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SummaryFull waveform inversion (FWI) is a high-precision subsurface imaging technique that inverts subsurface parameter models by minimizing the discrepancy between observed and synthetic seismic data. However, complicated wave propagation mechanisms, non-convexity of the loss function, and limited seismic acquisition system necessitate the incorporation of sufficient prior and physical constraints to alleviate the ill-posedness and cycle-skipping. Although the implicit FWI (IFWI) can encode implicit spectral bias (i.e., inverting model parameters from low frequencies to high frequencies) to reduce the dependency on an accurate initial model, its limited high-frequency inversion capability results in thousands of iterations for the final results. In this paper, we indicate that the frequency hyperparameters of the sine activation function in IFWI modulate the spectral bias, making a trade-off between inversion accuracy and stability, i.e., lower frequencies yield robust FWI but lower accuracy, while higher frequencies achieve higher accuracy on the premise of an accurate initial model. To improve both the stability and accuracy of IFWI, we propose a novel implicit FWI method with an adaptive Fourier reparameterization strategy (termed FR-IFWI), which explicitly encodes multi-frequency information by reparameterizing the network weights using a learnable coefficient matrix and fixed Fourier frequency bases. The role of learnable matrices in neural networks can evolve from determining frequencies in IFWI to actively selecting frequencies from fixed frequency bases through FR-IFWI, which alleviates the dependence on activation function frequency and obtains more robust and accurate inversion results. Extensive numerical experiments on the modified Marmousi, 2D SEG/EAGE Salt and Overthrust models confirm that FR-IFWI successfully achieves superior inversion efficiency and accuracy compared with conventional FWI and IFWI methods.

For billions of years, Earth's continents have remained remarkably stable, forming the foundation for mountains, ecosystems and civilizations. But the secret to their stability has mystified scientists for more than a century. Now, a new study by researchers at Penn State and Columbia University provides the clearest evidence yet for how the landforms became and remained so stable—and the key ingredient is heat.

Deep inside caves, water dripping from the ceiling creates one of nature's most iconic formations: stalagmites. These pillars of calcite, ranging from centimeters to many meters in height, rise from the cave floor as drip after drip of mineral-rich water deposits a tiny layer of stone.

Accurately modeling gross primary productivity (GPP) and evapotranspiration (ET) in terrestrial ecosystems is essential for understanding and predicting the global carbon and water cycles. However, current models face considerable uncertainties and limitations when estimating these two core components.

An international research team led by the University of Bremen has investigated what influenced the expansion of the Patagonian ice sheet during the last ice age. The scientists found evidence that the advances and retreats of glaciers in South America over the past 120,000 years were primarily influenced by changes in summer solar radiation and the duration of the summers.

A new study has challenged the long-standing assumption that global warming will inevitably turn humid subtropical forests into carbon sources, revealing these ecosystems may instead continue accumulating soil carbon under moderate temperature rises. The study was published in One Earth on Oct. 6.

Magnetotelluric (MT) data, which contain measurements of electric and magnetic field variations at Earth's surface, provide insights into the electrical resistivity of Earth's crust and upper mantle. Changes in resistivity, or the ability to conduct an electrical current, can indicate the presence of geologic features such as igneous intrusions or sedimentary basins, meaning MT surveys can complement other kinds of geophysical surveys to help reveal Earth's subsurface. In addition, such surveys can play an important role in improving understanding of the risks space weather poses to human infrastructure.

How do volcanoes work? What happens beneath their surface? What causes the vibrations—known as tremor—that occur when magma or gases move upward through a volcano's conduits? Professor Dr. Miriam Christina Reiss, a volcano seismologist at Johannes Gutenberg University Mainz (JGU), and her team have located such tremor signals at the Oldoinyo Lengai volcano in Tanzania.

