Publications
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Eruptive history and tectonic setting of Medicine Lake Volcano, a large rear-arc volcano in the southern Cascades Eruptive history and tectonic setting of Medicine Lake Volcano, a large rear-arc volcano in the southern Cascades
Medicine Lake Volcano (MLV), located in the southern Cascades ∼ 55 km east-northeast of contemporaneous Mount Shasta, has been found by exploratory geothermal drilling to have a surprisingly silicic core mantled by mafic lavas. This unexpected result is very different from the long-held view derived from previous mapping of exposed geology that MLV is a dominantly basaltic shield volcano...
Authors
Julie M. Donnelly-Nolan, Timothy L. Grove, M. A. Lanphere, Duane E. Champion, David W. Ramsey
The last 1000 years of natural and anthropogenic low-oxygen bottom-water on the Louisiana shelf, Gulf of Mexico The last 1000 years of natural and anthropogenic low-oxygen bottom-water on the Louisiana shelf, Gulf of Mexico
The relative abundance of three species of low-oxygen tolerant benthic foraminifers, the PEB index, in foraminiferal assemblages from sediment cores is used to trace the history of low-oxygen bottom-water conditions on the Louisiana shelf. Analyses of a network of box cores indicate that the modern zone of chronic seasonal hypoxia off the Mississippi Delta began to develop around 1920...
Authors
L.E. Osterman, R.Z. Poore, P.W. Swarzenski
Collision tectonics of the Central Indian Suture zone as inferred from a deep seismic sounding study Collision tectonics of the Central Indian Suture zone as inferred from a deep seismic sounding study
The Central Indian Suture (CIS) is a mega-shear zone extending for hundreds of kilometers across central India. Reprocessing of deep seismic reflection data acquired across the CIS was carried out using workstation-based commercial software. The data distinctly indicate different reflectivity characteristics northwest and southeast of the CIS. Reflections northwest of the CIS...
Authors
D.M. Mall, P.R. Reddy, Walter D. Mooney
Titan's diverse landscapes as evidenced by Cassini RADAR's third and fourth looks at Titan Titan's diverse landscapes as evidenced by Cassini RADAR's third and fourth looks at Titan
Cassini's third and fourth radar flybys, T7 and T8, covered diverse terrains in the high southern and equatorial latitudes, respectively. The T7 synthetic aperture radar (SAR) swath is somewhat more straightforward to understand in terms of a progressive poleward descent from a high, dissected, and partly hilly terrain down to a low flat plain with embayments and deposits suggestive of...
Authors
J. I. Lunine, C. Elachi, S. D. Wall, M.A. Janssen, M.D. Allison, Y. Anderson, R. Boehmer, P. Callahan, P. Encrenaz, E. Flamini, G. Franceschetti, Y. Gim, G. Hamilton, S. Hensley, W.T.K. Johnson, K. Kelleher, Randolph L. Kirk, R.M. Lopes, R. Lorenz, D.O. Muhleman, R. Orosei, S.J. Ostro, F. Paganelli, P. Paillou, G. Picardi, F. Posa, J. Radebaugh, L.E. Roth, R. Seu, S. Shaffer, Laurence A. Soderblom, B. Stiles, E. R. Stofan, S. Vetrella, R. West, C. A. Wood, L. Wye, H. Zebker, G. Alberti, E. Karkoschka, B. Rizk, E. McFarlane, C. See, B. Kazeminejad
Permeability of continental crust influenced by internal and external forcing Permeability of continental crust influenced by internal and external forcing
The permeability of continental crust is so highly variable that it is often considered to defy systematic characterization. However, despite this variability, some order has been gleaned from globally compiled data. What accounts for the apparent coherence of mean permeability in the continental crust (and permeability–depth relations) on a very large scale? Here we argue that large...
