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SummaryHigh-quality maps of subsurface temperature and the geothermal gradient are useful when assessing the geothermal potential of a region. However, determining geothermal potential is a challenge when direct measurements of in-situ temperature and thermal property information are sparse and indirect geophysical methods are sensitive to a range of parameters, not just temperature. Here, we produce subsurface temperature maps of Ireland using a joint geophysical-petrological inversion, where seismic and other geophysical and petrophysical data are inverted directly for temperature in 1D columns and are collated into a pseudo 3D temperature volume. Additionally, the inversion produces new models for Moho and LAB depth and for the average crustal radiogenic heat production.To assess the robustness of the resulting temperature model, an uncertainty analysis has been performed by inverting all of the 1D columns for a range of reasonable input parameters applicable to the Irish crust (rather than the ‘best’ input parameters). The resulting uncertainty model suggests temperature estimates at 2 km depth in our model could vary by ± 2 to 5°C with an average of 3.5°C in most locations. The uncertainty model can be used to assess confidence in different regions of the temperature model. In addition, 3D forward modelling was performed to assess the lateral heat flow variations when compared to the purely 1D inversion. The upper-crustal geothermal gradient ranges from 20 to 40°C/km indicating a higher geothermal gradient for Ireland than previously reported with subsurface temperatures at 2 km depth > 60°C everywhere, sufficient for residential and industrial heating purposes. The temperature gradient is typically higher in areas with thinner lithosphere. However, in some locations, the observed geotherms are elevated further due to high radiogenic heat production in granitic rocks. In Northern Ireland, a thin lithosphere, coupled with a weakly conductive basalt layer overlying warm crust, results in elevated temperatures. These are the first temperature maps for Ireland that include uncertainty estimates, providing ranges for the subsurface temperature values, and demonstrate that the maps are comparable to direct independent borehole temperature measurements, which are observed to fall within the model uncertainty. Our new methodology provides workflows for determining the geothermal potential in areas with limited direct temperature measurements. The final temperature model with uncertainty provides useful constraints for geothermal exploration and utilisation on the island of Ireland.

SummaryThe role of pre-existing lithospheric heterogeneities in rifting processes remains unclear. The Eastern and Main Ethiopian rifts lie within the same geodynamic province and are kinematically connected through the Turkana Depression, but they transect heterogeneous lithosphere: Pan-African accreted terranes, failed Mesozoic-Paleogene rift systems, zones of Eocene-Oligocene flood magmatism. Rifting in these pre-extension heterogeneities offers the opportunity to evaluate their relative importance in Oligo-Miocene to Recent stretching and magmatism. We use 3D Rayleigh shear-wavespeed (Vs) models inverted from ambient noise signals recorded on a temporary seismic network to image heterogeneities in lithospheric structure, and to evaluate their influence on syn-rift faulting and magmatism. Crustal feeder zones for Eocene-Oligocene flood magmatism in southwestern Ethiopia are marked by ≤ 50 km-wide, 10-15 km-thick mid-lower crustal fast wavespeed (Vs ≥ 3.8 km/s) anomalies that are localized rather than widespread. Evidence for active magma intrusions only occurs beneath aligned chains of Quaternary eruptive centers in Lake Turkana and ≤ 1 Ma shield volcanoes east of the Turkana rift having localized low Vs (≤3.4 km/s) at 0-20 km depth. Evidence for widespread lower crustal intrusions, however, is lacking. Pan-African oceanic accreted terranes in southern Ethiopia have high Vs anomalies of 3.6 km/s throughout the crust and overlay previously imaged high wavespeed lithospheric mantle that has been interpreted as cold and strong Proterozoic accreted terrane. The integrated strength of this lithospheric-scale pre-existing mechanical heterogeneity resisted Oligocene-Miocene stretching and subsequently contributed to the unusual breadth of this East African rift sector lying north of the Turkana Depression.

