs, used with permission. Image dated 22 May 2023.

The marker is situated on Ho Bon commune. And this is the aftermath of the event:-

Satellite image of the aftermath of the August 2023 landslides around Ho Bon commune in Vietnam. Image copyright Planet Labs, used with permission. Image dated 25 December 2023.

Image compare showing the landslides around Ho Bon commune in Vietnam. Images copyright Planet Labs.

This image highlights the landslides to the south of Ho Bon commune:-

Satellite image of the aftermath of the August 2023 landslides to the south of Ho Bon commune in Vietnam. Image copyright Planet Labs, used with permission. Image dated 25 December 2023.

Toan et al. (2025) do not claim that their mapping is comprehensive – and I think this is right as there appears to be more failures in the imagery than they have described. They note that the majority of the landslides that they mapped were debris flows, but I would probably characterise most of the failures in the imagery as shallow, disrupted landslides. They note that areas without forest cover were most seriously affected by landslides.

A really interesting aspect of this event is the number of failures that originate from the ridge line – this is commonly the case for earthquake initiated failures, but not for those triggered by rainfall. But Toan et al. (2025) note that this area has water traps on the ridgelines to feed water for rice field irrigation, so it is likely that these increased the rate of saturation, triggering failure.

In some locations, multiple shallow landslides combined to generate channelised debris flows. Parts of Ho Bon commune itself were damaged by such an event.

In total, Toan et al. (2025) document 88 damaged or destroyed houses, and extensive damage to the main road (NH32) through the area. They do not document any fatalities.

References

Planet Team 2025. Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://www.planet.com/

Toan, D.T., Duc, D.M., Quynh, D.T. et al. 2025. Extreme-rainfall-induced series of landslides and large flow-like landslides in Ho Bon commune, Mu Cang Chai district, Yen Bai province, Vietnam, in August 2023. Landslides. https://doi.org/10.1007/s10346-025-02544-5

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.

California produces more than a third of the vegetables and three quarters of the fruits and nuts in the United States. But water constraints are leaving more and more fields unplanted, or “fallowed,” particularly in the state’s famed farming hub, the Central Valley.

In a study published in Communications Earth and Environment, researchers showed that these fallowed agricultural lands are producing a different problem: dust storms, which can cause road accidents and health problems and can have far-reaching environmental impacts. Using remote sensing methods, the team found that 88% of anthropogenic dust events in the state, such as dust storms, come from fallowed farmland.

California’s frequent droughts could mean a rise in fallowed farmland. In 2014, the state passed the Sustainable Groundwater Management Act (SGMA), a policy aimed at ensuring the sustainability of groundwater resources. A report by the Public Policy Institute of California suggested that to meet the SGMA’s demands, farmers may need to fallow hundreds of thousands of additional acres, potentially worsening dust events.

Tracking Down Agricultural Dust

Dust can come from both natural sources, such as wind blowing across a desert, and anthropogenic sources, such as when transportation, construction, or agricultural activities kick up particles. Previous studies identified agriculture as a significant source of human-generated dust, but study author Adeyemi Adebiyi and his colleagues wanted to narrow down which agricultural practices produced the most.

“If you stop irrigating the land, it becomes dry, and we’re already in a dry climate. It’s easy for it to become a new dust source.”

Fallowed land was a logical culprit. “If you stop irrigating the land, it becomes dry, and we’re already in a dry climate,” said Adebiyi, an atmospheric scientist at the University of California, Merced. “It’s easy for it to become a new dust source.”

The researchers started by pinpointing fallowed land across California between 2008 and 2022 using U.S. Department of Agriculture datasets. The data showed that 77% of the state’s fallowed land was in the Central Valley. 

The team then examined NASA satellite images of atmospheric aerosols, identifying which aerosols were dust particles on the basis of the way they scatter light. When they overlaid the regions that regularly experienced dust events with the agricultural data, they saw that dust events were tightly associated with fallowed fields.

The problem appears to be getting worse. Between 2008 and 2022, both the area of fallowed land and corresponding dust levels have increased: In this period, the amount of dust in the atmosphere over the Central Valley grew by about 36% per decade.

