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Gully washer. Duck drownder. Toad strangler. Cob floater. Sod soaker. Whatever their names, summer in the Midwest isn't summer without strong, sudden storms with towering clouds. While the Indian subcontinent is famous for its monsoon season, what many people don't know is that the midwestern United States has its own monsoon season, very nearly as strong.

Author(s): Bhavesh Ramkorun, Saikat C. Thakur, Ryan B. Comes, and Edward Thomas, Jr.

Carbonaceous dusty nanoparticles spontaneously grow in nonthermal plasmas from a gas mixture of argon and acetylene. These particles levitate and grow within the bulk plasma for a duration known as the growth cycle (Tc), after which they gradually move away. In experiments operating at 500 milliTorr…

[Phys. Rev. E 112, 045211] Published Tue Oct 21, 2025

AbstractGeophysical measurements such as induced polarization (IP) are invaluable for understanding the physical properties of rocks, including pore structure, hydraulic properties, and mineral content. However, collecting reliable IP measurements from low-permeability rocks poses substantial challenges due to the difficulty of saturating their tight pore spaces. Additionally, IP measurements on rocks that are not cored to fit conventional sample holders, or are irregularly shaped, are particularly difficult to obtain. In this work, we address these challenges through (1) the use of reliable saturation procedures developed for low-permeability samples, and (2) a molding procedure designed to overcome the difficulties of measuring IP on irregularly shaped or broken rock cores. Core-scale gravimetric porosity measurements closely match values obtained from destructive mercury intrusion porosimetry (MICP) on rock fragments, confirming the effectiveness of the saturation procedure. Direct comparisons of IP measurements between molded and unmolded cores demonstrate that the molding process does not significantly alter the intrinsic electrical response of the samples. Fully saturated mudstones exhibit strong statistically significant relationships between the mean relaxation time (τmean) and permeability (k), and between effective porosity (1/formation factor, F) and interconnected porosity (ϕ) (Archie’s law). Conversely, partial saturation due to ineffective saturation methods introduces substantial scatter to these petrophysical correlations. Overall, these findings underscore the potential of these methods to enhance the reliability and accuracy of SIP measurements on challenging rock samples.

SummaryOn January 18, 2021, a blind mid-crustal Mw ∼6.4 earthquake occurred near San Juan, Argentina. The observation of associated ground deformation with single interferograms is obscured by strong tropospheric signals. We apply appropriate corrections to the data and reconstruct the deformation field associated to the event through InSAR time series approach. We show it is possible to retrieve this signal to invert the fault parameters. The observed ground deformation is consistent with a high angle NW-dipping fault plane at a centroid depth of ∼19 km. The geometry of this fault supports the reactivation of pre-existing structures within the Cuyania Terrane, suggesting a direct structural connection and strain transfer to the actively deforming, east-vergent Precordillera front. We analyze our findings to deduce a static friction coefficient ≤0.3 for mid-crustal faults of the region.

SummaryWe refined the Attenuated ProPagation of Local Earthquake Shaking (APPLES) ground-motion-based earthquake early warning (EEW) approach, and directly compare APPLES performance with that of the source-characterization-based U.S. ShakeAlert EEW system for a suite of historical earthquakes in the U.S. West Coast and Japan. APPLES is an extension of the Propagation of Local Undamped Motion (PLUM) algorithm in which observed shaking intensity at seismic stations is used to forward-predict intensity distributions to surrounding areas using an attenuation model derived from an intensity prediction equation. We test new configuration options within APPLES, such as using the second highest estimated ground motion rather than the maximum, to better match median ground-motion observations and reduce alerts for small magnitude earthquakes, both of which are key alerting priorities within ShakeAlert. We evaluate these configurations alongside ShakeAlert by comparing the ground-motion estimation accuracy and available warning times relative to station observations and ShakeMap distributions. Our preferred APPLES configuration produces accurate ground-motion estimates and corresponds better with median observations compared to ShakeAlert’s estimates. This preferred configuration substantially reduces alert issuance for M < 5.0 earthquakes compared to the previous APPLES configuration, and alert-release criteria can further restrict alerts to primarily M ≥ 5.5 earthquakes without requiring magnitude estimation. Prioritizing matching median-observed ground motions may reduce APPLES warning times compared to configurations that were tuned to avoid missed alerts (such as those that use the maximum estimated ground motions), which can lead to shorter warning times compared to ShakeAlert for the same alert threshold. However, station-based warning time assessments demonstrate that APPLES can outperform ShakeAlert for high target thresholds. APPLES is a simple, independent EEW approach that may improve the robustness of EEW for the West Coast of the U.S.

