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Source scaling of earthquakes in and around the North Anatolian Fault Zone based on coda-derived source spectra: Toward a more accurate and unbiased Mw catalogue

Geophysical Journal International - Tue, 04/28/2026 - 00:00
SummaryMoment magnitude (Mw) is a widely accepted magnitude scale as a direct physical measure of the long-period seismic energy released at the foci, and thus its reliable quantification is of great importance for accurate probabilistic seismic hazard assessment (PSHA) studies. Yet, a robust estimation of Mw and radiated energy (ER) over a wide range of magnitudes is difficult, mainly due to the existing strong lateral heterogeneous nature of the crust. Furthermore, converting short-period magnitudes such as local magnitude (ML) to Mw can often lead to significant bias. To address this issue, we employ a coda envelope-based source spectral method, which depends on a regional empirical calibration approach that can lower the threshold for reliable Mw and ER estimates. To achieve this aim, we analysed horizontal component waveforms recorded at broadband stations operated by the Kandilli Observatory and Earthquake Research Institute and the Disaster and Emergency Management Presidency from 51 selected moderate local and regional earthquakes (ML ≥ 4.0) that occurred between 2013 and 2024 in and around the central North Anatolian Fault Zone (CNAFZ), including the 23 November 2022 Mw 6.0 Düzce and the 18 April 2024 Mw 5.6 Tokat events. The Java-based Coda Calibration Tool (CCT) implemented on these waveforms enabled a successful establishment of the coda-derived source spectrum that allowed us to obtain robust estimates of apparent stress (σA) and Mw across the CNAFZ. Following the calibration with reference events, we extend reliable magnitude estimation to smaller earthquakes (3.5 ≤ ML < 4.0), confirming robust predictions. Beyond providing a more thorough event catalogue in the CNAFZ, our results reveal low σA levels, comparable to those reported in recent studies in the Marmara Sea, and indicate non-self-similar rupture behaviour that may improve future regional seismic hazard assessments. This approach may also serve as a framework for reliable small-to-moderate earthquake analysis in other tectonically active regions in Türkiye, thereby supporting broader seismic risk management efforts.

Computational geodynamics to model mantle convection and magma oceans with the Thermal Lattice Boltzmann Method and strong scaling on exascale clusters

Geophysical Journal International - Tue, 04/28/2026 - 00:00
SummaryThe Thermal Lattice Boltzmann Method (TLBM) offers an alternative to classical PDE based numerical methods for modelling planetary dynamics. It solves the Lattice Boltzmann Equation on a unitary discrete lattice which requires no matrix operations, and hence scales extremely well on HPC clusters. We describe the TLBM equations which are capable of modelling solid state mantle convection and turbulent magma ocean dynamics, and we present how to obtain the physical (dimensional) time scale from the lattice time scale (number of time steps), convert quantities in physical (dimensional) units (η, κ, σ…) to unitary (dimensionless) lattice units, and strong scaling performance in 3D to 300K cores. We present examples to illustrate use of the TLBM to model plate tectonics, 2D and 3D mantle convection, turbulent magma ocean dynamics, and planetary accretion. We present a table of run times which demonstrate the TLBM’s high throughput performance. The TLBM’s performance enables 3D global convection modelling of the whole mantle on a lattice with up to ∼2 × 1011 grid points corresponding to a resolution of 3 km, and magma ocean dynamics modelling into the ultimate turbulent regime of Ra ≳ 1014, to at least Ra = 1015 (demonstrated to date in 2D for an aspect ratio of 1), and projected to be possible up to Ra = 1018 in 2D or Ra = 1015 in 3D for low aspect ratio models. The TLBM is fast and makes it possible to run huge models which opens exascale computing to planetary dynamics research. We believe that the TLBM provides a valuable new means to advance geodynamical research into the future by enabling fast and high-resolution planetary dynamics simulations including of global mantle convection, magma ocean dynamics into the ultimate turbulent regime, and planetary accretion.

