What caused terrestrial dust loading and climate downturns between A.D. 533 and 540?
Dallas H. Abbott, Dee Breger, Pierre E. Biscaye, John A. Barron, Robert A. Juhl, Patrick McCafferty
2014, GSA Special Papers (505) 421-437
Sn-rich particles, Ni-rich particles, and cosmic spherules are found together at four discrete stratigraphic levels within the 362-360 m depth interval of the Greenland Ice Sheet Project 2 (GISP2) ice core (72.6°N, 38.5°W, elevation: 3203 m). Using a previously derived calendar-year time scale, these particles span a time of increased...
Implementation of NGA-West2 ground motion models in the 2014 U.S. National Seismic Hazard Maps
Sanaz Rezaeian, Mark D. Petersen, Morgan P. Moschetti, Peter Powers, Stephen C. Harmsen, Arthur D. Frankel
2014, Earthquake Spectra (30) 1319-1333
The U.S. National Seismic Hazard Maps (NSHMs) have been an important component of seismic design regulations in the United States for the past several decades. These maps present earthquake ground shaking intensities at specified probabilities of being exceeded over a 50-year time period. The previous version of the NSHMs was...
Guidelines for use of fishes in research
J. A. Jenkins, H.L. Bart Jr., James D. Bowker, P.R. Bowser, J.R. MacMillan, J.G. Nickum, J. D. Rose, P. W. Sorenson, G.W. Whitledge, J.W. Rachlin, B.E. Warkentine, H. L. Bart
2014, Report
The 2004 and 2014 Guidelines were developed to provide a structure that advances appropriate attention toward valid experimental designs and procedures with aquatic animals while ensuring humane treatment of the experimental subjects. At a practical level, the Guidelines are intended to provide general recommendations on field and laboratory endeavors, such...
Stream sediment sources in midwest agricultural basins with land retirement along channel
Tanja N. Williamson, Victoria G. Christensen, William B. Richardson, Jeffrey W. Frey, Allen C. Gellis, K. A. Kieta, Faith A. Fitzpatrick
2014, Journal of Environmental Quality (43) 1624-1634
Documenting the effects of agricultural land retirement on stream-sediment sources is critical to identifying management practices that improve water quality and aquatic habitat. Particularly difficult to quantify are the effects from conservation easements that commonly are discontinuous along channelized streams and ditches throughout the agricultural midwestern United States. Our hypotheses...
Path durations for use in the stochastic‐method simulation of ground motions
David M. Boore, Eric M. Thompson
2014, Bulletin of the Seismological Society of America (104) 2541-2552
The stochastic method of ground‐motion simulation assumes that the energy in a target spectrum is spread over a duration DT. DT is generally decomposed into the duration due to source effects (DS) and to path effects (DP). For the most commonly used source, seismological theory directly relates DS to the...
Relaxed selection causes microevolution of seawater osmoregulation and gene expression in landlocked Alewives
Jonathan P. Velotta, Stephen D. McCormick, Rachel J. O’Neill, Eric T. Schultz
2014, Oecologia (175) 1081-1092
Ecological transitions from marine to freshwater environments have been important in the creation of diversity among fishes. Evolutionary changes associated with these transitions likely involve modifications of osmoregulatory function. In particular, relaxed selection on hypo-osmoregulation should strongly affect animals that transition into novel freshwater environments. We used populations of the...
Pulverization provides a mechanism for the nucleation of earthquakes at low stress on strong faults
Karen R. Felzer
2014, Frontiers in Earth Science (2)
An earthquake occurs when rock that has been deformed under stress rebounds elastically along a fault plane (Gilbert, 1884; Reid, 1911), radiating seismic waves through the surrounding earth. Rupture along the entire fault surface does not spontaneously occur at the same time, however. Rather the rupture starts...
Performance and effects of land cover type on synthetic surface reflectance data and NDVI estimates for assessment and monitoring of semi-arid rangeland
Edward M. Olexa, Rick L Lawrence
2014, International Journal of Applied Earth Observation and Geoinformation (30) 30-41
Federal land management agencies provide stewardship over much of the rangelands in the arid andsemi-arid western United States, but they often lack data of the proper spatiotemporal resolution andextent needed to assess range conditions and monitor trends. Recent advances in the blending of com-plementary, remotely sensed data could provide public...
Continuous estimation of baseflow in snowmelt-dominated streams and rivers in the Upper Colorado River Basin: A chemical hydrograph separation approach
Matthew P. Miller, David D. Susong, Christopher L. Shope, Victor M. Heilweil, Bernard J. Stolp
2014, Water Resources Research (50) 6986-6999
Effective science-based management of water resources in large basins requires a qualitative understanding of hydrologic conditions and quantitative measures of the various components of the water budget, including difficult to measure components such as baseflow discharge to streams. Using widely available discharge and continuously collected specific conductance (SC) data, we...
