The soil in high-elevation, cooler, drier tropical forests in the Colombian Andes stores more carbon from fires than lower, warmer regions, new research shows.
Penn State Assistant Professor of Anthropology Jacob Holland-Lulewicz is among a group of archaeologists who have spent years conducting research on the barrier islands off the coast of Georgia. The islands have changed shape and even numbers over the centuries, with Hurricane Irma splitting one into two distinct masses in 2018 and potential changes on the horizon now that the current hurricane season is underway.
Northwestern University and University of California, Los Angeles (UCLA) scientists have developed a new process-based framework that provides a more accurate and dynamic approach to landslide prediction over large areas.
Deep below the surface of the ocean, unseen waves roil and churn the water. These internal waves, traveling between water layers of different temperatures and densities, draw cold, nutrient-rich water up from the depths and play a major role in oceanic circulation. Understanding and modeling their behavior is critical for developing more accurate simulations of an increasingly unpredictable climate.
The Pacific Northwest boasts an extensive network of more than 600 seismic monitoring stations that help researchers track tectonic and volcanic phenomena, including earthquakes.
Driven by high temperatures in the Gulf, Hurricane Ian rapidly intensified from a Category 3 to Category 5 before making landfall in Southwest Florida on September 28, 2022. The deadly storm caught many by surprise and became the costliest hurricane in state history.
AbstractProgressively denser mapping of ocean-floor magnetization has led to detailed reconstructions of past plate motions in the Cenozoic. These reconstructions often reveal rapid kinematic changes that provide crucial information for identifying geodynamic mechanisms that may have caused them, and for quantifying force budgets upon plates. In parallel to these advances, the notion of thin, low-viscosity asthenosphere beneath tectonic plates that facilitates their motions has emerged and consolidated. This weak, mobile layer promotes the formation of the pressure-driven Poiseuille flow that, in turn, generates basal shearing upon plates. In addition, it can be linked to dynamic topography variations due to pulsing plume activity. In this study, we use publicly available finite-rotation compilations of the North American plate (NA) to investigate its kinematic history since Oligocene time. After removing data that are possibly impacted by significant noise, we find that NA experienced a westward speedup near 27 Ma. Next, we explore the role that asthenospheric Poiseuille-type flow caused by increased Canary plume activity may have had in generating this kinematic change. Such plume activity is inferred from the combination of anomalously shallow residual bathymetry and records of past ocean-floor magmatism offshore northwestern Africa. We compare estimates of torque variation upon NA that are (i) required to explain the reconstructed kinematic change, and (ii) predicted by the Poiseuille-type flow associated with the Canary plume activity. Our results indicate that these two torque-variations estimates are in agreement with each other, both in terms of direction and magnitude. This inference suggests that the increased Canary plume activity is a geodynamically-plausible process to explain the Oligocene plate-motion change of NA.
SummarySeismic traveltime tomography represents a popular and useful tool for unravelling the structure of the subsurface across the scales. In this work we address the case where the forward model is represented by the eikonal equation and derive a formalism to solve the inverse problem where gradients are calculated efficiently using the discrete adjoint state method. Our approach provides gradients with respect to both velocity structure and source locations, allowing us to perform a consistent joint inversion. The forward problem is solved using a second-order fast-marching method, which provides a strategy to efficiently solve the adjoint problem. We allow for arbitrary positions of both sources and receivers and for a refined grid around the source region to reduce errors in computed traveltimes. We show how gradients computed using the discrete adjoint method can be employed to perform either deterministic inversion, i.e., solving an optimization problem, or for a probabilistic (Bayesian) approach, i.e., obtaining a posterior probability density function. We show applications of our methodology on a set of synthetic examples both in 2D and 3D using the L-BFGS algorithm for the deterministic case and the Hamiltonian Monte Carlo algorithm for the probabilistic case.
For decades, medium-range weather forecasting—predicting conditions 1 to 5 days ahead—has relied heavily on traditional numerical models. However, this approach often struggles when applied to specific regions with limited historical data.
When an earthquake causes a landslide, debris flow, or erosion, it can change the makeup of nearby lakes by introducing larger sediment particles, causing faster sediment buildup, and affecting carbon sequestration. The sediments that build up on lake bottoms act as a historical archive, recording the lake's biological, physical, and chemical changes and how they affect microbes such as diatoms (microscopic glass-like algae). Yet little is known about how sudden, earthquake-driven disturbances may affect lake ecosystems.
