Feed aggregator

Gravity with an “Edge”: What Lies Beneath Aristarchus Crater

EOS - Mon, 09/15/2025 - 12:00
Editors’ Highlights are summaries of recent papers by AGU’s journal editors. Source: Earth and Space Science

The surface of the Moon hides a complex and varied geology underneath. To unravel the Moon’s rich geological history, we rely on geophysical data acquired over decades of lunar missions. However, processing and interpretation of the remotely acquired data is not straightforward. Hence, new and sophisticated methods of processing and analyzing data are needed to extract the information necessary to detect and define lunar subsurface structures.

Ai et al. [2025] apply a new method combining an edge-detection algorithm, noise reduction techniques, and 3D inversion with high resolution gravity data from the Gravity Recovery and Interior Laboratory (GRAIL). The new approach allows them to sharply define the location and shape of a negative gravity anomaly beneath the Aristarchus Crater (the brightest feature on the Moon, located in Oceanus Procellarum, or “Ocean of Storms”). It confirms a complex geological setting involving crustal relief, fracturing caused by the impactor that formed the crater, dilation, and uplift of a volcanic unit. This study is important because it demonstrates a new method that will be useful to other researchers working on the Moon, and it advances our knowledge of lunar geology.  

Density contrast between subsurface masses in the subsurface of Aristarchus Crater. The distinction between negative anomaly (blue) and positive anomaly areas emerges very clearly, representing different geological processes.  The panels on the right indicate the performance of the models. Credit: Ai et al. [2025], Figure 21

Citation: Ai, H., Huang, Q., Ekinci, Y. L., Alvandi, A., & Narayan, S. (2025). Robust edge detection for structural mapping beneath the Aristarchus Plateau on the Moon using gravity data. Earth and Space Science, 12, e2025EA004379. https://doi.org/10.1029/2025EA004379

—Graziella Caprarelli, Editor-in-Chief, Earth and Space Science

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.

Generation of a 100-PW near-circularly-polarized attosecond x-ray pulse in the QED regime

Physical Review E (Plasma physics) - Mon, 09/15/2025 - 10:00

Author(s): Meiqi Sun, Ze Chen, Lipan Qin, Zhongyi Chen, Yan Tian, Jin Yan, Yan Wang, Xunjie Ma, Xueqing Yan, and Yunliang Wang

An ultraintense, isolated circularly polarized (CP) attosecond x-ray pulse is often required for many application of pump-probe techniques. A quantum electrodynamics (QED) effect dominated coherent synchrotron emission (CSE) regime is proposed for the generation of an ultraintense isolated, nearly C…


[Phys. Rev. E 112, 035207] Published Mon Sep 15, 2025

How the death of the dinosaurs reengineered Earth

Phys.org: Earth science - Mon, 09/15/2025 - 09:00
Dinosaurs had such an immense impact on Earth that their sudden extinction led to wide-scale changes in landscapes—including the shape of rivers—and these changes are reflected in the geologic record, according to a University of Michigan study.

A physical interpretation of Cole-Cole equations and their ambiguous time constants for Induced Polarization models

Geophysical Journal International - Mon, 09/15/2025 - 00:00
SummaryThe Cole-Cole (CC) equation was introduced as an empirical formula that in many cases matched laboratory measurements of dispersive frequency-dependent dielectric, conductive or resistive physical properties. The CC formula has four parameters, a high and low frequency limit, one of which is often normalised into a polarizability η or a chargeability m, a time constant τ and a frequency dependence c. The chargeability can be directly related to the volume fraction of polarizable material in a uniform conductive background. In an electrically resistive host, the chargeability is given by the fraction of pores blocked by sulphides or other electronically conductive polarizers in the Pelton conceptual model. Fundamentally, an electrochemical model predicts that uniformly sized, non-reactive polarizers would produce exponential or Debye decays during the return to equilibrium after excitation, while uniformly-sized, chemically-reactive materials such as sulphides should exhibit Warburg decays. Numerically, the frequency dependence c can be matched and predicted from the standard deviation of a log-normal size distribution of polarizable material. Using a simple circuit analogy, excitation by a Voltage or a Current source can produce very different decay time-constants. This analogy and mathematical analysis predict that the time constants from fitting a CC conductivity model (${{\tau }_\sigma }$) can be very different from a CC resistivity model (τρ). A published laboratory sulphide measurement example with ${{\tau }_\rho }$ = 10 days, m = 0.96 and c = 0.2 corresponds to ${{\tau }_\sigma }$ = 88 ms, or 7 orders of magnitude shorter in time. Further, the physical circuit analogy confirms the electrochemical model that while the different time constants are mathematically independent of m and c, ${{\tau }_\sigma }$ is an intrinsic time-constant fundamentally related to the grain size of polarizable material and as such a far better parameter than τρ to use for mineral discrimination studies. Published tabulations of fitted parameters need to specify c as well as the chargeability and CC time-constant to allow for transformation between conductivity and resistivity time-constants. The maximum phase time constant ${{\tau }_\phi } = \sqrt {{{\tau }_\sigma }{{\tau }_\rho }} $ is a fitting rather than experimentally measurable parameter, that is still dependent on m and c, but less dependent than ${{\tau }_\rho }$ as previously discussed in the literature.

