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New Satellite Adds Evidence of an Earth-Shaking Wave

EOS - Tue, 07/01/2025 - 13:21

On 16 September 2023, a low hum started swaying seismometers around the world. Unlike during the short and jagged frenzy of an earthquake, this signal wobbled every 92 seconds and continued for 9 days. About a month later, while seismologists were still puzzling over the incident, the hum started again and lasted roughly a week.

Researchers traced the confusing signals to East Greenland, where satellite imagery revealed the scars of recent rockslides in Dickson Fjord. They deduced that millions of cubic meters of rock and ice had suddenly fallen into the sea on 16 September, creating a 200-meter (650-foot) tsunami and a long-lasting wave called a seiche. Rather than ricochet out to sea, crooked topography kept the tsunami sloshing back and forth between the fjord’s parallel walls. The later hum was from a second, smaller rockslide and seiche.

The area is unpopulated, meaning no one was threatened by the initial wave but no one observed the event either.

Seiches typically need a continuous energy source such as a windstorm to persist, but the long-lasting waves in Dickson Fjord appeared to be self-sustaining. Two teams independently developed simulations showing Dickson Fjord could support a long-lasting seiche. A new study in Nature Communications builds on that work, using satellite data to provide the first direct observations of the seiche.

“To really robustly be able to say, ‘This is what was shaking the Earth at this time,’ we needed that observational evidence,” said Thomas Monahan, an oceanographer at the University of Oxford and first author of the new paper.

Before (left) and after images show the obvious collapse of a glacier in Greenland’s Dickson Fjord. Credit: Søren Rysgaard As Above, So Below

East Greenland is remote, and the seiche mostly dissipated before the Danish military arrived 3 days after the initial wave to investigate the collapsed mountain face in Dickson Fjord. By then, the amplitude of the wave was already too small to detect from the boat. However, the shift in sea surface was visible from space thanks to the international Surface Water and Ocean Topography (SWOT) satellite, launched in 2022.

“We’ve never had the capability to do things in these regions at this level before.”

SWOT uses two altimeters spaced 10 meters apart to triangulate small changes in water height. Prior to SWOT, satellites had one altimeter and could offer a one-dimensional footprint of the ocean. Now, Monahan said, researchers can obtain precise, high-resolution imagery of the sea surface, even between the deep walls of a distant fjord.

“We’ve never had the capability to do things in these regions at this level before,” he said.

The satellite passed over Dickson Fjord several times during the main event and the smaller rockslide that followed. Monahan and his colleagues examined SWOT data from four transits, tracking the sea surface slope along the same transect each time.

The water was sloshing back and forth between the fjord walls.

The researchers extended their search to rule out other causes. The timing of the waves did not match the timing of winds recorded by a weather station in the fjord or the pattern of tides recorded by SWOT over the next 13 months. The magnitude of the wave did, however, match the seismic signal, further suggesting the fjord’s geometry had trapped a wave.

A sloshing tsunami in Dickson Fjord shimmied seismometers for 9 days starting on 16 September 2023. This data visualization of the fjord on 17 September 2023 shows the sloshing water and adds direct observational evidence to earlier models. Credit: NASA Earth Observatory “Science at Its Best”

The study further confirmed the seiche but also showed the early utility of SWOT, which had finished calibrating just 2 months before the initial rockslide.

“They’re sort of perfect partners, satellite and seismic data.”

“It’s a nice surprise to see the result,” said Yao Yu, a physical oceanographer who works with SWOT data at the Scripps Institution of Oceanography. The satellite is built for oceans, rivers, and lakes, she said, but the new study shows it can also collect good data from high-latitude fjords in areas unreachable by prior satellites. “A lot of things we never expected SWOT can do, it’s actually working very well,” she said.

SWOT’s spatial resolution is especially important in the Arctic, where seismometers are sparse. The satellite provides only intermittent observations, but it can access remote locations. That fills a gap, said Stephen Hicks, a seismologist at University College London and coauthor on one of the original seiche papers.

