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Source: Global Biogeochemical Cycles

Throughout the first half of 2020, average monthly temperatures in Siberia reached 6°C above the norm. The situation climaxed on 20 June, when the temperature in the town of Verkhoyansk climbed to 38°C (100.4°F), the highest temperature ever recorded north of the Arctic Circle. With the extreme heat came wildfires, insect outbreaks, and thawing permafrost.

Now Kwon et al. suggest that the effects of the 2020 heat wave were still detectable the following year in the form of warmer- and wetter-than-usual soils.

The researchers obtained data on temperatures, precipitation, and other climatic factors from the European Centre for Medium-Range Weather Forecasts and incorporated them into a model of high-latitude ecosystems. To capture the effect of the 2020 Siberian heat wave, they replaced data from 2020 with data from each of the previous 5 years (2015 to 2019), which provided five estimates of what regional ecosystems might have looked like in 2021 had the heat wave not occurred.

The analysis indicated that the high heat caused soil temperature to remain roughly 1.2°C, or about 150%, warmer in 2021 than it would have been without the heat wave, even though air temperatures had returned to normal. The warmer temperatures also melted soil ice, resulting in wetter soil than usual. Root zone soil water availability, a measure of how much water soil can hold in the rooting depth of plants, increased by 10.9% in forests in 2021 and by 9.3% in grasslands. However, some of this meltwater left the soil via runoff.

In response to warmer, wetter soil, microbes proliferated and caused the soil ecosystem to emit more carbon dioxide than usual, the modeling indicated. In forests, this effect was largely offset by an increase in photosynthesis as plants flourished under the new conditions. In grasslands, on the other hand, photosynthesis initially increased during the heat wave event but then quickly decreased until 2021 as plants used up the available water and died off. As a result of the 2020 heat wave, the researchers reported, forests gained an additional 6 grams of carbon per square meter in the first half of 2021, whereas grasslands lost 10.9 grams of carbon per square meter. (Global Biogeochemical Cycles, https://doi.org/10.1029/2025GB008607, 2025)

—Saima May Sidik (@saimamay.bsky.social), Science Writer

Citation: Sidik, S. M. (2025), In the Arctic, consequences of heat waves linger, Eos, 106, https://doi.org/10.1029/2025EO250313. Published on 22 August 2025. Text © 2025. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

SummaryThere are two fundamental probabilities in the seismic phase picking process – the probability of the existence of a seismic phase (detection probability) and the probability associated with the phase arrival time estimation (timing probability). The nearly ubiquitous approach in developing deep learning phase picking models is to use a kernel, such as a truncated Gaussian, to mask the labeled phase arrival time and train a segmentation model. Once a model is trained, the times of the peaks in the output are taken as phase arrival times (picks), and the height of the peaks are taken as “probability” of the picks. Here, we show that this “probability” represents neither the detection nor the timing probability because this approach forces the output to follow the shape of the kernel. We introduce an approach using two models to estimate these two distinct probabilities. We use a binary classifier with a calibrated confidence to address the detection probability and a multi-class classifier to obtain a probability mass function to address the timing probability. This new approach can make the deep learning-based phase picking process more interpretable and provide options to logically control seismic monitoring workflows.

SummaryThis study introduces a new method for calculating acoustic-gravity waves in a spherically layered atmosphere. The method introduces a model assumption and divides the atmosphere into finely stratified layers to solve the PDE with respect to the radial coordinate. The time-domain synthetic signal is obtained by summing over the orders of the associated Legendre functions and then applying the FFT. The method is applied to numerically simulate wave behaviour, including Earth curvature effects, and compares with the horizontally layered model (HLM). Results show that at near-field distances, our method aligns closely with HLM, but significant differences emerge in the far field, particularly beyond an epicentral distance of 50°, where Earth curvature becomes critical. Our method successfully simulates head waves of seismic phases, and Rayleigh waves, even for waves travelling multiple times around the Earth, which HLM cannot achieve. Simulations using a homogeneous Earth model reveal head wave characteristics consistent with previous studies, with the strongest energy observed in Rayleigh head waves. The application of the AK135 Earth model highlights the visibility of seismic phases through the Earth’s core. We validate our method by comparing synthetic records with actual data from the 1999 Chi-Chi earthquake. The synthetic records show good agreement with observed seismic signals and ionospheric perturbations in terms of arrival time and wave envelope. These results demonstrate the accuracy of our method in simulating acoustic-gravity waves at large epicentral distances.