Geodetic Observations Revealing Crustal Deformation and Tectonic Transition in the Northeastern Nam Co Region, Southeastern Tibetan Plateau

Geophysical Journal International - Mon, 09/15/2025 - 00:00
SummaryThe northeastern Nam Co region, historically impacted by significant earthquakes such as the 1951 Ms 8.0 Beng Co and 1952 Ms 7.5 Gulu events, exhibits intricate crustal deformation patterns shaped by strike-slip and extensional fault systems. This study integrates multi-source geodetic data to analyze three-dimensional deformation patterns and fault interaction. In this region, we established 16 new GNSS campaign-model observation stations. By aligning these with existing GNSS data within a unified reference frame, we obtained a high-resolution horizontal velocity field. Additionally, ascending and descending InSAR deformation velocity fields were derived utilizing Sentinel-1A data and SBAS-InSAR technology. By fusing the GNSS and InSAR velocity fields, we extracted and analyzed the three-dimensional deformation velocity field. Utilizing an enhanced back-slip dislocation model that accounts for fault dip angles, we inverted the slip behaviors of three major faults and investigated their tectonic transition patterns. The deformation field reveals distinct kinematic behaviors among these faults. Specifically, the Beng Co fault demonstrates dextral strike-slip motion, increasing from 4.8 ± 0.1 mm/yr in west to 5.4 ± 0.1 mm/yr east, accompanied by thrusting at a rate of 3.5 ± 0.1 mm/yr. Notably, the locking depths deepen eastward from 12.6 ± 0.6 km to 17.4 ± 0.8 km. In contrast, the Dong Co and northern Yadong-Gulu faults exhibit sinistral strike-slip rates of 1.0 ± 0.1 mm/yr and 4.2 ± 0.1 mm/yr, respectively, paired with maximum extensional rates of 2.0 ± 0.3 mm/yr and 5.2 ± 0.5 mm/yr. Collectively, these faults form a stable strike-slip to extension coupled system, modulating regional crustal deformation through kinematic interactions. This study quantifies a tectonic transition model, elucidating how strike-slip faulting evolves into extensional structures in central Tibetan Plateau. Our findings contribute to a deeper understanding of strain partitioning and intracontinental deformation mechanisms within the central Tibetan Plateau.

Editorial Board

Publication date: October 2025

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 275

Author(s):

Absorbing and scattering aerosols over semi-arid region in India: Temporal variation and possible sources

Publication date: October 2025

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 275

Author(s): Pawan S. Soyam, Pramod D. Safai, Shivdas Bankar, Kiran Todekar, Neelam Malap, Sunil Kondle, Pradeep Zambare, Mahendra Mane, Sanjay S. Kale, Thara Prabhakaran

Forecasting near-surface air temperature via SARIMA and LSTM: A regional time-series study

Publication date: October 2025

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 275

Author(s): Muhammed M. Aksoy, Md. Najmul Mowla, Mehmet Bilgili, Engin Pinar, Tahir Durhasan, Davood Asadi

Automatic Detection of Sunspots on full-disk continuum images using the MiniMax Optimization and Feature Extraction

Publication date: October 2025

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 275

Author(s): Madhan Veeramani, Sudhakar M.S.