Authors
S.A. Rojstaczer, S. E. Ingebritsen, D.O. Hayba
Modeling the spatial distribution of landslide-prone colluvium and shallow groundwater on hillslopes of Seattle, WA Modeling the spatial distribution of landslide-prone colluvium and shallow groundwater on hillslopes of Seattle, WA
Landslides in partially saturated colluvium on Seattle, WA, hillslopes have resulted in property damage and human casualties. We developed statistical models of colluvium and shallow-groundwater distributions to aid landslide hazard assessments. The models were developed using a geographic information system, digital geologic maps, digital topography, subsurface exploration results, the
Authors
W.H. Schulz, D. J. Lidke, J. W. Godt
Oxygen isotope geochemistry of the lassen volcanic center, California: Resolving crustal and mantle contributions to continental Arc magmatism Oxygen isotope geochemistry of the lassen volcanic center, California: Resolving crustal and mantle contributions to continental Arc magmatism
This study reports oxygen isotope ratios determined by laser fluorination of mineral separates (mainly plagioclase) from basaltic andesitic to rhyolitic composition volcanic rocks erupted from the Lassen Volcanic Center (LVC), northern California. Plagioclase separates from nearly all rocks have δ18O values (6·1–8·4‰) higher than expected for production of the magmas by partial melting...
Authors
T.C. Feeley, M.A. Clynne, G.S. Winer, W.C. Grice
The Breccia Museo formation, Campi Flegrei, southern Italy: Geochronology, chemostratigraphy and relationship with the Campanian Ignimbrite eruption The Breccia Museo formation, Campi Flegrei, southern Italy: Geochronology, chemostratigraphy and relationship with the Campanian Ignimbrite eruption
The Breccia Museo is one of the most debated volcanic formations of the Campi Flegrei volcanic district. The deposit, made up of six distinctive stratigraphic units, has been interpreted by some as the proximal facies of the major caldera-forming Campanian Ignimbrite eruption, and by others as the product of several, more recent, independent and localized events. New geochemical and
Authors
L. Fedele, C. Scarpati, M. Lanphere, L. Melluso, V. Morra, A. Perrotta, G. Ricci
Non-spore forming eubacteria isolated at an altitude of 20,000 m in Earth's atmosphere: extended incubation periods needed for culture-based assays Non-spore forming eubacteria isolated at an altitude of 20,000 m in Earth's atmosphere: extended incubation periods needed for culture-based assays
On 13 August 2004, an atmospheric sample was collected at an altitude of 20,000 m along a west to east transect over the continental United States by NASA’s Stratospheric and Cosmic Dust Program. This sample was then shipped to the US Geological Survey’s Global Desert Dust program for microbiological analyses. This sample, which was plated on a low nutrient agar to determine if...
Authors
Dale W. Griffin
Geologic map of Mount St. Helens, Washington prior to the 1980 eruption Geologic map of Mount St. Helens, Washington prior to the 1980 eruption
It is rare that a geologic map exists for a volcano prior to such a catastrophic modification as that produced by the eruption of Mount St. Helens in 1980. As such, this map provides an important historical record of the volcano prior to that eruption. The map has not been reviewed or checked for conformity to USGS editorial standards or stratigraphic nomenclature, and it has not been...
Authors
Clifford A. Hopson
Predicted surface displacements for scenario earthquakes in the San Francisco Bay region Predicted surface displacements for scenario earthquakes in the San Francisco Bay region
In the immediate aftermath of a major earthquake, the U.S. Geological Survey (USGS) will be called upon to provide information on the characteristics of the event to emergency responders and the media. One such piece of information is the expected surface displacement due to the earthquake. In conducting probabilistic hazard analyses for the San Francisco Bay Region, the Working Group on
Authors
Jessica R. Murray-Moraleda
Modeled tephra ages from lake sediments, base of Redoubt Volcano, Alaska Modeled tephra ages from lake sediments, base of Redoubt Volcano, Alaska
A 5.6-m-long lake sediment core from Bear Lake, Alaska, located 22 km southeast of Redoubt Volcano, contains 67 tephra layers deposited over the last 8750 cal yr, comprising 15% of the total thickness of recovered sediment. Using 12 AMS 14C ages, along with the 137Cs and 210Pb activities of recent sediment, we evaluated different models to determine the age-depth relation of the core...
Authors
C.J. Schiff, D. S. Kaufman, K.L. Wallace, A. Werner, T.-L. Ku, T.A. Brown