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937 records · Page 12Linked to original sources
USGS2026

Decadal-scale characteristics of natural and anthropogenic dune morphology along North Carolina Barrier Islands (SE Atlantic Coast)

Dunes offer protection to coastal communities from storms, yet quantitative research characterizing human influences on dune systems across decades and 10–100 km spatial scales constitutes a known data gap. This study analyzed a multidecadal archive of dune crest elevations and positions to map mesoscale spatiotemporal trends in foredune morphology across the barrier island coastline of North Carolina, SE Atlantic coast. Results are summarized within four categories of coastline representing a range of coastal management intensities, integrating beach width and dune lateral accommodation space to assess the comparative influence of differing intensities of anthropogenic intervention on dune morphology. These categories account for the presence of structures, roads, and alongshore connectivity to anthropogenic sediment sources (beach nourishment). These categories show distinct dune and beach system characteristics. Dunes are largest in the areas with the longest legacy of coastal management. As categories decrease in development intensity, dune and beach system characteristics generally depart from the large, static dunes and narrow beaches consistent with hold-the-line management. Where small or transgressive dunes exist on heavily developed coasts, they coincide with relatively strong hydrodynamic forcing or sediment-limiting geology. There is evidence of indirect coastal management influence on undeveloped barrier islands with alongshore connectivity to developed barriers. While this analysis was conducted at the mesoscale, the results provide researchers with the framework to make insights at smaller scales than those demonstrated in this study.

North Carolina↗
USGS2026

Groundwater source water assessment area delineation of public supply wells in the Treasure Valley, western Idaho

The Idaho Department of Environmental Quality (IDEQ) is responsible for assessing the source water for public water supply systems including the delineation of source water assessment areas for wells, which are defined as the subsurface areas contributing water to a well during a period of time. Part of the IDEQ assessment plan is to update source water assessments over time. The U.S. Geological Survey (USGS) developed a new groundwater-flow model for part of the western Snake River Plain aquifer in southwestern Idaho. This groundwater- flow model provided a new opportunity for IDEQ to update source water assessment for public water supply wells within the model boundary. The USGS, in cooperation with IDEQ, used the USGS Treasure Valley Groundwater Flow Model along with a MODPATH particle tracking post-processing program to reassess public-water supply source water assessment areas. The USGS created an automated script that requests a well location, depth, and pumpage rate, and then incorporates that information into the Treasure Valley Groundwater Flow Model combined with the MODPATH model to create 3-, 6-, and 10-year time of travel zones that are output to a geographic information system shapefile. The TVSWA_Delineator script provides a fast, transparent tool for IDEQ to reassess or create new public-water supply source water assessment area delineations based on new and updated information and is available as a Python script and a Windows executable with the compiled script and all necessary components. TVSWA_Delineator utilizes a quadtree approach to rediscretize the Treasure Valley Groundwater Flow Model grid around the pumping well location from 1-mile cell lengths telescoped down to 1/16 mile. This rediscretization increases the source water assessment area delineation resolution near the pumping well and minimizes the effect of weak sinks in the MODPATH model. The stress inputs for each month of the final 10 years (2006 to 2015) of the Treasure Valley Groundwater Flow model historical simulation were averaged for the particle tracking analysis. The MODPATH model used backwards tracking of particles released at each stress period to create the source water assessment area delineations. This report documents the creation of the TVSWA_Delineator Python script, including adaptations made to the Treasure Valley Groundwater Flow Model, creation of a companion MODPATH model, and post-processing results to provide source water assessment areas.

Idaho↗
USGS2025

Preface to the focus section on earthquake-induced ground deformation

Ground failure due to earthquake-induced liquefaction, surface fault rupture, and landsliding has caused substantial damage in the past and continues to pose risks to critical infrastructure in the future. The consideration of ground failure is central to engineering analysis and design, ranging from site-specific engineering assessments of ground failure potential to broader regional-scale ground failure assessments of near-real-time earthquake impacts or longer-term portfolio risk. Uncertainties in all aspects of the problem complicate the prediction of earthquake-induced ground failure, including the identification of hazard-susceptible geomaterials, characterizing their spatial extent and physical properties, spatio-temporal variability in groundwater conditions, characterization of earthquake ground motions, assessing ground failure severity, and linking ground failure severity to infrastructure damage and loss.