“They’re sort of perfect partners, satellite and seismic data,” he said. The new study backs up and builds upon the original research, he added, and “that’s sort of science at its best.”

—J. Besl (@J_Besl), Science Writer

Citation: Besl, J. (2025), New satellite adds evidence of an Earth-shaking wave, Eos, 106, https://doi.org/10.1029/2025EO250236. Published on 1 July 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.

Fire forensics reveals ancient infernos, offers future insights

Phys.org: Earth science - Tue, 07/01/2025 - 12:11
Eastern Australia is one of the most fire-prone regions in the world, with bushfires responsible for the deaths of about 800 people and millions of animals since about 1850.

The 19 June 2025 landslide at the Rubaya mining site in the Democratic Republic of Congo

EOS - Tue, 07/01/2025 - 06:43

A major slope failure killed many people, possibly over 300, in an area of unlicenced mining of the mineral Coltan.

On 19 June 2025, a very significant landslide occurred at the Rubaya mining site in Masisi territory, North Kivu, which is located in the eastern part of the Democratic Republic of the Congo (DRC). The landslide, which reportedly affected a place called Bibatama, killed at least 21 people, but in all probability many more people died. Local news site Mines.cd reports over 300 fatalities.

The Rubaya mining area is a large, unlicenced and unregulated shallow excavation for the extraction of Coltan (known industrially as tantalite), an ore from which niobium and tantalum are extracted. The primary use of tantalum is in mobile phones, but it is also used in computer hard drives and road vehicle electronics.

These types of disastrous mining landslides in less developed countries rarely attract much interest (imagine what would have happened if this event had occurred in Canada or Australia), so I decided to see whether I could find anything out about it. I must note that landslides at this site are common – for example, about 100 people were killed in a landslide in 2013.

The Rubaya mining area is well covered in Google Earth – this is an image from 2021. The marker gives the general location – we’ll come back to this spot below:-

Google Earth image from 2021 showing the Rubaya mining area in the DRC.

Zoom in and you find a landscape scarred by shallow workings and landslides:-

Google Earth image from 2021 showing a part of the Rubaya mining area in the DRC.

The Rubaya mining area has a very challenging history. In recent years, possession has alternated between the military and various militias, who have run the site as a protection racket. Since April 2024, the site has been controlled by the March 23 Movement (M23), a rebel group with a long history of human rights violations.

I have been trying to use Planet Labs images to try to identify the location of the 19 June 2025 landslide. I think the most likely location is in the mining area located at [-1.58203, 28.89378]:-

Google Earth image from 2021 showing the likely location of the 19 June 2025 landslide in the Rubaya mining area in the DRC.

This mining area has expanded rapidly in recent years. The 2021 Google Earth image shows that it has been subject to a number of landslides.

I have downloaded a Planet Labs image from 14 June 2025 – five days before the landslide, and I have draped onto the Google Earth DEM. Of course, the Planet Labs imagery has a lower spatial resolution than the Google Earth imagery:-

Planet Labs image of the likely site of the 19 June 2025 landslide in the Rubaya mining area. Image copyright Planet Labs, used with permission. Image dated 14 June 2025.

The image shows a higher level of mining activity than was the case in 2021, and possibly some further landslides. By comparison, the image below was captured on 25 June 2025, after the landslide:-

Planet Labs image of the aftermath of the 19 June 2025 landslide in the Rubaya mining area. Image copyright Planet Labs, used with permission. Image dated 25 June 2025.

And here is a slider to allow the images to be compared:-

Image copyright Planet Labs, using the Google Earth DEM.

I think the landslide is visible on the left side of the mining area. A series of shallow workings have been destroyed, and the track and runout zone of the landslidecan be seen. The feature that is probably the landslide is about 250 metres long.

These types of landslides in unlicenced and unregulated mining sites are a major contributor to global landslide fatalities, but they are rarely investigated.

Finally, in an interesting twist, the FT reported last week that an ally of Donald Trump, Gentry Beach, is seeking to “snap up” the Rubaya mine site.

