Nature Geoscience, Published online: 15 January 2025; doi:10.1038/s41561-024-01626-8
Photochemical modelling suggests that H2 outgassing from crustal hydration could have supported transient warming episodes on early Mars in a CO2-rich atmosphere with abrupt transitions to cold climate states in a CO-rich atmosphere.
A hidden world teeming with life lies below beach sands. New Stanford-led research sheds light on how microbial communities in coastal groundwater respond to infiltrating seawater.
New research has tracked the evolution of a glacier lake dammed by a glacier surge using satellite images, to help better understand its life cycle and the hazard it presents to nearby communities.
Author(s): M. W. C. Dharma-wardana, Dennis D. Klug, Hannah Poole, and G. Gregori
Recent cutting-edge experiments have provided in situ structure characterization and measurements of the pressure (P), density (ρ¯), and temperature (T) of shock compressed silicon in the 100 GPa range of pressures and up to ∼10000K. We present first-principles calculations in this P,T,ρ¯ regime to …
[Phys. Rev. E 111, 015205] Published Tue Jan 14, 2025
Nature Geoscience, Published online: 14 January 2025; doi:10.1038/s41561-024-01624-w
Near-daily sampling of volcanic ash during a three-month eruption reveals shifts in mantle-derived liquid magma (melt) composition, highlighting its potential as a monitoring and forecasting tool. These shifts align with the amplitude of volcanic tremor, a persistent seismic signal, suggesting a link between magma viscosity, shallow bubble escape dynamics, and tremor changes.
SummaryLow-frequency laboratory measurements provide direct access to the elastic properties of samples within the seismic frequency band, offering calibration data for seismic survey analysis. Additionally, µCT imaging can quantify actual saturations and provides insights into phase distributions at the pore scale. To conduct laboratory triaxial measurements at seismic frequencies while simultaneously imaging the rock interior, we developed an X-ray transparent low-frequency apparatus. Our apparatus determines rock mechanical properties at seismic frequencies (0.5â150 Hz) and strain amplitudes (10−7â10−5), measuring Youngâs modulus, Poissonâs ratio, and attenuation. In addition P- and S-wave velocities at ultrasonic frequencies are measured. We conducted imbibition-drainage experiments to assess the effect of saturation and patch size on seismic and ultrasonic elastic properties in sandstone. Additional tests with liquid and gaseous CO2 reveal the impact of partial CO2-gas saturation. The imbibition-drainage experiment demonstrated that P-wave velocity at ultrasonic frequencies was elevated during drainage and reduced during imbibition. Drainage caused patchy saturation, while imbibition resulted in uniform saturation. This implies that ultrasonic measurements, with wavelengths comparable to the pore fluid patch size, are likely influenced by scattering. In contrast, low-frequency measurements, where the wavelength surpasses the patch size, capture effective medium properties and therefore are not affected by scattering effects. The results of the CO2 test suggest that low-frequency measurements can detect even low gas saturations (4% gaseous CO2). In contrast, ultrasonic velocity measurements primarily reflect the response of the fully saturated sample at low gas saturations and do not indicate a reduction in velocity. Identifying fluid-solid interactions and estimating saturation via µCT imaging is crucial, especially with minimal gas presence. Our combined approach allows precise determination of elastic properties at seismic frequencies and shows the importance of low-frequency over ultrasonic measurements.
SummaryIntraplate earthquakes in stable continental regions exhibit diverse characteristics in terms of timing, spatial distribution, and magnitude. They are often unexpected, and their underlying physical mechanisms are not well understood. This complexity is particularly apparent in Norway, where seismicity is mostly localised on the continental margin and coastal areas. Various studies have attempted to explain the causes of seismicity in Norway by invoking different sources of stress, ranging from regional stress due to ridge push to local effects such as topography or deglaciation. In this study, we revisit these questions by investigating the distribution of seismicity in southwestern Norway using an enhanced earthquake catalogue. To achieve this, we revised the Norwegian National Seismic Network seismic catalogue from 2000 to 2023 and built a new catalogue using machine-learning-based techniques on data from a temporary seismic deployment in the region. Thanks to the increased station density during this deployment, we were also able to calculate new fault plane solutions that consistently showed a WNW-ESE direction for the most compressive axis. Furthermore, we demonstrate that seismicity in southwestern Norway, while diffuse, tends to be localised around the major crustal shear zones of the region, such as the Bergen Arc Shear Zone and the Hardangerfjord Shear Zone.
The Indiana Geological and Water Survey at Indiana University has been publishing critical research that addresses landslide risks across the Hoosier state. New high-resolution imagery and digital elevation measurements being collected by the Indiana Geographic Information Office will aid this work.
Five wildfires—the biggest of which are the Palisades and the Eaton fires—are still currently burning (as of 10 January 2025) in areas of north Los Angeles. At least 10 people are known to have lost their lives and many more properties have been burnt to the ground.