Seismological Research Letters↗
USGS2025

S/P amplitude ratios with Distributed Acoustic Sensing and application to earthquake focal mechanisms

Distributed acoustic sensing (DAS), which transforms a fiber optic cable into an array of high frequency strainmeters, has the potential to help us characterize earthquakes with a dense sampling of measurements. While earthquake focal mechanisms are frequently determined using P -wave polarities and S / P amplitude ratios with inertial seismometers, the dense sampling of DAS over potentially large portions of the focal sphere can aid our solutions. Here, we consider ∼200 regional earthquakes and thousands of S / P measurements on a DAS cable colocated with a network of inertial seismometers near Arcata, California. We demonstrate the S / P ratio measurements made on DAS are similar to those made on the inertial seismometers and can be used to constrain focal mechanism solutions.

California↗
USGS2024

GRAPES: Earthquake early warning by passing seismic vectors through the grapevine

Estimating an earthquake's magnitude and location may not be necessary to predict shaking in real time; instead, wavefield-based approaches predict shaking with few assumptions about the seismic source. Here, we introduce GRAph Prediction of Earthquake Shaking (GRAPES), a deep learning model trained to characterize and propagate earthquake shaking across a seismic network. We show that GRAPES’ internal activations, which we call “seismic vectors”, correspond to the arrival of distinct seismic phases. GRAPES builds upon recent deep learning models applied to earthquake early warning by allowing for continuous ground motion prediction with seismic networks of all sizes. While trained on earthquakes recorded in Japan, we show that GRAPES, without modification, outperforms the ShakeAlert earthquake early warning system on the 2019 M7.1 Ridgecrest, CA earthquake.

Shimane/HiroshimaPrefectures↗
USGS2021

Factors influencing distribution of Coccidioides immitis in soil, Washington State, 2016

Coccidioides immitis and Coccidioides posadasii are causative agents of Valley fever, a serious fungal disease endemic to regions with hot, arid climate in the United States, Mexico, and Central and South America. The environmental niche of Coccidioide s spp. is not well defined, and it remains unknown whether these fungi are primarily associated with rodents or grow as saprotrophs in soil. To better understand the environmental reservoir of these pathogens, we used a systematic soil sampling approach, quantitative PCR (qPCR), culture, whole-genome sequencing, and soil chemical analysis to identify factors associated with the presence of C. immitis at a known colonization site in Washington State linked to a human case in 2010. We found that the same strain colonized an area of over 46,000 m 2 and persisted in soil for over 6 years. No association with rodent burrows was observed, as C. immitis DNA was as likely to be detected inside rodent holes as it was in the surrounding soil. In addition, the presence of C. immitis DNA in soil was correlated with elevated levels of boron, calcium, magnesium, sodium, and silicon in soil leachates. We also observed differences in the microbial communities between C. immitis -positive and -negative soils. Our artificial soil inoculation experiments demonstrated that C. immitis can use soil as a sole source of nutrients. Taken together, these results suggest that soil parameters need to be considered when modeling the distribution of this fungus in the environment.

Washington↗
USGS2025

U.S. Geological Survey geomagnetic variometer data: Capitalizing on seismic infrastructure

The U.S. Geological Survey’s Geomagnetism Program is collaborating with the Earthquake Hazards Program and Global Seismographic Network Program to densify magnetic field observations. This collaboration focuses on the installation of magnetometers, or magnetic variometers, at existing seismic stations. Along with improving the density of space weather observations for hazard monitoring, these data can be used to correct colocated magnetic field induced noise in seismic data. Such corrections are especially useful during time periods of large magnetic storms where the magnetic field‐induced instrument noise can be of similar amplitude to earthquake ground‐motion records.

contiguous United States↗
USGS2026

Small-volume tephra deposits of the May 1924 explosions from Halemaʻumaʻu, Kīlauea volcano, and their origin