Reference

Planet Team 2024. Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://www.planet.com/

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Out-of-plane signals from deep mantle subducted slabs at teleseismic distances: insights from 3D global modeling and three-component array analysis

Geophysical Journal International - Tue, 07/01/2025 - 00:00
SummaryGlobal seismology mainly uses seismic waves propagating in the sagittal plane along the great circle path (GCP). However, heterogeneities in the mantle laterally deviate the path of seismic signals, which arrive out-of-plane (OOP) at arrays of sensors at teleseismic distances. Detection and back-projection of these signals have, in the past, provided independent evidence for the location of distant subducted slabs in the deep mantle, complementing global tomographic imaging. To infer physical properties of these subducted slabs, 3D waveform modeling of OOP waves for a finite-thickness slab is needed but still missing. In this study, we conduct a series of synthetic tests using a spectral element solver. We test the detectability of OOP signals and, by progressively adding complexities, we evaluate to which extent these signals can be used to infer physical properties of the modeled slab. We carry out three-component array analysis and investigate focal mechanism dependency. Our results show that the transverse component might be the best candidate for such studies, also for P-to-P OOP signals. Vertical and radial component recordings are usually dominated by P-SV energy arriving from the earthquakes along the GCP, which masks possible OOP signals. Contrary, the transverse component filters out any P-SV energy arriving directly from the source and, owing to its intrinsic directionality, allow for higher resolution measurement of P-to-P OOP signals. This is especially the case prior to the arrival of the S-wavefield. We pick a series of OOP arrivals which are back-projected using a multi-phase trial-and-error approach, that is considered successful only when different OOP seismic phases converge to the modeled (true) structure. We retrieve the location of the slab, its bottom and top edges, and its thickness in the lower mantle. These inferences are tested against varying topography, orientation and size of the modeled slab. The insights gained with modeling are confirmed with real data examples, supporting higher resolution mapping of 3D mantle structure based on OOP seismology.

Deep Crustal Structure and Seismogenic Potential of the Southwest Iberian Margin: Insights from Seismic and Gravimetric Data

Geophysical Journal International - Tue, 07/01/2025 - 00:00
SummaryWe investigate the lithospheric structure of the Southwest Iberian margin along an active seismic profile southwest of São Vicente Cape, ranging from the southern Tagus Abyssal Plain to the westernmost part of the Gulf of Cadiz. This profile, approximately 320 km long, intersects almost perpendicularly three major thrust faults: the Tagus Abyssal Plain, Marquês de Pombal and Horseshoe faults. The crustal structure, derived from spatially coincident wide-angle seismic (WAS) and multichannel seismic (MCS) data, was validated and constrained using gravimetric data. Joint travel-time inversion of refracted phases identified in WAS and reflected seismic phases from both WAS and MCS records were used to build a detailed two-dimensional P-wave velocity (Vp) structure. The resulting model reveals a Vp distribution with abrupt lateral velocity and structural variations, characterized by a rugged basement top and sharp changes in crustal thickness. Three main lithospheric domains consisting of continental, oceanic, and exhumed mantle affinity were identified from south to north. The travel-time inversion of the deepest reflected seismic phases reveals four major southeast-dipping reflectors, likely corresponding to major regional thrust faults with significant seismic and tsunamigenic potential. Integrating the modelled and interpreted seismic results with the locations of recent well-constrained earthquakes suggests that the Marquês de Pombal and Tagus Abyssal Plain extend deeper than previously thought, with fairly high seismic activity in the deep levels. This has significant implications for their seismogenic potential and should be taken into account for accurate assessment of seismic hazards in the region.

Research reveals important gaps in knowledge about coastal sand nourishments

Phys.org: Earth science - Mon, 06/30/2025 - 20:47
For years, sand nourishment has been an important way to protect the Dutch coast against erosion and rising sea levels. But we know surprisingly little about one type of nourishment, shoreface nourishment. A recent scientific review article published in Earth-Science Reviews by the University of Twente maps out existing knowledge in this area and underlines the need for further research.

