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At least 289 records · Page 16Linked to original sources
USGS2026

Competing effects of elastic heterogeneity and viscous flow on interseismic coupling at Cascadia

Interseismic coupling maps are important tools for estimating future earthquake hazard at subduction zones. Often interseismic coupling is estimated from surface velocities using a homogeneous elastic Earth model. However, inversions that incorporate viscoelastic mantle flow or elastic heterogeneity show that each can change the spatial distribution and magnitude of estimated coupling. We present here a Bayesian inversion of surface deformation for the boundaries of coupling zones at the Cascadia subduction zone that incorporates both elastic heterogeneity and a viscoelastic earthquake cycle model. We find that elastic heterogeneity deepens inferred coupling and worsens fit to surface deformation compared to homogeneous elastic models, but viscoelasticity partly offsets these effects and yields similar coupling and a better fit to the vertical data than homogeneous elastic models. We also find that, of all geometries and viscosities tested, downgoing plate thickness and oceanic mantle viscosity have the greatest impact on modeled displacements and coupling.

California, Oregon, Washington↗
USGS2026

Listening for extinction: Range-wide occupancy highlights critical risks and priorities for northern spotted owls

The northern spotted owl ( Strix occidentalis caurina ) continues to decline across its range, threatened by habitat disturbances and invasive barred owls ( Strix varia ). We conducted a range-wide spotted owl occupancy assessment using 2.1 million h of passive acoustic recordings from 4081 survey stations within 1027 randomly selected 5-km 2 hexagons across six physiographic regions. Applying multistate occupancy models, we estimated probabilities of landscape use (by at least one northern spotted owl) and pair occupancy (occupied by both a male and a female), while accounting for imperfect and sex-biased detection probability. Detection probability of pairs was low in most regions, primarily due to undetected females, but increased with survey effort. If management decisions can only be made when there is a high probability of detecting both sexes when they are present, then longer surveys are one approach to support the decisions. Landscape use and pair occupancy were positively associated with old-growth forest structure and topographic diversity. We also found a pronounced latitudinal gradient in spotted owl landscape use rates with estimated mean landscape use of 0.17 (SE = 0.03) and 0.16 (SE = 0.02) in the two most northern regions, and 0.54 (SE = 0.04) and 0.52 (SE = 0.05) in the two most southern regions. Pair occupancy rates were higher in southern regions (0.29, SE = 0.03, 0.43, SE = 0.05) and very low in northern regions (0.04, SE = 0.01, 0.03, SE = 0.01). In contrast to spotted owls, barred owls were detected in 90% of northern hexagons and 50% of southern hexagons, and barred owl calling intensity was over eight times higher than spotted owls. These results highlight extinction risks in several regions and suggest that management actions, such as spatially targeted barred owl control and protection of structurally complex habitats, have a narrow temporal window in which they can be effective in lowering the probability of regional extirpations. We generated predictive maps of landscape use and pair occupancy, which could help guide regional conservation strategies. This study demonstrates how passive acoustic monitoring and machine learning can be used for broad-scale ecological monitoring, identifying extinction risk thresholds, supporting adaptive management, and improving conservation outcomes for wide-ranging and elusive species that can reliably be detected through unique vocalizations.

California, Oregon, Washington↗
USGS2026

Morphodynamics of snow barchans at Concordia Station, Antarctica

Barchans are crescent-shaped dunes that form and migrate under unimodal wind regimes in areas of low sediment availability. While sand barchan morphodynamics has been extensively studied, snow barchans remain poorly documented. Here, using hourly time-series images taken near Concordia Station, Antarctica, we measure the sizes (lengths 0.3 m to 13 m, widths 0.4 m to 7.5 m) and migration rates (0.13 m h −1 to 3.5 m h −1 ) of 44 populations of snow barchans during 2017–2022. We compare this dataset with established height–velocity and length-width relationships for sand barchans in both air and water. Our results show that snow barchans follow the same scaling as sand barchans, allowing us to estimate a characteristic sintering (bonding of snow particles) time of about one day. This sintering process limits the size of snow barchans when active, reduces their aspect ratios, and, once wind falls below the transport threshold, explains their preservation over a few years. During wind events, migrating barchans are too small to maintain their shape and orientation, making them highly responsive to fluctuations in wind direction. Thus, studying snow barchans improves understanding of an elementary bedform encountered in multiple environments and also of the surface properties of snow on different timescales, offering insights into snow accumulation and wind-blown snow in ice cores.