Ocean tides can trigger city-sized icebergs to break off from Antarctic ice shelves, scientists said on Thursday, offering a potential way to predict these dramatic events in the future.
Author(s): Michal Hnatič, Tomáš Lučivjanský, Lukáš Mižišin, Yurii Molotkov, and Andrei Ovsiannikov
We present a two-loop field-theoretic analysis of incompressible helical magnetohydrodynamics (MHD) in fully developed stationary turbulence. A key feature of helical MHD is the appearance of an infrared-unstable “masslike” term in the loop diagrams of the magnetic response function. Physically, thi…
[Phys. Rev. E 112, 015211] Published Thu Jul 24, 2025
SummaryHigh-quality maps of subsurface temperature and the geothermal gradient are useful when assessing the geothermal potential of a region. However, determining geothermal potential is a challenge when direct measurements of in-situ temperature and thermal property information are sparse and indirect geophysical methods are sensitive to a range of parameters, not just temperature. Here, we produce subsurface temperature maps of Ireland using a joint geophysical-petrological inversion, where seismic and other geophysical and petrophysical data are inverted directly for temperature in 1D columns and are collated into a pseudo 3D temperature volume. Additionally, the inversion produces new models for Moho and LAB depth and for the average crustal radiogenic heat production.To assess the robustness of the resulting temperature model, an uncertainty analysis has been performed by inverting all of the 1D columns for a range of reasonable input parameters applicable to the Irish crust (rather than the ‘best’ input parameters). The resulting uncertainty model suggests temperature estimates at 2 km depth in our model could vary by ± 2 to 5°C with an average of 3.5°C in most locations. The uncertainty model can be used to assess confidence in different regions of the temperature model. In addition, 3D forward modelling was performed to assess the lateral heat flow variations when compared to the purely 1D inversion. The upper-crustal geothermal gradient ranges from 20 to 40°C/km indicating a higher geothermal gradient for Ireland than previously reported with subsurface temperatures at 2 km depth > 60°C everywhere, sufficient for residential and industrial heating purposes. The temperature gradient is typically higher in areas with thinner lithosphere. However, in some locations, the observed geotherms are elevated further due to high radiogenic heat production in granitic rocks. In Northern Ireland, a thin lithosphere, coupled with a weakly conductive basalt layer overlying warm crust, results in elevated temperatures. These are the first temperature maps for Ireland that include uncertainty estimates, providing ranges for the subsurface temperature values, and demonstrate that the maps are comparable to direct independent borehole temperature measurements, which are observed to fall within the model uncertainty. Our new methodology provides workflows for determining the geothermal potential in areas with limited direct temperature measurements. The final temperature model with uncertainty provides useful constraints for geothermal exploration and utilisation on the island of Ireland.
SummaryThe role of pre-existing lithospheric heterogeneities in rifting processes remains unclear. The Eastern and Main Ethiopian rifts lie within the same geodynamic province and are kinematically connected through the Turkana Depression, but they transect heterogeneous lithosphere: Pan-African accreted terranes, failed Mesozoic-Paleogene rift systems, zones of Eocene-Oligocene flood magmatism. Rifting in these pre-extension heterogeneities offers the opportunity to evaluate their relative importance in Oligo-Miocene to Recent stretching and magmatism. We use 3D Rayleigh shear-wavespeed (Vs) models inverted from ambient noise signals recorded on a temporary seismic network to image heterogeneities in lithospheric structure, and to evaluate their influence on syn-rift faulting and magmatism. Crustal feeder zones for Eocene-Oligocene flood magmatism in southwestern Ethiopia are marked by ≤ 50 km-wide, 10-15 km-thick mid-lower crustal fast wavespeed (Vs ≥ 3.8 km/s) anomalies that are localized rather than widespread. Evidence for active magma intrusions only occurs beneath aligned chains of Quaternary eruptive centers in Lake Turkana and ≤ 1 Ma shield volcanoes east of the Turkana rift having localized low Vs (≤3.4 km/s) at 0-20 km depth. Evidence for widespread lower crustal intrusions, however, is lacking. Pan-African oceanic accreted terranes in southern Ethiopia have high Vs anomalies of 3.6 km/s throughout the crust and overlay previously imaged high wavespeed lithospheric mantle that has been interpreted as cold and strong Proterozoic accreted terrane. The integrated strength of this lithospheric-scale pre-existing mechanical heterogeneity resisted Oligocene-Miocene stretching and subsequently contributed to the unusual breadth of this East African rift sector lying north of the Turkana Depression.