SummaryMetallic infrastructure, such as steel sheet situated within landfills, poses significant challenges to accurate tracking of leachate using induced polarization (IP) methods. The application of IP method is efficient to delineate leakage; however, the presence of metallic structures can cause an interference on the survey and generate high-chargeability anomalies as observed in field survey. To comprehensively validate the interference caused by steel sheets, both numerical and empirical field tests were conducted. As expected, both results demonstrate that interference diminishes as the distance between survey line and metallic structure increases. Additionally, at consistent intervals, the chargeability values inverted using integral chargeability (IC) exhibit a monotonic increase with depth. Moreover, the interference induced by metallic structures is also affected by the controlling factors (i.e. depth, width and thickness) of the structure alongside the intrinsic resistivity and chargeability. Strategic utilization of the size, chargeability, and spatial positioning of metallic structures relative to survey lines can significantly enhance background polarization. This approach offers a promising framework for improving the spatial resolution of subsurface targets exhibiting low polarization effects. The optimization of survey line placement, which must consider the dimensions and electrical properties of metallic structures such as steel sheets, is essential for accurately characterizing landfill leachate using the IP method.

SummaryNorthern Europe experiences vertical land motion and sea level changes that deviate from the average as a consequence of past changes in ice sheet cover in Fennoscandia and the British Isles. The process, called Glacial Isostatic Adjustment (GIA), is controlled by the subsurface structure. Numerical models of GIA can be compared to observations of uplift or past sea level changes to constrain the subsurface structure, and such models can also be used to correct present-day sea level observations to reveal sea level changes due to climate change. GIA models for northern Europe usually adopt a homogeneous upper mantle viscosity even though seismic studies indicate contrasting elastic lithosphere thickness and upper mantle structure between Northwestern Europe and Eastern Europe. This raises the question whether the effect of lateral variations in structure (3D viscosity) can be detected in observations of GIA and whether including such variations can improve GIA model predictions. In this study we compare model output from a finite element GIA model with 3D viscosity to observations of paleo sea level and current vertical land motion. We use two different methods to derive 3D viscosities, based on seismic velocity anomalies and upper mantle temperature estimates. We use three different reconstructions of the Eurasian ice sheet, one based on an inversion using a 1D model, and two others based on glacial geology and modelling. When we use these two reconstructions, we find that the data are fit better using 3D viscosity models. Models with two separate 1D viscosities for Fennoscandia and for the British Isles cannot replicate a 3D model because a 3D model redistributes GIA-induced stresses differently from a combination of models with separate 2D viscosities. The fit to data across Fennoscandia is improved when, as indicated by seismic models, the upper mantle viscosity is higher than for the rest of Northern Europe. The best fit is obtained with a model with dry olivine rheology, in agreement with other evidence from Fennoscandia.

SummaryIn both onshore and offshore seismic exploration, seismic source localization plays a crucial role in ensuring operational safety and environmental protection. With the continuous advancement of the Marchenko method in the fields of seismic migration and internal multiple elimination, this paper investigates a seismic source localization method based on the Marchenko method, aiming to further extend application domain of this method. The key to this method lies in the data reconstruction based on convolution operations. The conventional Marchenko method is then applied to obtain a seismic profile, which includes the location of the seismic source. In the experiments, this study first uses an anticline model to simulate seismic source localization in onshore seismic exploration. The results show that the proposed method can accurately estimate both the distance to the seismic source and its depth. Furthermore, in large-scale marine model experiments, the method is also able to reliably determine the distance between the seismic source and the observation stations.

SummaryFor the interpretation of Spectral Induced Polarization spectra, the determination of the Relaxation Time Distributions (RTD) can be useful, for instance to extract the grain size distribution. However, this is an ill-posed problem, and retrieving the RTD often requires regularization during the inversion process. In this note, we use Bézier curves and simulated annealing to determine the RTD. The procedure that does not require any regularization nor smoothing, by reducing the number of parameters thanks to Bézier curves which are intrinsically continuous and infinitely derivable. We successfully applied our methodology to three examples (Cole-Cole model, Davidson-Cole model, and an experimental spectrum), demonstrating its interest and efficiency.