Geomorphica↗
USGS2026

Adult digeneans of fishes from the lagoon flats of Palmyra Atoll, Eastern Indo-Pacific, with the description of three new species of the Monorchiidae Odhner, 1911

Palmyra Atoll is considered a well-conserved and relatively pristine area with high fish diversity. Since digenean trematodes represent one of the most abundant and diverse parasites of marine fish, the aim of this study was to perform taxonomic analysis of adult digeneans in fishes from the intertidal lagoon of Palmyra Atoll. Parasitological analyses were conducted on 653 individual fishes from 44 species collected from the intertidal sand flats, lagoon, and submerged reefs. Along with morphological descriptions of the adult digeneans, we report prevalence, mean intensities, host species, and tissue microhabitats. We identified 306 individual digeneans representing ten species across six families: one enenterid, Enenterum elongatum Yamaguti 1970; one gyliauchenid, Ichthyotrema vogelsangi Caballero & Bravo-Hollis 1952; one lepocreadiid, Diploproctodaeum arothroni Bray & Nahhas 1998; two opecoelids, Opecoelus mulloidichthydis Yamaguti 1970 and Paropecoelus parupenei Yamaguti 1970; one zoogonid, Lecithostaphylus nitens (Linton 1898) Linton 1940; and four monorchiids, Hurleytrematoides coronatus Yamaguti 1970; Sinistroporomonorchis palmyrensis n. sp.; Sinistroporomonorchis crenimugilis n. sp.; and Lasiotocus glossodontae n. sp. The composition of adult digenean species in fishes from Palmyra Atoll’s sand flats shows significant affinities with previously reported for the Eastern Indo-Pacific (EIP) marine ecoregion, specifically Hawaii and the Central Indo-Pacific (CIP), as well as the Great Barrier Reef.

Parasitology Research↗
USGS2026

Comparative screening of private, public, and bottled drinking water in vitro bioactivity

This study compares in vitro bioactivity profiles of extracts from private tapwater (51 samples), public tapwater (143 samples), and bottled water (31 samples), using high-throughput, multiplex, transcription factor screening. Of 48 biological end points tested, 25 showed significant (≥50% above the field blank) activity. Frequently detected (≥10% of samples) bioactivities (in decreasing order) included xenobiotic metabolism (pregnane X receptor [ PXR ], aryl hydrocarbon receptor [ AhR ]), antioxidant response (antioxidant response element-binding nuclear factor erythroid 2-related factor 2 [ NRF2 ], activator protein 1 [ AP-1 ]), endocrine signaling (estrogen receptor [ ER ], peroxisome proliferator-activated receptor [ PPAR ]), and metals response (metals response element [ MRE ]). Significant bioactivities were observed across all drinking water supplies, with some statistical differences identified. Bioactivities were moderately to strongly correlated with several individual exposure and corresponding benchmark- or activity-weighted metrics, particularly for disinfection byproducts. Significant (α = 0.05) but weak correlations between measured bioactivity resemblance patterns and those of the inorganic–organic exposure, toxicity-quotient (TQ), and exposure-activity-ratio (EAR) resemblance matrices suggest that key drivers of observed drinking water bioactivity were not captured by the extensive, targeted exposure assessment. Results highlight the need for effects-based monitoring combined with improved exposure analysis to better assess health risks from low-level contaminant mixtures in drinking water.