Having grown up in California and spent the first decade of his career studying dust in the Central Valley, Thomas Gill, an Earth scientist at the University of Texas at El Paso who wasn’t involved in the study, has long worried that land use changes could lead to dust issues. “This study by Adebiyi et al., unfortunately, shows that my worries have been coming true,” he said.

“These fallowed land locations are emblematic of the properties you would normally see in a typical desert-type location.”

Daniel Tong, an atmospheric scientist at George Mason University who also wasn’t involved in the study, agreed that the work provides some much-needed conclusive data on the connection between land use and dust levels. “This is a very useful study,” he said.

Adebiyi’s team used additional remote sensing data to determine that compared with nearby nonfallowed land, fallowed fields have lower soil moisture and are about 4.2°C hotter. Combined with a lack of vegetation, these factors work together to make such areas more prone to wind erosion. “These fallowed land locations are emblematic of the properties you would normally see in a typical desert-type location,” Adebiyi said.

Far-Reaching Effects

The dust from fallowed fields has wide-reaching consequences. “California is already the state with the largest number of fatalities caused by dust storms,” said Tong, who authored a 2023 study about windblown dust fatalities in the United States. One concern, he said, is that more dust storms could increase road accidents. Dust also contributes to respiratory problems and cardiovascular disease and carries the Coccidioides fungus, which causes the dangerous infection valley fever. Cases of valley fever increased by 800% in California between 2000 and 2018.

“There’s also been a great population increase in the Central Valley,” Gill said. “So not only do you have more particulate matter, but you have more people living there who are vulnerable to its effects.”

Fallowed fields and the dust they produce may also work counter to the groundwater management goals of the SGMA. The Central Valley dust blows east into the Sierra Nevada Mountains, where it speeds snowmelt, a significant reservoir of water for the state. The researchers also found that the heat concentrated in fallowed fields can spread out to nearby fields, causing surrounding crops to need more water. “It’s a double whammy,” Adebiyi said.

He noted the importance of preventing fields from becoming completely bare while still conserving water. One strategy is to plant native, drought-resistant plants that protect the soil from wind erosion without needing much irrigation.

The researchers are now conducting similar studies on the connection between fallowed lands and dust in other agricultural states, such as Kansas, Montana, and Washington. Their findings suggest that addressing dust problems will become increasingly important nationwide.

“The implications are beyond California,” Adebiyi said. “They’re across the United States.”

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

Citation: Chapman, A. (2025), Fallowed fields are fueling California’s dust problem, Eos, 106, https://doi.org/10.1029/2025EO250223. Published on 13 June 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.

Editors’ Highlights are summaries of recent papers by AGU’s journal editors. Source: AGU Advances

Carbon dioxide (CO2) is a key driver of global climate change and the ability to monitor human-based emissions of this gas is crucial for quantifying the effectiveness of carbon-reduction policies. In recent years, space-based platforms like the Orbiting Carbon Observatory (OCO-2 and OCO-3) missions have provided atmospheric CO2 observations with near-global coverage and efforts to ingest these data into local, regional, and national carbon accounting methodologies have been successful. However, space-based observations are influenced by physical and environmental factors that affect their coverage.

Roten and Chatterjee [2025] investigate these factors and determine that the time needed to constrain emissions varies among cities within the United States. Key factors that affect these space-based platforms include the type of orbit they are in, the location of clouds in Earth’s atmosphere, and the distribution of atmospheric aerosols. The characteristics of the instruments’ orbits also vary the frequency of urban observations in both space and time. Results show that cities on the west coast are more frequently observed than cities in the northeast. These limitations should be considered when cities are seeking to monitor their emission reduction efforts with space-based technologies.