According to a study by the Department of Physics and the Institute of Environmental Science and Technology of the Universitat Autònoma de Barcelona (ICTA-UAB), the Mar Menor saltwater lagoon in Murcia, Spain, the largest in Europe, contains sediments with levels of lead, arsenic, zinc, mercury, copper, and silver that exceed toxicity thresholds and values reported for similar coastal ecosystems worldwide. The findings are published in the journal Marine Pollution Bulletin.

Heat waves in the UK have led to unseasonable drying of vegetation bypassing natural ecological processes that limit the spread of wildfires, a new study has found.

Greenland is melting, the Alps are melting and the Himalayas are melting—yet in one vast mountain region, huge glaciers have remained stable, or even gained mass, in recent decades. Can it last?

A new fossil fuel site approved for development off Western Australia's coast is estimated to contribute 876 million tons of carbon dioxide (CO2) emissions over the course of its lifetime, according to new research led by The Australian National University (ANU) in collaboration with the ARC Center of Excellence for the Weather of the 21st century.

Reconstruction of landslides on the banks of Lake Rupanco in Chile, triggered by the 22 May 1960 Mw-9.5 earthquake, suggests that a slope failure with a volume of 161 million cubic metres triggered a tsunami with a maximum amplitude of 33.3 metres. About 120 people were killed.

A very interesting paper (Quiroga et al. 2025) has just been published in the journal Landslides that examines combined landslide – tsunami threats at Lake Rupanco [40.82, -72.50] in Chile. The context is a series of landslides, and a resultant tsunami, that was triggered by the 22 May 1960 Mw=9.5 Great Chilean earthquake. The paper reconstructs that landslides and models the tsunami that they generated.

This event is particularly interesting as the loss of life was significant. Quiroga et al. (2025) document about 120 fatalities:-

“The most severely impacted area was Las Gaviotas, a settlement situated on the southeast shore…, where tsunami run-up heights reportedly exceeded 10 m, according to eyewitness accounts… One of the most significant losses was the destruction of the popular Termas de Rupanco hotel located near geothermal springs …, which was swept away by the landslides, resulting in 11 confirmed fatalities … At that time, a road was also under construction along the southern shoreline to connect Osorno with Las Gaviotas; both the road and several worker camps were destroyed…”

The Chilean Enterreno site has a photograph of the Termas de Rupanco hotel prior to the tsunami:-

Hotel Termas de Rupanco, which was destroyed by the landslide-induced tsunami 1960. Image from Enterreno. Posted by Francisco Vidal Guzmán under a by-nc licence.

Quiroga et al. (2025) have tracked the source of the tsunami to a series of landslides that occurred on the north side of Lake Rupanco. The scars of these failures are still very visible on Google Earth:-

Google Earth image of the site of the landslides on the banks of Lake Rupanco triggered by the 22 May 1960 earthquake in Chile.

Quiroga et al. (2025) have identified eight landslide scars in this area, of which the most significant is the bowl-shaped scar in the centre of the image above. This is the most likely source of the tsunami. It is a rotational failure with lower runout zone, with a volume of 161 million m3. Of this volume, 12.1 million m3 became submerged to generate the wave.

Reconstruction of the wave suggests that it has a maximum amplitude of 33.3 metres close to the landslide itself. At Las Gaviotas, where the hotel was located, the wave had a maximum amplitude of 8.6 metres, arriving 261 seconds after initiation.

This elegant and useful paper illustrates well the threat posed by large landslides into lakes. For those located in the hotel, the events would have been terrifying, starting with a major earthquake for which the shaking would have been intense and long-lasting, followed by the noise and dust generated by the collapsing slopes, and finally the impact of this enormous tsunami. Keeping people safe in such circumstances is a very major challenge.

Reference

Quiroga, J.P., Aránguiz, R., Hernández-Madrigal, V.M. et al. 2025. Reconstruction and numerical modeling of historical and paleo-tsunamigenic landslides in Lake Rupanco, Chile. Landslides. https://doi.org/10.1007/s10346-025-02629-1.