ES&T Water↗
USGS2026

The effect of solar energy development on plant diversity across spatial scales

Utility-scale solar energy development is a novel and rapidly expanding land-use with largely unknown consequences for plant diversity. Construction disturbance and associated increases in environmental heterogeneity in solar facilities relative to undisturbed ecosystems can affect plant diversity at multiple spatial scales. We assessed the effects of modified construction methods, designed to reduce impacts of a utility-scale solar facility, on plant diversity across spatial scales (1–4000 m 2 ) in the Mojave Desert, USA one year after construction. Vegetation surveys across three soil–vegetation types revealed that species richness and evenness were largely unaffected by solar infrastructure at local scales in two of the three soil–vegetation types, but in creosote bush ( Larrea tridentata )-white bursage ( Ambrosia dumosa ) communities with deep soils, both metrics increased. Beta diversity remained unchanged by solar infrastructure while gamma diversity (4000 m 2 ) increased or had a small reduction depending on the soil–vegetation type. These results suggest that low-impact construction can have neutral to positive effects on plant diversity.

Nevada↗
USGS2026

Tropical and subtropical drylands dominate the interannual variability in global net terrestrial carbon flux irrespective of different global ecosystem classifications or geographic scales

Global terrestrial ecosystems exhibit substantial interannual variability (IAV) in net carbon (C) flux. Determining the biogeographic origin of this variability is essential for the understanding and forecasting of global C cycling and carbon-climate feedbacks. Currently, most studies identify either global drylands or moist tropical forests as the dominant source of IAV. Considering this, we investigated whether the use of three different global ecosystem classifications of drylands and moist tropical forests, as well as two alternative geographical scales, could alter which ecosystem is the dominant contributor to terrestrial net C flux IAV. Using the simulation results of 18 dynamic global vegetation models from the TRENDY v11 model intercomparison, we calculated the absolute and area-weighted contributions of net C flux IAV for: individual 0.5° grid cells, global ecosystem classifications, and ecoregions (intermediate scale between grid cells and global ecosystems). For all three of the global ecosystem classification schemes, we found the drylands IAV contributions of 41%, 32%, and 37% were significantly greater than the associated IAV contributions of 20%, 19%, and 24% from the moist tropical forests ( p < 0.001). However, the moist tropical forests had a higher IAV contribution per unit area across all three classification schemes (∼3% versus ∼1%–2% ( p < 0.001)). At the ecoregion scale, this switch between drylands and moist tropical forests was absent; as seven of the ten highest absolute and nine of the ten highest area-weighted contributing ecoregions were drylands. Specifically, we found tropical and subtropical grasslands, savannas, and shrublands to be particularly substantial contributors to global terrestrial net C flux IAV, with the Cerrado’s absolute IAV contribution of 3.52% exceeding all but one of the other 763 global ecoregions IAV contributions (all p < 0.05). Our findings demonstrate that drylands persist as the dominant contributor to global terrestrial net C flux IAV, irrespective of different global ecosystem classifications or geographic scales.

Environmental Research: Climate↗
USGS2026

Establishing realistic length standards for Cutthroat Trout, Rainbow Trout, and Mountain Whitefish