Predicted mean effective revisit time (τ) values from the Orbiting Carbon Observatory are spatially distributed at a 1km × 1km resolution across CONUS. White points indicate the locations of target cities and their sizes represent the mean CO2 emitted from each city during time interval τ. Much of the west had τ values short enough to facilitate sub-monthly observations; conversely, much of the northeast could not be constrained at such a scale (τ > 30 days). Credit: Roten and Chatterjee [2025], Figure 7

Citation: Roten, D., & Chatterjee, A. (2025). Coverage-limiting factors affecting the monitoring of urban emissions with the orbiting carbon observatory missions. AGU Advances, 6, e2024AV001630. https://doi.org/10.1029/2024AV001630

—Don Wuebbles, Editor, AGU Advances

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.

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.

On 11 June, the Environmental Protection Agency announced a proposal to repeal federal limits on power plant carbon emissions, including a Biden-era rule requiring power plants to control 90% of their carbon pollution and a 2015 standard limiting carbon dioxide emissions from new fossil fuel-fired power plants.

If made final, the plans mean that coal, oil, and gas-powered plants in the United States will no longer need to comply with federal limits on carbon dioxide emissions. 

In the announcement, the agency argued that carbon emissions “are global in nature,” so any of their potential public health harms are not able to be accurately attributed to emissions from the United States. However, the U.S. power sector ranks among the world’s largest sources of carbon pollution, and emissions from the U.S. power sector already contribute to billions of dollars in global health damages, according to a report from the Institute for Policy Integrity.

The carbon pollution standards that the EPA aims to erase “have been criticized as being designed to regulate coal, oil and gas out of existence,” EPA administrator Lee Zeldin said in a statement. “According to many, the primary purpose of these Biden-Harris administration regulations was to destroy industries that didn’t align with their narrow-minded climate change zealotry.”

The Associated Press estimates that the Biden-era carbon pollution limits could prevent up to 30,000 premature deaths each year. 

“By giving a green light to more pollution, [Zeldin’s] legacy will forever be someone who does the bidding of the fossil fuel industry at the expense of our health,” Gina McCarthy, a former EPA administrator, told the New York Times. 

The announcement comes a day after Jarrod Agen, an energy advisor to President Trump and executive director of the White House’s National Energy Dominance Council, reaffirmed the administration’s intention to re-focus U.S. energy production on coal and natural gas.

“The president’s priorities are around turning around fossil fuels,” Agen said, adding that President Trump “is not focused on wind and solar.”

 
Related

•  Trump EPA Moves to Repeal Climate Rules that Limit Greenhouse Gas Emissions from U.S. Power Plants
•  Trump’s EPA Plans to Claim U.S. Power Sector Emissions Are Insignificant. It’s Absurd.
•  EPA Axes Biden’s Climate and Pollution Limits on Power Plants
• Document Shows EPA Plans to Loosen Limits on Mercury From Power Plants
•  Get Involved: AGU Science Policy Action Center
 

The EPA is also “hopeful” it will be able to reverse a 2009 declaration that greenhouse gases threaten the public health and welfare of current and future generations, according to POLITICO. The agency has already exempted at least 66 coal-fired power plants from federal limits on air pollution.

In the same announcement, the EPA also proposed the removal of a rule known as the Mercury and Air Toxics Standards, which tightened emissions of mercury and other toxic metals from power plants. Documents outlining Zeldin’s plans for the mercury rule, reviewed by the New York Times, said the Biden administration “improperly targeted coal-fired power plants” when it created the original rule. 

—Grace van Deelen (@gvd.bsky.social), Staff Writer

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Source: Paleoceanography and Paleoclimatology

Great apes began to diverge from other primates around 25 million years ago, according to eastern African fossil records. Though it would take another 20 million or so years for upright-walking hominins to appear, understanding the habitats of early apes helps clarify how environments drove the evolution of our distant ancestors.

Munyaka et al. excavated and analyzed fossils from an approximately 20-million-year-old early Miocene site in western Kenya called Koru 16. The now-extinct Tinderet Volcano repeatedly blanketed the area in ash, preserving it for millions of years, and today, the site hosts fossils from an array of plants and animals.

Many prior studies focused on the area around Koru 16: The first primate fossils from the site were discovered in 1927, and famed anthropologist Louis Leakey led multiple digs there.

