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SummaryAccurate characterization of the magnitude-frequency distribution of seismicity, and its associated uncertainties, is essential for seismic hazard assessment. This distribution is commonly described by the Gutenberg–Richter (GR) relation, parameterized by the b-value, which has been identified as a potential proxy for investigating many spatiotemporally varying Earth phenomena. Estimating the spatiotemporal variability of b-values often requires windowing, forcing a trade-off between resolution and statistical reliability. New probabilistic methods circumvent this by inferring both the number and locations of change points directly from earthquake catalogs. Nevertheless, accurately determining the b-value remains difficult because the GR relation only holds over a limited range of magnitudes. This research develops a general statistical model to address several methodological challenges in estimating the magnitude-frequency distribution of observed seismicity, including variations in space or time. The approach simultaneously solves for the b-value and magnitude-range limits. This avoids potential bias due to inaccurate manual truncation of earthquake catalogs. The model considers the entire observed catalog and parameterizes the decay of the distribution at both low and high magnitudes. Consequently, robust uncertainties in estimated b-values reflect uncertainty in the range of magnitudes over which the GR relation is observed to be valid. Importantly, spatiotemporal variations in the parameters that define the magnitude range are considered to be independent from the b-value, as we assume the physical factors that influence the GR relation are independent of the factors that limit the observed earthquake catalog. We demonstrate this methodology through application to simulated and observed earthquake catalogs. In particular, the value of our approach is highlighted through application to observed records of induced seismicity associated with fluid-injection operations in western Canada. Our results demonstrate accurate b-value estimates and associated uncertainties. Furthermore, the additional parameters that define the magnitude range serve as proxies for other factors including seismic network performance, recording duration, potential geometric limitations on earthquake size, and potential injection characteristics (in induced seismicity cases). Our approach also allows for the investigation of how these other factors may vary in space/time. Results from this work contribute to rigorous propagation of accurate b-value estimates, including uncertainties, into subsequent analyses such as seismic hazard models and regulatory protocols that are applied to industrial activity.

SummarySeismic emissions from wind turbines (WTs) depend on the rotation of the WT blades and the wind direction-dependent movement of the WT. Mechanical coupling between the WT foundation and the subsurface generates complex seismic wavefields, making it challenging to manually separate the contributions of different signal sources, thus complicating data labelling. We address this challenge by applying unsupervised machine learning techniques that do not require labelled data. Our analysis focuses on seismic WT emissions recorded near Wind Farm Tegelberg in the eastern Swabian Alb, Southwest Germany. Specifically, we extract time-averaged wavelet features by temporal averaging the wavelet transformation of the continuous three-component seismic data and subsequently apply the clustering algorithm Hierarchical Density-Based Spatial Clustering of Applications with Noise (HDBSCAN). The resulting clusters not only capture the variations in the WT rotation rate but also reveal a clear dependency on wind direction, associated with the radiation pattern of different surface waves. Our results demonstrate the potential of HDBSCAN to uncover meaningful, source-related patterns in continuous seismic records.

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.

NOAA has finalized a rule that will expedite the permit and license application process for deep seabed mining and allow companies to mine beyond U.S. jurisdictional boundaries.

The changes were published in a 113-page regulation on 21 January.

The changes revise the Deep Seabed Hard Mineral Resources Act (DSHMRA) of 1980, which required individuals or corporations who wanted to explore and mine mineral-rich nodules in the deep sea to apply for an exploration license and a commercial recovery (large-scale extraction) permit separately. Now, applicants may apply for both the exploration license and commercial recovery permit at the same time. 

“By issuing the permit simultaneously, they’re committing to exploitation without the information that you would need to evaluate its impacts.”

“Deep seabed mining is key to unlocking a domestic source of critical minerals for the United States,” Neil Jacobs, NOAA administrator, said in a statement. “This consolidation modernizes the law and supports the America First agenda by enabling U.S. companies to access these resources more quickly, strengthening our nation’s economic resilience and advancing the discovery and use of critical seafloor minerals.” 

Critics are concerned that the move will loosen environmental oversight. “By issuing the permit simultaneously, they’re committing to exploitation without the information that you would need to evaluate its impacts,” Emily Jeffers, senior attorney at the Center for Biological Diversity, told Agence France-Presse.

Beyond U.S. Boundaries

The updated rule also states that DSHMRA gives NOAA the ability to issue exploration licenses and permits for the seabed beyond national jurisdiction. The International Seabed Authority (ISA), an autonomous international governing body, regulates deep sea mining in international waters for countries that are part of the 1982 Law of the Sea Convention. The United States has never been a party to that treaty but has mostly followed its guidelines.

