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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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Impacts of climate change on groundwater availability and spring flows: Observations from the highly productive Medicine Lake Highlands/Fall River Springs Aquifer System Impacts of climate change on groundwater availability and spring flows: Observations from the highly productive Medicine Lake Highlands/Fall River Springs Aquifer System

Medicine Lake Highlands/Fall River Springs Aquifer System, located in northeastern California, is home to some of the largest first-order springs in the United States. This work assesses the likely effects of projected climate change on spring flow. Four anticipated climate futures (GFDL A2, GFDL B1, CCSM4 rcp 8.5, CNRM rcp 8.5) for California, which predict a range of conditions...
Authors
Lauren K Mancewicz, L. Davisson, Shawn J Wheelock, Erick R. Burns, Simon R. Poulson, Scott W. Tyler

Apparent age dependence of the fault weakening distance in rock friction Apparent age dependence of the fault weakening distance in rock friction

During rock friction experiments at large displacement, room temperature and humidity, and following a hold test, the fracture energy increases approximately as the square of the logarithm of hold duration. While it's been long known that failure strength increases with log hold time, here the slip weakening distance, dh, also increases. The weakening distance increase is large, hundreds...
Authors
Nicholas M. Beeler, Allan Rubin, Path Bhattacharya, Brian D. Kilgore, Terry Tullis

A practical solution: The Anthropocene is a geological event, not a formal epoch A practical solution: The Anthropocene is a geological event, not a formal epoch

The Anthropocene has yet to be defined in a way that is functional both to the international geological community and to the broader fields of environmental and social sciences. Formally defining the Anthropocene as a chronostratigraphical series and geochronological epoch with a precise global start date would drastically reduce the Anthropocene’s utility across disciplines. Instead, we...
Authors
Philip Gibbard, Andrew M Bauer, Matthew Edgeworth, William F Ruddiman, Jacquelyn L. Gill, Dorothy J. Merritts, Stanley C. Finney, Lucy E. Edwards, Michael J.C. Walker, Mark Maslin, Erle C. Ellis

Syn-eruptive hydration of volcanic ash records pyroclast-water interaction in explosive eruptions Syn-eruptive hydration of volcanic ash records pyroclast-water interaction in explosive eruptions

Magma-water interaction can dramatically influence the explosivity of volcanic eruptions. However, syn- and post-eruptive diffusion of external (non-magmatic) water into volcanic glass remains poorly constrained and may bias interpretation of water in juvenile products. Hydrogen isotopes in ash from the 2009 eruption of Redoubt Volcano, Alaska, record syn-eruptive hydration by vaporized...
Authors
Michael R. Hudak, Ilya N. Bindeman, Matthew W. Loewen, Thomas Giachetti

Context dependency of disease-mediated competitive release in bat assemblages following white-nose syndrome Context dependency of disease-mediated competitive release in bat assemblages following white-nose syndrome

White-nose syndrome (WNS) has caused dramatic declines of several cave-hibernating bat species in North America since 2006, which has increased the activity of non-susceptible species in some geographic areas or during times of night formerly occupied by susceptible species—indicative of disease-mediated competitive release (DMCR). Yet, this pattern has not been evaluated across multiple...
Authors
Sara Bombaci, Robin E. Russell, Michael J. St. Germain, Christopher A. Dobony, W. Mark Ford, Susan Loeb, David S. Jachowski

Origin of the J-M Reef and Lower Banded series, Stillwater Complex, Montana, USA Origin of the J-M Reef and Lower Banded series, Stillwater Complex, Montana, USA

The origin and parental magma for layered cumulates in the Lower Banded series (LBS) and the J-M Reef Pd-Pt deposit of the Stillwater Complex remains poorly constrained. We present whole-rock lithogeochemistry and mineral chemistry from LBS rocks collected from drill holes and surface samples from the Mountain View area of the complex that in total span nearly the entirety of the LBS...
Authors
Michael Jenkins, James E. Mungall, Michael L. Zientek, Gelu Costin, Zhuo-sen Yao