Analytical solutions for benchmarking cold regions subsurface water flow and energy transport models: one-dimensional soil thaw with conduction and advection
Barret L. Kurylyk, Jeffrey M McKenzie, Kerry T. B. MacQuarrie, Clifford I. Voss
2014, Advances in Water Resources (70) 172-184
Numerous cold regions water flow and energy transport models have emerged in recent years. Dissimilarities often exist in their mathematical formulations and/or numerical solution techniques, but few analytical solutions exist for benchmarking flow and energy transport models that include pore water phase change. This paper presents a detailed derivation of...
A mass balance approach to investigating geochemical controls on secondary water quality impacts at a crude oil spill site near Bemidji, MN
Gene-Hua Crystal Ng, Barbara A. Bekins, Isabelle M. Cozzarelli, Mary Jo Baedecker, Philip C. Bennett, Richard T. Amos
2014, Journal of Contaminant Hydrology (164) 1-15
Secondary water quality impacts can result from a broad range of coupled reactions triggered by primary groundwater contaminants. Data from a crude-oil spill research site near Bemidji, MN provide an ideal test case for investigating the complex interactions controlling secondary impacts, including depleted dissolved oxygen and elevated organic carbon, inorganic...
Major element and oxygen isotope geochemistry of vapour-phase garnet from the Topopah Spring Tuff at Yucca Mountain, Nevada, USA
Richard J. Moscati, Craig A. Johnson
2014, Mineralogical Magazine (78) 1029-1041
Twenty vapour-phase garnets were studied in two samples of the Topopah Spring Tuff of the Paintbrush Group from Yucca Mountain, in southern Nevada. The Miocene-age Topopah Spring Tuff is a 350 m thick, devitrified, moderately to densely welded ash-flow tuff that is zoned compositionally from high-silica rhyolite to latite. During...
Time-averaged discharge rate of subaerial lava at Kīlauea Volcano, Hawai‘i, measured from TanDEM-X interferometry: Implications for magma supply and storage during 2011-2013
Michael P. Poland
2014, Journal of Geophysical Research B: Solid Earth (119) 5464-5481
Differencing digital elevation models (DEMs) derived from TerraSAR add-on for Digital Elevation Measurements (TanDEM-X) synthetic aperture radar imagery provides a measurement of elevation change over time. On the East Rift Zone (EZR) of Kīlauea Volcano, Hawai‘i, the effusion of lava causes changes in topography. When these elevation changes are summed...
Emplacement and erosive effects of the south Kasei Valles lava on Mars
Colin M. Dundas, Laszlo P. Keszthelyi
2014, Journal of Volcanology and Geothermal Research (282) 92-102
Although it has generally been accepted that the Martian outflow channels were carved by floods of water, observations of large channels on Venus and Mercury demonstrate that lava flows can cause substantial erosion. Recent observations of large lava flows within outflow channels on Mars have revived discussion of the hypothesis...
A hierarchical integrated population model for greater sage-grouse (Centrocercus urophasianus) in the Bi-State Distinct Population Segment, California and Nevada
Peter S. Coates, Brian J. Halstead, Erik J. Blomberg, Brianne Brussee, Kristy B. Howe, Lief Wiechman, Joel Tebbenkamp, Kerry P. Reese, Scott C. Gardner, Michael L. Casazza
2014, Open-File Report 2014-1165
Greater sage-grouse (Centrocercus urophasianus, hereafter referred to as “sage-grouse”) are endemic to sagebrush (Artemisia spp.) ecosystems throughout Western North America. Populations of sage-grouse have declined in distribution and abundance across the range of the species (Schroeder and others, 2004; Knick and Connelly, 2011), largely as a result of human disruption...
Spatially explicit modeling of greater sage-grouse (Centrocercus urophasianus) habitat in Nevada and northeastern California: a decision-support tool for management
Peter S. Coates, Michael L. Casazza, Brianne E. Brussee, Mark A. Ricca, K. Benjamin Gustafson, Cory T. Overton, Erika Sanchez-Chopitea, Travis Kroger, Kimberly Mauch, Lara Niell, Kristy Howe, Scott Gardner, Shawn Espinosa, David J. Delehanty
2014, Open-File Report 2014-1163
Greater sage-grouse (Centrocercus urophasianus, hereafter referred to as “sage-grouse”) populations are declining throughout the sagebrush (Artemisia spp.) ecosystem, including millions of acres of potential habitat across the West. Habitat maps derived from empirical data are needed given impending listing decisions that will affect both sage-grouse population dynamics and human land-use...
Causal networks clarify productivity-richness interrelations, bivariate plots do not
James B. Grace, Peter B. Adler, W. Stanley Harpole, Elizabeth T. Borer, Eric W. Seabloom
2014, Functional Ecology (28) 787-798
Perhaps no other pair of variables in ecology has generated as much discussion as species richness and ecosystem productivity, as illustrated by the reactions by Pierce (2013) and others to Adler et al.'s (2011) report that empirical patterns are weak and inconsistent. Adler et al. (2011) argued we need to...