An unprecedented Antarctic heat wave hit in the dead of winter—what it signals for the decades ahead

Phys.org: Earth science - Mon, 04/27/2026 - 23:40
In the middle of the Antarctic winter, during months of darkness when temperatures often dip below −30°C, the continent warmed dramatically. In July and August 2024, temperatures in parts of East Antarctica rose by up to 28°C above average and stayed high for more than two weeks. To put that in perspective, a similar anomaly in the UK would push January temperatures into the mid-30°Cs.

Simulations predict ground motion for earthquakes on Bay Area's Hayward fault

Phys.org: Earth science - Mon, 04/27/2026 - 22:20
The Hayward fault, part of the larger San Andreas fault system, runs 74 miles through the East Bay of the San Francisco Bay Area. The fault is overdue for an earthquake that could cause extensive damage to such a dense population zone.

Rivers worldwide reveal greenhouse gas rise that's been overlooked for decades

Phys.org: Earth science - Mon, 04/27/2026 - 21:20
Rivers worldwide are under severe stress: they are warming, losing oxygen, and as a result emitting increasing amounts of greenhouse gases. Researchers at Karlsruhe Institute of Technology (KIT) have now quantified these global trends over a period of more than two decades. Their results show that rising temperatures and anthropogenic land use are fundamentally transforming river systems, with serious consequences for the climate. The findings have been published in Global Change Biology.

Offshore winds identified as a culprit in coastal floods, research finds

Phys.org: Earth science - Mon, 04/27/2026 - 21:00
A Florida International University student has exposed a hidden driver of coastal flooding, and it could help improve warning systems for entire communities. Earth and Environment Ph.D. student Dafrosa Kataraihya's latest research, published in Natural Hazards, shows that winds hundreds of miles away are a culprit of coastal flooding.

How climate change affects nutrient dynamics in lakes and reservoirs

Phys.org: Earth science - Mon, 04/27/2026 - 19:20
Changes in nutrient dynamics caused by rising water temperatures and altered stratification patterns due to climate change are promoting the growth of harmful algal blooms. This is the outcome of a new long-term study led by the University of Bayreuth and conducted in the Franconian Lake District. The researchers report their findings in the journal Water Resources Research.

Amazon safeguards cut deforestation but miss rising forest degradation threat

Phys.org: Earth science - Mon, 04/27/2026 - 19:00
Antonio has spent the past seven years running toward fires that most others run from. A firefighter in the Brazilian Amazon since 2019, he works inside the Chico Mendes Extractive Reserve, one of the most biodiverse places on Earth. But things are changing, and fast. "2024 was the most extreme year for fires," Antonio said. "I had never seen anything like it. The forest burned like dry pasture—it was frightening for those of us who risk our lives to protect it."

Brazil's farm expansion has left a vast soil carbon debt—but one fix could help meet climate goals

Phys.org: Earth science - Mon, 04/27/2026 - 16:00
The conversion of Brazil's native biomes into agricultural areas has resulted in an estimated loss of 1.4 billion tons of soil carbon. This amount is equal to the emission of 5.2 billion tons of carbon dioxide (CO₂) equivalent, a unit of measurement used to standardize the emission of different greenhouse gases, and was calculated based on data collected from studies conducted over the past 30 years.

Trump Terminates Entire National Science Board

EOS - Mon, 04/27/2026 - 14:44
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 Trump Administration has terminated the positions of every member of an independent board meant to govern the National Science Foundation (NSF).

The National Science Board directs and approves large funding decisions for NSF’s approximately $9 billion basic science research budget. It is meant to function independently from the federal administration to keep science funding insulated from political pressure and budget cycles.

“I have watched the systematic dismantling of the scientific advisory infrastructure of this government with growing alarm, and the National Science Board is simply the latest casualty.”