Everglades ecosystems show mixed reactions to rising sea levels

Phys.org: Earth science - Mon, 06/30/2025 - 20:37
Scientists have discovered that changes in climate and water levels are reducing the ability of some ecosystems in the Everglades to sequester carbon, while the environmental shifts are enhancing the potential for carbon uptake by scrub mangroves.

New 3D glacier visualizations provide insights into a hotter Earth

Phys.org: Earth science - Mon, 06/30/2025 - 20:10
As glaciers retreat due to a rise in global temperatures, one study shows that detailed 3D elevation models could drastically improve predictions about how they react to Earth's warming climate.

Southern Ocean saltier, hotter and losing ice fast as decades-long trend unexpectedly reverses

Phys.org: Earth science - Mon, 06/30/2025 - 19:00
Researchers have discovered a dramatic and unexpected shift in the Southern Ocean, with surface water salinity rising and sea ice in steep decline.

How rare earth elements move and accumulate in the desert and other cold regions

Phys.org: Earth science - Mon, 06/30/2025 - 18:33
They're in the headlines every week—critical minerals like lithium, cobalt, nickel, graphite and the rare earth elements essential for high-technology and national security applications.

Santorini earthquakes traced to sideways magma movement in crust, not traditional volcanic centers

Phys.org: Earth science - Mon, 06/30/2025 - 13:10
When the island of Santorini was rattled by thousands of small earthquakes earlier this year, many people were left mystified about the source of the tremors.

Obtaining Local Streamflow at Any Resolution

EOS - Mon, 06/30/2025 - 13:06
Editors’ Highlights are summaries of recent papers by AGU’s journal editors. Source: Water Resources Research

One of the challenges in global hydrology is to simulate water resources globally at a resolution that is fine enough to be of local relevance. However, these hyper-resolution (less than 1 kilometer) simulations are limited by the very high computational demand of routing water through the global river system.

Shrestha et al. [2025] devise a very clever upscaling algorithm for stream directions that allows simulating streamflow at low-resolution, while still being able to locally refine ate points of interest, such as locations where streamflow is measured. This computational breakthrough opens the door to very detailed global hydrological simulations, not only for global hydrology, but for Earth system science at large.

Citation: Shrestha, P. K., Samaniego, L., Rakovec, O., Kumar, R., & Thober, S. (2025). A novel stream network upscaling scheme for accurate local streamflow simulations in gridded global hydrological models. Water Resources Research, 61, e2024WR038183.  https://doi.org/10.1029/2024WR038183  

—Marc F. P. Bierkens, Editor, Water Resources Research

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.

A New Exoplanet Resets the Scale

EOS - Mon, 06/30/2025 - 11:21

If astronomers have learned one lesson from 6,000 or so confirmed exoplanets, it’s to expect the unexpected. Even so, a giant planet orbiting a red dwarf star recently caught them by surprise. It is the largest planet relative to its host star yet discovered, and it defies the leading theory of giant-planet formation, according to a new study.

TOI-6894 b orbits an M dwarf star roughly one fifth the size and mass of the Sun—60% the mass of the next-smallest star with a giant planet. TOI-6894 b is the size of Saturn and half its mass. The planet is 40% the diameter of the host star, making it by far the highest planet-star size ratio yet seen.

“Because the star is so low mass, based on what we currently understand about planet formation and protoplanetary disks, we wouldn’t have expected it to be able to form a gas-giant planet,” said Edward Bryant, an astrophysicist at the University of Warwick in the U.K. and first author of the study, published in Nature Astronomy.

The planet was first detected by the Transiting Exoplanet Survey Satellite (TESS) in early 2020 and confirmed with additional observations over the following 3 years. TESS looks for the dip in a star’s brightness that occurs when a planet passes between it and Earth, blocking some of its light.

TESS, a planet-hunting space telescope, stares into space in this illustration. It has discovered more than 600 confirmed exoplanets, with thousands of candidate worlds awaiting confirmation. Credit: NASA Goddard Space Flight Center

Bryant and his colleagues scoured observations of 91,000 stars in the TESS catalog to determine the frequency of giant planets around low-mass red dwarfs, which are the smallest and faintest stars in the galaxy and the most common. They reported the discovery of several such planets in 2023.