NGA-West2 Research Project
Yousef Bozorgnia, Norman A. Abrahamson, Linda Al Atik, Timothy D. Ancheta, Gail M. Atkinson, Jack W. Baker, Annemarie S. Baltay Sundstrom, David M. Boore, Kenneth W. Campbell, Brian S.J. Chiou, Robert B. Darragh, Steve Day, Jennifer Donahue, Robert W. Graves, Nick Gregor, Thomas C. Hanks, I. M. Idriss, Ronnie Kamai, Tadahiro Kishida, Albert Kottke, Stephen A. Mahin, Sanaz Rezaeian, Badie Rowshandel, Emel Seyhan, Shrey Shahi, Tom Shantz, Walter Silva, Paul A. Spudich, Jonathan P. Stewart, Jennie Watson-Lamprey, Kathryn Wooddell, Robert Youngs
2014, Earthquake Spectra (30) 973-987
The NGA-West2 project is a large multidisciplinary, multi-year research program on the Next Generation Attenuation (NGA) models for shallow crustal earthquakes in active tectonic regions. The research project has been coordinated by the Pacific Earthquake Engineering Research Center (PEER), with extensive technical interactions among many individuals and organizations. NGA-West2 addresses...
Late Holocene sea level variability and Atlantic Meridional Overturning Circulation
Thomas M. Cronin, Jesse R. Farmer, R. E. Marzen, E. Thomas, J.C. Varekamp
2014, Paleoceanography (29) 765-777
Pre-twentieth century sea level (SL) variability remains poorly understood due to limits of tide gauge records, low temporal resolution of tidal marsh records, and regional anomalies caused by dynamic ocean processes, notably multidecadal changes in Atlantic Meridional Overturning Circulation (AMOC). We examined SL and AMOC variability along the eastern United...
Habitat structure and body size distributions: Cross-ecosystem comparison for taxa with determinate and indeterminate growth
Kirsty L. Nash, Craig R. Allen, Chris Barichievy, Magnus Nystrom, Shana M. Sundstrom, Nicholas A.J. Graham
2014, Oikos (123) 971-983
Habitat structure across multiple spatial and temporal scales has been proposed as a key driver of body size distributions for associated communities. Thus, understanding the relationship between habitat and body size is fundamental to developing predictions regarding the influence of habitat change on animal communities. Much of the work assessing...
A depth-averaged debris-flow model that includes the effects of evolving dilatancy. I. Physical basis
Richard M. Iverson, David L. George
2014, Proceedings of the Royal Society A (471)
To simulate debris-flow behaviour from initiation to deposition, we derive a depth-averaged, two-phase model that combines concepts of critical-state soil mechanics, grain-flow mechanics and fluid mechanics. The model's balance equations describe coupled evolution of the solid volume fraction, m, basal pore-fluid pressure, flow thickness and two...
The implications of microbial and substrate limitation for the fates of carbon in different organic soil horizon types of boreal forest ecosystems: a mechanistically based model analysis
Y. He, Q. Zhuang, Jennifer W. Harden, A. David McGuire, Z. Fan, Y. Liu, Kimberly P. Wickland
2014, Biogeosciences (11) 4477-4491
The large amount of soil carbon in boreal forest ecosystems has the potential to influence the climate system if released in large quantities in response to warming. Thus, there is a need to better understand and represent the environmental sensitivity of soil carbon decomposition. Most soil carbon decomposition models...
Hierarchical model analysis of the Atlantic Flyway Breeding Waterfowl Survey
John R. Sauer, Guthrie S. Zimmerman, Jon D. Klimstra, William A. Link
2014, Journal of Wildlife Management (78) 1050-1059
We used log-linear hierarchical models to analyze data from the Atlantic Flyway Breeding Waterfowl Survey. The survey has been conducted by state biologists each year since 1989 in the northeastern United States from Virginia north to New Hampshire and Vermont. Although yearly population estimates from the survey are used by...
Adding fling effects to processed ground‐motion time histories
Ronnie Kamai, Norman A. Abrahamson, Robert Graves
2014, Bulletin of the Seismological Society of America (104) 1914-1929
Fling is the engineering term for the effects of the permanent tectonic offset, caused by a rupturing fault in the recorded ground motions near the fault. It is expressed by a one‐sided pulse in ground velocity and a nonzero final displacement at the end of shaking. Standard processing of earthquake...
Comparison of NGA-West2 directivity models
Paul A. Spudich, Badie Rowshandel, Shrey Shahi, Jack W. Baker, Brian S-J Chiou
2014, Earthquake Spectra (30) 1199-1221
Five directivity models have been developed based on data from the NGA-West2 database and based on numerical simulations of large strike-slip and reverse-slip earthquakes. All models avoid the use of normalized rupture dimension, enabling them to scale up to the largest earthquakes in a physically reasonable way. Four of the...