Ionospheric TEC prediction in low-latitude Indian region during geomagnetic storm periods based on XGBoost with optuna framework and comparison with IRI-Plas 2020

Publication date: October 2025

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 275

Author(s): T. Muthukumaran, R. Mukesh, S. Kishore Kumar, Andrew F. Jude, J. Kenisha, G. Cynthia, S. Logesh, Sarat C. Dass, S. Kiruthiga

Assessing the accuracy of classic meteorological models: GPT3, HGPT2, and PVoxel with global radiosonde data

Publication date: October 2025

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 275

Author(s): Haopeng Hu, Pengfei Xia, Xianjie Li, Shirong Ye

Novel real-time detection method of cycle slips using ultra-high rate GNSS observations in urban environments

Publication date: October 2025

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 275

Author(s): Shengyue Ji, Qixiang Peng, Ying Xu, Jing Wang, Duojie Weng, Wu Chen, Huan Luo

Evolution and decay of a stable and a dynamic airglow patch

Publication date: October 2025

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 275

Author(s): Nina K. Eriksen, Yukitoshi Nishimura, Matthew Zettergren, Dag A. Lorentzen, Kjellmar Oksavik, Lisa J. Baddeley, Keisuke Hosokawa, Kazuo Shiokawa, Leslie Lamarche, Mark E. Redden, Asti Bhatt

Input Excitation-Based Refined Hysteresis Identification and Compensation for Piezoelectric Actuators of Satellites

Publication date: Available online 30 August 2025

Source: Advances in Space Research

Author(s): Zeyu Bao, Yi Deng, Weipeng Li, Yangyang Cui

Induced Seismic Swarm Triggered by Tunnel Excavation and Pore Pressure Diffusion Mechanism

Geophysical Journal International - Sat, 09/13/2025 - 00:00
SummarySeismic activity induced by underground engineering projects often involves complex causal mechanisms, and represents significant hazards, including ground subsidence, disruption of surface and underground water systems, ecological damage, structural damage to buildings, and even casualties. Consequently, induced seismicity has become an important topic in the risk assessment and protective measures for underground engineering projects. During the construction of the Hongtu Tunnel on the Dafenghua Expressway in Guangdong, China, a series of earthquakes occurred nearby, with the biggest of magnitude ML = 3.7, alongside significant water inflows at multiple locations. This study analyzed seismic network data from 2017 to 2022 around the tunnel area to investigate the potential relationship between the seismic swarm and tunnel construction and uncover the underlying mechanisms. After velocity model corrections and double-difference relocation, the earthquakes were primarily distributed at depths of 1∼4 km. Three concealed, steeply dipping NE-trending faults, each 3∼7 km in length, were identified based on the earthquake distribution. The swarm began about one month after the onset of water inflows in the tunnel and grew significantly after the peak daily inflow, culminating in the ML 3.7 mainshock. A strong spatiotemporal correlation was observed between the seismic swarm and the water inflows. During the first year of the swarm, the seismicity displayed migration characteristics consistent with pore pressure diffusion, with an initial diffusion depth of approximately 2 km and a diffusion rate of 0.0039∼0.0446 m²/s, and best fit by the classical parabolic diffusion model (α = 0.5). After 2021, the earthquakes occurred more consistently, mainly exhibiting stress-triggering characteristics. Over time, the seismicity gradually extended to greater depths, with focal mechanisms changing from normal faulting to strike-slip faulting. The local stress field shifted from extensional to shear, which reflected the sustained influence of pore pressure diffusion on fault activation. Fluid diffusion not only initially activated the faults but also promoted repeated fault slip during the seismic swarm, indicating that prolonged water inflow significantly altered fault activity patterns and the regional stress field. This study is the first to reveal the phenomenon of long-distance induced seismicity caused by tunnel water inflow and the role of pore pressure diffusion in triggering such events, which offers new insights into the safety of underground construction and the study of fluid-related geological processes.

EPA Proposes That Major Polluters No Longer Report Their Emissions

EOS - Fri, 09/12/2025 - 22:04
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.

The EPA proposed today that approximately 8,000 polluting facilities, including oil refineries, power plants, and steel mills, should no longer be required to report their greenhouse gas emissions.

Since 2010, the Greenhouse Gas Reporting Program has required that such facilities—spanning several dozen categories—report their emissions of greenhouse gases, such as carbon dioxide, to the government. The data is made public each October. According to the EPA’s own website, as it appeared today, the data can be used to “identify opportunities to cut pollution, minimize wasted energy, and save money,” as well as to “develop common-sense climate policies.”

 
Related

The EPA statement claimed that the reporting program “has no material impact on improving health and the environment.” EPA Administrator Lee Zeldin said in the statement that the program is “nothing more than bureaucratic red tape that does nothing to improve air quality.”