Objective Proportional size distribution (PSD) is a simple index used to summarize length data that is easily communicated, provides insight on fish population dynamics (e.g., growth, recruitment), and is often used to establish management objectives. However, the current length categories for Cutthroat Trout Oncorhynchus clarkii and Rainbow Trout O. mykiss were based on the all-tackle world records (an atypically large adfluvial Cutthroat Trout and a steelhead [anadromous Rainbow Trout]). Consequently, the length categories (stock [S], quality [Q], preferred [P], memorable [M], trophy [T]) are so large for these two species that the index is of limited use for most populations throughout western North America, particularly for large length-groups. In addition, length standards have not been proposed for Mountain Whitefish Prosopium williamsoni . As such, we sought to provide new length standards for Cutthroat Trout, Rainbow Trout, and Mountain Whitefish that allow fisheries scientists to calculate useful PSD values. Methods We compiled data from nearly 3 million fish across the western United States. A percentile-based approach was used to identify the individual total length that would form the basis of estimating length standards. We placed each fish into its respective 10-digit hydrological unit code, obtained the maximum length (all lengths are total length) for each 10-digit hydrological unit code by species, and then identified the 99th percentile of the maximum lengths. The species-specific 99th percentile value was then used to estimate potential length standards for each length category. For Mountain Whitefish, we used the current world-record length as the basis for generating length standards. We compared PSDs calculated using existing and revised length standards to provide insight on potential issues with the proposed values. Results We propose the following minimum total lengths for PSD calculations: 18 cm (7 inches; S), 28 cm (11 inches; Q), 35 cm (14 inches; P), 43 cm (17 inches; M), and 53 cm (21 inches; T) for Cutthroat Trout; 20 cm (8 inches; S), 30 cm (12 inches; Q), 40 cm (16 inches; P), 50 cm (20 inches; M), and 60 cm (24 inches; T) for Rainbow Trout; and 15 cm (6 inches; S), 25 cm (10 inches; Q), 30 cm (12 inches; P), 38 cm (15 inches; M), and 48 cm (19 inches; T) for Mountain Whitefish. Revised values provided more realistic estimates of PSD for Cutthroat Trout and Rainbow Trout than existing values. The proposed length standards for Mountain Whitefish resulted in PSD values that were realistic and useful for characterizing length structure. Conclusions The length standards presented here provide fisheries scientists with tools to aid in the study and management of Cutthroat Trout, Rainbow Trout, and Mountain Whitefish populations.

Colorado, Idaho, Montana, Nevada, Oregon, Utah, Wa↗
USGS2026

Modeling observational uncertainty improves estimation of breeding-season parameters that inform lek-based monitoring for Centrocercus urophasianus (Greater Sage-Grouse)

Counts of males on leks are widely used as abundance indices to monitor populations of lek-breeding species, but they can be influenced by variation in male attendance, inter-lek movement, and mortality. When there is imperfect observability of males on leks, estimates of lek attendance and inter-lek movement are likely to be biased low. We compared traditional multi-state mark–recapture (MSMR) and MSMR models with state uncertainty (MSMR-SU) to determine how accounting for uncertainty in GPS-derived lek attendance improves inference of rates underlying lek-based abundance indices for male Centrocercus urophasianus (Greater Sage-Grouse). We found that modeling observational uncertainty with MSMR-SU models consistently reduced bias in lek attendance and inter-lek movement estimates for adult and yearling males compared to MSMR models. Estimates of daily maximum male lek attendance (adults: 0.79; yearlings: 0.68) and inter-lek movement rates (adults: 0.10; yearlings: 0.07) from MSMR-SU models were higher than daily maximum lek attendance (adults: 0.74; yearlings: 0.55) and inter-lek movement rates (adults: 0.01; yearlings: 0.04) from MSMR models. Consistent with previous studies, adults exhibited higher lek attendance and mortality rates than yearlings. However, unlike earlier studies, inter-lek movement rates were similar between age classes, with adults tending to move earlier in the lekking season than yearlings. Wind speed and precipitation had a weak negative effect on lek attendance. Greater distance to the nearest known lek strongly reduced inter-lek movement. Accounting for lekking-season mortality shifted the estimated date of maximum lek attendance earlier in the season by 8–9 days for adults and 1–3 days for yearlings. Accounting for state uncertainty due to error in state assignment should reduce bias in demographic estimates for use in wildlife conservation and management decisions.

Colorado, Wyoming↗
USGS2026

What we know about wildlife outcomes of the conservation reserve program: A meta-analysis

