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A long stretch of humid heat followed by intense thunderstorms is a weather pattern historically seen mostly in and around the tropics. But climate change is making humid heat waves and extreme storms more common in traditionally temperate midlatitude regions such as the midwestern U.S., which has seen episodes of unusually high heat and humidity in recent summers.

Three hundred years ago, the central United States was a land of wetlands—more than 150 million hectares of them. All that water made the region highly attractive to farmers, who, over time, converted most of it into agricultural land.

For the wetlands that remain, protections secured by the Clean Water Act are often the only thing preventing wetland conversion or development, especially when state protections are weak, said Kylie Wadkowski, a landscape ecohydrologist and doctoral candidate at Stanford University. 

With wetlands, “you actually can’t do whatever you want,” said Elliott White Jr., a coastal socioecosystem scientist at Stanford University. “That’s how this Sackett case came about.”

The Supreme Court’s 2023 Sackett v. EPA decision ruled in favor of two landowners backfilling a lot containing wetlands. The decision changed the definition of the term “waters of the United States”—which is used in the Clean Water Act—to exclude wetlands without continuous surface connections to larger, navigable bodies of water. In November 2025, the Trump administration’s EPA proposed to set new rules for water regulations that may be even looser than the updated Sackett definition.

According to research by Wadkowski and White presented on 15 December 2025 at AGU’s Annual Meeting in New Orleans, the changing definition will leave millions of hectares of wetlands unprotected and more vulnerable to development. 

Wadkowski and White are the first to analyze wetland protections in detail on a nationwide scale, said Adam Ward, a hydrologist at Oregon State University who was not involved in the research. “This represents a huge advance in understanding what is being protected and what is losing protections,” he said.

What Will Happen to Wetlands?

Wadkowski and White found that under Sackett, 16.4 million hectares of wetlands, an area about the size of Wisconsin, are either unprotected or have undetermined status. Under the EPA’s newest proposed rule, that number could increase; the proposed rule contains many subjective and ill-defined terms that could be interpreted by regulators to mean even more wetlands lose protections, Ward said.

The approach the researchers took—using the available wetland, stream, and land conversion data with spatial modeling—was “incredibly logical,” Ward said. “They’re using machine learning tools, using the information we have to try and gap-fill and create the most comprehensive analysis that they can, and that’s a huge step in the right direction.”

Rates of vulnerability were not consistent across the United States. A breakdown of protections based on land management categories showed that 43.5% of wetlands on lands managed by tribes was protected under Sackett, compared to the national average of 66%.

Wetlands in the Great Plains states North Dakota, South Dakota, Nebraska, Montana, and Minnesota were the least protected. This area of the country is often called the “prairie pothole” region because many of its wetlands are depressions in the landscape fed by groundwater and disconnected from larger surface water bodies. Under Sackett, these geographically isolated wetlands rely entirely on state-level protections, which are also often weaker in agricultural regions, Wadkowski said.

“The economic pressure and agricultural [conversion] happens a lot more in the Plains states,” she said. “And those are also the states that have less state level protections.”

With a rule that “emphasizes overland [surface] flow and connection to streams and rivers, it shouldn’t surprise us at all that it excludes wetlands that aren’t wet because of overland [surface] flow,” Ward said.

Wadkowski plans to continue to evaluate how various legal frameworks might affect wetland conversion rates in the future by comparing their estimates of protected wetlands under Sackett and the new EPA proposal with past data on wetland conversion rates under previous definitions of “waters of the United States.”

Informing Policy

To best protect wetlands, policymakers should ensure their policies line up with the available science, White said. 

Part of that strategy includes acknowledging that wetlands that are not connected to larger bodies of water year-round via surface water and therefore may not be protected under the Sackett decision may still be connected to broader water systems through groundwater, Wadkowski said. “Think about water bodies as not just on the surface.”

“Policymakers need to more thoughtfully engage with the scientific community for a more clear understanding of what a wetland is and what wetlands actually need.”