SummaryThe widespread, multi-year crustal deformation induced by megathrust earthquakes (Mw8+) is primarily controlled by the combined effects of continuous aseismic slip on the fault plane (afterslip) and viscoelastic relaxation driven by coseismic stress perturbations in the upper mantle. However, till today it remains a considerable challenge to separate these two mechanisms in geodetic observations. We derived the first 3-year GNSS observations following the 2021 Chignik Mw8.2 earthquake to investigate the mechanisms of postseismic deformation. We established a model capable of simultaneously simulating afterslip and viscoelastic relaxation, and constrained the upper mantle rheology beneath the Alaska Peninsula. The best-fit model effectively reproduces the GNSS observations and reveals a notable viscosity difference between the mantle wedge and the oceanic asthenosphere, with steady-state viscosities of $3 \times {{10}^{18}}$ Pa s and $4 \times {{10}^{19}}$ Pa s, respectively. The inferred mantle wedge viscosity beneath the Alaska Peninsula is lower than the values reported for south-central and southeastern Alaska, suggesting an eastward increase in viscosity along the subduction zone. Two main patches of afterslip are identified during the first 3 years. The patch of up-dip afterslip overlaps with the 1938 Chignik Mw8.3 earthquake rupture zone, and demonstrates a close spatial correlation with the slow slip event in 2018. The above new results enhance our insights into the spatial variability of regional rheology and slip behavior along the Alaska-Aleutian subduction zone.

A team of Johns Hopkins researchers is using an innovative X-ray imaging approach to reveal how compression reshapes the tiny spaces and stresses within sandstone—findings that could predict how this common rock used for fuel reservoirs behaves under deep subterranean pressure. The results appear in the Journal of Geophysical Research: Solid Earth.

New research from Purdue University reveals how moisture influences atmospheric blocking, a phenomenon that often drives heat waves, droughts, cold outbreaks and floods, helping solve a mystery in climate science and improving future extreme weather predictions.

Last summer, Stephanie McNamara got her first glimpse of Great Sand Dunes National Park and Preserve in southern Colorado. The park is a monument to sand, where dunes stretch across 30 square miles and tower nearly 750 feet high, making them the tallest such formations in North America.

A research team has developed a new artificial intelligence (AI) tool that can automatically identify and track tropical easterly waves (TEWs)—clusters of clouds and wind that often develop into hurricanes—and separate them from two major tropical wind patterns: the Intertropical Convergence Zone (ITCZ) and the monsoon trough (MT).

A new Stanford study challenges the decades-old view that the rise of land plants half a billion years ago dramatically changed the shapes of rivers.

Researchers at the University of California, Irvine and other institutions have spotted a contradiction in worldwide wildfire trends: Despite a 26% decline in total burned area from 2002 to 2021, the number of people exposed to wildfires has surged by nearly 40%.

Lib4RI has completed the digitization of more than 700 historical snow and avalanche reports from the WSL Institute for Snow and Avalanche Research SLF. These reports, published between 1938 and 2005, document decades of avalanche observations and snow research by researchers from Switzerland and around the world. These reports are now accessible to all in the institutional repository DORA.

Heat-stressed Victorian mountain ash forests are thinning fast, turning from carbon sinks to carbon sources, new research reveals.

A recent study led by Prof. Zeng Fanjiang from the Xinjiang Institute of Ecology and Geography of the Chinese Academy of Sciences has revealed concerning trends in soil organic carbon (SOC) loss due to prolonged human disturbance in hyper-arid desert ecosystems.

Beneath Australia's soils lie ancient aquifers which supply 30% of the water consumed across the country. The groundwater they hold can be some of the oldest water on the planet, dating back as far as two million years.

Large earthquakes along some of New Zealand's major faults are commonly clustered in time and place, according to recent research.

Deep beneath the ocean's surface lies Earth's largest carbon reservoir: marine sediments that have accumulated organic matter over millions of years. Long assumed to be permanently "locked away," this vast carbon pool is far more dynamic than scientists previously believed, according to a new international study.

It took only 1.3 seconds for the Sagaing Fault to open a gash in Earth’s surface and shift it by 2.5 meters during the magnitude 7.7 Myanmar earthquake earlier this year. When video surveillance some 120 kilometers south of the earthquake’s epicenter caught the moment, the footage sent a shock wave of excitement through the global seismology community.

