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Nonempirical approximation for the ionic thermal contribution to the equations of state based on average-atom models

Physical Review E (Plasma physics) - Wed, 04/09/2025 - 10:00

Author(s): A. A. Ovechkin, P. A. Loboda, and P. A. Sapozhnikov

A simple nonempirical approximation is proposed to calculate the ionic thermal contribution to the average-atom equations of state. The approximation represents the main regularities of temperature and mass-density dependences of the ionic thermodynamic-function components revealed from the pseudoat…


[Phys. Rev. E 111, 045204] Published Wed Apr 09, 2025

Coseismic damage of the 2019 Ridgecrest earthquake consistent with Mohr-Coulomb failure

Geophysical Journal International - Wed, 04/09/2025 - 00:00
SummaryAccording to the classical Mohr-Coulomb-Anderson theory, faults form at an angle from the largest regional compressive stress that is approximately 30° for most rocks. However, real settings are more complex and faults often present orientations inconsistent with the angles predicted by the classical theory applied to the present-day regional stress field. The Ridgecrest region hosts a young fault system that is part of the Eastern California Shear Zone, and the 2019 earthquake sequence unveiled orthogonal ruptures at multiple scales, apparently at odds with the classical brittle failure model. We use the Ridgecrest region as a case study and compare surface ruptures that developed during the 2019 earthquake sequence to the expected orientations derived from classical faulting theory and to observations from rock experiments. We focus on the off-fault secondary fractures that developed coseismically at the northern termination of the mainshock fault. We calculate coseismic stress changes from published slip models superimposed to a background stress field. We find that a combination of tectonic regional stresses oriented with the largest compressive stress at N10E–N14E and very weak intensity of coseismic stresses best captures the orientation of off-fault fractures in the classical Mohr-Coulomb-Anderson framework, with an internal rock friction coefficient μ = 0.6. The secondary fractures also show a scale separation: long fractures are most compatible with shear failure, while short fractures cluster along the direction of the largest horizontal stress. The latter is compatible with either local normal faulting or early tensile failures that would later coalesce to form longer faults, consistent with growth of shear fractures in laboratory experiments. Finally, the different orientations of fractures that developed during and prior to the 2019 events suggest that the tectonic stress has rotated over geological timescales. When accounting for the specificity of the area, orthogonal faulting is thus compatible with brittle fracturing with typical experimental values of rock friction coefficient.

Weather Alert Translations on Hold Until Further Notice

EOS - Tue, 04/08/2025 - 20:53
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.

This month, the National Weather Service (NWS) announced that, until further notice, it will no longer be offering automated translation services for its severe weather alerts. These alerts warn U.S. residents about imminent dangers including thunderstorms, tropical cyclones, flooding, and extreme heat. The news was reported by Earth.org, The Washington Post, the Associated Press, and other outlets.

The agency attributed the change to a contract lapse with Lilt, an artificial intelligence company that worked with NWS forecasters to develop software that could accurately translate weather terminology into Spanish, simplified Chinese, Vietnamese, French, and Samoan.

The agency’s short announcement came on 1 April. Credit: NCEP/NWS

The agency’s product translation page states that the NWS “is committed to enhancing the accessibility of vital, life-saving information by making urgent weather updates available in multiple language.” However, it also notes that “changes or discontinuations may occur without advance notice.” A banner atop the page now reads, “The translated text production functionality on this site may be interrupted after 3/31/2025. Further details will be provided when available.”

 
Related

According to the U.S. Census Bureau, 67.8 million people in the United States speak a language other than English at home, including nearly 42 million Spanish speakers and more than 2 million French (including Patois, Cajun, Creole, and Haitian) speakers. The Census Bureau lists communication barriers, such as those that exist in households with limited English, as a measure of social vulnerability. Previous research has documented that a lack of translated emergency alerts, or poorly translated alerts, can leave communities uninformed, confused, and ultimately more vulnerable to danger.

The NWS is part of NOAA, which has faced drastic cuts under the Trump administration. More than 1,000 employees have been laid off from the agency, though a handful have been rehired. More mass layoffs are expected as the Department of Government Efficiency eliminates thousands of federal positions.

A NOAA employee told PBS that if the contract with Lilt is not reinstated within 30 days of its 1 April expiration, restarting it will be a complex and lengthy process that involves seeking bids from several companies.

—Emily Dieckman (@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.

Heavy methane emissions from Swedish lakes baffle researchers

Phys.org: Earth science - Tue, 04/08/2025 - 20:30
Unexpectedly strong methane emissions have been detected at several locations in Lake Siljan, Sweden, according to a new study from Chalmers University of Technology. The findings, based on a novel measurement technique developed by the researchers, reveal persistent and concentrated methane leaks never before observed in a lake environment. Scientists will now investigate whether these emissions are unique to Siljan—or part of a broader phenomenon that could occur in lakes worldwide.