In a 24 April notice from the Presidential Personnel Office, all the scientists serving on the board were informed their positions had been eliminated. The emails dismissing board members provided no reason for the termination.

“I am deeply disappointed, though I cannot say I am entirely surprised,” Willie E. May, one of the terminated board members and vice president of research and economic development at Morgan State University in Maryland, told The New York Times

“I have watched the systematic dismantling of the scientific advisory infrastructure of this government with growing alarm, and the National Science Board is simply the latest casualty,” he said. 

Ranking member of the House Committee on Science, Space, and Technology Zoe Lofgren (D-CA) called the terminations “the latest stupid move made by a president who continues to harm science and American innovation.”  

 
Related

The terminations come after a year that shocked higher education and research budgets. Last year, NSF granted 51% less funding to scientists than the 2015-2024 average and terminated hundreds of active grants. Last May, the Trump administration proposed cutting $5 billion from NSF’s budget, though the proposal was rejected. The president’s budget request for fiscal year 2027 once again proposes to reduce the foundation’s budget by more than half. In a February 2026 meeting of the National Science Board, NSF leadership said the foundation was seeking to reduce grant solicitations.

The Trump administration has also restructured scientific advisory groups elsewhere in the federal government, eliminating 152 federal advisory committees at science agencies, merging all of the Department of Energy’s advisory committees into one and dismantling the Environmental Protection Agency’s research office.

“Without a functional National Science Board in the near term, the agency is left without the guidance and oversight of independent experts, and the public is left without information on how NSF is carrying out its mission,” Gretchen Goldman, president and CEO of the Union of Concerned Scientists, wrote in a blog post about the terminations. 

—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 © 2026. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Tracing the Path of PFAS Across Antarctica

EOS - Mon, 04/27/2026 - 13:16
Seeking Solutions to PFAS Pollution Chemical Companies Are Churning Out New PFAS. Where in the World Are They Ending Up? The Persistence of PFAS A Peculiar Polymer Paired with Sunlight Could Remove PFAS Tracing the Path of PFAS Across Antarctica Pollution Is Rampant. We Might As Well Make Use of It.

Per- and polyfluoroalkyl substances (or PFAS) have been widely used in thousands of common nonstick, waterproof, or stain-resistant products since the 1950s. These “forever chemicals” do not break down easily: PFAS make their way into the air, soil, and water, as well as into human and animal bloodstreams and to some of Earth’s most pristine environments. They have been detected even in Antarctica, despite its reputation as a relatively untouched landscape far from the types of products—fast-food wrappers, firefighting foam, nonstick cookware—that contain PFAS.

Research into how PFAS arrive in Antarctica is limited, and most tends to focus on the continent’s coasts, rather than its interior. A new study published in Science Advances aimed to fill some of these gaps by examining PFAS accumulation across a 1,200-kilometer stretch of Antarctica, from the snow pits of Zhongshan Station in East Antarctica to the 4,093-meter peak of Dome A. By examining layers of snow collected from the coast to the interior, researchers sought to better track and understand how PFAS levels vary by location and how these forever chemicals have been able to travel long distances through the upper atmosphere to be deposited in remote regions.

“For substances to get there, they have to be able to transport long distances,” said Ian Cousins, a chemist at Stockholm University and one of the study’s authors. “We know PFAS are very persistent, so that helps. By looking at the patterns of the PFAS contamination in the samples, it gives us clues as to how they’re transported.”

PFAS Arrive by Air and by Sea

Along the 1,200-kilometer route, researchers from the Chinese Academy of Sciences collected 39 snow samples at 30-kilometer intervals, scraping the first few centimeters of snow from the surface to analyze for traces of PFAS.

Zhongshan Station sits near Prydz Bay, and there, researchers collected snow from a 1-meter-deep pit, with samples taken every 5 centimeters. At Dome A, the summit of the East Antarctic Ice Sheet, samples were collected at 10-centimeter intervals from another snow pit; this one was 3 meters deep, providing information about the past several decades of PFAS use.