More than 50 explosive eruptions occurred from Halemaʻumaʻu at Kīlauea volcano over 17 days from May 11 to 27, 1924. Ballistics weighing as much as 14,000 kg were ejected and most landed within 2 km of the vent. Fine ash made up a major component of the tephra and was dispersed tens of kilometers downwind. Draining of the Halemaʻumaʻu lava lake occurred in late February 1924, with the crater floor eventually subsiding by a further ∼70 m (to ∼180 m below the crater rim) by the time the first explosions took place during the night of May 10–11. The largest explosions occurred on May 17–18 and smaller explosions continued until May 27, at which point Halemaʻumaʻu had more than doubled in width and depth. The explosions generated plumes reaching up to ∼10 km high with ballistics ejected up to 2 km from the crater. Almost 100 years later, we investigate and characterize the preserved tephra deposits within ∼3 km of the 1924 crater rim. Grain size and shape analyses were performed on 202 samples collected from 34 tephra profiles using dynamic image analysis, with a subset of layers from nine tephra profiles used for componentry (200 grains per layer in the 0.5–1 mm size fraction). Additionally, we characterize the average diameters (using the five largest clasts) at 216 locations and measure the average diameters of 2291 ballistics (largest per ∼100 m 2 area). Physical descriptions from fieldwork and grain size distributions were used to subdivide the tephra layers into five lithofacies: coarse homogeneous, fine homogenous, red ash, accretionary lapilli-bearing, and finely laminated. Grain size versus shape data show a range of values that demonstrate most grains are dense, smooth, and equant, in alignment with lithic clasts dominating the tephra componentry. The fine grained and accretionary lapilli-bearing nature of some of these lithofacies confirms that water influenced the style of the explosions. However, we also note juvenile clasts within many of the tephra layers, indicating that many of the layers were formed during phreatomagmatic explosions (sensu stricto), despite the eruptive mechanism being dominantly phreatic. Juvenile clasts are more abundant higher in the tephra profiles, suggesting that juvenile magma was more involved later in the explosive sequence. Thermal and hydrologic modeling indicate that groundwater inflow into a short-lived, small-diameter volcanic conduit (10-m to 120-m-diameter used for modeling) during the 78–85 days preceding the first explosion provides a physically plausible mechanism for this eruptive sequence.

Hawaii↗
USGS1999

Water-quality assessment of south-central Texas — Descriptions and comparisons of nutrients, pesticides, and volatile organic compounds at three intensive fixed sites, 1996-98

Water-quality samples were collected during April 1996-April 1998 at three intensive fixed sites in the San Antonio region of the South-Central Texas study unit as part of the U.S. Geological Survey National Water-Quality Assessment Program. The sampling strategy for the intensive fixed-site assessment is centered on obtaining information about the occurrence and seasonal patterns of selected constituents including nutrients, pesticides, and volatile organic compounds. The three sites selected to determine the effects of agriculture and urbanization on surface-water quality in the study unit are Medina River at LaCoste (agriculture indicator site), Salado Creek (lower station) at San Antonio (urban indicator site), and San Antonio River near Elmendorf (integrator site). Concentrations of two nutrients, dissolved nitrite plus nitrate nitrogen and total phosphorus, were largest at the integrator site, which is downstream of municipal wastewater treatment plants. Nitrite plus nitrate nitrogen concentrations at this site often exceeded the U.S. Environmental Protection Agency (EPA) maximum contaminant level (MCL) for drinking water. All total phosphorus concentrations at the site exceeded the EPA recommended maximum concentration for streams not discharging directly into reservoirs. Nitrite plus nitrate nitrogen concentrations at the integrator site tended to be smaller, and total phosphorus concentrations at the urban site tended to be larger in samples collected during stormflow than during base flow. The most detections and largest concentrations of three pesticides (atrazine, diazinon, and prometon) were in samples collected at the urban site. Some pesticide concentrations at the agriculture site showed a seasonal pattern of increasing concentrations during spring, the peak application season. Four pesticides (atrazine, deethylatrazine, diazinon, and prometon) were detected in at least 38 percent of samples collected at all three sites. The concentrations of all detected pesticides that have an MCL were less than the MCL at the three sites. More volatile organic compounds (VOC) were detected at the urban indicator site than at the agriculture indicator site, mostly likely because more sources are located in urbanized areas. The most VOCs detected and the largest concentrations of two VOCs (chloroform and tetrahydrofuran) were in samples from the integrator site. More VOCs were detected in samples collected at the integrator site during stormflow than during base flow. The concentrations of all detected VOCs that have an MCL were less than the MCL at the three sites.