SummaryThe Eastern Continental Margin of India (ECMI) is a classic passive margin formed during the Mesozoic breakup of the supercontinent Gondwanaland. Since its formation, the margin has undergone complex post-rift thermal subsidence, magmatic activity, and interactions with adjacent tectonic plates. Extensive shipborne magnetic data have been acquired over the years, providing substantial coverage of the area. However, knowledge about the regional thermal structure and magnetic nature of the upper mantle of the ECMI and adjacent deep offshore Bay of Bengal is not understood uniformly throughout the region. In this study, we estimate Curie depth from shipborne magnetic data using a power spectrum inversion technique within a Bayesian framework, incorporating fractal source distribution and a priori sediment thickness to constrain the top depth of magnetic slab. The Curie depth is a proxy for the 580°C isotherm, providing insight into the regional thermal structure and crustal rheology that controls post-rift thermal evolution and mantle magnetization. The obtained Curie depths range from 16 km to 28 km with corresponding surface heat flow values varying between 55 and 85 mW/m². A shallower Curie depth and higher heat flow are observed in northern part of the offshore Krishna-Godavari (KG) basin and the southern part of Mahanadi basin, linked to rift-related magmatic intrusions and mantle plume activity. Conversely, deeper Curie depths and lower heat flow characterize the Cauvery basin and the southern ECMI. Our results show, across much of the region from the Continent-Ocean Transition (COT) zone to deep offshore areas, the Curie depth lies below the Moho, suggesting that magnetic sources extend into the upper mantle. This suggests the presence of serpentinised upper mantle and exhumed mantle peridotite which provides the secondary magnetization. The obtained thermal lithosphere thickness varies from 50 to 90 km, shallower in the Krishna-Godavari and Mahanadi basins and deeper towards the Cauvery and central basins. Geotherms intersects mantle adiabat at 50 km depth in the KG and Mahanadi basins, signifying these are thermal overprint basins linked to magmatic activity. The obtained thermal lithosphere deepens from north to south, mirroring trends in the Lithosphere-Asthenosphere Boundary (LAB). Finally, a positive correlation between Curie depth and effective elastic thickness (Te) reflects the regional variation in crustal strength and tectono-magmatic processes controlling the margin evolution.

Researchers have developed a novel method to detect and study how ice forms in mixed-phase clouds, significantly boosting scientists' ability to forecast weather and model climate change.

The seismic signature of a fireball meteoroid event can be used to tell whether the fireball fragmented or remained intact as it fell through the atmosphere, according to new research published in Seismological Research Letters.

Megathrust earthquakes are large earthquakes that occur on faults found along the boundaries between tectonic plates. The Nankai Trough is a megathrust earthquake zone lying off the southwestern coast of Japan, and experts estimate that this zone could generate a potentially devastating (magnitude 8 or 9) large earthquake sometime in the next 30 years. In addition to the direct catastrophic impact of such powerful ground shaking, a seismic event of this magnitude could trigger cascading hazards such as destructive tsunamis.

Author(s): Zijin Zhang, Anton V. Artemyev, and Vassilis Angelopoulos

The transport of energetic particles in the heliosphere is profoundly influenced by interactions with coherent structures in the turbulent magnetic field of the solar wind, particularly current sheets. While prior studies have largely relied on idealized turbulence models, this work quantifies the r…

[Phys. Rev. E 112, 015209] Published Wed Jul 23, 2025

Author(s): Ilnaz I. Fairushin and Anatolii V. Mokshin

In this paper, the theoretical model of weak decaying collective excitations characteristic of many-particle systems with long-range interaction potentials is developed using the example of one-component strongly coupled Yukawa plasmas. The proposed model is based on the self-consistent relaxation t…