At first, Jesse Kearse, a geophysicist at Kyoto University, was simply in awe of the tectonic forces, but as he rewatched the video, he soon realized its scientific value. “Of all the instrument records we have of earthquakes from the past 100 years, most are from far away,” he said. This was the first real-time observation of a major rupture close to a fault.

Kearse and Yoshihiro Kaneko analyzed the video frame by frame using a technique called pixel cross correlation. Their findings, published in The Seismic Record, revealed the pulse-like nature of major earthquake propagation and the curvature of fault slip.

How Earthquakes Move Along a Fault

Seismologists have long understood that a fault doesn’t rupture all at once. Instead, it experiences a traveling, localized zone of slip, said David Wald, a geophysicist at the U.S. Geological Survey in Golden, Colo., who was not involved in the new research.

Wald’s work on the 1992 magnitude 7.2 Landers earthquake in California helped to establish that earthquakes propagate in pulses. But this work was “always a step removed from reality, modeling the rupture propagation process” as opposed to watching it in real time, he said.

“Seeing is believing.”

“Seeing is believing,” Wald said of the Myanmar footage. “We were all blown away by the video, which confirms how a short slip duration, large slip, and thus high slip velocity produce a large pulse of ground shaking.”

Analysis of the Myanmar earthquake video showed that the traveling slip zone was only several kilometers wide, even though the earthquake ultimately ruptured a more than 400-kilometer-long section of the fault. Pulse-like rupture is a more efficient way to move Earth’s massive crust, Kaneko noted. “This video provides the first visual confirmation of it occurring in real time.”

Although crumpled landscapes left by earthquakes have shown that seismic ruptures can cause permanent offsets of many meters, until now it wasn’t clear whether that movement happens within 1 or 2 seconds. “The historic record shows the offset but not how quickly that happened,” Kearse said. “It’s becoming clear that these pulse-like ground motions are really large amplitude, meters per second of ground velocity. For large buildings, that’s very difficult to engineer for.”

Curved Slip Movement along the Kekerengu Fault, which ruptured during the 2016 Kaikōura earthquake in New Zealand, left slickenlines on the wall of an outcrop. Credit: Kate Clark, Earth Sciences New Zealand

The video analysis was challenging because ground shaking caused the camera to tilt and wobble. But Kearse and Kaneko managed to isolate the fault motion by systematically analyzing stationary targets in the footage. To their surprise, they watched the slip curve before it settled into horizontal motion.

Geologists know that earthquakes leave curved scratch marks known as slickenlines on fault surfaces. In a previous study, Kearse and his colleagues described these grooves on exposed surfaces of the Kekerengu Fault, one of several that ruptured in New Zealand’s 2016 magnitude 7.8 Kaikōura earthquake. When they fed those data into a model, the team found a link between the curvature of slickenlines and the direction that a fault ruptured.

The analysis of the Myanmar earthquake footage delivered real-time evidence of this connection between slip curve and rupture direction. “What our new study contributes is a quantitative analysis of both the speed and direction of the curved slip while the rupture is actively unfolding,” Kaneko said.

The research “fortifies the slickenline story.”

The research “fortifies the slickenline story” and may help seismologists better anticipate the ground shaking likely to occur in future events, said John Vidale, an Earth scientist at the University of Southern California. This understanding is particularly important for faults with the potential to rupture in massive earthquakes, including California’s San Andreas Fault and New Zealand’s Alpine Fault. Such earthquakes would affect major population centers differently, depending on the direction in which the earthquake traveled.

The Myanmar video also highlights the potential of autonomous cameras as tools in seismology, according to Haiyang Kehoe, an Earth scientist who will be joining the University of Oregon in December. “The proliferation of home security systems and traffic cameras increases the likelihood that some portions of future earthquake ruptures will be recorded with a similar amount of clarity.”

For Laura Wallace, a geodetic scientist at the University of Texas and the GEOMAR Helmholtz Centre for Ocean Research Kiel in Germany, the work opens new potential for using slickenlines from paleoearthquakes to investigate whether a particular fault has a tendency to rupture in one direction or another. “Such insights would provide important information for future seismic hazard forecasts.”

—Veronika Meduna (@veronikameduna.bsky.social), Science Writer

Citation: Meduna, V. (2025), Video shows pulsing and curving fault behavior, Eos, 106, https://doi.org/10.1029/2025EO250307. Published on 21 August 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.

