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
Documentation for the 2008 update of the United States National Seismic Hazard Maps Documentation for the 2008 update of the United States National Seismic Hazard Maps
The 2008 U.S. Geological Survey (USGS) National Seismic Hazard Maps display earthquake ground motions for various probability levels across the United States and are applied in seismic provisions of building codes, insurance rate structures, risk assessments, and other public policy. This update of the maps incorporates new findings on earthquake ground shaking, faults, seismicity, and...
Authors
Mark D. Petersen, Arthur D. Frankel, Stephen C. Harmsen, Charles S. Mueller, Kathleen M. Haller, Russell L. Wheeler, Robert L. Wesson, Yuehua Zeng, Oliver S. Boyd, David M. Perkins, Nicolas Luco, Edward H. Field, Chris J. Wills, Kenneth S. Rukstales
Viscoelastic love-type surface waves Viscoelastic love-type surface waves
The general theoretical solution for Love-Type surface waves in viscoelastic media provides theoreticalexpressions for the physical characteristics of the waves in elastic as well as anelastic media with arbitraryamounts of intrinsic damping. The general solution yields dispersion and absorption-coefficient curves for the waves as a function of frequency and theamount of intrinsic...
Authors
Roger D. Borcherdt
Atmospheric contribution of gas emissions from Augustine volcano, Alaska during the 2006 eruption Atmospheric contribution of gas emissions from Augustine volcano, Alaska during the 2006 eruption
Airborne surveillance of gas emissions from Augustine for SO2, CO2 and H2S showed no evidence of anomalous degassing from 1990 through May 2005. By December 20, 2005, Augustine was degassing 660 td−1 of SO2, and ten times that by January 4, 2006. The highest SO2 emission rate measured during the 2006 eruption was 8650 td−1 (March 1); for CO2, 13000 td−1 (March 9), and H2S, 8 td−1...
Authors
K.A. McGee, M.P. Doukas, R. G. McGimsey, C.A. Neal, R.L. Wessels
Summer season variability of the north residual cap of Mars as observed by the Mars Global Surveyor Thermal Emission Spectrometer (MGS-TES) Summer season variability of the north residual cap of Mars as observed by the Mars Global Surveyor Thermal Emission Spectrometer (MGS-TES)
Previous observations have noted the change in albedo in a number of North Pole bright outliers and in the distribution of bright ice deposits between Mariner 9, Viking, and Mars Global Surveyor (MGS) data sets. Changes over the summer season as well as between regions at the same season (Ls) in different years have been observed. We used the bolometric albedo and brightness temperature...
Authors
Wendy M. Calvin, Timothy N. Titus