The Sackett decision and the new EPA proposal do not reflect the scientific consensus, White said. “Policymakers need to more thoughtfully engage with the scientific community for a more clear understanding of what a wetland is and what wetlands actually need.” Scientists, too, need to better engage with policymakers, he added.

For example, said Ward, part of the reason that wetland rule frameworks are so contentious is that none have yet been informed by enough clear, comprehensive science to make enforcement efficient or practical. “We have heaps of scientific understanding, but the scientific community writ large has not been invited to formally weigh-in on how to design a rule that reflects our understanding,” he wrote in an email.

In a presentation on 15 December at AGU’s Annual Meeting, Ward made the case for a new, large-scale U.S. headwater stream monitoring network, which would help reduce some of the uncertainty inherent in wetland regulations. “If you don’t understand the stream network, you can’t possibly understand the wetland protections,” he said.

Scientific engagement, however, has been made more difficult by the courts, according to Ward: Within the past 5 years, the Supreme Court has begun to invoke the major questions doctrine, which preserves major rulemaking on matters of environmental regulations for Congress, giving agencies like the EPA less incentive to seek input from scientists. 

“In parallel with our advances in understanding [wetland science] is a court system that is essentially cutting scientists out of the loop,” Ward said.

The public comment period for the EPA’s newest proposed rule closes on 5 January.

—Grace van Deelen (@gvd.bsky.social), Staff Writer

Citation: van Deelen, G. (2026), After Sackett, a Wisconsin-sized wetland area is vulnerable, Eos, 107, https://doi.org/10.1029/2026EO260018. Published on 5 January 2026. 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.

Recurring high-energy flood events are not the exception but the rule in the Ahr Valley in western Germany—and this occurs over periods of centuries to millennia. This is shown in a study recently published in the journal Earth Surface Processes and Landforms and led by Leipzig University. Researchers from the Helmholtz Center for Environmental Research (UFZ) and the Leibniz Institute for the History and Culture of Eastern Europe (GWZO), both in Leipzig, also participated in the study.

A new study reveals that microplastics are impairing the oceans' ability to absorb carbon dioxide, a process scientists find crucial for regulating Earth's temperature.

Source: AGU Advances

Single-celled algae in the ocean known as coccolithophores play an important role in the marine carbon cycle when they take up bicarbonate from seawater to build their shells. Coccolithophore numbers have been increasing globally in recent years, meaning their influence is growing, even as scientists still don’t fully understand the factors driving their explosive growth. One explanation could be changes to the alkalinity of ocean water, specifically, greater amounts of bicarbonate available for the tiny creatures to use.

For more information on how coccolithophores grow and flourish, Zhang et al. looked to the last time the phytoplankton surged in number, between 300,000 and 500,000 years ago. Using fossilized coccolithophore morphology and examining carbon isotope ratios, the authors constructed models that allowed them to pick apart the ingredients for coccolithophore success.

Comparisons of inorganic to organic carbon ratios in the shells, as well as comparisons of photosynthesis and calcification rates revealed by carbon isotope ratios, showed a large increase in calcification linked to greater bicarbonate uptake. Though increasing alkalinity was likely a factor in the coccolithophores’ increased growth, it doesn’t explain all of it, the authors say. Instead, greater nutrient availability allowed coccolithophore populations to swell, both by giving them more food to use and by allowing them to move to shallower depths where there was more sunlight for photosynthesis.

The findings have implications for the present day, as we see marine phytoplankton numbers shifting alongside changes in ocean chemistry. Previous works focused on the change in seawater alkalinity and pH. But more information on how nutrient availability influences coccolithophore growth is needed, the authors conclude, especially in light of proposed geoengineering schemes that could shift the types of nutrients available. (AGU Advances, https://doi.org/10.1029/2024AV001609, 2025)

—Nathaniel Scharping (@nathanielscharp), Science Writer

Citation: Scharping, N. (2026), How a move to the shallows 300,000 years ago drove a phytoplankton bloom, Eos, 107, https://doi.org/10.1029/2026EO260010. Published on 5 January 2026. 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.