At a trailhead surrounded by sagebrush, a naturalist welcomes a group of visitors to Mono Lake beside a sign that reads "Oasis in the Desert."

Editors’ Vox is a blog from AGU’s Publications Department.

Stemflow, or the flow of water along the surface of a plant’s stem, has been a subject of inquiry in forest hydrology since the latter half of the 1800s given its relevance to water balance studies. The consequences of stemflow to ecological and soil biogeochemical processes led to an influx of research in subsequent years.

Today, stemflow is a burgeoning research area for diverse groups of people because it sits at the nexus of the geosphere, atmosphere, and hydrosphere. Recent interest in the topic stems from an engineering and urban planning perspective as, despite its long history of study, research has not focused on the physics of how water moves down the stem and what forces control these actions.

A new article in Reviews of Geophysics takes the first step in exploring and defining the hydrodynamics of stemflow. Here, we asked the authors to give an overview of stemflow hydrodynamics, how scientists have applied established theory in new ways to explore this broadening field, and potential future research directions.

In simple terms, what is stemflow?

Stemflow is the aboveground flow of water along the exterior surface of a plant stem.

Stemflow is the aboveground flow of water along the exterior surface of a plant stem. It is initiated after precipitation intercepted by leaves and branches drains from outlying parts of the plant crown down the stem/trunk to the soil surface around the plant base. Unlike raindrops that pass unhindered through a plant canopy or penetrate it by dripping or splashing from vegetative surfaces (known as throughfall), stemflow experiences longer contact time with the surface of the stem.

On trees, this lengthened exposure of stemflow-bark interactions enables higher nutrient leaching and subsequent delivery of concentrated nutrients and water to roots. The funneling of enriched waters to the tree base is the primary reason that stemflow is a main contributor to what is termed ‘hot spots’ and ‘hot moments’ in biogeochemical cycling of near-trunk soils. This indicates that the input of water, solutes, particulates, and other matter are uneven in space and time with soils near tree trunks representing an area of disproportionately high rates of biogeochemical cycling.

What role does stemflow play in the broader environment?

Stemflow connects the atmosphere, biosphere, and geosphere. It links the canopy of a tree to the soil and acts as a pathway that delivers water and the substances it carries down the trunk to the ground. Along this path, water interacts with the bark and the organisms living on or within it, including fungi, bacteria, lichens, mosses, metazoans, and insects. For these reasons, stemflow has been traditionally studied in forest hydrology and forest ecology circles, but there is now elevated interest within the engineering and urban planning communities to quantify it.

For example, with respect to pollutant cycling, stemflow can account for some differences in the spatial patterning of radiocesium, a radioactive form of the element cesium, in near-trunk soils. In urban planning and stormwater design, for instance, stemflow could exacerbate stormwater runoff in areas without favorable soil conditions (i.e., paved areas, areas with compacted soils) where water could infiltrate. The role of trees in meeting different ecosystem services within broader green infrastructure plans is still being explored.

(a) Fluid movement on an inclined smooth plane showing how an initially uniform advancing front breaks down into zones of fast-moving regions (or fingering). The goal of hydrodynamics is to predict the conditions that lead to such instabilities based on force imbalances (here between gravitational effects and surface tension). (b) Similar network features to panel (a) of connected instabilities along a vertical concrete wall in a parking garage after a rainfall event. (c) Preferential paths of water movement along a vertical stem. (d) Water bubbling due to leaching of solutes as water moves along the stem. Such bubbling impacts how water properties (viscosity, surface tension, density) and the forces that depend on them are formulated. (e) The physics of water movement inside the stem (xylem and phloem) has been uncovered well before stemflow despite the fact that stemflow can be observed by the naked eye and its observation commenced well before those associated with the xylem and phloem. The complexity of the physics required for describing water movement along the exterior surface of the plant is one of the main reasons for this ‘knowledge lag.’ Credit: Katul et al. [2025], Figure 1

How do scientists observe and measure stemflow?

The first stemflow measurements were conducted by Karl Eduard Ney in 1870.  Later, in 1881, W. Riegler established a link between the arrangement of branches and leaves and the amount of water flowing down the tree trunk. Riegler’s work paved the way to a line of inquiry common in ecology: exploring relations between structure (in this case tree architecture, bark properties, etc.) and function (amount and chemical composition of water in stemflow, sustenance of life dwelling on bark surfaces, etc.).

