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SummaryThe 1957 Andreanof, Aleutian Is., earthquake (1957 March 9, 51.53°N, 175.63°W, d=25 km) is among the most enigmatic great earthquakes instrumentally recorded. The length of the aftershock area is very long (about 1,200 km), and tsunami excitation has been recently confirmed to be very extensive, yet its instrumental seismic magnitude Ms is only about 8.1 to 8.3. Detailed analyses of long-period surface waves in the past gave an Mw=8.4, and the seismic-tsunami disparity remains unresolved. The main difficulty in seismic studies is the absence of high-quality seismic data. Here we investigate the cause of this disparity by carefully analyzing some historical seismograms with modern digitization methods. We also take advantage of the 1996 Aleutian Is. earthquake (Mw=7.87) that occurred very close to the 1957 event. For the 1996 event, high-quality modern broad-band seismograms are available which can be effectively used as empirical Green’s functions for the analysis of the 1957 event. Using the Wiechert (Strasbourg, Uppsala), Milne-Shaw (Wellington), and Benioff (Uppsala, Pasadena) seismograms of the 1957 event, we could determine that the 1957 event had significant secondary excitation of long-period (150 s) waves during about 1,000 s following the first event. The Mw of the combined source is approximately 8.4. Because of the limited bandwidth of the old instruments, we cannot detect long-period energy beyond 150 s. However, the unusually long-lasting excitation over nearly 1,000 s suggests that the event had significant excitation at periods longer than 150 s with a much larger Mw for the total event. Although we cannot address this question quantitatively because of our band-limited data, our numerical experiment using a source with a slow component shows that if the time scale of the slow source is longer than 500 s, our data can be made compatible with an Mw =8.8 to 8.9 event, thereby reconciling the results from seismic and tsunami data.

Over the past 50 years, geographers have embraced each new technological shift in geographic information systems (GIS)—the technology that turns location data into maps and insights about how places and people interact—first the computer boom, then the rise of the internet and data-sharing capabilities with web-based GIS, and later the emergence of smartphone data and cloud-based GIS systems.

A new study led by researchers at the Lamont-Doherty Earth Observatory offers the clearest evidence yet that a centuries-long drought transformed life on Rapa Nui (Easter Island) beginning around the year 1550.

In recent years, as extreme weather events have occurred with increasing frequency, scientists have been searching within the chaotic atmospheric system for clues that can enhance forecasting capabilities—factors such as ENSO, sea ice, the stratospheric polar vortex, and tropical convective activity. These factors provide critical basis for weather and climate predictions across different time scales.

Arctic sea ice has declined by more than 42% since 1979, when regular satellite monitoring began. As the ice grows thinner and recedes, more water is exposed to sunlight. Ice reflects sunlight but dark water absorbs it, advancing warming and accelerating ice loss. Climate models indicate that the Arctic will see ice-free summers within the coming decades, and scientists still aren't sure what this will mean for life on Earth.

For decades, scientists have generally thought that rivers emit more carbon dioxide, a greenhouse gas, than they take in. But a new analysis of every river network in the contiguous United States—including underrepresented rivers in deserts and shrublands—challenges this assumption, uncovering hints that many Western waterways may be soaking up carbon dioxide from the atmosphere.

In Arizona's Willcox Basin, just over an hour east of Tucson, fissures are tearing through the earth, wells are running dry, and strange areas are flooding when it rains. The cause is clear. As large agricultural producers pump more and more groundwater for irrigation, the water table is falling, and the land surface itself is sinking.

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

Marine heatwaves (MHWs)—prolonged periods of unusually warm ocean temperatures—are intensifying globally, disrupting marine ecosystems and biological processes. While their impacts on marine life are better documented, how MHWs influence precipitation has remained largely unexplored.

Zeng et al. [2025] investigate the relationship between MHWs and precipitation using two decades of high-resolution observational and reanalysis data (2002–2021). On average, MHWs shift global mean precipitation anomalies from −1.69 mm/day before peak intensity to +2.82 mm/day afterward. The study further identifies four distinct MHW types based on precipitation anomalies before and after the peak. The most common type (~46%) features reduced precipitation throughout its lifetime, followed by events (~26%) where precipitation transitions from negative to positive. In these latter cases, warmer early-stage oceans enhance evaporation and moisture convergence, increase moist static energy, and trigger stronger rainfall after the peak, which blocks solar radiation and accelerates MHW decay.