This is an authorized translation of an Eos article. Esta es una traducción al español autorizada de un artículo de Eos.

Las olas de calor marinas describen casos de aguas extraordinariamente cálidas que pueden permanecer en la superficie del océano durante meses. Al igual que las olas de calor que experimentamos en tierra, las olas de calor marinas pueden alterar la química ambiental y estancar los procesos biológicos. Mientras que las pérdidas catastróficas de megafauna son indicadores evidentes de un sistema de estrés, los investigadores han comenzado a recopilar datos suficientes para entender cómo los organismos microbianos en la base de las redes tróficas oceánicas están respondiendo a las olas de calor.

Un nuevo estudio publicado en Nature Communications presenta una década de mediciones que documentan dos olas de calor sucesivas en el noreste del Océano Pacífico. El equipo interdisciplinario de autores de este artículo utilizó una combinación de una boya robótica autónoma, un crucero oceanográfico y datos satelitales para entender cómo las comunidades microbianas de la región se reorganizaron en respuesta a estos eventos extremos.

Los investigadores descubrieron que la producción de materia orgánica incrementó en la superficie del océano durante las olas de calor, pero las partículas ricas en carbono no se hundieron, ni flotaron, más bien, se quedaron en su lugar.

La bomba biológica de carbono

Fitoplancton—diminutos microbios fotosintetizadores—activan la bomba biológica de carbono. Al usar la luz solar y el dióxido de carbono (CO2) para crecer, el fitoplancton extrae carbono de la atmósfera y lo incorpora al ciclo del carbono océanico. El zooplancton se alimenta en los extensos campos con estos organismos similares a plantas, transportando carbono a zonas más profundas de la columna de agua en forma de pellets fecales y pedazos de plancton a medio comer. Eventualmente, algunas de estas partículas se sumergen lo suficientemente como para alimentar los ecosistemas de las profundidades oceánicas.

“La capacidad del océano para capturar carbono depende de los microbios en la base de la red trófica.”

Esta bomba de carbono representa un amortiguador globalmente relevante frente a los impactos del cambio climático, ya que el océano absorbe aproximadamente la cuarta parte del CO2 emitido por la actividad humana. Algunas estimaciones sugieren que nuestras concentraciones atmosféricas actuales de CO2, podrían incrementar hasta un 50% si la bomba biológica de carbono dejará de transportar carbono hacia las profundidades del océano.

“La capacidad del océano para capturar carbono depende de los microbios en la base de la red trófica, entonces es muy importante que nosotros comencemos a entender cuáles son los impactos de las olas de calor marinas en las comunidades microbianas”, explicó Mariana Bif, autora principal del nuevo estudio. Bif es profesora asistente en la Universidad de Miami y anteriormente fue investigadora en el Instituto de Investigación del Acuario de la Bahía de Monterey, o MBARI por sus siglas en inglés.

Cuando la red trófica se enreda

En ambas olas de calor marinas rastreadas en el estudio, los investigadores encontraron que la bomba de carbono biológica mostraba señales de sobrecalentamiento. Las partículas ricas en carbono se quedaron estancadas aproximadamente a los 200 metros (660 pies) debajo de la superficie, pero durante las dos olas de calor, distintos mecanismos causaron esta acumulación.

La primera ola de calor incluida en el estudio empezó en el 2013, cuando vientos inusualmente débiles sobre el Pacífico no lograron devolver el aire cálido del verano hacia el territorio continental de los Estados Unidos. La ola de calor, apodada “the Blob” fue noticia cuando las aguas cálidas, estancadas y deficientes en oxígeno provocaron mortandades masivas de fauna en todos los rincones del Pacífico antes de disiparse en 2015.