As part of the new research, scientists uncovered fossils of approximately 1,000 leaves and many vertebrates at two subsites between 2013 and 2023. The specimens included those of a new type of large-bodied ape and two other previously known ape species, bringing the total number of vertebrate species discovered at the site to 25.

By examining the shapes of fossilized leaves, the geochemistry of fossilized soils (paleosols), and the distribution and density of fossil tree stumps, the researchers determined that the Koru 16 site was likely located within a warm, wet forest, with rainfall amounts similar to those of modern-day tropical and seasonal African forests. However, the ancient ecosystem likely hosted more deciduous plants than do modern tropical forests. The vertebrate fossils the researchers analyzed were consistent with apes, pythons, and rodents that might have lived in such an environment.

The researchers suggest that this ancient forest environment—which was interspersed with open areas and frequently disturbed by fires, floods, or volcanic eruptions—played a role in shaping the course of evolution for early apes. (Paleoceanography and Paleoclimatology, https://doi.org/10.1029/2025PA005152, 2025)

—Madeline Reinsel, Science Writer

Citation: Reinsel, M. (2025), Early apes evolved in tropical forests disturbed by fires and volcanoes, Eos, 106, https://doi.org/10.1029/2025EO250221. Published on 12 June 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.

On 17 May 2025, a failure occurred in a mine waste facility at the Tawau gold mine in Malaysia. Images suggest that this might have been an overtopping event in a contaminated water storage pond.

On 17 May 2025, there was a failure of a mine waste storage facility at Bukit Mantri in Malaysia. The precise circumstances of this event, and its consequences, are not entirely clear to me. However, it appears that a substantial amount of cyanide has escaped, possibly reaching the Kalumpang River.

The event occurred at a gold mine at Bukit Mantri, which is located at [4.5095, 118.1094]. Reports suggest that a tailings dam or water retention dam failed on 17 May 2025. There is reportedly a video that captured the event, although I have been unable to track this down. The still below, posted in a report by Tuhua Bambangan, reportedly shows the event:-

Image reportedly showing the failure of a mine waste storage facility at the Tawau gold mine in Bukit Mantri, Malaysia. Image from a video, originally posted by Tuhau Bambangan.

If this is indeed the reported failure then it appears to have been an overtopping event. A report in Sabah News Today has an image of the aftermath, which is consistent with the above image, showing a major break in the dam.

The Planet Labs satellite image below shows the mine site at Bukit Mantri, captured two days before the failure on 15 May 2025. I have circled the most likely location of the failure:-

Satellite image of the Bukit Mantri mine site before the mine waste storage facility failure. Image copyright Planet Labs, used with permission. Image dated 15 May 2025.

The image below was captured on 25 May 2025, eight days after the failure:-

Satellite image of the Bukit Mantri mine site after the mine waste storage facility failure. Image copyright Planet Labs, used with permission. Image dated 25 May 2025.

And here is a slider to compare the two images:-

Before and after Planet Labs images of the possible location of the Bukit Mantri wine waste failure.

I think the break in the dam is probably just visible, with some sediment deposited on the downstream side, although a higher resolution is needed for certainty.

The operators of the mine have been ordered to cease operations, and there are calls for a proper investigation. Concerns had been raised about this site for a while – for example, Sabah News Today published an article two months ago in which they claimed that:

“A subsidiary of Alumas Resource Berhad has been identified as currently conducting illegal gold mineral mining operations in Bukit Mantri, Balung Tawau.”

I have repeatedly written about mine waste failures over the years. It is depressing that 2025 has, to date, been a bumper year for such events.

Acknowledgements

Thanks to loyal reader Steven for spotting this event, and to Planet Labs for their amazing images.

Planet Team. 2024. Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://www.planet.com/

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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.

Climate.gov, NOAA’s portal to the work of their Climate Program Office, will likely soon shut down as most of the staff charged with maintaining it were fired on 31 May, according to The Guardian. The site is funded through a large NOAA contract that also includes other programs. A NOAA manager told now-former employees of a directive “from above” demanding that the contract remove funding for the 10-person climate.gov team.