Measuring stemflow is based on capturing the volume of water that flows down a tree stem or trunk during and after a rainfall event.

Measuring stemflow is based on capturing the volume of water that flows down a tree stem or trunk during and after a rainfall event. The water capturing mechanism involves attaching collars or gutters around the tree trunk. These capturing mechanisms direct water into a nearby collection system. The collection system is usually formed by a container or containers where changes in water volume within the container can be measured over time, which allows the calculations of flow rates and relate them to rainfall data.

The instrumentation used to record the changes in volume of water with time varies in time scale. Tipping-bucket gages and containers with automated pressure recording devices as well as optical methods have all been employed in field studies to track the volume of water changes in time. These devices enable determination of stemflow on time scales of a few minutes to multiple years. Stemflow measurements are certainly an area that can benefit from rapid advancements in instrumentation and dedicated facilities. Stemflow hydrodynamics, once completed, may also enable ‘in-silico’ (or computer modeling) studies addressing relations between ‘structure’ and ‘function.’

What is stemflow hydrodynamics?

Hydrodynamics is a branch of fluid mechanics concerned with the motion of fluids (especially water) and the forces acting upon them. The other key branch of fluid mechanics is hydrostatics, which deals with forces acting on fluids when the fluid is at rest (as may be the case for water behind a dam). Stemflow hydrodynamics is a subset of hydrodynamics that seeks to explore fundamental connections between water depth, velocity, and flow rates on stems in relation to the governing forces.

Stemflow hydrodynamics deals with three conservation laws: water mass (left), scalar mass (middle), and momentum (right). These conservation laws consider a small element repeated across the three panels featuring each conservation law.  For the conservation of mass, there is a certain mass per unit area (perpendicular to the flow direction) per unit time (known as flux) that enters and leaves (indicated by qin and qout), and the bark itself absorbs water (indicated by a sink Sw). The imbalance between these fluxes and sinks impacts the water depth (h) variation along the stem and in time as well as the velocity. The middle and right panels repeat such balances for scalars (where Sc represents leaching) and forces (wall friction, gravitational force and surface tension at the contact line between the waterfront, the atmosphere, and the bark surface). Credit: Katul et al. [2025], Figure 3

At any point on the stem where water flows, these forces are primarily classified as body forces (gravitational), surface forces (friction), and line forces (surface tension). Any imbalance between these forces cause water to accelerate when the driving forces (gravity) exceed the resistive forces or to decelerate when resistive forces exceed the driving forces. Describing the resulting flow rate and the forces acting on water as it traverses the stem remains a daunting challenge to be confronted by stemflow hydrodynamics. The force imbalance and the resulting acceleration/deceleration is mathematically expressed as a conservation of momentum equation much like Newton’s second law that states the net force imbalance per mass determines the acceleration of a solid object having a fixed mass.  

What is thin film theory and how can it apply to stemflow hydrodynamics?

Thin film theory is a branch of fluid mechanics that describes the depth and velocity of a thin layer of fluid moving over a surface. Its name derives from certain approximations to the conservation laws of mass and linear momentum when the film’s thickness is much smaller than the length or width of the domain (e.g. trunk height). It was utilized to find approximate solutions for seemingly intractable engineering problems that were otherwise difficult to solve, such as coating processes in industry (e.g., paint, polymer films), lubrication layers between surfaces, mucus transport in lungs and airways, tear films on eyes, microfluidics and lab-on-a-chip devices, among others. The theory also has an extensive history and usage in hydraulics and hydrology where it is referred to as the shallow water equations.

These equations were originally proposed in the 19th century by Adhémar Jean Claude Barré de Saint-Venant. The significance of these equations cannot be overstated as Saint-Venant was one of the 72notable French scientists and engineers whose names are inscribed on the Eiffel Tower in Paris (France). In hydrology and hydraulics, the shallow water equations are routinely used to describe unsteady flow in streams and rivers, flood routing, flood waves following a dam break, overland flow on hillslopes, estuarine and tidal modeling, among others. All these flow types are based on the so-called small slope approximation and do not account for line forces or surface tension. Stemflow, however, occurs on almost vertical stems and therefore does not satisfy the small slope approximation. Moreover, surface tension can play a role in the force balance as water traverses the stem. These factors may have played a role in why the Saint-Venant equations were overlooked in the study of stemflow.

What are the major unsolved or unresolved questions and where are additional research, data, or modeling efforts needed? 