En 2019, la nubosidad irregular sobre el océano y  prepararon el escenario para que otra ola de calor barriera con el noreste del Pacífico. Esta segunda ola de calor elevó nuevamente las temperaturas y pasó a conocerse como “the Blob 2.0”.

Bif y sus coautores encontraron que durante ambas olas de calor, la comunidad microbiana marina experimentó un cambio en sus “mandos intermedios”.

Dentro de los primeros años del Blob, las condiciones físicas y químicas favorecieron a especies más pequeñas de fitoplancton, lo que a su vez favoreció a un nuevo grupo de alimentadores zooplanctónicos. Esta discreta red trófica, eventualmente creó una capa oceánica llena de partículas orgánicas que eran demasiado ligeras para hundirse en las aguas más densas de las profundidades.

Durante el Blob 2.0, las concentraciones de las partículas de materia orgánica fueron aún más altas, pero el incremento no provino totalmente de la producción primaria. Esta vez las condiciones favorecieron a especies frugales. Los organismos oportunistamente capaces de alimentarse de detritos y de materia orgánica de menor calidad se volvieron más predominantes, mostrando que el sistema estaba ciclando y reciclando carbono para mantenerlo en la parte superior de la columna de agua. Dentro de esta comunidad, los parásitos prosperaron, y organismos (incluido un grupo de radiolarios) que nunca antes se habían observado en el noreste del Pacífico comenzaron a aparecer regularmente.

Midiendo en medio de la nada

La gama de tecnología utilizada en el estudio lo distingue de esfuerzos previos para catalogar los efectos de las olas de calor marinas

“Ahora nosotros estamos entrando en una era de ‘big data’ en la biogeoquímica oceánica, mientras que antes estábamos limitados a lo que podíamos recolectar desde los barcos.”

“Ahora nosotros estamos entrando en una era de ‘big data’ en la biogeoquímica oceánica, mientras que antes estábamos limitados a lo que podíamos recolectar desde los barcos,” dijo Stephanie Henson, científica principal en el Centro Nacional de Oceanografía en Southampton (NOC Southampton, por sus siglas en inglés), Reino Unido. Henson no participó en el estudio.

Henson explicó que las boyas autónomas y otros sistemas de monitoreo avanzado están permitiendo a los investigadores trabajar con un set de datos que se extiende más allá de la duración de un crucero oceanográfico.

“La gente ha estado estudiando las respuestas a las olas de calor marinas en sistemas como los arrecifes de coral, etcétera”, dijo Henson, explicando que los investigadores han observado que no todas las respuestas biológicas son iguales de una ola de calor marina a otra. Sin embargo, señaló que este estudio fue el primero que demuestra que los flujos de carbono en el océano, también presentan respuestas complejas a las olas de calor marinas.

Para revisar los signos vitales del Pacífico antes, durante y después de cada una de las olas de calor, los investigadores recurrieron a la Red Global de Biogeoquímica Oceánica (GO-BGC, por sus siglas en inglés). Los instrumentos GO-BGC son un subconjunto de la red Argo, una red global de miles de boyas robóticas autónomas. Cada boya se desplaza libremente con las corrientes oceánicas, monitoreando el pH, la salinidad, la temperatura y otros parámetros

Mariana Bif se prepara para desplegar una boya GO-BGC en la Bahía de Bengala. La boya derivará libremente en las corrientes oceánicas a aproximadamente 1.000 a 2.000 metros de profundidad, regresando a la superficie cada 10 días para enviar datos sobre la temperatura, salinidad y química oceánica, vía satélite, a los investigadores en tierra. (El océano Índico no fue parte del nuevo estudio, pero Bif utilizó boyas GO-BGC en el Pacífico para realizar la investigación.) Créditos: Sudheesh Keloth, Julio, 2025

A pesar de todo lo que pueden hacer, las boyas no son capaces de recolectar muestras microbianas. Para esto, en lugar de que Bif buscara la data, la data llegó a Bif.

