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SUMMARYSeismic ambient noise tomography has been a powerful tool for seismic imaging, but most existing approaches fail to accurately predict detailed correlation waveforms in the presence of spatially heterogeneous noise distributions. Full-waveform ambient noise inversion allows for high-resolution waveform-based inversion even in substantially heterogeneous noise fields. Unfortunately, the computational cost of this approach is constrained by the noise distribution, rather than the inversion domain: global-scale applications are viable, but smaller-scale applications require a modified approach. We present a general finite-domain full-waveform ambient noise inversion methodology, providing approximation mechanisms for treating out-of-domain propagation from distant noise sources. This makes the problem tractable on much smaller domains. In a numerical example, we demonstrate that this approach enables inversion for both structure within a chosen domain and approximate noise source distribution outside it.

AbstractThe British Isles' lithospheric structure, shaped by a dynamic geological history, remains incompletely understood, particularly regarding anelastic parameters, such as attenuation. In this study, we present a teleseismic attenuation model for the British Isles, using time-domain analysis of teleseismic P-wave data from 28 deep earthquakes. We constructed a 2D differential attenuation map (Δt*) that reveals significant regional variations. Our findings show a weak anticorrelation between Δt* and shear wave velocity at upper mantle depths, suggesting that variations in the lithosphere-asthenosphere system influence this pattern. A high-attenuation zone extends from Scotland across the Irish Sea to southwest England, potentially linked to mantle upwelling associated with the Iceland plume. This model provides new insights into the mantle dynamics beneath the British Isles, offering a crucial reference for future geophysical studies in the region.

How does climate change affect the way humans organize themselves? How has it shaped the course of human evolution? An international team of scientists, including scientists from the Université de Montréal, think the key to answering those questions is to pay more attention to the archaeological record.

For more than a century, a patch of cold water south of Greenland has resisted the Atlantic Ocean's overall warming, fueling debate among scientists. A new study identifies the cause as the long-term weakening of a major ocean circulation system.

A study led by researchers from Brown University finds that rainfall patterns across northern Africa remained largely stable between 3.5 and 2.5 million years ago—a pivotal period in Earth's climate history when the Northern Hemisphere cooled and places like Greenland became permanently glaciated.

The Earth is rapidly warming, and similar climate upheavals over 300 million years ago once triggered massive fluctuations in marine life.

A powerful magnitude 7.7 earthquake that struck Myanmar on March 28, 2025, became a widespread catastrophe due to the collapse of vulnerable buildings, which directly led to the majority of deaths and destruction, according to a new report by the United Nations University Institute for Water, Environment and Health (UNU-INWEH).

Over the last two decades, the scientific community has made rapid strides in understanding climate change and air pollution—but progress on their combined effects remains limited. Traditional models often gloss over the complex web of interactions between land, sea, and sky, especially when simulating compound events like heat waves coinciding with stagnant air. These gaps are particularly troubling in densely populated coastal and urban zones, where human exposure is highest.

Volcanic islands, such as the islands of Hawaii and the Caribbean, are surrounded by coral reefs that encircle an island in a labyrinthine, living ring. A coral reef is punctured at points by reef passes—wide channels that cut through the coral and serve as conduits for ocean water and nutrients to filter in and out. These watery passageways provide circulation throughout a reef, helping to maintain the health of corals by flushing out freshwater and transporting key nutrients.

A research team led by the University of Aberdeen has developed a pioneering AI model to improve accuracy and reduce computational time in land cover mapping, particularly for vegetation.

Due to global warming, the North Atlantic Oscillation, an atmospheric circulation pattern that strongly influences European weather, is becoming more extreme in the summer, according to a study published in Communications Earth & Environment.

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.

Author(s): Guoqing Yang, Min Chen, Xiaobo Zhang, Huanyu Song, Suming Weng, Ping Li, Tongpu Yu, and Zhengming Sheng

Laguerre-Gaussian (LG) laser beams have many interesting applications due to their unique field structure. However, the generation of intense LG beams remains challenging because of the limited damage threshold of intensity for optical elements used for the conversion from normal Gaussian beams to L…

[Phys. Rev. E 111, 065211] Published Fri Jun 20, 2025

Author(s): Amir Jafari

We employ well-known concepts from statistical physics, quantum field theories, and general topology to study magnetic reconnection and topology change and their connection in incompressible flows in the context of an effective field theory without appealing to magnetic field lines. We consider the …

[Phys. Rev. E 111, 065212] Published Fri Jun 20, 2025

Author(s): Evgeny V. Polyachenko and Ilia G. Shukhman

Landau-damped oscillations in collisionless plasmas, described by van Kampen and Case, are quasimodes, representing a continuous superposition of singular eigenfunctions, not true eigenmodes. Recent work by Ng et al. shows that even rare collisions replace these singular modes with discrete regular …

[Phys. Rev. E 111, 065213] Published Fri Jun 20, 2025

SUMMARYInduced seismicity poses a significant challenge to the safe and sustainable development of Enhanced Geothermal Systems (EGS). This study explores the application of machine learning (ML) for forecasting cumulative seismic moment (CSM) of induced seismic events to evaluate reservoir stability in response to fluid injections. Using data from the Cooper Basin (Australia), the St1 Helsinki geothermal project (Finland), and a controlled laboratory injection experiment, we evaluate ML models that integrate catalog and operational features with various frameworks. Results indicate that feature-rich models outperform simpler ones in complex seismic environments like the Cooper Basin and laboratory cases, where seismicity is promoted by earthquake interaction and fault reactivation. However, in scenarios like St1 Helsinki, with minimal event clustering, additional features offer limited predictive benefits. While ML models are promising, several challenges impede reliable forecasting, including data scarcity from operational wells, the extrapolation demands of cumulative output (i.e. CSM), and the difficulty of predicting abrupt CSM increases for large seismic events. Enhancing model robustness requires synthetic data augmentation and improved feature selection capable of capturing diverse reservoir dynamics. These advancements may enable more accurate near real-time forecasts of problematic induced seismic events, informing operational decisions to mitigate seismic risks while maximizing energy extraction, and hence offering a pathway for broader adoption of ML in renewable energy development and management.

As Earth's largest carbon reservoir, the ocean locks carbon away from the atmosphere. However, scientists still struggle to measure and monitor exactly how much carbon is stored in the ocean, hindering efforts to model and respond to our changing climate.

Ocean waters are getting greener at the poles and bluer toward the equator, according to an analysis of satellite data published in Science on June 19.

In Europe, people are increasingly exposed to extreme heat events—with serious consequences for human health, ecosystems, and agriculture. Researchers at the Max Planck Institute for Meteorology have developed and tested a method that can be used to improve the prediction of European hot summers up to a few years in advance.