The Conservation Reserve Program (CRP) is one of the most extensive private-land conservation programs in the United States, aimed at mitigating habitat loss and supporting biodiversity in agricultural landscapes. Individual studies of CRP effects on wildlife report mixed results, necessitating a comprehensive synthesis. We conducted a meta-analysis and vote-counting assessment of 96 studies (1009 case studies, i.e., individual analyses of a wildlife response to a CRP predictor variable) to evaluate effects on wildlife density, occurrence, reproduction, habitat use, and species diversity. Formal meta-analyses were performed for wildlife density and avian nest success. We found CRP generally benefited wildlife, with vote counting indicating positive effects in 32% of all comparisons (i.e., including comparisons to any type of non-CRP land) and in 64% of comparisons to cropland. Formal meta-analysis indicated avian nest success was significantly higher on CRP lands compared to non-CRP lands, but CRP enrollment did not consistently increase wildlife density, likely due to species-specific and ecological factors we did not account for. The literature was strongly biased toward birds (90% of case studies), with limited research on mammals, invertebrates, amphibians, and reptiles. High heterogeneity in effect sizes suggests that variation in conservation practices, study methodologies, and ecological contexts plays a critical role in shaping measured wildlife responses to CRP. Our results demonstrate CRP provides important benefits to wildlife, particularly by enhancing avian reproductive success. However, variation in wildlife effects highlights the need for studies that incorporate more detailed information on CRP management practices and increased research on non-avian taxa. Addressing these gaps may provide additional information allowing for the implementation of improved conservation strategies and maximize CRP's ecological benefits in agricultural landscapes.

Conservation Science and Practice↗
USGS2026

A framework for estimating age and growth using sibship relationships inferred from genomic data

Pedigree reconstruction based on genomic data offers a novel approach for estimating age and growth in wild populations. However, frameworks that use reconstructed pedigrees to parameterize growth models have not been available. We developed a sibship age and growth framework and evaluated the approach using simulation and an empirical application to Sea Lamprey ( Petromyzon marinus ) age and growth analysis. Simulation research revealed that the framework may be widely applicable to semelparous fishes. Applicability to iteroparous fishes was constrained to scenarios in which the percentage of multi-age sibling groups was low. Age assignment using the framework was unbiased for sibling groups first captured at younger ages. Age assignment for sibling groups first captured at older ages (after growth rate had substantially slowed) was biased low due to the hierarchal approach that we adopted to estimate sibling group age-at-first capture. However, this did not result in biased growth parameter estimates. Model output allowed for identification of unreliable age assignments. Finally, the empirical application provided evidence that the framework could address knowledge gaps that have been challenging to address with established age and growth methods.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2026

Bathymetric survey and storage capacity of Upper Lake Mary near Flagstaff, Arizona in 2024

The U.S. Geological Survey (USGS), in cooperation with the city of Flagstaff, collected bathymetric, light detection and ranging (lidar), and land-survey data of Upper Lake Mary in Arizona during the months of April and October 2024. The city of Flagstaff uses a combination of groundwater from well fields throughout the Flagstaff area and surface water, mainly from Upper Lake Mary, for its potable water supply. The purpose of the survey is to update previous surveys using new technology and compare the results to previous surveys to determine if there was a decrease in storage capacity that could affect the city’s water supply. The lakebed was mapped in April 2024 using a vessel equipped with a multibeam echosounder (MBES) and mobile lidar scanner with positioning captured using a real-time kinematic global navigation satellite system (RTK GNSS) base and receivers. In October 2024, areas of the reservoir that were too shallow for the boat and shoreline that were not captured by the vessel-based lidar were surveyed on foot using hand-held RTK GNSS receivers. At full pool (spillway elevation of 6,831.82 feet above NAVD 88 [2,082.34 meters (m)], Upper Lake Mary has a storage capacity of 16,449.80 acre-feet (20,290,611.73 cubic meters) and a surface area of 953.57 acres (3,860,926.075 square meters). The reservoir is 5.7 miles (9.7 kilometers) long and varies in width from 326 feet (99.36 m) near the central, narrow portion of the reservoir to 2,613 feet (796.44 m) in the upper portion. Comparisons between this survey and the previous two surveys from the 1950s and 2006 indicate no apparent decrease in reservoir area or storage capacity. Results of the 2024 survey indicate that Upper Lake Mary’s storage capacity increased by 0.9 percent from the 2006 survey and a 1.6 percent increase in surface area from the 2006 survey.