Now, NOAA’s insistence that the United States can regulate U.S. companies’ deep sea mining beyond U.S. waters is expected to cause controversy among members of the ISA, which has for years been negotiating rules to govern mining in international waters. In December, the Trump administration announced it had received an application for mining exploration in international waters from the Metals Company.

The final rule follows an executive order issued last year calling for the rapid development of deep sea mining capabilities both domestically and beyond U.S. jurisdictional boundaries.

 
Related

•  NOAA Accelerates Permitting Timeline for Deep Seabed Mining Applications
•  Read the Regulation: Deep Seabed Mining: Revisions to Regulations for Exploration License and Commercial Recovery Permit Applications
•  US Finalizes Rule for Deep-Sea Mining Beyond Its Waters
 

In a response to that order, the ISA called it “surprising because for over 30 years the US has been a reliable observer and significant contributor to the negotiations of the International Seabed Authority.” In the statement, the ISA also said any unilateral action to mine the deep sea “sets a dangerous precedent that could destabilize the entire system of global ocean governance.”

The deep sea has never been commercially mined. Compared to other ecosystems, little is known about the ecology of the ocean floor or how these ecosystems support marine life. Disturbing these ecosystems could have wide-ranging consequences.

“Once nodules are removed by mining, all biodiversity and functions directly dependent on the minerals will be lost for millions of years at the mined location, as nodules need millions of years to re-form,” Sabine Gollner, a deep-sea marine biologist at the Royal Netherlands Institute for Sea Research told Eos in 2024. 

—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.

U.S. forests have stored more carbon in the past two decades than at any time in the last century, an increase attributable to a mix of natural factors and human activity, finds a new study.

Ask people how Stonehenge was built and you'll hear stories of sledges, ropes, boats and sheer human determination to haul stones from across Britain to Salisbury Plain, in south-west England. Others might mention giants, wizards, or alien assistance to explain the transport of Stonehenge's stones, which come from as far as Wales and Scotland.

During the last ice age, the Atlantic Ocean's powerful current system remained active and continued to transport warm, salty water from the tropics to the North Atlantic despite extensive ice cover across much of the Northern Hemisphere, finds new research led by UCL scientists.

Through sand extraction and the disposal of dredged harbor silt, about 200 million tons of sediment are relocated every year in the coastal waters of the North Sea. The Wadden Sea is particularly strongly affected. This is the result of a new study by the Helmholtz Center Hereon, which for the first time evaluated comprehensive data on dredging activities along the North Sea coasts.

This story was originally published in the Louisiana Illuminator.

A new study says river deltas around the world aren’t just disappearing because of rising seas, but also because the land itself is sinking down into the waters, either as fast or faster than the rising oceans.

Researchers found some of the most rapid sinking is happening along the Mississippi River Delta in Louisiana. The study aims to better guide coastal restoration in disappearing river deltas around the globe, helping leaders, scientists and people living in coastal communities with hard decisions on what can— and should—be saved.

“Coastal areas account for less than 1% of the entire land area we have,” said Leonard Ohenhen, a professor at the University of California, Irvine and the lead author of the study. “But a whole significant population, more than 600 million people, live in those areas.”

“You have a sort of a hodgepodge of different reasons why deltas are sinking.”

The study, published this week in the academic journal Nature, found the contributions of  subsidence, or slowly submerging land, to disappearing coasts is often overlooked.

The fight to preserve rapidly sinking land has been a decades-long battle in the Mississippi River Delta, as well as a source of contention between scientific and political figures in the state. But deltas across the world are sinking, too, and fast.

“You have a sort of a hodgepodge of different reasons why deltas are sinking,” Ohenhen said.

He said river deltas naturally sink to some degree, with sediment carried downstream by rivers piling up and pushing down on the spongy, soft land already there. Humans can accelerate this natural process by engineering rivers such as the Mississippi and by extracting groundwater or oil.

“Relative sea level rise in the area is also really important. That’s the sea level rise plus subsidence,” said Alisha Renfro, a coastal scientist with the National Wildlife Federation. “It really helps us understand where we can make investments in restoration long-term that we might actually be able to hold on to.”

This map from the report shows which areas of the Mississippi River Delta are sinking. Areas in red and yellow are areas of land sinking more rapidly, while spots in blue and purple are building land upwards. Credit: University of California, Irvine

Lack of sediment is the main driver of subsidence in the Mississippi River Delta, Ohenhen said, creating hotspots of rapidly sinking pieces of land amid slightly more stable areas. Most of the deltas studied in the paper, around 70%, have subsidence problems primarily the result of groundwater withdrawal. But some, like the Amazon and Mississippi deltas, had subsidence issues driven by the disappearance of river-carried sediment to replenish the delta’s land.