Computer simulations suggest CO₂ can be stored underground indefinitely

Phys.org: Earth science - Tue, 04/08/2025 - 18:56
We have to stop emitting carbon dioxide (CO2) if we want to save the climate—there is no doubt about that. But that alone will not be enough. In addition, it will also be necessary to capture CO2 that is already present in the atmosphere, and store it permanently, for example, by pumping it deep into the ground.

Life recovered rapidly at site of dino-killing asteroid. A hydrothermal system may have helped

Phys.org: Earth science - Tue, 04/08/2025 - 18:26
About 66 million years ago, an asteroid slammed into the planet, wiping out all non-avian dinosaurs and about 70% of all marine species.

Universal spatiotemporal scaling laws govern daily population flow in cities

Phys.org: Earth science - Tue, 04/08/2025 - 17:06
While the daily ebb and flow of people across a city might seem chaotic, new research reveals underlying universal patterns. A study published in the journal Nature Communications by a team led by Chair Professor Bo Huang from the Department of Geography at the University of Hong Kong (HKU) unveils fundamental spatiotemporal scaling laws that govern these population dynamics.

Using orbital cycles to understand early life

Phys.org: Earth science - Tue, 04/08/2025 - 14:10
Chengdu University of Technology-led research has established a high-resolution astrochronological framework spanning approximately 57.6 million years of the early Ediacaran Period. This calibrated timeline provides precise constraints on major climatic events and the appearance of early complex life, offering critical context for understanding environmental change and biological innovation during Earth's early history.

Satellite radar shows ground rising beneath the part of Aral Sea that has dried up

Phys.org: Earth science - Tue, 04/08/2025 - 14:00
A team of Earth scientists affiliated with Peking University and the Southern University of Science and Technology, both in China, and a researcher from the University of Southern California, in the U.S., have found that the land below parts of the Aral Sea that have dried up over the past several decades is slowly rising.

An Atmospheric River Exacerbated Türkiye’s 2023 Earthquake Crisis

EOS - Tue, 04/08/2025 - 13:53

On 6 February 2023, a pair of powerful earthquakes—magnitudes 7.8 and 7.5—struck southern Türkiye and northwestern Syria 9 hours apart, killing 59,000 people and causing catastrophic damage.

While in the area mapping earthquake-triggered landslides the following month, Istanbul Technical University geomorphologist Tolga Görüm and his team noticed an atmospheric river approaching the disaster zone. They found this worrying, because an earthquake can weaken surrounding slopes for months and possibly years, making them vulnerable to heavy rainfall.

In a recent Communications Earth & Environment study, Görüm and colleagues documented the atmospheric river’s characteristics and how it caused flooding, landslides, and, tragically, further loss of life in the already devastated region. According to the team, the case study demonstrates a need for updated hazard models that better integrate various atmospheric and seismic hazards, particularly as climate change is expected to intensify atmospheric rivers in some regions.

A Once-in-20-Year Storm

“This was the heaviest rainfall event in the area in the last 20 years.”

For the study, the scientists analyzed global climate data from the European Centre for Medium-Range Weather Forecasts’ Reanalysis v5 (ERA5). The data revealed that the atmospheric river, originating over the Red Sea, carried more moisture than did 99.99% of all such events recorded in the region. When that moisture hit southern Türkiye’s Taurus Mountains on 14 and 15 March 2023, the resulting upward airflow along the slopes produced extreme rainfall.

“This was the heaviest rainfall event in the area in the last 20 years,” Görüm said. In the Turkish town of Tut, the storm delivered up to 183 millimeters (7.2 inches) of rain within 20 hours. In addition, warm temperatures had caused snowmelt in the mountains just before the atmospheric river arrived, leaving the soil saturated with water and further reducing its stability.

By analyzing the strength of shaking, the steepness of the terrain, and the position of the slopes, the scientists estimated that the shear strength of hillsides—the ability of soil and rock to resist sliding when subjected to a force—in the Tut region was weakened by 52%–77%.

An atmospheric river hit the town of Tut 36 days after two powerful earthquakes, initiating catastrophic landslides. Credit: Tolga Görüm

The consequences were severe. “The atmospheric river hit the area, triggered significant sediment movement, and killed more than 20 people,” Görüm said. Twelve of those deaths were within the study area. The resulting landslides, debris flows, and flooding also disrupted ongoing recovery efforts from the earthquake.