“It’s quite interesting that we see the historical production record of PFAS in this pit on the top of this mountain in Antarctica,” said Cousins.

PFAS pollution arrives in Antarctica in two ways: via upper atmospheric transport and sea spray. Some PFAS are formed in the atmosphere when volatile precursor chemicals like fluorotelomer alcohols used in textile and paper products break down through reactions with sunlight and oxidants into more stable compounds. The resulting PFAS are later deposited into the snow and ice through precipitation.

Storm winds near the coast create sea spray. “When you have waves, it makes bubbles in the ocean. When the bubbles burst, these sea spray aerosols can be super enriched with PFAS. This has been shown to be a very important transport route,” Cousins said.

To distinguish between sources, researchers measured sodium in the snow to trace the ocean’s salty influence. Sodium levels decreased farther inland, reflecting the fading influence of sea spray toward the interior of the continent. But surprisingly, PFAS concentrations actually increased moving from the coast into the interior.

“That was kind of a bit counterintuitive to me,” explained Cousins, who said he expected PFAS levels to be highest near the coast. “You see the opposite, actually.”

The inland increase is likely explained by higher snowfall totals in the coastal regions, which lead to PFAS concentrations becoming diluted. Inland, where snowfall is lower, even small amounts of PFAS can result in relatively higher concentrations within snow samples.

Additional factors shape PFAS distribution. PFAS levels are higher at the onset of precipitation events when they are rapidly removed from the air. Temperature inversions, too, can trap chemicals. In coastal areas, PFAS are more influenced by sea spray in the winter, whereas stronger sunlight drives the degradation of atmospheric precursors into PFAS in the summer months.

PFAS Presence at Both Poles

This new study also offers implications for the way that PFAS circulate globally. Though industrial activity in the Northern Hemisphere contributes most heavily to PFAS emissions, large-scale atmospheric circulation allows these compounds to reach polar regions. Rapid transport in the upper troposphere may act as an efficient pathway to shuttle PFAS across both hemispheres before they are deposited in the cold, remote regions at both ends of Earth.

“This completes the global picture with agreeing measurements at both poles, solidifying our understanding of the global distribution and drivers of PFAS contamination.”

Even though PFAS levels are higher in the Arctic, both polar regions show similar trends in PFAS concentrations since the 1990s. “It really matches decades of the same records that have been reported from the Arctic,” said Cora Young, an atmospheric chemist at York University, who was not involved in the new study.

“This completes the global picture with agreeing measurements at both poles, solidifying our understanding of the global distribution and drivers of PFAS contamination. The role of CFC [chlorofluorocarbon] replacements, changes in regulation, all of these things are important in the Northern Hemisphere and also the Southern Hemisphere,” said Young.

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

Citation: Owen, R. (2026), Tracing the path of PFAS across Antarctica, Eos, 107, https://doi.org/10.1029/2026EO260129. Published on 27 April 2026. Text © 2026. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Enhancing the reliability of Dst prediction interval with uncertainty matching technique using machine learning

Publication date: Available online 20 April 2026

Source: Advances in Space Research

Author(s): R. Chen, J. Yang, Z. Huang

Investigating Temporal Variability in Blazars: A Comparative Study of Characterization Methods

Publication date: Available online 20 April 2026

Source: Advances in Space Research

Author(s): M.A. Hashad, A.M. Elazab, N.M. Ragab, T. Sharshar, H.M. Badran

Leaders and associated space debris around the Classical Laplace Plane

Publication date: Available online 17 April 2026

Source: Advances in Space Research

Author(s): Elvis Lacruz, Daniel Casanova

Long-Term Atmospheric Dynamics: Air Temperature Inversion Trends at King Abdulaziz Airport (Jeddah, Saudi Arabia), a High-Traffic Aviation Center