Steven Hallam, microbiólogo de la Universidad de Columbia Británica y coautor en el nuevo estudio, se puso en contacto con Bif después de leer una entrevista con ella sobre su trabajo en olas de calor marinas. Él tenía la corazonada de que las muestras de ADN planctónico almacenadas en el refrigerador de su laboratorio podrían ser de ayuda para la investigación de Bif sobre el ciclo del carbono en el océano. Científicos del grupo de laboratorio de Hallam habían publicado previamente investigaciones sobre comunidades bacterianas en la misma región, usando muestras recolectadas durante los cruceros oceanográficos a lo largo del transecto Line P frente a la costa de Columbia Británica.

Después de un intercambio por correo electrónico, el grupo de laboratorio de Hallam analizó las muestras, expandiendo el análisis de las bacterias a la composición de la comunidad entera, lo que resultó en una contribución significativa al estudio de Bif.

Mientras la historia de cómo el ADN planctónico vino a Bif es un testimonio del poder entre la comunicación y colaboración en la ciencia, Henson notó que los transectos de la Line P, no necesariamente se superponen espacialmente con las regiones de mayor impacto de las olas de calor marinas, y combinar los conjuntos de datos de diferentes escalas (como los datos obtenidos en barcos y los datos de flotadores autónomos) debería hacerse cautelosamente.

Además, Henson añadió, “Es lo mejor que podemos hacer por el momento”

Incertidumbres persistentes

Respecto a las investigaciones futuras, Bif está involucrada en algunos nuevos proyectos explorando regiones marinas desoxigenadas, pero dijo: “Mi enfoque siempre es en los flotadores BGC-Argo”.

Bif indicó que será interesante observar los datos de BGC-Argo desde los flotadores que están en medio de la ola de calor marina afectando actualmente el Pacífico Norte. Esa ola de calor ya está mostrando señales de desaceleración, aunque los científicos dicen que probablemente permanecerá durante el invierno.

“No estoy seguro de si esto va a tener el alcance que tuvieron algunas de las olas de calor marinas anteriores en la región”, dijo Nick Bond, quien no estuvo involucrado en esta investigación pero estudió las olas de calor marinas como parte de su rol anterior como climatólogo del estado de Washington. Ahora él es investigador sénior en la Universidad de Washington.

“Lo que no medimos, no podemos entenderlo. Necesitamos más inversiones para monitorear el océano.”

Bond añadió que mientras haya “evidencia tentativa” de que el calentamiento climático puede estar incrementando la frecuencia de olas de calor marina en el Pacífico, aún hay mucho más por aprender antes de que los científicos puedan pronosticar con precisión cómo se comportarán en el futuro.

Mientras tanto, otra incógnita que se avecina para este campo de investigación se está desarrollando nuevamente en tierra firme.

“Hay un poco de incertidumbre en la comunidad porque al momento, para el programa global Argo, Estados Unidos contribuye aproximadamente con la mitad de los flotadores que se despliegan”, dijo Henson, aludiendo su preocupación a los recortes presupuestarios recientes en Estados Unidos. Sin embargo, ella explicó que otros países están intensificando sus contribuciones para mantener a flote el programa Argo.

“Lo que no medimos no podemos entenderlo. Necesitamos más inversiones para monitorear el océano” dijo Bif.

—Mack Baysinger (@mack-baysinger.bsky.social), Escritor de ciencia

This translation by translator (@Cecilia Ormaza) was made possible by a partnership with Planeteando y GeoLatinas. Esta traducción fue posible gracias a una asociación con Planeteando and GeoLatinas.

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.

Yukon Geological Survey

Contributors: Derek Cronmiller, Theron Finley, Panya Lipovsky, Jan Dettmer

A guest post featuring images and a commentary of landslides in Yukon Territory in Canada triggered by the 6 December 2025 M=7.0 Hubbard Glacier Earthquake.