“It was a very deliberate, targeted attack,” Rebecca Lindsey, the former program manager for climate.gov, told The Guardian. Lindsey was fired in February as part of the government’s purge of probationary employees. She said that the fate of the website had been under debate for months, with political appointees arguing for its removal and career staffers defending it.

“We operated exactly how you would want an independent, non-partisan communications group to operate,” Lindsey said. “It does seem to be part of this sort of slow and quiet way of trying to keep science agencies from providing information to the American public about climate.”

 
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Another former NOAA employee noted that the climate.gov purge spared two website developers. For some, this raised concerns that the climate.gov site might survive, but host anti-science content and misinformation under the guise of a once-trusted source of climate science.

This move comes amid a slew of other anti-science actions from the Trump Administration, including blocking EPA science funding, halting maintenance of key Arctic data, removing access to longstanding NOAA datasets, proposing to slash NASA’s Earth science funding, and pulling U.S. scientists out of domestic and international climate change reports.

“Hiding the impacts of climate change won’t stop it from happening,” said one former NOAA contractor, “it will just make us far less prepared when it does.”

—Kimberly M. S. Cartier (@astrokimcartier.bsky.social), Staff Writer

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Next time you explore a beach or a desert, look down at the sand. You might spot patches of small ripples just a few centimeters tall. Wind can shape these miniature dunes in less than half an hour and blow them away just as quickly. Unlike the processes that form larger dunes that define desert landscapes and shorelines, those that shape mini dunes have been elusive.

“There have been some observations of such small, meter-scale bedforms, but not many quantitative studies,” said Camille Rambert, a doctoral student at École Supérieure de Physique et de Chimie Industrielles de la Ville de Paris and lead author on the new research. “And there have not been any models to explain their formation.”

Recently, a group of researchers used high-resolution laser scanning in the Namib Desert in Namibia to watch how tiny dunes form. Those scans informed dune formation models, which found that the key factor is how sand grains bounce on smooth versus grainy surfaces.

Blowing in the Wind

Although small sand bedforms are a common phenomenon in most sandy places, their ephemeral nature has made it challenging for geomorphologists to decode what makes a small dune form where only flat, featureless sand exists.

“More sand can be transported on a consolidated surface than on the erodible surface.”

A team of researchers, including Rambert, set out to the Namib Desert in coastal southern Africa seeking to understand how these bedforms take shape. The team used a laser scanner sitting on the surface to collect repeated high-resolution topographic maps of nearby flat areas, roughly 5 meters wide × 5 meters long, nestled between larger dunes. The scanner measured the distance from the laser emitter to the ground and also measured near-surface wind speed and direction. The team could detect vertical changes to the surface of about half a millimeter and horizontal changes of about a centimeter.

“From those measurements, we can deduce how bedforms evolve,” Rambert said. “Do they grow and migrate, or do they shrink?”

They developed a mini dune formation model on the basis of well-established physics governing large dune formation, but with a key twist: The small dunes started on consolidated surfaces like gravel or hard-packed sand rather than on an erodible foundation such as loose sand. That difference altered how far wind could transport a sand grain and how the grain bounced or stuck when it landed.

Researchers created digital elevation maps showing how small dunes form in the Namib Desert using a high-resolution terrestrial laser scanner. Credit: University of Southampton

“This difference in surface materials affects the sand transport,” Rambert said. “More sand can be transported on a consolidated surface than on the erodible surface.”

If a grain wasn’t swept away by the next gust of wind, its presence made the surface a little rougher and more likely to trap the next grain of sand—and the next. The gradual buildup of grains into tiny bumps altered near-surface wind patterns, which helped trap even more sand and created distinctive dune patterns in the bedform.

These patches of mini dunes disappeared when a strong enough wind blew the sand grains off the consolidated surface. If the wind had been gentler, those patches might have continued growing.

The team found that their model observations accurately portrayed what they saw in the laser scans from the Namib. They published these results in Proceedings of the National Academy of Sciences of the United States of America.