Putting hard numbers to and pinpointing causes of subsidence—like human activity—is invaluable to restoring coastal land.

“I would say that really validates what, not just my organization, but what a lot of people have recognized for a long time—that this was a significant contributing factor in subsidence,” said James Karst with the nonprofit advocacy group Coalition to Restore Coastal Louisiana, referring specifically to the lack of sediment sent to the Mississippi River Delta.

Decisions about what pieces of the coast can be saved are even more urgent with the cancellation of two large-scale restoration projects in Louisiana.

Known as sediment diversions, the Mid-Barataria and Mid-Breton plans would have diverted freshwater from the Mississippi River into surrounding wetlands. They were scrapped by the state because of the prospective impact on fisheries for oysters, crabs and other marine species. Fish and oyster harvesters celebrated the projects’ demise, while scientists and coastal restoration advocates warned that time is running out to save the coast.

Boaters fish in the canals and wetlands just outside of New Orleans, Louisiana. Coastal restoration projects spearheaded by the state hope to preserve areas of subsiding land that are at risk of disappearing. Credit: Elise Plunk/Louisiana Illuminator

“In light of the cancellation of Mid-Barataria, I think what we, everybody, should be thinking of is, ‘What is the next best thing?’” Karst said. “Clearly it is not going to move forward, but we can’t do nothing.”

“People should be aware that we are in a part of the world that is changing and that is changing rapidly.”

“People should be aware that we are in a part of the world that is changing and that is changing rapidly,” he added. “If we want to position ourselves as individuals and as communities, we should be anticipating these changes and anticipating how they will affect us.”

While the average rate of subsidence for the Mississippi River Delta is around 3.3 millimeters per year, Ohenhen said, some areas of Louisiana are sinking at a rate of 3 centimeters per year, one of the fastest rates of all the deltas studied. That is paired with sea level rising by at least 7 millimeters per year along the Gulf Coast, he said, also one of the highest rates in the world. This puts some areas of Louisiana’s land at higher risk of loss than anywhere else.

“In the Mississippi River Delta, for example, that is one of the only deltas in the world where you have active relocation of people from the delta due to land loss,” Ohenhen said. “The time that we need to respond to these changes is now before the situation gets significantly worse.”

—Elise Plunk (@plunk.bsky.social), Louisiana Illuminator

This story is a product of the Mississippi River Basin Ag & Water Desk, an independent reporting network based at the University of Missouri in partnership with Report for America, with major funding from the Walton Family Foundation.

A new paper (Jia et al. 2026) has found that the 8 February 2025 Junlian rock avalanche was caused by progressive weakening of the rock mass through wetting and drying cycles.

On 8 February 2025, the major Junlian rock avalanche landslide occurred at Jinping Village in Sichuan Province, China. A paper (Jia et al. 2026) has now been published in the journal Landslides that provides more details about the possible causes of this event. This link should provide access to the paper.

An earlier paper (Zhao et al. 2025), which I noted in June, has already described this landslide. This is a photograph of the aftermath of this event:

The aftermath of the 8 February 2025 Junlian rock avalanche in Sichuan, China. Image by Xinhua.

Unfortunately, the paper does not give a lat / long for this landslide, but I have previously noted that it is at [27.99885, 104.60801].

As a reminder, Zhao et al. (2025) determined that the initial failure was 370,000 m3, increasing to 600,000 m3 through entrainment. The landslide had a runout distance of 1,180 metres and a vertical elevation change of 440 m. In total, 29 people were killed.

The slightly odd thing about this failure is that the rainfall event that appears to have triggered it was unexceptional (c. 85 mm over the previous 30 days). I hypothesised that a progressive failure mechanism could have been in play.

Jia et al. (2026) have made some really interesting observations. First, this site was subject to previous landslides, most notably in February 2013. The paper notes that:

“all 173 people from 29 households under threat [from this earlier event] were included in the geohazard risk avoidance relocation subsidy program. Some farmers self-demolished their houses, but as some occasionally returned during the farming season, the Mu’ai Town Government, with support from the county government, organized mandatory demolition of unremoved houses in the area in 2018. ”

Further failures occurred in 2021 and 2022, whereupon all the households immediately below the unstable slope were relocated. However, homes located at a greater distance from the cliff were left in place – these were the people affected by the 2025 event.

Jia et al. (2026) suggest that initial movement of the landslide in the years before 2025 weakened the rock mass and opened pathways for the movement of water into the shear zone. Critically, their work suggests that successive wetting and drying cycles led to degradation of the the sandstones and mudstones forming the slope, moving the mass towards failure.