The catastrophe was the result of unfortunate timing. Using a computational model, the scientists ran simulations for earthquakes occurring in different seasons and tracked landslide probability over 5 years. They found that had the earthquakes occurred during summer or fall instead of winter, the recovery period wouldn’t have coincided with peak atmospheric river season, and the landslide hazard would have been significantly reduced.

Ben Leshchinsky, a civil engineer at Oregon State University who has studied cascading hazards but wasn’t involved in the research, said this study “highlights the importance of remembering there is a legacy to hazards. It’s incredibly important to keep following what happens so we can make sure we recover more quickly and plan for recovery in a smarter, more resilient way.”

Anticipating the Worst

Preparing for contemporaneous disasters might become increasingly relevant. Using 40 years of data, the researchers showed that Türkiye has experienced a significant increase in atmospheric river frequency and intensity, likely driven by climate change.

The landslides and flooding that followed the atmospheric river in the earthquake-struck zone damaged roads and bridges, inhibiting recovery efforts. Credit: Tolga Görüm

This trend extends beyond Türkiye to other seismically active regions worldwide. “On the Pacific coast [of the United States], the frequency and magnitude of atmospheric rivers is even higher than our area,” Görüm noted, adding that Southern California is seismically similar to Türkiye. These parallels suggest that lessons learned from Türkiye’s experience could help vulnerable communities around the globe develop more comprehensive disaster preparedness plans.

“This paper…reinforces the argument that we need to be thinking about these coincident hazards.”

Bruce Malamud, a geophysicist at Durham University who wasn’t involved in the study, noted that it can be dangerous when multiple hazards coincide, because government agencies focusing on different hazards work independently, so their disaster responses aren’t coordinated. “What’s important about this paper is that it reinforces the argument that we need to be thinking about these coincident hazards,” he said.

Having spent time in the disaster zone following the 2023 earthquakes, Görüm saw damaged cities and the struggles of response crews to rescue people; he understands more than most the need to warn communities of additional hazards. “It was like a nightmare,” he said.

It’s taxing to work in those conditions, he said, “but at the same time it’s quite important. You have to learn from this type of event.”

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

Citation: Chapman, A. (2025), An atmospheric river exacerbated Türkiye’s 2023 earthquake crisis, Eos, 106, https://doi.org/10.1029/2025EO250132. Published on 8 April 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.

Strange Branching of Water Flows Through Rivers and Lakes

EOS - Tue, 04/08/2025 - 12:00
Editors’ Highlights are summaries of recent papers by AGU’s journal editors. Source: Water Resources Research

Rivers can split into branches, a phenomenon called bifurcation. Typically, the branches return again to the main river or the same floodplain after some distance downstream from the bifurcation, such as around an island, in a braided river, or in a river delta. Some bifurcations, however, are different, branching off and never returning, and seemingly defying conventions of hydrology, the science of Earth’s water and especially its movement in relation to land.

In their new article, Sowby and Siegel [2025] describe such curious bifurcations of rivers and lakes in North and South America. Some rivers diverge rather than converge; some rivers flow in two directions; some lakes have not one but two outlets; and some watersheds have strange boundaries. Some of these irregular water bodies are remote and wild while others are developed and controlled; some are streams small enough to step over and others are lakes over 100 kilometers long; and some are protected in national parks, but others are not. Their irregularities illustrate various aspects and manifestations of the complexity of Earth’s water system on land and how much we have still to learn about it.

These irregularities raise interesting questions: How should the watershed boundaries of such water bodies be defined on maps? Whose water is it before or after it bifurcates? If contaminated, who is responsible? Should flows in a bifurcated river be manually controlled, or left to nature? How can such interesting hydrological features be preserved and studied? The authors explore the natural settings and the societal uses, impacts, and management of these unusual bodies of water on land, along with the implications for our ability to quantitatively model and predict their characteristics and involved water system interactions.

Citation: Sowby, R. B., & Siegel, A. C. (2025). Unusual drainages of the Americas. Water Resources Research, 61, e2024WR039824. https://doi.org/10.1029/2024WR039824

—Georgia Destouni, Editor-in-Chief, Water Resources Research

Text © 2024. 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.