Oregon's Cascade Range mountains might not hold gold, but they store another precious resource in abundance: water. Scientists from the University of Oregon and their partners have mapped the amount of water stored beneath volcanic rocks at the crest of the central Oregon Cascades and found an aquifer many times larger than previously estimated—at least 81 cubic kilometers.
Researchers from the Hong Kong Polytechnic University, alongside mainland collaborators, have uncovered an unexpected phenomenon: severe wintertime ozone (O3) pollution in Lanzhou, China, driven primarily by alkene emissions from local petrochemical industries.
Plates at subduction zones typically move just a few centimeters per year. But when accumulated stress at these convergent plate boundaries releases suddenly, the plates can slip several meters and cause some of Earth's largest earthquakes. The timing and location of such megathrust earthquakes depend on factors such as the shape, roughness, composition, and fluid content of the fault.
Author(s): Daniel Plummer, Pontus Svensson, Dirk O. Gericke, Patrick Hollebon, Sam M. Vinko, and Gianluca Gregori
By performing an ensemble of molecular dynamics simulations, the model-dependent ionization state is computed for strongly interacting systems self-consistently. This is accomplished through a free energy minimization framework based on the technique of thermodynamic integration. To illustrate the m…
[Phys. Rev. E 111, 015204] Published Mon Jan 13, 2025
Abstract
In this paper, we propose a novel algorithm for fast frequency and phase synchronization of high-stability oscillators synchronized with 1 PPS signal from satellite navigation systems. The algorithm uses a model of a control object in the space of state variables and controls the frequency of an oscillator operating in a phase-locked loop. A new element is the introduction to the theoretical analysis and the design process, the time of entering synchronization. Currently, the literature lacks theoretical analysis and design methodology that considers the impact of the synchronization time on the choice of the steering algorithm and its parameters. All the data needed to determine the numerical values of the model were found experimentally for three different classes of control objects. Short synchronization times, a detailed description of the design methodology, and the use of values measured in the real system distinguish the proposed algorithm from the solutions described in the literature. The effect of optimization was achieved thanks to the algorithm’s two-stage operation. In the first stage, the algorithm aims to minimize the phase error quickly. The best solution for this stage is Sliding Mode Control (SMC). In the second stage, the algorithm strives to maximize the control quality, understood as minimizing the values of Maximum Time Interval Error (MTIE) and Time Deviation (TDEV). The Model Predictive Control (MPC) and Linear-Quadratic Regulator (LQR) optimal control algorithms were used at this stage. The paper also investigated the influence of the tuning parameters of these algorithms (weights as a function of cost) on the long-term behavior of the control system.
Nature Geoscience, Published online: 13 January 2025; doi:10.1038/s41561-024-01627-7
Space exploration has expanded the realm of geoscience to the outermost Solar System. A new generation of missions shines the way.
SummaryHaematite-bearing red beds are widespread across the Earth and play a pivotal role in palaeomagnetic studies. However, chemical remanent magnetisation (CRM) typically associated with authigenic haematite is not fully understood, which precludes more accurate interpretations of natural remanent magnetisation (NRM) in red beds. Here, we use electron microscopy, rock magnetism, and palaeomagnetism to investigate authigenic haematite in Early Triassic red beds in North China. Our findings reveal that the biotite-hosted haematite grains with grain sizes of several to tens of microns carry a significant portion of the NRM in these sedimentary rocks. We propose that these authigenic haematite particles primarily form during the early stages of diagenesis process. This authigenic haematite's growth is controlled by the crystal structure of the host biotite. Furthermore, this authigenic haematite displays high coercivity (> 100 mT) and high unblocking temperature (> 650 ° C), comparable to that of typical detrital haematite (30–1000 mT, > 650 ° C), which is usually the primary carrier of detrital remanent magnetisation (DRM) in such red beds. This study highlights the significance of combining mineralogical analysis with rock magnetism and palaeomagnetism to differentiate between CRM and DRM and thereby identify the primary NRM component within red beds. We hypothesize that the abundant iron supplied by biotite promotes the growth of authigenic haematite. This study illustrates the need to use caution when studying sedimentary NRM, particularly in rocks from source areas containing acidic igneous and metamorphic rocks (e.g. granite, diorite, and biotite gneiss) that contain a large proportion of iron-bearing minerals, such as the biotite observed in this study.
The micromechanics of friction has been investigated from the viewpoint of the healing of real contacts. In this study, the underlying processes of friction are discussed from the viewpoint of the contact junc...
Constraining the effective rheology of major faults contributes to improving our understanding of the physics of plate boundary deformation. Geodetic observations over the earthquake cycle are often used to e...
On February 8, 2022, approximately 40 of the 49 Starlink satellites were reported to have lost altitude, leading to atmospheric re-entry. SpaceX reported that the orbital decay on Starlink satellites was consi...
Melting ice sheets are often considered synonymous with climate change in the media, with evocative images of lone polar bears floating on ever-shrinking rafts of ice. While impacts such as sea level rise and salinity changes are commonly reported, one lesser-known consequence is the effect on volcanoes.