SummaryThe extension of direct current resistivity methods to induced polarization methods has enriched the tools available for subsurface exploration. This enrichment involves an increase in the number of parameters used in the models, as well as addressing different physical phenomena than those observed with direct current. Accounting for non-linearities, if they exist, can further enhance the sophistication of our models. Non-linearities are often observed, particularly in laboratory experiments. However, we question their origin, and the experiment described here suggests that the non-linearities observed under typical experimental conditions may be artifacts related to the electrodes, rather than reflecting the actual response of the subsurface. Indeed, we first replaced the polarizable injection electrodes with non-polarizable electrodes. The non-linearities observed due to the presence of harmonics were significantly reduced. Then, we replaced the voltage control with a current control, which completely eliminated the non-linearities still present.We know that it is impossible to prove the non-existence of a phenomenon that does not exist. This fundamental epistemological principle (as pointed out by Russell and Popper) means that we are not claiming that nonlinearity does not exist. We are simply describing an experiment that can raise doubts about its existence.

For years, we believed the Himalayas were a climatic sanctuary—untouched, pristine, and resilient to the turbulence of modernization. But what happens when mountain cities begin to mimic the dynamics of megacities in the plains?

Burning fossil fuels has elevated atmospheric carbon dioxide, causing massive changes in the global climate including extreme temperatures and weather events here in the Midwest. Meanwhile, human activities have increased the amount of nutrients like nitrogen and phosphorus in grasslands and forests. These are the elements in fertilizer that make lawns greener and farmland more productive.

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Major floods in Alaska have caused the death of at least one person and displaced thousands more over the course of the last two weeks. Many of the displaced may not be able to return home for 18 months or longer, according to Alaska Gov. Mike Dunleavy.

Tropical Storm Halong formed in the Northern Philippine Sea on 5 October, and had become a category 4 typhoon by 7 October. Though it was considered an ex-typhoon by the time it reached western Alaska, the storm brought wind speeds of up to 113 miles per hour (181 kilometers per hour), along with severe flooding across the Yukon Delta, Kuskokwim Delta, and Norton Sound.

 
Related

•  Hundreds evacuated, homes destroyed as Alaska communities reel from devastating flooding
•  Gov. Dunleavy’s Request for Federal Assistance
•  Alaska Representatives’ Letter of Support
•  Murkowski: FEMA ‘on the ground’ as west coast Halong evacuations continue
 

Among the hardest hit population centers were the villages of Kipnuk and Kwigillingok, home to a combined 1,000 people, mostly Alaska Native or American Indian. At this time of year, the remote villages can only be reached by water or by air.

In Kipnuk, water levels rose 5.9 feet (1.8 meters) above the normal highest tide line. In Kwigillingok, water levels measured 6.3 feet (1.9 meters) above the normal highest tide line—more than double the previous record set in 1990. According to a letter from the governor’s office to President Trump, 90% of structures in Kipnuk and 35% of structures in Kwigillingok have been destroyed.

The Alaska Air and Army National Guard, the U.S. Coast Guard, and Alaska State Troopers evacuated hundreds of residents to the regional hub of Bethel, then to the capital of Anchorage in what the Alaska National Guard called the state’s largest airlift operation in history.

“It’s been an all-hands-on deck endeavor, and everybody is trying to support their fellow Alaskans in their time of need,” said Col. Christy Brewer, the Alaska National Guard director of joint operations, in a 19 October statement.

Silence From FEMA

But calls for assistance from the Federal Emergency Management Agency seem to have so far gone unanswered, leaving some people asking, “Where is FEMA?”

An urgent question. According to the FEMA Daily Briefing a presidential disaster declaration was requested on October 16th. To the best of my knowledge it hasn’t been granted. Any event of this size should be an easy and immediate yes.

— Dr. Samantha Montano (@samlmontano.bsky.social) 2025-10-18T23:13:44.421Z

As reported by the New York Times, the EPA revoked a $20 million grant in May that was intended to protect Kipnuk from extreme flooding. The grant cancellation was likely part of a larger effort by the administration to shift the burden of disaster response to states.

On 16 October, Dunleavy submitted a request to President Trump to declare a major disaster for the state.

The letter notes that Alaska has seen 57 state-declared disasters since November 2018, 14 of which have been approved for federal disaster assistance. There have been 14 state-declared disasters in Alaska in the last 12 months alone, including fires, freezes, landslides, and floods.