SummaryThe Eastern Continental Margin of India (ECMI) is a classic passive margin formed during the Mesozoic breakup of the supercontinent Gondwanaland. Since its formation, the margin has undergone complex post-rift thermal subsidence, magmatic activity, and interactions with adjacent tectonic plates. Extensive shipborne magnetic data have been acquired over the years, providing substantial coverage of the area. However, knowledge about the regional thermal structure and magnetic nature of the upper mantle of the ECMI and adjacent deep offshore Bay of Bengal is not understood uniformly throughout the region. In this study, we estimate Curie depth from shipborne magnetic data using a power spectrum inversion technique within a Bayesian framework, incorporating fractal source distribution and a priori sediment thickness to constrain the top depth of magnetic slab. The Curie depth is a proxy for the 580°C isotherm, providing insight into the regional thermal structure and crustal rheology that controls post-rift thermal evolution and mantle magnetization. The obtained Curie depths range from 16 km to 28 km with corresponding surface heat flow values varying between 55 and 85 mW/m². A shallower Curie depth and higher heat flow are observed in northern part of the offshore Krishna-Godavari (KG) basin and the southern part of Mahanadi basin, linked to rift-related magmatic intrusions and mantle plume activity. Conversely, deeper Curie depths and lower heat flow characterize the Cauvery basin and the southern ECMI. Our results show, across much of the region from the Continent-Ocean Transition (COT) zone to deep offshore areas, the Curie depth lies below the Moho, suggesting that magnetic sources extend into the upper mantle. This suggests the presence of serpentinised upper mantle and exhumed mantle peridotite which provides the secondary magnetization. The obtained thermal lithosphere thickness varies from 50 to 90 km, shallower in the Krishna-Godavari and Mahanadi basins and deeper towards the Cauvery and central basins. Geotherms intersects mantle adiabat at 50 km depth in the KG and Mahanadi basins, signifying these are thermal overprint basins linked to magmatic activity. The obtained thermal lithosphere deepens from north to south, mirroring trends in the Lithosphere-Asthenosphere Boundary (LAB). Finally, a positive correlation between Curie depth and effective elastic thickness (Te) reflects the regional variation in crustal strength and tectono-magmatic processes controlling the margin evolution.
Researchers have developed a novel method to detect and study how ice forms in mixed-phase clouds, significantly boosting scientists' ability to forecast weather and model climate change.
The seismic signature of a fireball meteoroid event can be used to tell whether the fireball fragmented or remained intact as it fell through the atmosphere, according to new research published in Seismological Research Letters.
Megathrust earthquakes are large earthquakes that occur on faults found along the boundaries between tectonic plates. The Nankai Trough is a megathrust earthquake zone lying off the southwestern coast of Japan, and experts estimate that this zone could generate a potentially devastating (magnitude 8 or 9) large earthquake sometime in the next 30 years. In addition to the direct catastrophic impact of such powerful ground shaking, a seismic event of this magnitude could trigger cascading hazards such as destructive tsunamis.
Author(s): Zijin Zhang, Anton V. Artemyev, and Vassilis Angelopoulos
The transport of energetic particles in the heliosphere is profoundly influenced by interactions with coherent structures in the turbulent magnetic field of the solar wind, particularly current sheets. While prior studies have largely relied on idealized turbulence models, this work quantifies the r…
[Phys. Rev. E 112, 015209] Published Wed Jul 23, 2025
Author(s): Ilnaz I. Fairushin and Anatolii V. Mokshin
In this paper, the theoretical model of weak decaying collective excitations characteristic of many-particle systems with long-range interaction potentials is developed using the example of one-component strongly coupled Yukawa plasmas. The proposed model is based on the self-consistent relaxation t…
[Phys. Rev. E 112, 015210] Published Wed Jul 23, 2025