“This study highlights the importance of bed heterogeneities, such as whether a surface is sand covered or not, in how meter-scale bedforms evolve,” Joel Davis, a planetary geologist at Imperial College London in the United Kingdom, wrote in an email. Davis was not involved with the research. “It’s intriguing [that] those small-scale variations in dynamics…could influence whether these small bedforms become a larger dune field, or simply disappear.”

Dunes Beyond Earth

Scientists have discovered dunes on both Mars and Saturn’s moon Titan, but the instruments that have explored those distant worlds are far less advanced than the laser scanners on Earth.

“Studies like these, on the dynamics of Earth dunes, are particularly useful for investigating dunes in a planetary setting, such as on Mars or Titan,” wrote Davis, who studies Martian dunes.

Meter-scale dunes, like this one in Namibia, form because sand grains bounce differently on smooth surfaces than on rough ones. Credit: University of Southampton

Some of Mars’s dunes form inside craters, which presumably trap a lot of loose sand, but they are also found outside the craters in less sandy areas. “We don’t really know why they have formed in these locations, but perhaps bed heterogeneities are a control on this,” Davis wrote. “It would be interesting to see if we could identify any metre-scale bedforms in these expansive interdune areas of Mars…similar to the Namibia examples.”

What’s more, Earth’s dunes tend to be either very short (centimeters) or very long (tens to hundreds of meters). Though hundreds of dunes near Mars’s north pole are the same shape as Earth dunes, most of them are 1–2 meters long. Planetary geologists are still puzzling over this.

“Mars, and also other planetary bodies such as Titan, are, in a way, laboratories where the physical conditions are different than on Earth.”

“This is a hotly debated topic that is rapidly evolving,” wrote Lior Rubanenko in an email. Rubanenko is a planetary surfaces researcher at the Planetary Science Institute in Tucson, Ariz., who was not involved with the new research.

“Mars, and also other planetary bodies such as Titan, are, in a way, laboratories where the physical conditions are different than on Earth­—different atmospheric density, different grain size and material type,” Rubanenko wrote. “This allows us to conduct and observe ‘planet-size’ experiments which challenge our current paradigms.”

“Comparing observations of dunes between these planets can help us better understand the mechanisms that govern sand transport and dune formation,” he added.

—Kimberly M. S. Cartier (@astrokimcartier.bsky.social), Staff Writer

Citation: Cartier, K. M. S. (2025), Mini dunes form when sand stops bouncing, Eos, 106, https://doi.org/10.1029/2025EO250216. Published on 11 June 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
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Editors’ Highlights are summaries of recent papers by AGU’s journal editors. Source: Journal of Geophysical Research: Oceans

The surface waters of warm western boundary currents are poor in nutrients. Therefore, intrusions of these nutrient-depleted water into the region are considered to reduce biological production. Although warm waters of the Kuroshio, one of the western boundary currents, often intrude into the South China Sea through the Luzon Strait, their biogeochemical consequences are not well understood.

Li et al. [2025] use data from 20 cruises conducted in the South China Sea between 2004 and 2015, reveal that the Kuroshio intrusion counterintuitively increases the chlorophyll pigments that are contributed by small phytoplankton called picophytoplankton and nanophytoplankton. Previous studies have pointed out that global warming has weakened the Kuroshio intrusion into the South China Sea. Therefore, this study raises concerns that global warming would cause a decrease in primary production in the future.

Schematics of the study showing surface chlorophyll concentration, which is proportional to phytoplankton biomass and abundant in the mixed water property between South China Sea (KI=0%) western Pacific (KI=100%), is intensified with strong Kuroshio intrusion (blue curve) in the South China Sea. Credit: Li et al. [2025], Figure 9

Citation: Li, W., Shang, Y., Li, C., Xu, C., Laws, E. A., Liu, X., & Huang, B. (2025). A stronger Kuroshio intrusion leads to higher chlorophyll a concentration in the northern South China Sea. Journal of Geophysical Research: Oceans, 130, e2024JC021389. https://doi.org/10.1029/2024JC021389

—Takeyoshi Nagai, Editor, JGR: Oceans

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