Understanding these dynamical processes is crucial for predicting future climate extremes in a warming world. This is among the first studies to identify precipitation–MHW relationships at different stages based on observations. These findings reveal dynamic air-sea feedbacks, showing that MHWs not only affect marine ecosystems but also modify regional precipitation patterns.

Citation: Zeng, S., Dong, L., Wu, L., Song, F., Zhang, Z., & Jing, Z. (2025). Distinct impacts of different marine heatwaves on precipitation. Journal of Geophysical Research: Atmospheres, 130, e2025JD044381. https://doi.org/10.1029/2025JD044381

—Yun Qian, Editor, JGR: Atmospheres

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.

Asteroids are primordial pieces of our solar system’s history, but they aren’t exactly pristine relics. Their surfaces in particular are eroded by solar radiation and pockmarked with meteorite impacts. Detailed studies of asteroids’ interiors are also lacking, simply because very few probes have been able to study them up close.

However, a promising new study uses data from the Gaia space observatory to understand the links between asteroid tumbling behavior, collision history, and interior structure. The key to the study is the discovery that rotation speeds of asteroids in the main belt, between Mars and Jupiter, don’t follow a random distribution.

When rotation period is plotted against asteroid size, asteroids fall into two distinct populations: slow spinners, which take more than about 24 hours to complete a rotation, and fast spinners, whose rotations take less than 24 hours. Small asteroids are more likely than large ones to be slow spinners.

“People found an excess [of] faster rotating asteroids and also an excess [of] slow rotating asteroids,” with fewer asteroids rotating at a medium speed, said Wen-Han Zhou, a planetary scientist at the University of Tokyo. In his Ph.D. research at the University of Nice, he and his collaborators realized that many of the slow rotators were also tumbling: rotating chaotically, rather than spinning steadily along a clearly defined axis.

“Asteroids are not islands in space; they collide with each other.”

“Asteroids are not islands in space; they collide with each other,” Zhou said. “When an asteroid spins very slowly, a tiny collision can make it tumble. This [also] tumbles the materials inside, which will dissipate the energy.”

This dissipation effect comes from internal friction. In their recent Nature Astronomy article, Zhou and his colleagues linked an asteroid’s rate of rotation, whether it is tumbling or spinning smoothly, its size, and its internal structure into a single theoretical framework. In this theory, fast rotating asteroids are stable spinners because any collision that sends them tumbling also jumbles their innards, causing internal friction that dissipates the chaos and brings the asteroids back to stability. Slow spinners, however, lock into tumbling chaotically because their guts don’t jumble enough to dissipate the energy.

“In my research, I propose slow rotators are all tumbling,” Zhou said. “This is a very strong statement, but so far it is consistent with observation.”

Zhou and collaborators also concluded that these slow tumblers are all rubble-pile asteroids: loose aggregates of small chunks barely held together by mutual gravitation, rather than being monolithic hunks of rock. This has implications for planetary defense.

“Imagine a bunch of pieces of Styrofoam stuck together with cohesive forces. You try to disrupt that, good luck!” said Alessondra Springmann, an asteroid researcher based in Colorado. Springmann has studied near-Earth asteroids using radar at the Arecibo Observatory in Puerto Rico but was not involved in this new research.

Knowing more “about an asteroid’s internal properties can help us if it ever came time to redirect an asteroid away from Earth.”

Scientists have tried. They found that smashing a projectile into a rubble pile, like NASA’s Double Asteroid Redirection Test (DART) mission did to the near-Earth asteroid Dimorphos, might not destroy it. The asteroid might simply re-form itself after being smashed. (Notably, Dimorphos is much smaller than the main belt asteroids in Gaia’s data.) Radar data on its rotation could tell planetary defenders what methods are useful well in advance. But so, too, could learning more about an asteroid’s innards.

Knowing more “about an asteroid’s internal properties can help us if it ever came time to redirect an asteroid away from Earth,” Springmann said.