The team’s new analysis shows that the transits of TOI-6894 b are record breakers, reducing the star’s brightness by 17% and hinting at how large the planet is relative to its star. The transits also show that it orbits every 3.37 days.

The follow-up observations with ground-based telescopes measured changes in the star’s radial velocity—back-and-forth “wobbles” in its motion caused by the planet’s gravitational pull that revealed the planet’s mass.

A Special Case?

The leading theory of giant planet formation, called core accretion, posits that such worlds form early in a star’s lifetime, when it is still encircled by a protoplanetary disk—a wide disk of gas and dust that comprises the raw building materials for planets. Heavier materials coalesce to form larger and larger bodies, eventually creating a core that can be several times the mass of Earth. When the core grows large enough, it gobbles up the surrounding gas, building a layered giant planet similar to Saturn or Jupiter.

“It’s a surprise to find a giant planet around such a tiny star because we just didn’t think there would be enough material there.”

“The total amount of heavy material in the disk determines how big of a core you can make,” said Joel Hartman, a research astronomer at Princeton University and a member of the study team. “It’s a surprise to find a giant planet around such a tiny star because we just didn’t think there would be enough material there.” Some studies, he added, have suggested that stars less than about one third the mass of the Sun should not be able to form giant planets at all.

“Theorists who model planet formation [with core accretion] are not able to create planets like TOI-6894 b,” said Emily Pass, an astrophysicist at the Massachusetts Institute of Technology who was not involved in the study. “So the question becomes, Are planets like TOI-6894 b special cases that formed in a different way, or does our entire model of giant planet formation need a revision?” Pass explained. “Understanding the occurrence rate of [such] planets will help test the various possibilities.”

Hinting at the Formation Mechanism

One possibility is a modified accretion mechanism, in which the growing planet hoovers up both heavy materials and gas simultaneously, forming a more mixed world.

“None of these theories can really explain this planet.”

Another possibility is direct collapse. “Instead of the core being built from the ground up, the disk fragments under its own self-gravity and directly collapses,” Bryant said. “If the disk becomes unstable in the right way, you can form giant planets around these low-mass stars. The problem is that some of the simulations predict that you would only form planets that are much, much more massive than Jupiter, which would be many times more massive than this planet. So none of these theories can really explain this planet. We’re really limited by our understanding of protoplanetary disks,” he said.

Hints of the planet’s formation mechanism may be found in its atmosphere, which is scheduled for study in the next year by the James Webb Space Telescope (JWST). As the planet passes in front of the star, starlight shining through the atmosphere will reveal its composition.

“We should be able to tell the difference in whether a planet formed from direct collapse versus core accretion by looking at the atmosphere’s metallicity,” which is the makeup of elements heavier than hydrogen and helium, Hartman said. “In the gravitational instability case, all the materials collapsed together, so the elements should all be mixed together. In the core accretion model, all the heavy elements should be in the core, with a gaseous envelope on top of it.”

Two charts compare (a) the mass and (b) size of many exoplanets to their host stars. TOI-6894 b, in purple, clearly stands out from the crowd. Credit: Bryant et al., 2025, https://doi.org/10.1038/s41550-025-02552-4, CC BY 4.0

Because of the large transit signal, TOI-6894 b should be “amenable” to additional ground-based studies, Hartman said, although none are currently planned. “We’ll wait and see what JWST tells us,” Bryant said.

—Damond Benningfield, Science Writer

Citation: Benningfield, D. (2025), A new exoplanet resets the scale, Eos, 106, https://doi.org/10.1029/2025EO250235. Published on 30 June 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.

Landslides during periods of glacial retreat in Alaska

EOS - Mon, 06/30/2025 - 06:36

An excellent new paper (Walden et al. 2025) examines the occurrence of accelerated movement in rock slope landslides in Alaska as adjacent glaciers melt.