Randomization of a laser wave front by the turbulent gas-puff $Z$-pinch plasma column

Physical Review E (Plasma physics) - Tue, 04/08/2025 - 10:00

Author(s): A. Rososhek, E. S. Lavine, B. R. Kusse, W. M. Potter, and D. A. Hammer

In this paper, we present the first direct experimental evidence supported by numerical modeling of a turbulent plasma column formed during a gas-puff z-pinch implosion generated by the cobra current. Utilizing an imaging refractometer, we showed a significant decrease in spatial autocorrelation of …


[Phys. Rev. E 111, 045202] Published Tue Apr 08, 2025

Coherent puff and slugs in transitional drift-wave turbulence

Physical Review E (Plasma physics) - Tue, 04/08/2025 - 10:00

Author(s): P. Manz, S. Knauer, C. Moon, N. Fahrenkamp, D. Di Matteo, and A. Fujisawa

The long-term development of the transitional regime of drift-wave turbulence is studied in a magnetized plasma column by means of the conditional-average technique. In the transitional regime, small changes in the magnetic-field strength as control parameter lead to large changes in the correlation…


[Phys. Rev. E 111, 045203] Published Tue Apr 08, 2025

Mercury concentrations in tree rings may enable trees to be 'witnesses' of illegal gold mining activities in the Amazon

Phys.org: Earth science - Tue, 04/08/2025 - 04:00
For hundreds of years, the Amazon has been exploited for its gold. Today, the precious metal is just as sought after, but the remaining tiny gold particles are much harder to find. Mining often happens in artisanal and small-scale mining operations that release mercury (Hg) into the air, polluting the environment and harming human health.

Fault identification, complexity and evolution of the 2021, Atarfe-Santa Fe earthquake swarm (Granada basin, Spain)

Geophysical Journal International - Tue, 04/08/2025 - 00:00
SummarySeismic swarms are known to occur in regions with complex deformation and multiple fault systems. The identification of the affected faults, the evolution of the seismicity and the rupture characteristics are key to understand seismotectonics and seismic hazard of such areas. We here address the Atarfe-Santa Fe earthquake swarm with > 5000 events, including six magnitude 4+ earthquakes, recorded in 2021 in the Granada Basin area (S-Spain). We use continuous data from a dense local recording network and apply deep learning models to pick and associate seismic phase arrivals and construct an automatic event catalogue. A double difference relocation of 3196 earthquakes reveals the seismotectonic fine-structure of the swarm. We identify planar, southwest-dipping structures among the relocated hypocentres, consistent with the NW-SE trending, high-angle normal faults present in this sector of the Granada basin. Earthquakes concentrate between 4-7 km depth along three different lineaments. The distinctive pattern of three equidistant, parallel segments allows an association of the swarm with the Ermita los Tres Juanes, Atarfe and Pinos Puente normal faults. These faults outcrop at the upward extrapolation of the swarm, forming an arrangement of three structures that mimic the geometry of the relocated seismicity at depth. In the course of the swarm, the seismicity jumped from the Ermita los Tres Juanes to the Atarfe fault, in midst of a rapid succession of three magnitude 4 earthquakes within 20 minutes, then migrated laterally along both faults, and later migrated basinwards to the Pinos Puente fault, which produced fewer and smaller events. We estimate apparent source time functions for five earthquakes (Mw 4.1 to 4.4) through the deconvolution of empirical Green's functions from the records, suggesting rupture propagation towards NW, N and E directions. An isochrone back projection of apparent source time functions suggests km-scale ruptures with simple slip distributions, showing lateral and updip components of rupture. Our results shed light on the complexity of this seismic swarm in terms of the fault network involved, the propagation of seismicity across the faults and the variable directions of individual ruptures.

The effect of photoelectron interhemispheric transport on ion temperature in the topside ionosphere around sunset

Publication date: Available online 1 April 2025

Source: Advances in Space Research

Author(s): Zhenzhang Tang, Huijun Le, Libo Liu, Yiding Chen, Ruilong Zhang

Identification of the structural configuration of the Equatorial Atlantic Ridge from satellite-derived gravity data using the enhancement techniques

Publication date: Available online 31 March 2025

Source: Advances in Space Research

Author(s): Luan Thanh Pham, Franck Eitel Kemgang Ghomsi, Ahmed M. Eldosouky

Nanosatellite Differential Drag Control for Variable Size Triangular Formation Flying

Publication date: Available online 31 March 2025

Source: Advances in Space Research

Author(s): Yaroslav Mashtakov, Uliana Monakhova, Danil Ivanov

Multiscale Periodic Analysis of Sunspot Number Data and F10.7 Index

Publication date: Available online 31 March 2025

Source: Advances in Space Research

Author(s): Yi Shen, Chunmei Zhao, Peicheng Li, Mengjun Hu, Bingbing Zhang, Wang Li

A Novel Snow Depth Estimation Model for the Eastern Himalayas Using DInSAR

Publication date: Available online 29 March 2025

Source: Advances in Space Research

Author(s): Manmit Kumar Singh, Ritu Anilkumar, Rishikesh Bharti

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