Arizona↗
USGS2026

Black rails in Baja California

Summarizing records from 1905 to 2025, we document the presence and distribution of the California black rail ( Laterallus jamaicensis coturniculus ) in northwestern México, particularly Baja California and the Colorado River Delta. This subspecies has a restricted distribution in the western U.S. and northwestern México. We found few records over the past century: sparse detections in the early 1900s and an increase in reported records after 2000. Over 120 years, we compiled 35 documented records of California black rail occurrence in Baja California with a minimum reported count of 56 rails. Our call-broadcast survey methods reconfirmed previously occupied sites and documented the species at a previously unreported site. Surveys in the Baja California portion of the Colorado River Delta yielded 20 detections across nine survey events between 2000 and 2022. In April 2003, standardized surveys detected 12 California black rails: 7 in Bahía de San Quintín, 3 in Arroyo San Telmo, and 2 in Arroyo El Rosario. Our recent survey work (2022–2025) recorded maximum monthly counts of 31 detections at Bahía de San Quintín and 15 detections at Estero de Punta Banda, the latter representing a previously undocumented location for the subspecies. These surveys also yielded the first photographic and acoustic documentation of California black rail in México. The contribution of spatial and temporal data provided by citizen science platforms increased our understanding of the subspecies’ distribution. Enforceable protection of this subspecies’ habitat is needed to safeguard its persistence.

Baja California↗
USGS2026

Ringtail (Bassariscus astutus) survival in southwestern Oregon

The effective conservation and management of small carnivore populations requires understanding species’ life-history traits and identifying important vital rates that drive population trajectories. However, many of these species are rare or elusive and of state or federal conservation concern, and demographic information is often lacking and difficult to obtain. At the northern limit of their range in Oregon, USA, ringtail ( Bassariscus astutus ) occupy mid-elevation forests and are a species of conservation concern because of their limited distribution and suspected low density. We initiated a radio-telemetry study in 2020 to estimate monthly and annual survival of ringtail in southwest Oregon. We monitored 26 ringtail from November 2020 to October 2022 and estimated survival rates using a known-fate framework and Program MARK. Model-averaged monthly survival estimates ranged from lows of 0.963 (SE = 0.022, 95% CI = 0.887–0.988) in spring (Feb–May) of 2021 to highs of 0.980 (SE = 0.018, 95% CI = 0.889–0.997) in summer (Jun–Oct) of 2022. Model-averaged estimates of annual survival were 0.695 (SE = 0.176, 95% CI = 0.310–0.920) during 2020–2021 and 0.728 (SE = 0.168, 95% CI = 0.336–0.934) during 2021–2022. Predation was the leading cause of mortality, but notably, no mortalities could be attributed to avian predation. Survival rates were much higher within forested landscapes in Oregon than for populations in the southwestern United States, which may have implications for regional conservation and management strategies.

Oregon↗
USGS2026

Family life is critical for migration and survival in a long-lived social bird

Extended parental care is common among birds and particularly well known among long-lived migratory species. Yet, factors influencing the duration of parental care are poorly understood, and empirical evidence for the functional importance of family life for offspring development is scarce. Using unique tracking and genetic data of 55 adult and juvenile migratory Bewick’s swans, among which 18 parent-offspring pairs and 13 sibling pairs, we quantify variation in family bond duration and identify the cause and consequences of their dissolution. Families generally broke up during the second half of the first northward migration of the offspring, when offspring were nearly one year old. Earlier separation occurred on the wintering grounds in response to disturbance ( n = 10 juveniles) and led to delayed migration and, critically, lower survival (40 vs. 86%). Our results provide rare empirical evidence that family bonds, as a pathway for social learning, are not just important, but vital to the migration and survival of young family-living birds.