Texas↗
USGS2025

Expression of corticoid-regulatory genes in the gills of Atlantic salmon (Salmo salar) parr and smolt and during salinity acclimation

In teleost fishes, cortisol is the major corticoid and has both glucocorticoid and mineralocorticoid actions. However, how fish tissues discriminate between these distinct corticosteroid actions is unclear. In mammals, the major factors responsible for intracellular corticosteroid regulation are glucocorticoid receptors ( gr s) and the mineralocorticoid receptor ( mr ), but their role in osmoregulation of fish is unclear. 11β-hydroxysteroid dehydrogenases ( hsd11b s) control the levels of intracellular corticosteroids by converting from bioactive forms to inert forms. To investigate how Atlantic salmon ( Salmo salar ) respond to cortisol in different physiological or environmental conditions, we performed comparisons of parr and smolt, and osmotic challenge experiments to examine the physiological responses and gill transcript levels of genes underlying cortisol-signalling, including gr1 , gr2 , mr , hsd11b2 and hsd11b3 . Because cortisol may interact with growth hormone and prolactin during salinity changes, transcript levels encoding growth hormone receptors ( ghr1 , ghr2 ) and the prolactin receptor ( prlr ) were also examined. Hsd11b2 transcript levels in seawater-acclimated fish were consistently lower compared to fish acclimated to fresh water. After transfer to seawater, prlr transcript levels in fish significantly decreased and transcript levels of ghr1 , ghr2 and hsd11b3 showed no change or were slightly higher than those of freshwater control groups. Gr1 , gr2 and mr transcript levels were slightly but consistently higher in fish acclimated to fresh water relative to seawater. Our results indicate that changes in corticosteroid receptor and hsd11b2 transcript levels in the gills may be important mechanisms that regulate corticoid signals to achieve ion homeostasis in Atlantic salmon.

Journal of Fish Biology↗
USGS2026

Microclimate mediates the strength and direction of avian biotic interactions

Theory predicts that that the strength and direction of species interactions can shift from being competitive in benign environments toward being facilitative in stressful environments. However, the environmental context dependency of species interactions has rarely been tested in animal communities. We capitalized on a 15-year, landscape-scale dataset, collected annually in a relatively stable old-growth forest environment to test the long-held hypothesis that the strength and direction of species interactions might be mediated by climatic conditions. It is generally accepted that competitive and facilitative interactions drive the distributions of many species. Using multi-species dynamic occupancy models applied to long-term data, we tested whether annual settlement by bird species could affect either the persistence or settlement by other phylogenetically related species, and whether these interactions are mediated by microclimate. We found that species interactions were influenced by microclimate for some, but not all avian species pairs. Related species pairs more often showed settlement dynamics that were indicative of attraction rather than repulsion. In some cases, competitive interactions at warmer microclimates flipped to become facilitative in colder ones. However, the reverse was also true: facilitative interactions amplified for some species under warm conditions. Furthermore, species pairs that were closely related were more likely to exhibit competitive relationships along at least part of the microclimatic gradient. Our results highlight the importance of using long-term data to incorporate competitive and facilitative interactions into species distribution models and support the notion that the strength and direction of species interactions can be dependent on microclimatic environmental conditions.