The exceptional temperatures in recent days in both North America and Europe has once again highlighted the rate at which the climate is changing in response to anthropogenic increases in greenhouse gases. In most glaciated areas, retreat of the large ice masses is occurring. There has long been discussion of how the slopes adjacent to glaciers will respond to these changes.

There is a very good new open access paper (Walden et al. 2025) in the journal Natural Hazards and Earth System Sciences that examines this issue for eight landslides in southern coastal Alaska. These are large, rock slope failures in areas in which the adjacent glaciers are retreating rapidly. In some cases, the glacier has already retreated beyond the slope, leaving it bordering lakes or fjords. In other cases, the slope is still in contact with the ice, which is in retreat.

On of these landslides is at the actively retreating Barry Glacier – this is a very large rock slope failure, with an estimated volume of between 188 and 500 million cubic metres. This is a Google Earth image of the site in 1996:-

Google Earth image of the landslide at the Barry Glacier in Alaska in 1996.

And this is the same site in 2019:-

Google Earth image of the landslide at the Barry Glacier in Alaska in 2019.

And here is a slider to allow the images to be compared:-

Google Earth images.

The change in the glacier is, of course, startling, but the large rock slope landslide is also notable.

Walden et al. (2025) have used archive datasets extending back to the 1980s to examine these eight slopes as the glaciers below them changed. They found that six of the slopes have experienced a period of substantially increased rates of movement. In four sites, a pronounced acceleration was observed as the terminus of the glacier retreated past the landslide area. Two other sites showed rapid movement during a period of wet weather or as the glacier rapidly thinned. In two cases, the sites did not appear to undergo a change in behaviour.

This is illustrated by data from the Barry Glacier site. This is a part of Figure 4 from Walden et al. (2025), showing the measured landslide velocity (upper graph), the retreat of the terminus of the glacier (middle graph) and the change in thickness of the Barry glacier (lower graph). The pink shading shows onset of rapid movement. The slope underwent a really rapid phase of movement (over 20 metres per year) as the adjacent glacier thinned and the slope started to debuttress.

The behaviour of the rock slope at the Barry Glacier in Alaska. Part of Figure 4 from Walden at al. (2025).
Key parts of the original caption:
“Landslide and glacier evolution at the study sites. Row 1: landslide velocities from ITS-LIVE (black circles, with uncertainty estimates) and manual feature tracking (gray bars). Stars indicate the onset of slope-wide deformation, triangles stand for crack opening, and diamonds mean both deformation and crack opening. Row 2: terminus retreat (dark blue) and location of the landslide along the glacier centerline (light-blue shading). Row 3: glacier thickness change rates (purple) and absolute ice thickness (yellow; right-hand axis) below the landslide. … In all panels, light-red shading indicates the onset of landslide movement.

Large rock slopes are incredibly complex, and the ways in which they interact with their environment (including an adjacent glacier, but also rainfall, seismic forcing and suchlike) is also complex, so we would not expect them all to respond in the same way. But this study is important for two reasons.

First, it provides additional support for the notion that glacial debuttressing is an important element of the geomorphology of areas undergoing glacial retreat.

But second, large rock slope failures can be very hazardous, either through direct impact from the resulting rock avalanche or as a result of the generation of a localised displacement wave. This study once again highlights the need to monitor these types of slope better, to undertake hazard analyses and to ensure that local populations are prepared for the consequences of a rapid collapse event.

Reference

Walden, J., Jacquemart, M., Higman, B., Hugonnet, R., Manconi, A., and Farinotti, D. 2025. Landslide activation during deglaciation in a fjord-dominated landscape: observations from southern Alaska (1984–2022), Natural Hazards and Earth System Sciences, 25, 2045–2073, https://doi.org/10.5194/nhess-25-2045-2025.

Return to The Landslide Blog homepage Text © 2023. 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.