You Spin Me Round

The European Space Agency’s Gaia observatory was built primarily to map the Milky Way. Because it provided a sensitive wide-angle view of the whole sky, the observatory also incidentally provided data on other objects, including asteroids in the main belt of our solar system. To determine asteroid spin rates, asteroid researchers turned to Gaia data showing how reflected light varies over time as the objects spin. This is when they found the clear division between fast and slow rotators.

Scientists have a reasonable explanation for the behavior of the fastest spinners: the YORP effect (for Yarkovsky-O’Keefe-Radzievskii-Paddack). In essence, asteroids receive sunlight across their surface facing the Sun, but their uneven surfaces absorb and reemit that light in more or less random directions. Over many millions of years, that accumulated difference in light exposure can cause asteroids to spin until they reach the spin barrier of one rotation every 2.2 hours, at which point they break into pieces if they’re rubble piles.

But slow rotators defied easy explanation.

However, Gaia provided another clue: If the variations in light it measured were regular, then the asteroid was a stable spinner. If they were irregular, then the asteroid was tumbling. Many slow spinners were tumbling, whereas almost every fast rotator was stable.

Zhou and his collaborators realized that if most or all slow spinners are tumblers, it could explain why observed asteroids are split into two distinct populations. Asteroids are too faint for even Gaia to clearly distinguish between rotators and tumblers in every case, but when the researchers simulated main belt asteroids on a computer—including the effects of collisions and YORP—they produced something strikingly similar to the Gaia data.

Along the way, the researchers also realized tumbling behaviors are linked to possible internal structural properties, particularly deformability and internal friction, which are not typically measurable without placing a seismometer on an asteroid’s surface. In other words, these analyses could actually reveal the life history and internal properties of asteroids in new ways.

—Matthew R. Francis (@BowlerHatScience.org), Science Writer

Citation: Francis, M. R. (2025), What tumbling asteroids tell us about their innards, Eos, 106, https://doi.org/10.1029/2025EO250414. Published on 6 November 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.

Source: AGU Advances

This is an authorized translation of an Eos article. 本文是Eos文章的授权翻译。

众所周知，二氧化碳（CO2）浓度上升会导致地球大气温度升高。但缓慢的反馈过程，包括海洋的热量储存和碳循环的变化，意味着这种温度变化有时不会立即显现；地球可能需要数十年甚至数千年才能达到平衡。

然而，不同的气候模型对于何时达到这种平衡的预测却大相径庭。造成这些差异的原因之一是“模态效应”，即海面温度的不均匀变化会形成不同的海洋变暖模式，进而影响大气环流，最终影响云量、降水和热量传递。这些因素之间的复杂相互作用会加剧或减缓变暖，并影响气候对温室气体的敏感性。

帮助预测长期变暖模式的一种方法是回顾过去。挖掘古气候数据中的模式，特别是来自地球气候温暖时期的数据，可以为未来的变暖模式提供线索。刘小庆、张一歌等人分析了过去1000万年的海洋表面温度记录，以确定在二氧化碳浓度上升的情况下，不同海洋区域的相对升温情况。

该研究以地球上最大、最温暖的表层水体——西太平洋暖池为参考点，将其海表温度数据与其他17个海洋站点的海表温度数据进行比较，从而建立全球变暖模式。

随后，研究人员随后将这些古气候数据中显示的升温情况与几个模拟模型的结果进行比较，这些模型模拟了二氧化碳浓度相对于工业化前水平突然增加四倍的情况。他们发现，古气候数据和模型结果显示出相似的千年尺度升温模式，尤其是在高纬度地区。然而，当两者与过去160年的海表温度测量数据进行比较时，升温模式出现了显著的差异。受海洋热吸收的影响，现代升温仍处于过渡状态，而古气候模式则代表了完全的平衡响应。

研究人员指出，要达到新的平衡需要数千年的时间。该研究表明，与目前的瞬时气候变化相比，未来在中高纬度地区，包括北太平洋、北大西洋和南大洋的升温模式将更为显著。这种高纬度地区的升温幅度可能超过之前的估计，并且在千年尺度上的预测比在百年尺度上的预测更为明显。(AGU Advances, https://doi.org/10.1029/2025AV001719, 2025)

—科学撰稿人Rebecca Owen (@beccapox.bsky.social)