Oregon↗
USGS2025

The geology of Canadian potash: A critical mineral for feeding the world

Potash, potassium-bearing water-soluble salt, is the primary global economic source of potassium. Potash is recognized as a critical mineral in Canada as it is the largest source of potassium used in fertilizers. It is essential for global agricultural productivity and food security. Canada is the world’s largest potash exporter with vast deposits in the widely mined Prairie Evaporite of Saskatchewan, which formed in the epicontinental Elk Point Basin during the Middle Devonian. Potash is also found in the Windsor Group of Atlantic Canada where it formed in a series of tectonically active basins during the Mississippian that have undergone substantial post-depositional subsurface alteration and deformation. Potash deposits were mined in New Brunswick up until 2016. Both deposits are salt giants, recording times in the geologic record of extensive and long-lasting evaporite genesis under arid conditions in restricted seas. This paper reviews the geological and economic significance of Canadian potash, including (1) the genesis of each deposit, (2) diagenetic, erosional, and tectonic modification, and (3) exploration and mining in each basin. Underdeveloped regions, possible undiscovered resources, environmental considerations, and the importance of sustainable practices in light of climate change and socioeconomic risks are also addressed.

Facets↗
USGS2025

Evidence of mineral alteration in a salt marsh subterranean estuary: Implications for carbon and trace element cycling

Subterranean estuaries (STE) in salt marshes are biogeochemically active zones where interactions between terrestrial groundwater and seawater drive complex cycling of carbon and trace elements, influenced by mineral dissolution. These systems, characterized by fine-grained organic-rich peat overlying permeable coastal aquifers, play a crucial role as a blue carbon sink, yet their geochemical dynamics remain poorly understood. We investigated dissolved trace elements, carbon, silica, and radium isotopes in a salt marsh STE (Sage Lot Pond, Waquoit Bay, MA) over seasonal and annual cycles. Our results reveal that groundwater and estuarine water circulation through marsh peat and aquifer sediments leads to enrichments of dissolved organic and inorganic carbon (DOC and DIC), Si, Ba, and Mn, with variable source/sink behavior of Fe and net removal of U. Submarine groundwater discharge dominated Ba fluxes, whereas pore water drainage from marsh peat acted as the main sink for U and source of Si. Fe cycling was variable, with terrestrial Fe largely removed as groundwater passed through the STE, consistent with Fe-sulfide and amorphous phase formation. Radium isotope ratios identified two distinct subsurface flow pathways, influenced by metal-oxide cycling and organic matter breakdown. Si production was decoupled from DIC, suggesting Si originates from mineral alteration, whereas DIC results from both mineral weathering and microbial respiration. Silicate mineral alteration, coupled with marsh pore water drainage, accounts for up to 16% of annual DIC exports (66 g C m −2 y −1 ), highlighting the importance of STEs in coastal carbon and trace element cycling, especially as marshes face environmental change.

Massachusetts↗
USGS2024

Declining groundwater storage expected to amplify mountain streamflow reductions in a warmer world

Groundwater interactions with mountain streams are often simplified in model projections, potentially leading to inaccurate estimates of streamflow response to climate change. Here, using a high-resolution, integrated hydrological model extending 400 m into the subsurface, we find groundwater an important and stable source of historical streamflow in a mountainous watershed of the Colorado River. In a warmer climate, increased forest water use is predicted to reduce groundwater recharge resulting in groundwater storage loss. Losses are expected to be most severe during dry years and cannot recover to historical levels even during simulated wet periods. Groundwater depletion substantially reduces annual streamflow with intermittent conditions predicted when precipitation is low. Expanding results across the region suggests groundwater declines will be highest in the Colorado Headwater and Gunnison basins. Our research highlights the tight coupling of vegetation and groundwater dynamics and that excluding explicit groundwater response to warming may underestimate future reductions in mountain streamflow.

Nature Water↗
USGS2024

Time varying crustal anisotropy at Whakaari/White Island volcano

Whakaari/White Island has been the most active New Zealand volcano in the 21st century, producing small phreatic and phreatomagmatic eruptions, which are hard to predict. The most recent eruption occurred in 2019, tragically claiming the lives of 22 individuals and causing numerous injuries. We employed shear-wave splitting analyses to investigate variations in anisotropy during quiescence, unrest, and an eruption between 2018 and 2020. We examined spatial and temporal variations in 7972 shear-wave splitting measurements and derived 1402 V p /IV s ratio measurements. Comparing shear-wave splitting parameters from similar earthquake paths across different times indicates that the observed temporal changes are unlikely to result from variations in earthquake paths through media with spatial variability. Instead, these changes may stem from variations in anisotropy over time, likely caused by changes in crack alignment due to stress or varying fluid content.