The 6 December 2025 Mw=7.0 Hubbard Glacier Earthquake in the St. Elias Mountains of Yukon caused widespread mass wasting activity in an area near Mt. Logan, Canada. On 12 December 2025, the Yukon Geological Survey completed an overview flight of the area to collect photographs and document seismically induced activity in the region. Based on the preliminary USGS finite fault model, the earthquake rupture appears to have been shallow, with approximately 2 m of slip occurring at ~6 km depth but no evidence of earthquake surface rupture was identified. However, we documented extensive surface effects including more than 200 landslides, many snow and ice avalanches, and widespread damage to glaciers throughout the area.

View southwest towards Mt King George. Snow avalanche and serac collapse scars are visible on the ridge in the foreground, large rock avalanche scars on the NE face of Mt. King George are visible in the background, triggered by the Landslides from the 6 Dec 2025 Hubbard Glacier Earthquake.

Landslide activity was concentrated on the Mt King George massif, where rock–ice avalanches and rockfall were the most common failure types. Based on preliminary earthquake relocations, the King George massif directly overlies a portion of the fault rupture and rises to a height of 3,741 m, approximately 1,900 m above the surrounding Hubbard Glacier.

Landslide scars and debris on the NW end of the King George massif, looking toward Mt Logan (5,959 m). Note the lack of snow cover here due to concentrated avalanche and landslide activity, as compared to distant peaks.

Landslide activity continued for several days after the main earthquake, likely due to a combination of aftershocks and progressive failure of slopes that were damaged by the earthquake or destabilized by earlier landsliding. At least one rock avalanche occurred between 11 and 12 December as constrained by Landsat imagery.  At the time of the overview flight, slide scars on the east and northeast sides of Mt King George remained active, with ongoing rockslides and rockfall producing large dust clouds. The large slide scar on the east face of Mt King George appeared to have liquid water flowing down its centre, suggesting either discontinuous permafrost within the massif or significant heating associated with slope failure.

A large landslide scar on the east face of Mt King George appeared to have liquid water running out from approximately halfway down the scar (arrow). This scar was producing active rockfall at the time of the overview flight and filling adjacent valleys with dust.

The largest observed landslide was a rock and ice avalanche produced by a partial collapse of the southwest ridge of Mt King George. The basal failure surface occurred along a southwest-dipping planar discontinuity oriented subparallel with the pre-existing slope of the south flank of the ridge . The crown of the slide originated at approximately 3,000 m above sea level and descended roughly 1,300 m along a tributary glacier before coming to rest on the Hubbard Glacier, approximately 7.4 km from the source area. This corresponds to an overall travel angle of approximately 10 degrees. Such high mobility is typical of rock avalanches on glaciers (c.f.  Evans and Clague 1988), where movement is enhanced by the low-friction surface of the glacier, entrainment of snow and ice, and by water inputs generated through frictional melting (Sosio et al., 2012).

Source area and runout of the largest (9 square km) landslide triggered by the Mw=7.0 6 December 2025 Hubbard Glacier Earthquakeearthquake on the southwest ridge of Mt King George. The planar surface of failure for the largest rock and ice avalanche on the southern flank of the SW ridge of Mt King George.

Snow avalanches were common on all aspects and were triggered in a more extensive region than landslides. Some of the largest snow avalanches occurred on the north and east aspects of Mt King George and McArthur Peak (a sub-peak of Mt Logan) and produced plumes that in some cases extended 2-3 km across the glacier at the base of the slopes where they initiated. Damage to glaciers was also extensive; the collapse of snow bridges and seracs on icefalls was widespread on the Hubbard Glacier and adjacent tributaries. A partial collapse of a glacier occurred between Mt King George and Mt Queen Mary, an area immediately above many of the most intense aftershocks. This portion of glacier is covered by debris from a rock avalanche off the NE face on Mt King George which may have contributed to its failure. The most intensely affected area is in a popular recreation zone of Kluane National Park and may have significant impact on the objective hazards skiers and mountaineers face in the region over the coming years.