Behavioral Ecology and Sociobiology↗
USGS2026

Transdisciplinary approach to private well research

More than 60 million people in the United States and Canada rely on private drinking water systems (mostly private wells), which fall outside of national regulations for water quality and management. This decentralized infrastructure creates unique challenges. First, fragmented policy oversight leads to inconsistent data availability. Second, population heterogeneity in well users requires accounting for the social determinants of health and behavioral differences. Additionally, the individualized nature of well management creates persistent gaps between knowledge generation and the protective action. A broad goal of private well research is to (1) understand, predict, and prevent potential health problems related to well water consumption and (2) enable individual and collective action to reduce exposures to contaminants in well water. Here, we propose a conceptual model to advance private well research through a transdisciplinary approach that links water sources to health and prioritizes engagement among researchers, communities, and decision makers. We also identify challenges and opportunities aimed at improving data systems, refining hazard and risk assessments, linking interdisciplinary research and practical knowledge, and sustaining long-term partnerships. While our geographic focus is on North America, the principles and strategies outlined are globally relevant to addressing health risks associated with unregulated private drinking water sources.

Environmental Science and Technology↗
USGS2026

Global seasonal microseism intensity and hemispheric asymmetry

Earth’s microseism wavefield dominates seismic background levels at periods between approximately 4 and 20 s, and reflects periodic and secular variations in ocean swell energy. Ocean wave energy couples to the seismic wavefield via distinct primary microseism and secondary microseism (PM and SM) source mechanisms, which are excited by basal swell tractions and seafloor pressure variations due to crossing seas, respectively. This study examines annual amplitude variations for the globally dominant PM (14–20 s) and SM (4–10 s) period bands. Annual harmonic variations are represented by four‐term Fourier series fits to vertical‐component seasonally smoothed acceleration time series from 73 stations in the Global Seismographic and GEOSCOPE networks with over 20 yr of recording and at least 75% data completeness. These annual periodic functions fit between 14%–95% (PM) and 22%–97% (SM) of signal variance. Station annual peak‐to‐peak variations range between 1.2–14.3 dB (PM) and 1.5–20.6 dB (SM). An asymmetry in microseism features exists between the Northern (NH) and Southern (SH) Hemispheres. High‐latitude NH stations show highly correlated PM and SM annual amplitude variations. This character dominates the wider extratropical NH but diminishes at tropical latitudes, and widespread relative PM–SM decorrelation is observed in the SH. These hemispheric characteristics reflect systematic differences in both extratropical storm activity and ocean wave state. Greater annual variation and seasonal predictability in the NH reflect the influence of the large continental landmasses that enhance both storm intensity seasonality and SM‐generating coastal wave reflection. Notable clusters of low PM–SM correlation stations are also observed in continental Antarctica due to seasonal sea ice influences, and in East Asia, reflecting unusual PM and SM source responses to South Asian monsoonal and tropical cyclone ocean wave influences.

Seismological Research Letters↗
USGS2026

Sediment transport, terrace incision, and sediment chemistry in subbasins of differing land use, Stinking Water Creek Basin near Rangely, Colorado

In many areas of western Colorado, Late Cretaceous Mancos Shale is a source of sediment, salinity, and selenium to surface water. Natural weathering processes and human activity can expose and move sediments from the Mancos Shale, leading to increased salinity and selenium concentrations in surface water. The U.S. Geological Survey, in cooperation with the Bureau of Land Management, studied four subbasins of Stinking Water Creek near Rangely, Colorado, to provide information regarding landscapes on Mancos Shale that have undergone land-use change. Rangeland grazing is present in all four subbasins. Subbasins A1 and A2 have land use related to energy development and subbasins B1 and B2 do not. Aerial photographs, sediment chemistry, optically stimulated luminescence (OSL) ages, cross-section surveys, and Watershed Erosion Prediction Project (WEPP) modeling were used to characterize the history of land-use change by estimating stream channel incision rates and sediment, salinity, and selenium loads. All subbasins had upper and lower terraces and a modern streambed channel, and these surfaces were dated using OSL. In subbasins A1, A2, and B1, the streambed age was older than the terraces, indicating the channels are incising and widening into the older alluvium. In subbasin B2, however, the streambed age was much younger than the terraces, indicating aggradation is the main process. Differences in channel morphology were not always related to land use but to the subbasin position (upstream compared to downstream). Channels in subbasins A1 and A2 were generally wider and shallower than channels in subbasins B1 and B2. Landscape disturbances related to energy development in subbasins A1 and A2 could have caused channel evolution to progress from incision to widening processes.

Colorado↗