Сверхновые звёзды как источники космических лучей

Успехи физических наук - Sun, 06/29/2025 - 21:00

А.М. Быков

Огромное выделение энергии при вспышках сверхновых звёзд и наблюдения нетеплового радиоизлучения позволили В.Л. Гинзбургу и С.И. Сыроватскому более 60 лет назад обосновать гипотезу о ключевой роли сверхновых как источников основной компоненты галактических космических лучей. К настоящему моменту многоканальные наблюдения остатков сверхновых во всём диапазоне электромагнитных волн предоставили большой объём данных, подтвердивший факт ускорения протонов и электронов до энергий порядка 100 ТэВ. Остаются открытыми несколько вопросов, среди которых проблема происхождения и поиск источников наблюдаемых космических лучей высоких энергий в интервале от 100 ТэВ до 1000 ПэВ. Решение проблем эффективной конверсии кинетической энергии эжекты сверхновой, вращательной энергии пульсаров, а также анизотропных течений плазмы вокруг аккрецирующих чёрных дыр в популяцию релятивистских частиц требует кинетического моделирования нелинейных механизмов с широким динамическим диапазоном масштабов. Моделирование необходимо, чтобы определить максимальные энергии частиц, ускоряемых сверхальвеновскими течениями плазмы с вмороженными магнитными полями и бесстолкновительными ударными волнами. Задача сводится к выявлению физических механизмов сильного (сверхадиабатического) усиления магнитной турбулентности, необходимого для быстрого ускорения частиц механизмом Ферми. В обзоре представлены результаты кинетического моделирования и анализ нелинейных механизмов формирования сильной анизотропной магнитной турбулентности и спектров ускоренных частиц. Недавние наблюдения орбитальной обсерваторией IXPE (Imaging X-ray Polarimetry Explorer) поляризованного рентгеновского синхротронного излучения остатков сверхновых Тихо Браге, Кассиопея А, SN1006 и др. позволили с использованием нелинейных моделей заглянуть внутрь космических ускорителей частиц и понять механизмы модификации сильных ударных волн. Обсуждаются возможности ускорения ядер космических лучей мощными анизотропными истечениями плазмы в компактных релятивистских остатках коллапсировавших сверхновых звёзд. Молодые пульсары в двойных звёздных системах, а также аккрецирующие чёрные дыры — микроквазары могут ускорять ядра до энергий существенно выше ПэВ.

Natural hazards don't disappear when the storm ends or the earthquake stops—they evolve

Phys.org: Earth science - Sat, 06/28/2025 - 12:20
Hurricane Helene lasted only a few days in September 2024, but it altered the landscape of the Southeastern U.S. in profound ways that will affect the hazards local residents face far into the future.

Tiny ocean migrants play a massive role in Southern Ocean carbon storage, study finds

Phys.org: Earth science - Fri, 06/27/2025 - 18:24
A new study has revealed that small but mighty zooplankton—including copepods, krill, and salps—are key players in the Southern Ocean's ability to absorb and store carbon.

Study reveals uneven land sinking across New Orleans, raising flood-risk concerns

Phys.org: Earth science - Fri, 06/27/2025 - 18:00
Parts of New Orleans and its surrounding wetlands are gradually sinking, and while most of the city remains stable, a new study from Tulane University researchers suggests that sections of the region's $15 billion post-Katrina flood protection system may need regular upgrades to outpace long-term land subsidence.

Study challenges recent claims about rapid Antarctic 'greening'

Phys.org: Earth science - Fri, 06/27/2025 - 15:42
A new study challenges recent claims about dramatic "greening" in Antarctica and how this conflicts with decades of field-based ecological knowledge. The new opinion article, "Is Antarctica Greening?" published in Global Change Biology, responds directly to recent high-profile studies that asserted unprecedented ecological transformations based on remote sensing data.

New study tracks soil carbon pathways and confirms mineral-associated organic matter as the most stable carbon pool

Phys.org: Earth science - Fri, 06/27/2025 - 14:12
A global study has revealed that mineral-associated organic matter (MAOM) serves as the most stable long-term reservoir of carbon across diverse ecosystems, providing new insights into how carbon moves and stabilizes in soils.

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