“It is anticipated that more than 1,500 Alaskans will be evacuated to our major cities, many of whom will not be able to return to their communities and homes for upwards of 18 months,” Gov. Dunleavy wrote. “This incident is of such magnitude and severity that an effective response exceeds state and local capabilities, necessitating supplementary federal assistance to save lives, protect property, public health, and safety, and mitigate the threat of further disaster.”

On 17 October, Alaska’s senators and state representative (all Republicans) also submitted a letter to President Trump, urging him to approve the governor’s request for a major disaster declaration.

Also on 17 October, Vice President JD Vance said on X that he and the president were “closely tracking the storm devastation,” and that the federal government was working closely with Alaska officials. On 18 October, Lisa Murkowski (R-AK) said she believed FEMA representatives were “totally on the ground.”

However, as of 20 October, the incident is not listed in FEMA’s disaster declaration database.

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

These updates are made possible through information from the scientific community. Do you have a story about science or scientists? 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.

The ocean has helped mitigate global warming by absorbing about a quarter of anthropogenic carbon dioxide (CO2) emissions, along with more than 90% of the excess heat those emissions generate.

When farmland is abandoned and allowed to return to nature, forests and grasslands naturally regrow and absorb carbon dioxide from the atmosphere—helping fight climate change.

Imagine you're walking along a beach, talking to your friend, enjoying the sunshine. Time goes by and it's time to head back. But as you approach the headland you had walked around previously, you realize that's not possible anymore: the tide has come in and there is no path around it now. You're trapped in a bay with the tide continuing to submerge the beach.

A new review led by the MARUM—Center for Marine Environmental Sciences at the University of Bremen—highlights how hydrothermal vents on the seafloor shape iron availability and influence the global oceanic element cycles. The review study, titled "Iron's Irony," has been published in Communications Earth & Environment.

Ten years ago, close to 200 nations signed the Paris Agreement, an international treaty designed to cut greenhouse gas emissions and curtail global warming. Under the treaty, most nations made a 15-year promise to reduce emissions.

Source: AGU Advances

The ocean has helped mitigate global warming by absorbing around a quarter of anthropogenic carbon dioxide (CO2) emissions, along with more than 90% of the excess heat those emissions generate.

Many efforts, including assessments by the Intergovernmental Panel on Climate Change, have looked at how the oceans may continue to mitigate increasing emissions and global warming. However, few have looked at the opposite: How will the oceans respond if emissions and associated atmospheric heat levels begin to decrease in response to net negative emissions?

Frenger et al. examined what might happen in the Southern Ocean if after more than a century of human-induced warming, global mean temperatures were to be reduced via CO2 removal from the atmosphere. The Southern Ocean is a dynamic system, with large-scale upwelling and a robust ability to take up excess carbon and heat. To better understand how the Southern Ocean will behave in net negative carbon conditions, the researchers modeled how the ocean and the atmosphere would interact.

They used the University of Victoria climate model, UVic v. 2.9, to simulate multicentury timescales and carbon cycle feedbacks. UVic uses a combination of an atmospheric energy–moisture balance model, an ocean circulation and sea ice model, a land biosphere model, and an ocean biochemistry model. The researchers used UVic to model an idealized climate change scenario commonly used in climate modeling: Emissions increase until atmospheric CO2 levels double after 70 years, followed by a steep emissions cut and subsequent sustained net negative emissions.

The results showed that after several centuries of net negative emissions levels and gradual global cooling, the Southern Ocean abruptly released a burst of accumulated heat—an oceanic “burp”—that led to a decadal- to centennial-scale period of warming. This warming was comparable to average historical anthropogenic warming rates. The team said that because of seawater’s unique chemistry, this burp released relatively little CO2 along with the heat.

Frenger and colleagues note that their work uses a model with intermediate-level complexity and an idealized climate change scenario, but that their findings were consistent when tested with other modeling setups. They say the Southern Ocean’s importance to the global climate system, including its role in heat release to the atmosphere in a cooling climate, should be studied further and contemporary changes closely monitored. (AGU Advances, https://doi.org/10.1029/2025AV001700, 2025)

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

Citation: Derouin, S. (2025), The Southern Ocean may be building up a massive burp, Eos, 106, https://doi.org/10.1029/2025EO250385. Published on 20 October 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.

Tropical inland waters don't produce as many greenhouse gas (GHG) emissions as previously estimated, according to the results of an international research collaboration led by Charles Darwin University (CDU).