“Instead, it costs American businesses and manufacturing billions of dollars, driving up the cost of living, jeopardizing our nation’s prosperity and hurting American communities,” he said.

Environmental groups have pointed out that, without this data, regulations cannot be enacted to protect Americans from the harmful effects of greenhouse gas emissions and climate change.

“Some industries want to keep this secret so that the public can’t know who’s responsible and hold them to account,” David Doniger, a senior attorney at the Natural Resources Defense Council, told the Washington Post. “What the public doesn’t know, they can’t demand be regulated.”

The move is the latest of many moves by the Trump administration to reduce regulations surrounding greenhouse gas emissions and other environmental protections.

In June, for example, the EPA proposed repealing federal limits on power plant carbon emissions. In July, the agency proposed rescinding the 2009 Endangerment Finding, which found that greenhouse gas emissions threaten public health and welfare and has since underpinned the federal government’s efforts to mitigate climate change.

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

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.

NASA's GUARDIAN tsunami detection tech catches a wave in real time

Phys.org: Earth science - Fri, 09/12/2025 - 16:24
A massive earthquake and subsequent tsunami off Russia in late July tested an experimental detection system that had deployed a critical component just the day before.

Scientists respond to the planned termination of the only U.S. Antarctic research vessel

Phys.org: Earth science - Fri, 09/12/2025 - 14:20
On July 28, 170 researchers sent a letter to the National Science Foundation (NSF) and Congress after NSF's 2026 budget request included plans to end its lease of a U.S. research vessel in the Southern Ocean near Antarctica.

A pollution paradox: Wildfires in the western United States may improve air quality

Phys.org: Earth science - Fri, 09/12/2025 - 13:20
Climate change is driving more frequent and more intense wildfires around the world, including in the United States. These huge blazes cause a range of problems that affect health, the environment, property and the economy. However, a new study reveals a surprising paradox: the heat from wildfires in the western U.S. may actually improve air quality in the eastern part of the country.

Underwater Glacier-Guarding Walls Could Have Unintended Consequences

EOS - Fri, 09/12/2025 - 13:18
Source: AGU Advances

Warm water flowing into fjords and beneath ice shelves will continue to be a prime cause of glacial melting as global temperatures rise. This melting will, in turn, contribute to sea level rise and increasing inundation of coastal areas.

As emission reductions fall short of international goals, scientists and some members of the public are discussing possibilities for using geoengineering to mitigate coastal flooding and other detrimental effects of climate warming. One proposal involves building barriers in the ocean to block warm water from reaching glaciers. For example, some scientists have proposed placing a floating steel curtain or an underwater rock wall around parts of the Greenland ice sheet to limit the influx of warm, ice-melting currents.

Such barriers would be difficult to construct, and it’s not clear how effective they would be, Hopwood et al. point out in a recent commentary focusing on the potential effects of this method on Greenland’s largest glacier, Sermeq Kujalleq.

What’s more, underwater walls are likely to come with substantial downsides for marine ecosystems. Modeling suggests that such barriers would interrupt a process by which glacial runoff pulls nutrient-rich water up from the deep ocean. This disruption, in turn, would reduce phytoplankton levels near the surface and the fish populations that depend on them—ultimately affecting the Greenlanders that rely on these fish for their livelihoods. Walls might also disrupt fish migration patterns, adding to the problem. The side effects of underwater walls are “unlikely to be socially acceptable,” the authors write. Walls built to protect Antarctic glaciers would have similar effects on local ecosystems, they suggest.

The researchers note that although glacier-guarding barriers are both hypothetical and unrealistic at this point, interest in geoengineering is likely to grow in the coming decades. Thus, it is important to keep the unintended consequences of such projects in mind.

Some researchers have suggested that geoengineering approaches should be tested so that policymakers can assess their costs and benefits on the basis of real-world data. But before they seriously consider these techniques, write Hopwood and colleagues, it’s crucial that scientists have conversations with local stakeholders to understand how the potential trade-offs could affect their lives and livelihoods. (AGU Advances, https://doi.org/10.1029/2025AV001732, 2025)

—Saima May Sidik (@saimamay.bsky.social), Science Writer

Citation: Sidik, S. M. (2025), Underwater glacier-guarding walls could have unintended consequences, Eos, 106, https://doi.org/10.1029/2025EO250334. Published on 12 September 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.

Theme by Danetsoft and Danang Probo Sayekti inspired by Maksimer