This translation was made by Wiley. 本文翻译由Wiley提供。

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AbstractThe rheological properties of the mantle govern plate tectonics and mantle convection, yet constraining the rheological parameters remains a significant challenge. Laboratory experiments are usually performed under different temperature-pressure-strain-rate conditions than those of natural environments, leading to substantial uncertainties when extrapolating the parameters to real-world conditions. While traditional Bayesian inversion with Monte Carlo sampling methods offers sufficient exploration of the parameter space and accurate inversion results, the excessive computational cost limits its practical application to complex nonlinear problems. To address these limitations, we integrate finite-difference-based geodynamic forward modeling with Automatic Differentiation (AD) to build a framework to invert non-linear rheological parameters. By incorporating multisource observational data, including surface velocities and topography, we are able to invert critical rheological parameters of the lithosphere and mantle, including the viscosity pre-exponential factor, activation energy, stress exponent, yield stress, and plate-interface viscosity. To validate the method, a series of models with different levels of complexity from single- to multiple-subduction systems and consideration of data noises are designed to generate synthetic data that are further used for inversion. Our method can successfully restore the rheological parameters under various conditions, with minimal errors between predicted and true values, underscoring its stability and broad applicability. In general, this study introduces a highly efficient and practical geodynamic forward and inverse modeling approach that can be used to infer the rheology of the mantle.

AbstractSeismic waveforms are essential for deciphering the subsurface structures of the Earth. Traditional methods for seismic waveform selection rely heavily on manual identification by experienced seismologists, which can be inconsistent and challenging when complex structures or huge amount of seismic data volumes are involved. Recent advancements in machine learning, particularly supervised learning techniques, have shown promising progress in addressing these challenges; however, their dependence on large labeled datasets limits their application to weak or rare seismic phases. In this study, we propose a new strategy using hierarchical clustering for seismic waveform identification, which does not need labeled dataset and minimizes extensive parameter settings. Our strategy is especially powerful when dealing with multiple waveform phases that may shift according to epicentral distance or may be distorted due to attenuation or other factors. We apply our strategy to identify various seismic wave of both P and S phases, especially those sampling deep Earth such as SKS-SKPdS and ScP phases. The results show that the strategy performs excellently and can identify different anomalous signals. Our approach empowers researchers to conduct more detailed studies in previously overlooked regions or datasets, thereby leading to a better understanding of deep Earth’s structures.

SUMMARYRock glaciers are specific landforms consisting of a mixture of rock debris, ice, liquid water, and air. In the Alps, active rock glaciers are generally found at high elevations above 2500 m. Active rock glaciers creep and can develop anomalous slide-like behaviors called destabilization. Induced polarization is a non-intrusive geophysical method that has proven to be sensitive to the hydrogeological properties of porous media. In August 2023, we performed four induced polarization profiles at Plan-du-Lac (Vanoise, France), on a multi-unit rock glacier complex with a front located at a low altitude of 2200 m). Our goal was to determine its architecture and its water and ice contents in relation with its activity rate. The survey included two transverse high-resolution profiles with a 5 m spacing between the electrodes and two other longitudinal profiles with a 20 m spacing between the electrodes allowing a depth of investigation of roughly 200 m to image the rock glacier from its terminal front up to its root. The conductivity and normalized chargeability tomograms were inverted and then used to get the water content and cation exchange capacity (a proxy for the clay content) tomograms. In most of the units, ice has disappeared and the landforms associated with the former rock glacier were characterized by low water and clay contents with respect to the basement. This was consistent with these units being mostly formed by rock debris with a low water saturation except at their bases, which are water-saturated. Ice remains were found at the roots of the rock glacier, with a volume content up to ∼10 per cent (vol. per cent) for profile P2 and 16 per cent for profile P4. The roots of the rock glacier complex were still creeping as shown by InSAR data. This case study demonstrates the usefulness of the induced polarization method to quantitatively characterize gravitational instabilities associated with coarse materials and transitional rock glaciers.

