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The USGS provides unbiased, objective, and impartial scientific information upon which our audiences, including resource managers, planners, and other entities, rely.
Browse more than 65,000 articles authored by our scientists over the past 100+ year history of the USGS and refine search by topic, location, year, and advanced search.
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Sources and risk factors for nitrate, pathogens, and fecal contamination of private wells in rural southwestern Wisconsin, USA
Household well water can be degraded by contaminants from the land's surface, but private well owners lack means to protect the source water from neighboring disturbances. Rural residents of southwestern Wisconsin, USA, rely on private well water, and the combination of land use and fractured carbonate bedrock makes groundwater vulnerable to contamination. To identify the extent, sources...
Authors
Joel P. Stokdyk, Aaron Firnstahl, Kenneth R. Bradbury, Maureen A. Muldoon, Burney A Kieke, Mark A. Borchardt
The crystalline silica respiratory hazard from rhyolitic lava dome eruptions in New Zealand's Taupo Volcanic Zone: A case study from the 1315 CE Kaharoa eruption
The rhyolitic Kaharoa 1315 CE eruption was a complex, long-lived event from Tarawera volcano, New Zealand. Explosive phases were followed by around 5 years of lava dome extrusion and collapse which produced block-and-ash flows (BAF). Lava domes generate crystalline silica in the form of cristobalite, and rhyolitic magmas often contain quartz phenocrysts. Fine-grained ash containing...
Authors
Claire J. Horwell, Helen M. Emerson, Paul Ashwell, David Damby, Steve Self, Claire Nattrass, Rebecca J. Carey, Bruce F. Houghton
Airborne geophysical analysis to decipher salinization for coastal Louisiana
Coastal Louisiana is known for saltwater intrusion that threatens wetlands, aquifers, and rivers. However, the extent of saltwater intrusion is not well understood. This study develops an innovative framework with airborne electromagnetic (AEM) data to map chloride concentration distributions for wetlands in the Mississippi River deltaic plain and Chenier plain as well as for the...
Authors
Michael Attia, Frank T.-C. Tsai, Shuo Yang, Burke J. Minsley, Wade H. Kress
Cgsim: An R package for simulation of population genetics for conservation and management applications
Wildlife conservation and management increasingly considers genetic information to plan, understand and evaluate implemented population interventions. These actions commonly include conservation translocation and population reductions through removals. Change in genetic variation in response to management actions can be unintuitive due to the influence of multiple interacting drivers (e...
Authors
Shawna J Zimmerman, Sara J. Oyler-McCance
The tortoise and the antilocaprid: Adapting GPS tracking and terrain data to model wildlife walking functions
Context The relationship between slope and terrestrial animal locomotion is key to landscape ecology but underexplored across species. This is partly due to a lack of scalable methodology that applies to a diversity of wildlife. Objectives This study investigates the slope-speed relationship for two species, Texas tortoise (Gopherus berlandieri) and pronghorn (Antilocapra americana)...
Authors
Samuel Norton Chambers, Joshua W. Von Nonn, Matthew Alexander Burgess, Lance R. Brady, Jeffrey Bracewell, Daniel A. Guerra, Miguel L. Villarreal
Bridging social and ecological science to create spatially-explicit models of human-caused mortality of carnivores
Research indicates that human-caused mortality (HCM) is a key factor limiting numerous large carnivore populations. However, efforts to represent HCM in spatially explicit models have generally been limited in scope—often relying on proxies, such as road or human density. Yet such efforts fail to distinguish different sources of HCM, which can arise from different antecedent processes...
Authors
Jeremy T. Bruskotter, Neil H. Carter, Richard E.W. Berl, Joseph W. Hinton, Jazmin Murphy, L. Mark Elbroch, John A. Vucetich
Slow rupture, long rise times, and multi-fault geometry: The 2020 M6.4 southwestern Puerto Rico mainshock
The M6.4 mainshock of the southwestern Puerto Rico seismic sequence on 7 January 2020, was one of the most impactful modern earthquakes in the northeastern Caribbean. Due to its offshore location and complex aftershock distribution, its source kinematics remain poorly constrained. This active sequence illuminated a complex set of previously unrecognized structures that indicate multiple...
Authors
Margarita M. Solares-Colón, Dara Elyse Goldberg, Diego Melgar, Elizabeth A. Vanacore, Valerie J. Sahakian, William L. Yeck, Francisco Hernández, Alberto Lopez-Venegas
Machine learning provides reconnaissance-type estimates of carbon dioxide storage resources in oil and gas reservoirs
Oil and gas reservoirs represent suitable containers to sequester carbon dioxide (CO2) in a supercritical state because they are accessible, reservoir properties are known, and they previously contained stored buoyant fluids. However, planners must quantify the relative magnitude of the CO2 storage resource in these reservoirs to formulate a comprehensive strategy for CO2 mitigation...
Authors
E.D. Attanasi, Philip A. Freeman, Timothy C. Coburn
Bølling-Allerød productivity in the subarctic Pacific driven by seasonal upwelling
The Bølling-Allerød deglacial event is marked by high diatom productivity and opal deposition throughout the subarctic Pacific. This opal could either constitute a strengthened biological pump and thus carbon sequestration, or a weakened biological pump and release of marine-sequestered CO2 to the atmosphere. We quantify silicic acid supply at IODP Site U1340 in the Bering Sea using...
Authors
Kimberly A. deLong, Terrence Blackburn, Beth Elaine Caissie, Jason A. Addison, Zuzanna Stroynowski, Maria R. Sipala, Franco Marcantonio, Ana Christina Ravelo
Prospectivity modeling of the NASA VIPER landing site at Mons Mouton near the Lunar South Pole
We use a high-resolution digital elevation model and a numerical thermal model to produce a variety of inputs for a water-ice prospectivity model for the Volatiles Investigating Polar Exploration Rover (VIPER) landing site. These input data are maps of topography, surface slope, surface aspect, surface curvature, maximum temperature, depth to ice stability, permanently shadowed regions...
Authors
Joshua Aaron Coyan, Matthew Siegler, Jose Martinez Comacho, Ross A. Beyer, Mark Shirley
Detection of landslide-generated tsunami by shipborne GNSS precise point positioning
Precise point positioning (PPP) of ships using Global Navigation Satellite System (GNSS) data reveals the precise movements of marine vessels. This method may quantify anomalies in sea surface height with implications for oceanographic monitoring, exploration, and tsunami warning. The GNSS PPP data from the R/V Sikuliaq, a research ship of the University of Alaska Fairbanks, were...
Authors
Adam E. Manaster, Anne F Sheehan, Dara Elyse Goldberg, Katherine R. Barnhart, Ethan F. Roth
Statistical approaches for modeling correlated grade and tonnage distributions and applications for mineral resource assessments
Correlations between grade and tonnage exist in mineral resource data compiled from published reports, but they are not always addressed during quantitative assessment of undiscovered mineral resources. Failure to account for correlated grade and tonnage distributions can result in geologically unrealistic assessment results. Current software tools simulate univariate ore tonnage and...
Authors
Joshua Mark Rosera, Graham W. Lederer, John H. Schuenemeyer