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The world faces a "new reality" as we have reached the first of many Earth system tipping points that will cause catastrophic harm unless humanity takes urgent action, according to a report released by the University of Exeter and international partners.

SummaryA growing body of literature has contributed to linking the presence of bacteria with SIP signals. Yet, there are still unresolved questions concerning the contribution of cell density and microbial metabolic activity in porous media (soils and sediments) to SIP signals. Moreover, there is continued debate on whether cells themselves polarize or whether a cell-sediment interaction is a prerequisite for the measured responses. This study investigates the SIP response of Shewanella oneidensis MR-1 in isolation, that is, in the absence of a mineral porous medium using two setups (i) cells in aqueous suspension and (ii) alginate bead-packed reactors. Results from experiments conducted with static cell suspensions shed light on the strong control of cell settling that drives erratic, poorly reproducible and difficult to interpret SIP signals. However, incubating cells in bead packed reactors yielded reproducible trends in σ″, with strong (3 – 10 mrad) signals that followed the expected cell growth behaviour. Relating σ″ to measured cell density and metabolic activity (using ATP) highlighted the strongly linked contribution of both activity and cell density and SIP. Here, we report a lower frequency polarization peak between 0.01 and 0.1 Hz in the bead reactors, which we attribute to the polarization of cell colonies in the densely packed reactors. In summary, our findings shed light on the direct contribution of cells and their activity to polarization, in the absence of cell-sediment interactions and provide a novel approach for studying cell polarization in static incubation in a porous environment.

SummaryWe present DASPack, a high-performance, open-source compression tool specifically designed for distributed acoustic sensing (DAS) data. As DAS becomes a key technology for real-time, high-density, and long-range monitoring in fields such as geophysics, infrastructure surveillance, and environmental sensing, the volume of collected data is rapidly increasing. Large-scale DAS deployments already generate hundreds of terabytes and are expected to increase in the coming years, making long-term storage a major challenge. Despite this urgent need, few compression methods have proven to be both practical and scalable in real-world scenarios. DASPack is a fully operational solution that consistently outperforms existing techniques for DAS data. It enables both controlled lossy and lossless compression by allowing users to choose the maximum absolute difference per datum between the original and compressed data. The compression pipeline combines wavelet transforms, linear predictive coding, and entropy coding to optimise efficiency. Our method achieves up to 3 × file size reductions for strain and strain rate data in lossless mode across diverse datasets. In lossy mode, compression improves to 6 × with near-perfect signal fidelity, and up to 10 × is reached with acceptable signal degradation. It delivers fast throughput (100–200 MB s−1 using a single-thread and up to 750 MB s−1 using 8-threads), enabling real-time deployment even under high data rates. We validated its performance on 15 datasets from a variety of acquisition environments, demonstrating its speed, robustness, and broad applicability. DASPack provides a practical foundation for long-term, sustainable DAS data management in large-scale monitoring networks.

The timing of emissions reductions, even more so than the rate of reduction, will be key to avoiding catastrophic thresholds for ice-melt and sea-level rise, according to a new Cornell University study.

Glaciers are fighting back against climate change by cooling the air that touches their surfaces. But for how long? The Pellicciotti group at the Institute of Science and Technology Austria (ISTA) has compiled and re-analyzed an unprecedented dataset of on-glacier observations worldwide. Their findings, published today in Nature Climate Change, demonstrate that glaciers will likely reach the peak of their self-cooling power by the next decade before their near-surface temperatures spike up and melting accelerates.

Guided by the rhythms of the sea and the promise of discovery, Teledyne Marine and Rutgers University will set Redwing, an autonomous underwater vehicle, on its journey on Friday, Oct. 10, leading to its launch into the Atlantic Ocean off the coast of Martha's Vineyard in Massachusetts.

New research from the University of St Andrews has shed light on a crucial mechanism of lowering atmospheric CO2 during Earth's past ice ages.