Climatic aridity shapes post-fire interactions between Ceanothus spp. and Douglas-fir (Pseudotsuga menziesii) across the Klamath Mountains Climatic aridity shapes post-fire interactions between Ceanothus spp. and Douglas-fir (Pseudotsuga menziesii) across the Klamath Mountains

Climate change is leading to increased drought intensity and fire frequency, creating early-successional landscapes with novel disturbance–recovery dynamics. In the Klamath Mountains of northwestern California and southwestern Oregon, early-successional interactions between nitrogen (N)-fixing shrubs (Ceanothus spp.) and long-lived conifers (Douglas-fir) are especially important...
Authors
Damla Cinoglu, Howard E Epstein, Alan J. Tepley, Kristina J. Anderson-Teixeira, Jonathan R. Thompson, Steven S. Perakis

Depths inferred from velocities estimated by remote sensing: A flow resistance equation-based approach to mapping multiple river attributes at the reach scale Depths inferred from velocities estimated by remote sensing: A flow resistance equation-based approach to mapping multiple river attributes at the reach scale

Remote sensing of flow conditions in stream channels could facilitate hydrologic data collection, particularly in large, inaccessible rivers. Previous research has demonstrated the potential to estimate flow velocities in sediment-laden rivers via particle image velocimetry (PIV). In this study, we introduce a new framework for also obtaining bathymetric information: Depths Inferred from
Authors
Carl J. Legleiter, Paul J. Kinzel

Responses of American black bears to spring resources Responses of American black bears to spring resources

In temperate regions of the world, food resources are seasonally limited, which causes some wildlife species to seek out nutrient-rich resources to better meet their caloric needs. Animals that utilize high-quality resources may reap fitness benefits as they prepare for mating, migration, or hibernation. American black bears (Ursus americanus) are omnivores that consume both plant and...
Authors
Nathaniel R. Bowersock, Andrea R. Litt, Jerod A. Merkle, Kerry A. Gunther, Frank T. van Manen

Modeling scenarios for the management of axis deer in Hawai‘i Modeling scenarios for the management of axis deer in Hawai‘i

Axis deer (Axis axis) are invasive species that threaten native ecosystems and agriculture on Maui Island. To mitigate negative effects, it is necessary to understand current abundance, population trajectory, and how to most effectively reduce the population. Our objectives were to examine the population history of Maui axis deer, estimate observed population growth, and use species...
Authors
Steve C. Hess, Seth Judge

Recent nitrogen storage and accumulation rates in mangrove soils exceed historic rates in the urbanized San Juan Bay Estuary (Puerto Rico, United States) Recent nitrogen storage and accumulation rates in mangrove soils exceed historic rates in the urbanized San Juan Bay Estuary (Puerto Rico, United States)

Tropical mangrove forests have been described as “coastal kidneys,” promoting sediment deposition and filtering contaminants, including excess nutrients. Coastal areas throughout the world are experiencing increased human activities, resulting in altered geomorphology, hydrology, and nutrient inputs. To effectively manage and sustain coastal mangroves, it is important to understand...
Authors
Cathleen Wigand, Autumn Oczkowski, Benjamin Branoff, Meagan J. Eagle, Alana Hanson, Rose M. Martin, Stephen Balogh, Kenneth Miller, Evelyn Huertas, Joseph Loffredo, Elizabeth Watson

New insights on faulting and intrusion processes during the June 2007, East Rift Zone eruption of Kilauea volcano, Hawai'i New insights on faulting and intrusion processes during the June 2007, East Rift Zone eruption of Kilauea volcano, Hawai'i

The East Rift Zone (ERZ) of Kīlauea Volcano, Hawai'i, represents one of the most volcanically active regions in the world. The 2007 Father's Day (FD) dike intrusion, eruption, and accompanying slow-slip event (SSE) has been previously modeled using geodetic data to constrain the geometry of the intrusion and the timing and magnitude of the SSE. Here, we perform inversions of three...
Authors
J. Leeburn, C. Wauthier, Emily K. Montgomery-Brown, J. Gonzalez-Santana
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