[Phys. Rev. E 112, 015210] Published Wed Jul 23, 2025

SummaryThe stress and load path dependencies of elastic properties and their evolution under varying damage states is of critical interest to a multitude of communities, such as geophysicists understanding rock properties for subsurface engineering as well as both civil and geological engineers interested in fundamental damage mechanics of materials. Here, we perform a set of laboratory experiments on a Dakota Mahogany granite to understand the dependence of stress path, orientation, and magnitude on static and dynamic properties as well as dynamic evolution under varying states of damage. Localized strain and ultrasonic velocity, axial and radially aligned with respect to the sample, are recorded along four distinct load paths with varying ratios of mean and differential stress. Differential stress is found to be the predominant factor for variations in static Youngs modulus, while undamaged axial dynamic Youngs modulus is primarily a factor of increasing mean stress. Radial dynamic Young’s modulus demonstrates an overall positive correlation with increasing mean stress and negative correlation with differential stress. A novel relationship is constructed to predict phase velocity and orientation/polarization as a function of stress and load path. The effect of damage within the material is analyzed by subjecting the sample to increasing stresses along a single load path, after which the multipath testing is repeated. Ultrasonic velocity and thus dynamic moduli become less sensitive to increases in differential stress for wave propagation parallel with the maximum principle stress. For P-wave velocity aligned parallel, the contribution of differential stress decreases from nearly that of confining pressure (0.88) to below half at the highest damage state tested. Similar decreases also occur in the contribution of differential stress to the remaining three wave polarizations and orientations. This shows that the degradation of physical properties brought about by microcracking and subsequent decrease in velocity overcomes any increase resulting from consolidation with increasing stress. The results provide a way to anticipate changes in elastic response and subsurface acoustic velocity brought about by increased damage and changing stress state through the use of a new empirical model. Additional methods to establish the distribution of microcracks and their orientations within a damaged material through differences in velocity from loading to unloading are presented which provide useful tools for non-destructively assessing damage state.

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.

Nearly 300 current and former NASA employees have signed an open letter expressing concern that budget cuts to the agency will jeopardize safety, basic research, national security, and the nation’s economic health. 

The 21 July letter, titled “The Voyager Declaration,” in honor of the Voyager space probes, was addressed to Interim NASA Administrator Sean Duffy, who joined the agency on 9 July. 

“We are compelled to speak up when our leadership prioritizes political momentum over human safety, scientific advancement, and efficient use of public resources,” the letter states. “The consequences for the agency and the country alike are dire.”

The agency faces pressure to reduce its staff and a budget request proposing funding at levels described as an “extinction-level event for NASA science” by Casey Dreier, chief of space policy for the Planetary Society. 

 
Related

•  The Voyager Declaration
•  Hundreds of NASA Employees, Past and Present, Sign Letter of Formal Dissent
•  Get Involved: AGU Science Policy Action Center
 

In the letter, signatories asked Duffy to protect NASA from proposed budget and staffing cuts and dissented to several planned or already-enacted changes including spacecraft decommissioning; abandonment of international space mission partnerships; and termination of diversity, equity, inclusion, and accessibility programming.

The letter’s authors also pointed out a “culture of organizational silence” promoted at the agency that, combined with suggested changes to NASA’s Technical Authority—a system of safety oversight—represents a “dangerous turn away from the lessons learned following the Columbia disaster.” The letter was dedicated to astronauts who lost their lives in spaceflight incidents and was signed by at least 4 astronauts.

“We’re scared of retaliation,” Monica Gorman, an operations research analyst at NASA’s Goddard Space Flight Center and a signatory of the letter, told the New York Times. She said staff “go to the bathroom to talk to each other, and look under the stalls to make sure that no one else is there before we talk.”

Staff at the National Institutes of Health and the EPA signed similar letters to their administrators in June. Some of the signatories of the EPA letter have since been placed on leave. Stand Up for Science, a nonprofit science advocacy organization, helped coordinate all three letters. 

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

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

As temperatures, biodiversity losses, and sea levels rise globally, scientists are concerned about the likelihood of abrupt climatic shifts occurring, particularly within sensitive subsystems of the climate system such as the Amazon rainforest, Antarctic sea ice, and the Tibetan Plateau. Abrupt shifts can manifest as, for example, large and sudden changes in the rate of precipitation in a monsoon system, ice melt in Antarctica, or permafrost thaw in the Northern Hemisphere.

Editors’ Highlights are summaries of recent papers by AGU’s journal editors. Source: Journal of Geophysical Research: Solid Earth

Understanding how rocks break in the brittle upper crust is critical for predicting earthquakes, managing reservoirs, and modeling subsurface mechanics. In JGR: Solid Earth, two new studies by Jacob et al. [2025] and Hurley et al. [2025] use cutting-edge synchrotron-based X-ray diffraction techniques to reveal how stress evolves at the grain scale inside sandstone samples under load.