Partial collapse of a glacier between Mt King George and Mt Queen Mary. The length of the failure is approximately 2.4 km. Widespread collapse of seracs and snow bridges on the south side of Mt Queen Mary. The field of view mid-photo is approximately 5 km across. Widespread collapse of seracs and snow bridges on the south side of Mt Queen Mary. The field of view mid-photo is approximately 5 km across. Rock avalanche below Mt King George triggered by the 6 December 2025 Hubbard Glacier Earthquake. The runout distance is 1.4 km.

All photos provided courtesy of the Government of Yukon.

References:

Evans, S. G., & Clague, J. J. 1988. Catastrophic rock avalanches in glacial environments. In Proceedings of the Fifth International Symposium on Landslides, 2, pp. 1153–1158. Lausanne, Switzerland.

Sosio R., Crosta, G.B., Chen, J.H. and Hungr, O. 2012. Modelling rock avalanche propagation onto glaciers. Quaternary Science Reviews 47, 23–40

Return to The Landslide Blog homepage 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.

SummaryEfficient Markov chain Monte Carlo (MCMC) sampling from posterior distributions remains a central challenge in Bayesian geophysical inversion. Recent developments in computational statistics and optimal transport suggest that MCMC efficiency can be improved by reparameterising the sampling problem – specifically, by learning an invertible mapping that recasts the target distribution onto a simpler reference distribution. Here, we introduce a Metropolis–Hastings framework that leverages transport maps parameterised by invertible neural networks. These maps are trained on preliminary MCMC samples from the target distribution and used to propose new samples in a fixed reference space, where proposal design is independent of the target’s structure. The proposed samples are transformed back to the target space via the inverse map, and accepted or rejected according to a modified Metropolis–Hastings criterion. As sampling proceeds, the transport maps are updated, yielding proposals increasingly well adapted to the shape of the target distribution. Across a suite of numerical tests – including a 2-D Rosenbrock distribution, a 3-D earthquake location problem, and Gaussian mixtures up to 16 dimensions – transport-map-driven samplers consistently outperform standard MCMC, reducing integrated autocorrelation times by factors of 2.5 to over 6 (or equivalently, yielding sample sets 2.5–6 times larger for the same number of forward evaluations). This improvement comes at the non-negligible cost of training one or more transport maps, which we quantify systematically. We also provide a quantitative criterion for weighing training cost against sampling speed-up. This shows that transport-map MCMC is advantageous whenever the forward problem is nontrivial, making it a promising approach for Bayesian sampling in geophysics and beyond.

SummaryEarthquake locations and catalogs from routine earthquake monitoring are typically based on manually reviewed arrival-time picks from classical, rule-based automatic pickers. High-performance, deep-learning (DL) pickers can replace this standard approach, rapidly delivering much larger and complete catalogs. A transition to routine monitoring based on DL picks requires that resulting catalogs include all or almost all events identified by current procedures with locations of the same or higher quality. Here we verify these requirements by comparing the performance of DL and manual picking for earthquake relocation and tomographic inversion. We form a reference catalog with a subset of INGV bulletin events and picks from the 2016 Central Italy sequence. This catalog is re-picked using the DL picker PhaseNet trained on the Northern California Earthquake Data Center dataset and on the INSTANCE Italian dataset. We use these three pick sets for high-precision, non-linear earthquake relocation and for 3D tomographic inversion and relocation. Relative to the high-precision relocations using routine picks, those using DL picks show improved organization and clustering, and, in a ground-truth test, smaller hypocenter separation for event pairs with more similar waveforms. The tomographic inversions show statistically better convergence and more organized relocations using the DL picks than with the routine picks. We conclude that DL based monitoring can rapidly produce more consistent picks and higher quality catalogs than standard procedures, while freeing analyst time for improved quality control, assessment, interpretation, and dissemination of information on seismic activity, especially during significant seismic sequences.