This weakening was sufficient to render the slope vulnerable to the effects of the rainfall in February 20925, triggering the Junlian rock avalanche.

We might take away to key messages from this work. The first is the need to understand the likely runout characteristics of a slope in determining the safety of the population. This is devilishly difficult. That there was an ongoing programme to relocate the most vulnerable people is (on the face of it) good, but it depends on this calculation.

Second is the need to understand the complexities of the processes occurring in a slope. In the case of the Junlian rock avalanche, it was the progressive weakening of the rock mass through wetting and drying cycles that meant that the slope could fail under the influence of unexceptional rainfall. As we drive climate change, similar processes will be occurring in many more slopes in China and elsewhere. That is going to pose a major challenge in terms of keeping people safe.

References

Jia, W., Wen, T., Chen, N. et al. 2026. Dry–wet cycle may trigger the catastrophic landslide in Junlian on February 8, 2025. Landslides. https://doi.org/10.1007/s10346-026-02692-2

Zhao, B., Zhang, Q., Wang, L. et al. 2025. Preliminary analysis of failure characteristics of the 2025 Junlian rock avalanche, China. Landslides. https://doi.org/10.1007/s10346-025-02556-1.

Return to The Landslide Blog homepage Text © 2026. The authors. CC BY-NC-ND 3.0
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Our planet has experienced dramatic climate shifts throughout its history, oscillating between freezing "icehouse" periods and warm "greenhouse" states.

SummaryThe Semail Ophiolite in Oman represents one of the well-preserved ophiolite complexes globally and provides a unique window into the processes of obduction. The emplacement of Semail ophiolite onto the Arabian lithosphere is a result of intra-oceanic subduction, was strongly influenced by inheritance features preserved from pre-obduction tectonic processes. Therefore, a detailed characterization of the crustal architecture and rheological properties of the lithosphere are essential for improving our understanding of obduction processes. In this study, we investigated the crustal structure and Moho depth beneath the central Oman Mountains through analysis of P-wave receiver functions (PRFs) and Bouguer gravity anomalies. We utilize broadband seismic data recorded at 12 seismic stations spanning the ophiolite belt and surrounding regions (Ghaba basin and Saih Hatat Dome). PRFs analysis reveals noticeable lateral variations in Moho depths ranging from ∼39 km beneath the sedimentary basin to ∼46 km beneath the ophiolite belt, and decreasing to ∼30 km underneath Saih Hatat Dome (SHD). 2D forward modeling of Bouguer gravity anomalies (−36 to 91 mGal) constraints with seismological results shows flexural bending of the Moho topography and thin crust (∼ 30 km) beneath the SHD. The 2D forward flexural modelling analysis suggests that lithospheric flexure is due to the emplacement of the ∼5 km thick Semail Ophiolite. The presence of a thin crust beneath the SHD is caused by Permian rifting and thinning of the continental lithosphere. The observed high value of Vp/Vs (1.75 – 1.87) also provides support for Permian mafic intrusions to the lower crust. The Arabian lithosphere exhibits lower mechanical strength in the southern region (Te = 25 km) relative to the northern area, a characteristic likely inherited from pre-obduction magmatic processes. These results provide new geophysical constraints on the crustal architecture of the southern Oman Mountains and emphasize the role of surface loading in shaping lithospheric structure during ophiolite emplacement.

SummaryThis study aims to evaluate the effectiveness of the remove-restore method applied to GRACE (Gravity Recovery and Climate Experiment) gravity solutions, in which climate-related signals are first removed to allow a more meaningful interpretation of residual gravity signals associated with dynamic processes in Earth’s deep interior. By removing seasonal cycles and long-term trends, the analysis focuses on non-seasonal variations where causal attribution is clearer. Results indicate that climate correction reduces GRACE signal variability by approximately 30% over both oceanic and continental regions, with the strongest impact observed in major river basins. The correction is most effective for temporal scales below 10 years and spatial scales up to spherical harmonic degree 25. While overall variability decreases, certain frequency bands exhibit increased variability, suggesting a potential degradation of the signal due to model or data limitations. Globally, correlations between corrected GRACE signals and key climate indices largely diminish, confirming substantial removal of climate-related variability. However, the climate contribution to time-variable gravity beyond seasonal scales likely exceeds 30%, indicating incomplete correction and occasional alteration of residual signals that complicate the interpretation of deeper Earth processes. Despite these challenges, climate model-based correction shows promise for advancing source separation and deepening understanding of Earth’s interior dynamics via time-variable gravity data, contingent on future improvements in climate modelling.