Whakaari/White Island volcano↗
USGS2025

Multi-scale predictors of Northern Long-eared Bat (Myotis septentrionalis) occupancy in the United States

Historically, Myotis septentrionalis (Northern Long eared Bat) was among the most common forest-interior species in North America. Largely due to high mortality from white-nose syndrome, this species has experienced severe population declines across its range. To create an updated species distribution map representing summer occupancy probabilities from 2017 to 2022, we integrated stationary acoustic data with live-capture data from the database of the North American Bat Monitoring Program into a multi-scale, multi-method occupancy modeling framework. Our results provide data-driven predictions with quantified uncertainty for summer occupancy probabilities for Northern Long-eared Bats at 2 spatial scales across the range of the species, while also accounting for inherent observation biases (e.g., imperfect detection).

Journal of North American Bat Research↗
USGS2024

Layered intrusions in the Precambrian: Observations and perspectives

Layered intrusions are plutonic bodies of cumulates that form by the crystallization of mantle-derived melts. These intrusions are characterized by igneous layering distinguishable by shifts in mineralogy, texture, or composition. Layered intrusions have been fundamental to our understanding of igneous petrology; however, it is their status as important repositories of critical metals – such as platinum-group elements, chromium, and vanadium – that has predominantly driven associated research in recent decades. Many layered intrusions were emplaced during the Precambrian, predominantly at the margins of ancient cratons during intervals of supercontinent accretion and destruction. It appears that large, layered intrusions require rigid crust to ensure their preservation, and their geometry and layering is primarily controlled by the nature of melt emplacement. Layered intrusions are best investigated by integrating observations from various length-scales. At the macroscale, intrusion geometries can be discerned, and their presence understood in the context of the regional geology. At the mesoscale, the layering of an intrusion may be characterized, intrusion-host rock contact relationships studied, and the nature of stratiform mineral occurrences described. At the microscale, the mineralogy and texture of cumulate rocks and any mineralization are elucidated, particularly when novel microtextural and mineral chemical datasets are integrated. For example, here we demonstrate how mesoscale observations and microscale datasets can be combined to understand the petrogenesis of the perplexing snowball oiks outcrop located in the Upper Banded Series of the Stillwater Complex. Our data suggest that the orthopyroxene oikocrysts did not form in their present location, but rather formed in a dynamic magma chamber where crystals were transported either by convective currents or within crystal-rich slurries. Critical metals may be transported to the level of a nascent intrusion as dissolved components in the melt. Alternatively, ore minerals are entrained from elsewhere in a plumbing system, potentially facilitated by volatile-rich phases. There are many ore-forming processes propounded by researchers to occur at the level of emplacement; however, each must address the arrival of the ore mineral, its concentration of metals, and its accumulation into orebodies. In this contribution, several of these processes are described as well as our perspectives on the future of layered intrusion research.

Precambrian Research↗
USGS2025

Surface-wave relocation and characterization of the October 2023 tsunamigenic seismic unrest near Sofugan volcano, Izu Islands, Japan

A moderate-magnitude earthquake swarm occurred in the remote Izu Islands region of Japan between October 1 and 8, 2023. The swarm included 151 shallow earthquakes cataloged by the U.S. Geological Survey, which notably included a roughly 2.5-hr episode of 15 successive magnitude (M) < 5.5 earthquakes. Origin times were coincident with regionally recorded tsunami waves, but tsunamigenesis for moderate-magnitude earthquakes is uncommon, indicating that volcanic activity generated the ocean displacements. Leveraging a surface-wave relative relocation approach, we estimate precise epicentroid locations for the remote swarm. Final epicentroids and caldera analogs indicate a three-stage model to explain swarm activity: (a) caldera pressurization due to magma intrusion, (b) depressurization via dike propagation away from the caldera, and (c) eruption corresponding with caldera reactivation either by collapse or additional intrusion.

Sofugan volcano, Izu Islands↗