Publication date: Available online 17 April 2026

Source: Advances in Space Research

Author(s): Maghrabi Abdullrahman, Abdulah Al-Dosari, Mohammed Altlasi, Alsherhri Abdulah, Maohammed Almutairi

Effects of Radiation Induced Optical Degradation on Earth Bound Solar Sail Manoeuvring Capabilities

Publication date: Available online 17 April 2026

Source: Advances in Space Research

Author(s): Oliver Hetherington, Livio Carzana, Erik Klein, Pieter Visser, Patric Seefeldt, Jeannette Heiligers

A new model of the Ajisai spin axis motion derived from the photometric patterns

Publication date: Available online 17 April 2026

Source: Advances in Space Research

Author(s): L. Shakun, N. Koshkin, E. Korobeynikova, S. Melikyants, S. Strakhova, V. Dragomiretsky, V. Marsakova, A. Ryabov, S. Terpan

Venice is sinking. We analyzed every plan to save it, and none would preserve the city as we know it

Phys.org: Earth science - Sat, 04/25/2026 - 19:30
Venice has coexisted with the sea throughout its 1,500-year history, perhaps better than any other city on Earth. Yet over the past century it has flooded increasingly often, as the sea rises and the city itself sinks under its own weight.

Transdimensional ambient-noise tomography of the Zabargad Fracture Zone, Red Sea

Geophysical Journal International - Sat, 04/25/2026 - 00:00
SummaryThe Red Sea is one of the youngest ultraslow-spreading ridges on our planet and an ideal place to investigate the transition from continental rifting to oceanic spreading. Within this context, the Zabargad Fracture Zone (ZFZ) stands out as a particularly intriguing region. The ZFZ hosts notable features, including an offset in the Red Sea spreading axis, the Mabahiss Mons submarine volcano, and the Kebrit Deep brine pool. Additionally, this region is seismically active, posing a hazard to nearby coastal communities. Despite previous geophysical studies, few seismic velocity models image shallow subsurface structures in the ZFZ. In this work, we use approximately one year of seismic ambient noise recorded by five broadband stations and 14 ocean-bottom seismometers to estimate the shear-wave velocity structure of the ZFZ. For this, we compute vertical-vertical, radial-radial, and transverse-transverse noise correlations, obtain group- and phase-velocity dispersion curves of Rayleigh and Love waves in the 3 to 12 s period band, and employ transdimensional tomography to estimate 1-D and 3-D isotropic shear-wave velocity models of the ZFZ. Our 1-D velocity model suggests that, on average, the ZFZ crustal structure comprises a 1.5 km thick layer including hemipelagic sediments and evaporites, a 2.8 km thick oceanic basement, and a crust-mantle transition extending from 6.5 to 8 km below sea level. Meanwhile, our 3-D model agrees with previous geological and geophysical observations and reveals new subsurface structures. In particular, it shows low velocity areas to the east and south of Mabahiss Deep that correlate with known sedimentary basins. Moreover, our 3-D model contains a low-velocity area near Kebrit Deep that correlates with a region of low seismic activity and a recently inferred spreading-axis segment. Based on previous evidence of inactive hydrothermal vents, we infer that this low-velocity area indicates higher basement temperatures near Kebrit Deep compared to other areas. Lastly, our 3-D model displays a velocity contrast in the southern ZFZ that correlates with a contrast in free-air gravity anomalies and a gradient in evaporite topography. Based on these observations, we interpret this velocity contrast as a lineament related to folded evaporites. Our findings present new constraints on the crustal structure of the ZFZ and serve as a reference for other young ultraslow-spreading ridges.

Human-altered estuaries now drive stronger tides farther inland

Phys.org: Earth science - Fri, 04/24/2026 - 19:40
A study led by Wageningen University & Research shows that human interventions have significantly changed tides in river estuaries over the past centuries. In many regions around the world, the difference between high and low tide has increased, and the tidal wave is moving inland faster. These changes often appear to have a greater impact than the effects of sea-level rise.

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