SummaryFull-waveform inversion has been broadly adopted for acoustic and elastic media, but it lacks widely accepted methods for robust uncertainty quantification. This lack is in part due to an absence of assessment of proposed uncertainty quantification strategies. Here, we investigate four relatively inexpensive uncertainty estimation approaches based on truncated singular value decomposition of the inverse problem Hessian and its inverse. We numerically test these approaches across a range of parameter scales and application problems. We find that uncertainty estimates based on truncated singular value decomposition of the Hessian outperform those based on singular values of the inverse Hessian, due to both favorable singular value spectra of the former, and the greater ease of sampling the Hessian.

SummaryPalaeomagnetic studies of impact glasses offer valuable insights into their magnetization processes and thermal histories associated with impact cratering events. Australasian tektites are broadly distributed in the largest and youngest strewn field of the Cenozoic, and they provide a unique opportunity to investigate the intensity of Earth’s magnetic field around 788 ka and potential impact-induced magnetic fields. The northern part of the Australasian strewn field covers South China, and it corresponds to the uprange zone of the impactor’s trajectory. Magnetic properties of Australasian tektites in South China may contain unique information about this impact event, but their palaeomagnetic characteristics remain poorly constrained. Here, we report the first palaeointensity data of Australasian tektites sampled from the Early-Middle Pleistocene strata in South China. The results show that Muong Nong-type tektites recorded palaeointensities of 30 ± 8 μT, consistent with the geomagnetic field intensity around 780–790 ka. These findings suggest that around 788 ka, Earth’s magnetic field had partially recovered from the earlier intensity decline associated with the precursor event of the Matuyama–Brunhes reversal. By contrast, the splash-form tektites in South China are characterized by extremely weak natural remanent magnetization and unstable magnetization components, posing challenges for deriving reliable palaeointensity data. Although strong impact-induced remanent magnetization was not detected in the samples, this study demonstrates that Australasian tektites, particularly Muong Nong-type, are well suited for palaeomagnetic studies that may reveal potential impact-induced magnetization.

SummaryFluid-rock interactions in geological reservoirs can influence pore pressure and induce ground deformation at rates from millimeters to centimeters per year. Elastic deformation models often simplify structural heterogeneity that controls pore pressure and strain distributions, leading to inaccurate interpretations of reservoir properties from geodetic data. Here we investigate how depth-varying rock hydromechanical properties affect the magnitude, rate, and spatiotemporal characteristics of poroelastic deformation and pore pressure. Motivated by the Salton Sea geothermal field, we develop finite-element models of multilayered reservoirs to assess their transient and steady-state behavior in single-well fluid-extraction scenarios. These cases include (1) caprock-reservoir systems with varying permeability and caprock thickness, (2) compaction-induced porosity variations following Athy’s law, and (3) depth-dependent Young’s modulus. While uniformly lower porosity or permeability produces higher rates and earlier onset of deformation and pore-pressure changes, a less permeable or thicker caprock reduces vertical surface displacements, with pressure change reversals near the surface. Young’s modulus varying in alternating or linear profiles generally produces larger vertical displacements and non-monotonic displacement rate histories due to cross-layer fluid migration. Regarding spatiotemporal patterns, porosity or permeability decreasing with depth, or a thicker caprock, accelerates radial expansion of the deformation signal. In contrast, only layered mechanical properties can substantially alter the initial crossover distance and peak-value ratio between the vertical and radial surface displacements, indicating distinct impacts on deformation signatures. Our findings highlight the importance of accounting for structural heterogeneity in predicting and inferring the evolution of poroelastic processes in reservoir systems.

New UBC Okanagan research shows that wildfire can change how much water remains in streams during the driest months of the year.

In early January, a giant sinkhole formed at an intersection in the West Oak Lane neighborhood of North Philadelphia after a water main break. Just two weeks earlier, the city reopened a section of the Schuylkill River Trail in Center City that had been shut down for two months due to a sinkhole. Last summer, some residents of Point Breeze in South Philly also waited two months for a sinkhole on their block to be repaired.

The ocean is continuously ventilated when surface waters sink and transport, for example, oxygen and carbon to greater depths. The efficiency of this process can be estimated using the so-called water age, which describes the time elapsed since a water mass last was in contact with the atmosphere.

A new analysis of air quality data from the past 70 years shows that Canada's record wildfire smoke in 2023 is part of a broader, continent-wide trend toward smokier skies across North America.

A team of scientists announced Tuesday they have developed new deep-sea landers specifically to test their contentious discovery that metallic rocks at the bottom of the ocean are producing "dark oxygen".