SummaryFluid injection into the subsurface can trigger moderate-magnitude earthquakes days to months after shut-in, complicating hazard assessment. To investigate the governing mechanics, we implemented a fully coupled hydro–mechanical model that couples Darcy flow, poro-viscoelastic deformation and rate-and-state fault friction on a planar fault, allowing two-way feedbacks between pore pressure, volumetric strain and fault slip and the simulation of both aseismic and seismic transients. Compared with decoupled or one-way approaches, the fully coupled formulation generally yields longer post-injection delays, owing to poroelastic stress contributions and a more realistic evolution of volumetric strain. After shut-in, a slow poroelastic redistribution of volumetric compression broadens and migrates along the fault, constructively overlapping regions of elevated shear and reduced effective normal stress. This causes the nucleation of a delayed rupture away from the well, indicating that the point of peak instantaneous pressure does not necessarily coincide with the location of maximum coseismic slip. By scanning permeability and injection rate we construct an empirical injection-rate (IR)–permeability (k) phase diagram that delineates regimes of immediate, delayed and no induced seismicity; this diagram is offered as a conceptual, physics-informed screening tool that requires site-specific calibration. Our results indicate that two-way hydro-mechanical coupling and fault slip evolution should be considered when assessing post-injection seismic hazard and in the design of spatially distributed monitoring.

SummaryTraditional seafloor mapping relies on shipborne soundings which have limited spatial coverage. The Surface Water and Ocean Topography (SWOT) wide-swath altimetry satellite holds the potential for predicting more detailed seafloor topography. In this study, we integrate SWOT gravity data with single-beam shipborne depths to construct seafloor topography models in the Northwestern Pacific using the deep neural network (DNN) method. Compared to shipborne depth checkpoints, the root mean square (RMS) error of the differences between topography model predicted by DNN method and shipborne depths is approximately 97.5 m, improving by 19.5% and 9.9% compared to the gravity-geologic (GGM) method and the Smith and Sandwell (SAS) method respectively. Compared to traditional data, the integration of SWOT gravity data universally enhances prediction accuracy. Furthermore, the DNN method effectively demonstrates superior capability in balancing the characterization of overall structures with the retention of authentic topography features, which we demonstrated in the Mariana region of the NW Pacific Ocean. However, limited by spatial heterogeneity and physical mechanisms, accurate prediction of such complex, fine-scale topography using gravity data remains a significant challenge.

Publication date: December 2025

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 277

Author(s):

Publication date: December 2025

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 277

Author(s): Costas A. Varotsos, Ferdenant A. Mkrtchyan, Vladimir Yu. Soldatov

Publication date: December 2025

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 277

Author(s): Nambi Manavalan Rajan, Alok Taori, Degala Venkatesh, M. Mallikarjun, Sameer Saran, Rajiv Kumar, Dhiroj Kumar Behra, Goru Srinivasa Rao, Prakash Chauhan

Publication date: December 2025

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 277

Author(s): Congzhen Zhu, Mingzhong Wang, Lu Meng, Ali Mamtimin, Fan Yang, Chenlong Zhou, Honglin Pan, Jiantao Zhang

Publication date: December 2025

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 277

Author(s): Vladimir Obridko, Antonina Shibalova, Dmitry Sokoloff, Ilya Livshits

Publication date: December 2025

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 277

Author(s): Varuliantor Dear, Jiyo Harjosuwito, Annis Siradj Mardiani, Adi Purwono, Afrizal Bahar, Indah Susanti, Satrio Adi Priyambada, Rezy Pradipta

Publication date: December 2025

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 277

Author(s): Andrei Moldavanov

Publication date: December 2025

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 277

Author(s): Alexander Oreshko

Publication date: December 2025

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 277

Author(s): Farahnaz Fazel-Rastgar, S.H. Mthembu