There are numerous challenges that need to be addressed before a complete description of the governing equations of stemflow hydrodynamics can be declared. These challenges begin by expressing frictional and line forces as a function of velocity and depth, as well as formulating water losses to the bark interior as water travels across its surface. Below is a partial list of just three unresolved issues related to forces characterization and their connection to the local bark properties: 

Fluid Properties: The addition of surfactants due to plant residue (e.g., acids), dust particles (e.g., salt), or exuded sap (e.g., resin) can create foam or soap‐like flow to occur along the stem. These surfactants can alter water properties such as viscosity and surface tension in ways that await exploration. They can also introduce spatial gradients in interfacial properties such as surface tension that may lead to unbalanced planar stresses at the air-water interface that induce motion within the film.

Surface Tension: Much of the thin film theories represent surface tension as a static balance of all forces along the contact line between the bark surface, the moving waterfront, and the ambient air. However, in the case of an accelerating or decelerating water movement, additional terms disrupt the force balance along the contact line due to unsteadiness, inertia, and friction. These effects have not been quantified for bark surfaces. Surface tension also plays a key role in controlling the spatiotemporal evolution of traveling waves on the falling water sheet. It will be a challenging task to understand the effect of capillary forces on such nonlinear waves that are traveling on complex, nonstandard, and multiscale geometries such as a tree bark.

Breakdown of Sheet Flow: Thin film theory treats water movement as a sheet. However, protrusions and cavities within the bark disrupt the sheet flow representation. There are instances where water piles up in fissures and cracks – and is then suddenly released (jetting) or drips out, to contribute to stemflow volume elsewhere on the bark surface. The breakdown of the sheet flow approximation and what physics becomes appropriate when this breakdown occurs is not settled.

Breakdown of sheet flow due to the imbalance between surface tension (holding the water in cavities along the bark) and the weight of water piling up in cavities (pushing the water out). When the pile up force (or weight) exceeds the holding force (surface tension), the water can ‘drip’ or ‘jet’ out of cavities. When it jets out of cavities, the jetting water column may still break down into droplets whose size is larger than the holding cavity size. Credit: Katul et al. [2025], Figure 6

—Gabriel G. Katul (gaby@duke.edu; 0000-0001-9768-3693), Duke University, USA; Bavand Keshavarz (0000-0002-1988-8500), Duke University, USA; Amirreza Meydani (0000-0002-7932-1477), University of Delaware, USA; and Delphis F. Levia (0000-0002-7443-6523), University of Delaware, USA

Editor’s Note: It is the policy of AGU Publications to invite the authors of articles published in Reviews of Geophysics to write a summary for Eos Editors’ Vox.

Citation: Katul, G. G., B. Keshavarz, A. Meydani, and D. F. Levia (2025), Waterworks on tree stems: the wonders of stemflow, Eos, 106, https://doi.org/10.1029/2025EO255027. Published on 21 August 2025. This article does not represent the opinion of AGU, Eos, or any of its affiliates. It is solely the opinion of the author(s). 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.

Editors’ Highlights are summaries of recent papers by AGU’s journal editors. Source: Journal of Geophysical Research: Earth Surface

Cold regions with mountainous terrain can host a multitude of landslide hazards, including rock-ice avalanches. These mass movements are particularly dangerous, as the presence of ice can amplify the potential for the flow to travel exceptional distances. A better understanding of rock-ice avalanche mobility necessitates consideration of how the flow interacts with the material (e.g., snow, ice, and rock) that is encountered as it travels downslope.

Peng et al. [2025] develop a unique suite of small-scale physical experiments that consider variations in the ice content of the initial gravel-ice flow mixture, the slope angle along which the flow travels, and the type of erodible material that the flow overrides. The authors find that the flows exhibit higher mobility when overriding snow and ice is present compared to gravel and that, regardless of the erodible material type that the flows override, higher flow erosion rates correspond to higher flow mobility. This study highlights that the entrainment of snow, ice, and rock can significantly affect the mobility of rock-ice avalanches and is likely an important mechanism to consider when developing frameworks for hazard assessment.

Citation: Peng, C., Li, X., Yuan, C., & Huang, Y. (2025). Insights into the dynamics of rock-ice avalanches from small-scale experiments with erodible beds. Journal of Geophysical Research: Earth Surface, 130, e2025JF008303. https://doi.org/10.1029/2025JF008303

—Matthew A. Thomas, Editor, JGR: Earth Surface

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.