In both studies, researchers applied increasing axial compression to small cores of sandstone rocks, while scanning them with high-energy X-rays at a synchrotron radiation facility. Jacob et al. [2025] employed a technique called scanning three-dimensional X-ray diffraction to obtain high-resolution maps of intra-granular stress in the sandstone. By combining stress mapping with stepwise compression, the team observed increasing stress heterogeneity accompanied by dynamic reorientation of local stresses. High-stress clusters emerged and formed spatially persistent structures. These patterns were found to correlate with zones of higher grain rotation and strain, forming potential precursors to failure.

Hurley et al. [2025] combined X-ray tomography with three-dimensional X-ray diffraction and near-field high-energy diffraction microscopy to image stress and texture evolution in 3D. The researchers observed that larger grains showed more internal misorientation, possibly due to the presence of surface cements. By combining stress mapping with stepwise compression, the team showed that grain stresses demonstrated compressive stress alignment parallel to the loading direction and tensile stresses alignment orthogonal to the loading direction. This evolution was consistent with porosity evolution revealed by X-ray tomography, which showed pores closing parallel to the loading direction and opening normal to the loading direction.

Together, these studies reveal that rocks under stress behave more like collections of interacting grains than uniform solid blocks, showing similarities with inter-particle force transmission in granular materials. They also underscore the power of modern synchrotron tools in capturing these processes while performing rock deformation experiments, providing deeper insights into how brittle failure initiates in the Earth’s crust.

Citations:

Jacob, J.-B., Cordonnier, B., Zhu, W., Vishnu, A. R., Wright, J., & Renard, F. (2025). Tracking intragranular stress evolution in deforming sandstone using X-rays. Journal of Geophysical Research: Solid Earth, 130, e2025JB031614. https://doi.org/10.1029/2025JB031614

Hurley, R. C., Tian, Y., Thakur, M. M., Park, J.-S., Kenesei, P., Sharma, H., et al. (2025). Crystallographic texture, structure, and stress transmission in Nugget sandstone examined with X-ray tomography and diffraction microscopy. Journal of Geophysical Research: Solid Earth, 130, e2025JB031690. https://doi.org/10.1029/2025JB031690

—Yves Bernabé, Editor, JGR: Solid Earth

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.

Researchers from the University of Cambridge are using AI to speed up landslide detection following major earthquakes and extreme rainfall events—buying valuable time to coordinate relief efforts and reduce humanitarian impacts.

The magnetosphere, formed by Earth's magnetic field, acts as a protective shield that deflects solar wind—the flow of charged particles constantly streaming from the sun toward our planet. This magnetic barrier protects our atmosphere and the technology we increasingly depend on in near-Earth space, such as communication satellites.

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

Karst groundwaters are vital resources, providing drinking water to nearly 10% of the world’s population. However, human activities and global change have deteriorated the karst water quality and dependent ecosystems.

A new article in Reviews of Geophysics explores contaminant transport in karst groundwaters and recent efforts to model it. Here, we asked the authors to give an overview of karst aquifers, how scientists model contaminant transport, and future research directions.

What are karst aquifers and where do they form?

Karst aquifers are underground water reservoirs that develop in soluble rocks like limestone or dolomite. Over thousands of years, these rocks dissolve to form complex underground networks of channels, caves, and fractures (Figure 1). These unique systems are found all over the world—from Florida to the Dinaric Alps—and they supply drinking water for nearly one in ten people globally while supporting ecosystem functioning.

Figure 1: Conceptual representations of transport processes in karst aquifer at differing spatial scales. a) 3D block diagram of a karst aquifer scale, b) aquifer scale, c) borehole scale, d) single-fracture scale, e) pore-scale level (described at the Representative Elementary Volume, REV). Here, contaminant degradation is described by the chemical transformation influenced by physical, chemical, and (biogeo)chemical processes. The figure only describes anthropogenic contamination by indicating diffuse (areal) and point sources because both are key contamination sources in karst aquifers. Credit: Çallı et al. [2025], Figure 1

Why are karst aquifers important to understand?