SUMMARYIn October 2023, an earthquake sequence comprising four ∼ MW 6.0 events struck Herat Province in northwestern Afghanistan, causing severe casualties and property losses. The geometry of seismogenic faults and the mechanisms of the earthquake sequence are essential for regional seismic hazard assessment, but still remain poorly constrained. With Interferometric Synthetic Aperture Radar (InSAR) techniques, we extracted high-resolution co- and early post-seismic deformations of the events. Through a two-step inversion method, we inferred the geometry of the causative faults and the distributed slip models. The earthquake sequence ruptured two intersecting low-dip thrust faults, indicating that the complex geometry may have played a key role in controlling the propagation of the events. The ruptures of the four major events are clearly imaged at depths of 1-10 km without reaching the surface, showing a pattern of first spreading westwards, then jumping eastwards to the bend segment, and finally rupturing an adjacent fault. Post-seismic deformation further reveals reactivation of a secondary fault splay which underwent afterslip. Shallow afterslip up-dip of the co-seismic rupture dominates post-seismic deformation during 10 months following the earthquake sequence. Relying on the evolution of afterslip, we infer that significant rate-strengthening property in the shallow bend section may have hindered further co-seismic rupture propagation. Combining obtained results and the complex geological setting of the Herat region, we suggest that the earthquake sequence reflects N-S crustal shortening between two branches of the western Herat Fault System.

SUMMARYIn the last decade, the Dynamic Stern Layer (DSL) model has proven to be a reliable petrophysical model to comprehend induced polarization data at various scales from the representative elementary volume of a porous rock to the interpretation of field data. Preliminary works have demonstrated that such model can be extended to understand the induced polarization properties of ice-bearing rocks and to interpret field-acquired induced polarization data in the context of permafrost. That being said, the direct effect of ice was let aside. We first review the DSL model in presence of ice and discuss the role of ice as an interfacial protonic dirty semi-conductor in the complex conductivity spectra with an emphasis on the role of the complex-valued surface conductivity of ice crystals above 1 Hz. We propose a new combined polarization model including indirect and direct ice effects. By direct effects, we mean the effects associated with change in the liquid water content and salinity of the pore water. By direct effect, we mean the role of the interfacial properties of the ice surface and liquid water is still present in the pore space of the porous composite. In this case, the electrical current is not expected to cross the ice crystals. Instead, it would polarize the surface of the ice crystals and generate a very high chargeability that can reach one depending on the value of the volumetric content of ice. We apply the DSL model to a new set of complex conductivity spectra obtained in the frequency range 10 mHz-45 kHz using a collection of 25 rock samples including metamorphic and sedimentary rocks in the temperature range + 15/+20°C to -10/-15°C. We observe that the model explains very well the observed data in the low-frequency range (10 mHz-1 Hz) without any direct contribution of ice. In the high frequency range (above 1 Hz), we observe a weak contribution possibly associated with the contribution of ice crystals. We establish under what conditions the direct contribution of ice can be neglected. We also investigate the role of porosity, cation exchange capacity, and freezing curve parameters on the complex conductivity spectra of crystalline and non-crystalline rocks during freezing. Laboratory experiments demonstrate that in most field conditions including permafrost conditions, surface conductivity associated with conduction on the surface of clay minerals (and alumino-silicates in general) is expected to dominate the overall conductivity response. Therefore Archie’s law cannot be used as a conductivity equation in this context because of the contribution of surface conductivity. A large experimental and field dataset at the Aiguille du Midi (3842 m a.s.l., French Alps) for the resistivity versus temperature data of granitic rocks demonstrates the role of surface conductivity in the overall conductivity of the rock.

A research group led by Prof. Sun Xiaobing from the Hefei Institutes of Physical Science of the Chinese Academy of Sciences, investigated the impact of multiangular polarimetry on the quantification of marine aerosol remote sensing applications.

If you know what diatoms are, it's probably because of their beauty. These single-celled algae found on the ocean floor have ornate glassy shells that shine like jewels under the microscope.

Melting of the Antarctic ice sheet due to global warming has long-term, irreversible societal impacts with important implications for people around the world. Spatial patterns of sea level change from ice sheet mass loss vary in cause, and have worldwide impacts.

Tulane University researchers, collaborating with an international team of scientists, have discovered why some parts of Earth's crust remain strong while others give way, overturning long-held assumptions about how continents break apart.

An international study presents the first global assessment of blue carbon accumulated in the living parts of seagrass plants. According to the results, their leaves, rhizomes and roots store up to 40 million tons of carbon worldwide.