Karst aquifers are both vital and vulnerable. They respond quickly to environmental changes, and pollutants can spread rapidly through their distinctive underground networks. Because water moves so fast and through unpredictable pathways, it’s hard to know how long contaminants will persist or where they’ll go. Understanding them is key to ensuring safe drinking water and protecting the ecosystems that depend on them.

What are the main sources of contamination in karst aquifers?

Contaminants come from both natural and human-made sources. Industrial chemicals, agricultural runoff, sewage, and land use changes are common threats. Even natural elements like arsenic or uranium can pose risks if they dissolve into groundwater. Due to the thin soils and fast-moving water in karst aquifers, there’s little time or space for these pollutants to be filtered or degraded before they spread (Figure 1).

How do scientists monitor for contamination in karst aquifers?

Scientists use tracer tests—adding a harmless dye or chemical to water and tracking where it goes—to map water flow. They also analyze natural “tracers” like isotopes or chemical signals already in the water. These techniques help us understand how fast water travels, how long it stays underground, and how different sources mix (Figure 2). This information is essential for predicting contamination risks, and support efforts to protect karst water resources.

Figure 2: Monitoring spatiotemporal distributions of contaminant plumes across the karst systems. Here, the acronyms Adv, Dis, and Diff refer to advection (or advective flow), dispersion, and diffusion processes, respectively. Sp (sorption) and Rc (chemical reaction) indicate the impact of retardation and reactive processes on the movement of solute plume. In the figure, C0 and C refer to the initial solute concentration and the concentration of solute at a given time, respectively. Here, ti indicates the first detection time of solute of interest (e.g., at the observation well) and tobs refers to the observed concentrations at the time of interest. In the figure, the two-way red arrows indicate the solute/mass exchange between the conduit and the matrix. Credit: Çallı et al. [2025], Figure 3

What kinds of models are being developed to track the movement of contaminants within karsts?

Researchers are developing computer models that simulate how water and contaminants move through the complex karst network. These models range from simplified, large-scale representations to detailed simulations of karst flow through conduits and fractures (Figure 3). They help us explore different scenarios—like how a pollutant might spread after a flood or how land use changes affect water quality. Therefore, they are essential for effectively managing karst water quality and planning pollution prevention strategies.

Figure 3: Generic classification of karst simulation models based on the model parametrization considering process complexity and data requirement. a) Conceptualization of the karst aquifer physical boundaries depicted by the grey-shaded area with a blue-indicated karst conduit and conduit network (the blank circles also describe the swallets/sinkholes along the conduit network), b) Spatially lumped karst simulation models depicted based on the solute concentration distribution over different karst compartments including epikarst, conduit, and matrix, c) Spatially distributed karst simulation models described considering the spatial distribution of the solute concentration. The classification is adapted from Hartmann et al. [2014]. Herein, a tracer test is described only to demonstrate the spatial distributions of contamination plume across two main karst simulation approaches. Credit: Çallı et al. [2025], Figure 9

What are some of the challenges of karst transport modeling?

The biggest challenge is heterogeneity—karst systems are incredibly variable at all scales. We often lack detailed data on the shape of the underground conduits, flow speeds, or chemical conditions. This makes it difficult to build reliable models. Even small changes in how water moves can greatly affect contaminant behavior, so improving model accuracy is a major research focus.

What additional research, data, or modeling efforts are needed to overcome these challenges?

We need better field data—from tracer tests, groundwater monitoring, and mapping—to calibrate and validate models. Advances in remote sensing and machine learning also offer new tools. Future research should focus on integrating hydrological, chemical, and biological processes and on translating model results into actionable decisions. Collaboration across disciplines is key to (better) understanding, managing, and protecting karst water resources in a changing world.

—Kübra Özdemir Çallı (kuebra.oezdemir_calli@tu-dresden.de, 0000-0003-0649-6687), Institute of Groundwater Management, TU Dresden, Germany; and Andreas Hartmann (andreas.hartmann@tu-dresden.de, 0000-0003-0407-742X), Institute of Groundwater Management, TU Dresden, Germany

Citation: Çallı, K. Ö., and A. Hartmann (2025), Groundwater pollution in karst regions: toward better models, Eos, 106, https://doi.org/10.1029/2025EO255022. Published on 22 July 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.

Source: AGU Advances

As temperatures, biodiversity losses, and sea levels rise globally, scientists are concerned about the likelihood of abrupt climatic shifts occurring, particularly within sensitive subsystems of the climate system such as the Amazon rainforest, Antarctic sea ice, and the Tibetan Plateau. Abrupt shifts can manifest as, for example, large and sudden changes in the rate of precipitation in a monsoon system, ice melt in Antarctica, or permafrost thaw in the Northern Hemisphere.

Terpstra et al. sought to identify abrupt shifts that might occur in the future, focusing on climate subsystems discussed in the 2023 Global Tipping Points Report. The team examined outputs from 57 models from the Coupled Model Intercomparison Project Phase 6 (CMIP6). All the models simulated a climate change scenario over 150 years, with carbon dioxide concentration increasing by 1% annually until it reached 4 times preindustrial levels.

They then applied a method called Canny edge detection, which was originally created to identify edges in computer images, to the modeled climate data. In this case, they used it to detect edges, or points in time and space, where abrupt changes occurred within a decade across 82 variables, such as sea surface salinity, soil moisture content, and carbon mass in vegetation and soil. Prior research used a similar method to scan for edges in climate data, but not at the subsystem scale.

Although the researchers observed large variations among the model scenarios, 48 of the 57 showed an abrupt shift in at least one subsystem over the modeled period. Monsoon systems were outliers: Only one model indicated an abrupt shift in the Indian summer monsoon, and none indicated abrupt shifts in the South American and West African monsoons.

They also found that the more global warming a model simulated, the higher the likelihood was of abrupt shifts happening. At 1.5°C above average preindustrial temperatures, the target limit set by the Paris climate agreement, the researchers found that 6 out of 10 studied climate subsystems showed large-scale abrupt shifts across multiple models. (AGU Advances, https://doi.org/10.1029/2025AV001698, 2025)

—Sarah Derouin (@sarahderouin.com), Science Writer

Citation: Derouin, S. (2025), Abrupt climate shifts likely as global temperatures keep rising, Eos, 106, https://doi.org/10.1029/2025EO250270. Published on 22 July 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.

Lightning has a greater impact on forests than previously thought. Researchers at the Technical University of Munich (TUM) have developed new model calculations that, for the first time, estimate the global influence of lightning on forest ecosystems.

Loretta Mickley first started thinking about smoke in the summer of 2002.

Located about 3 miles offshore and 5 miles north of the Naval Postgraduate School is a first-of-its-kind ocean-sensing buoy. With 5G technologies and solar panels built in, the buoy has the capabilities to collect oceanographic and meteorological data 24 hours a day, seven days a week for the next three years.

SummaryIncorporating anisotropy in seismic imaging is important to produce correct locations and amplitudes of subsurface reflectors. The pure quasi-P-wave equation has a good accuracy to describe wave propagation in the anisotropic media, but it requires complicated computation strategies. To mitigate this issue, we present a novel pure quasi-P-wave equation in the vertical transverse isotropic (VTI) media with a nonlinear scalar operator, which is determined by the anisotropic parameters and the phase-velocity vector. Inaccurately calculating the directions of wave propagation results in incorrect phase-velocity vector and accumulated simulation error. Here, we utilize the optical flow to accurately calculate the direction of wave propagation while maintaining computational efficiency. Then, we optimize the wavefield simulation workflow and accelerate the calculation of optical flow. Numerical experiments show that the proposed wavefield simulation method can accurately describe wave propagation in the VTI media with good computational efficiency. Finally, we apply the proposed method to reverse-time migration to correct the anisotropic effects in seismic imaging. Numerical tests for benchmark models and a land survey demonstrate the feasibility and adaptability of the proposed method.