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- Geosciences (5)
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- Earthquake hazard analysis; Faults (Geology); Nevada – Yucca Mountain; Paleoseismology; Rocks – Surfaces – Dating (1)
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Articles 1 - 19 of 19
Full-Text Articles in Physical Sciences and Mathematics
Rapid Postseismic Transients In Subduction Zones From Continuous Gps, Timothy I. Melbourne, Frank H. Webb, Joann M. Stock, Christoph Reigber
Rapid Postseismic Transients In Subduction Zones From Continuous Gps, Timothy I. Melbourne, Frank H. Webb, Joann M. Stock, Christoph Reigber
All Faculty Scholarship for the College of the Sciences
Continuous GPS time series from three of four recently measured, large subduction earthquakes document triggered rapid postseismic fault creep, representing an additional moment release upward of 25% over the weeks following their main shocks. Data from two Mw = 8.0 and Mw = 8.4 events constrain the postseismic centroids to lie down dip from the lower limit of coseismic faulting, and show that afterslip along the primary coseismic asperities is significantly less important than triggered deep creep. Time series for another Mw = 7.7 event show 30% postseismic energy release, but here we cannot differentiate between afterslip …
Hierarchical Geostatistics And Multifacies Systems: Boise Hydrogeophysical Research Site, Boise, Idaho, Warren Barrash, Tom Clemo
Hierarchical Geostatistics And Multifacies Systems: Boise Hydrogeophysical Research Site, Boise, Idaho, Warren Barrash, Tom Clemo
CGISS Publications and Presentations
The geostatistical structure of a heterogeneous coarse fluvial aquifer is investigated with porosity data derived from neutron logs at a research well field (Boise Hydrogeophysical Research Site, or BHRS) that was designed, in part, to support three-dimensional geostatistical analysis of hydrologic and geophysical parameters. Recognizing that the coarse fluvial deposits include subdivisions (units between bounding surfaces), we adopt a hierarchical approach and examine the porosity geostatistics of the aquifer at three scales. At the BHRS, the saturated fluvial deposits as a whole (maximum interwell spacing ~80 m, thickness ~16–18 m) are at hierarchical level 1; five subhorizontal units within these …
On Porosity Prediction From Seismic Data In Ghawar Field, Saudi Arabia, Thomas M. Loretto
On Porosity Prediction From Seismic Data In Ghawar Field, Saudi Arabia, Thomas M. Loretto
Thomas M Loretto
No abstract provided.
Late Quaternary Slip Rates Across The Central Tien Shan, Kyrgyzstan, Central Asia, Stephen C. Thompson, Ray J. Weldon, Charles M. Rubin, Kanatbek Abdrakhmatov, Peter Molnar, Glenn W. Berger
Late Quaternary Slip Rates Across The Central Tien Shan, Kyrgyzstan, Central Asia, Stephen C. Thompson, Ray J. Weldon, Charles M. Rubin, Kanatbek Abdrakhmatov, Peter Molnar, Glenn W. Berger
All Faculty Scholarship for the College of the Sciences
Slip rates across active faults and folds show that late Quaternary faulting is distributed across the central Tien Shan, not concentrated at its margins. Nearly every intermontane basin contains Neogene and Quaternary syntectonic strata deformed by Holocene north‐south shortening on thrust or reverse faults. In a region that spans two thirds of the north‐south width of the central Tien Shan, slip rates on eight faults in five basins range from ∼0.1 to ∼3 mm/yr. Fault slip rates are derived from faulted and folded river terraces and from trenches. Radiocarbon, optically stimulated luminescence, and thermoluminescence ages limit ages of terraces and …
Whole Mantle Shear Structure Beneath The East Pacific Rise, Timothy I. Melbourne, Donald V. Helmberger
Whole Mantle Shear Structure Beneath The East Pacific Rise, Timothy I. Melbourne, Donald V. Helmberger
All Faculty Scholarship for the College of the Sciences
We model broadband seismograms containing triplicated S, S2, and S3 along with ScS to produce a pure path one‐dimensional model extending from the crust to the core‐mantle boundary beneath the East Pacific Rise. We simultaneously model all body wave shapes and amplitudes, thereby eliminating depth‐velocity ambiguities. The data consist of western North American broadband recordings of East Pacific Rise (EPR) affiliate transform events that form a continuous record section out to 82° and sample nearly the entire East Pacific Rise. The best fitting synthetics contain attenuation and small changes in lithospheric thickness needed to correct for …
Post Stack Seismic Attribute Analysis, Zafer Özer, Turan Kayiran
Post Stack Seismic Attribute Analysis, Zafer Özer, Turan Kayiran
Bulletin of the Mineral Research and Exploration
No abstract provided.
Constraints On Ground Motion At Yucca Mountain Provided By Precarious Rocks, Abdolrasool Anebshehpoor, James N. Brune, David Von Seggern, Kenneth D. Smith, Amy J. Smiecinski
Constraints On Ground Motion At Yucca Mountain Provided By Precarious Rocks, Abdolrasool Anebshehpoor, James N. Brune, David Von Seggern, Kenneth D. Smith, Amy J. Smiecinski
Publications (YM)
This report describes the methodology and results of the use of precariously balanced rocks to study seismic hazard at Yucca Mountain, Nevada, the site of a potential geologic repository for high-level radioactive waste. Precarious rocks are effectively strong-motion seismoscopes that have been in for place thousands of years. Numerous precarious rocks exist in and near Solitario Canyon, Nevada, immediately above the site of the potential repository. Estimates of toppling accelerations using computer models, physical models, and field tests indicate these rocks would be toppled by ground acceleration of a few tenths of the acceleration of gravity (g). Rock-surface age dating …
Transition From Contraction To Extension In The Northeastern Basin And Range: New Evidence From The Copper Mountains, Nevada, Jeffrey M. Rahl, Allen J. Mcgrew, Kenneth A. Foland
Transition From Contraction To Extension In The Northeastern Basin And Range: New Evidence From The Copper Mountains, Nevada, Jeffrey M. Rahl, Allen J. Mcgrew, Kenneth A. Foland
Geology Faculty Publications
New mapping, structural analysis, and 40Ar/39Ar dating reveal an unusually well‐constrained history of Late Eocene extension in the Copper Mountains of the northern Basin and Range province. In this area, the northeast‐trending Copper Creek normal fault juxtaposes a distinctive sequence of metacarbonate and granitoid rocks against a footwall of Upper Precambrian to Lower Cambrian quartzite and phyllite. Correlation of the hanging wall with footwall rocks to the northwest provides an approximate piercing point that requires 8–12 km displacement in an ESE direction. This displaced fault slice is itself bounded above by another normal fault (the Meadow Fork Fault), which brings …
On The Feasibility Of Geopressure Detection From Seismic Data In Saudi Arabia., Thomas M. Loretto, James J. Funk
On The Feasibility Of Geopressure Detection From Seismic Data In Saudi Arabia., Thomas M. Loretto, James J. Funk
Thomas M Loretto
No abstract provided.
Equatorial Ocean Circulation In An Extremely Warm Climate, T. C. Moore, D. K. Rea, Mitchell W. Lyle, Lee M. Liberty
Equatorial Ocean Circulation In An Extremely Warm Climate, T. C. Moore, D. K. Rea, Mitchell W. Lyle, Lee M. Liberty
CGISS Publications and Presentations
The warm climates of the early Paleogene and the associated diminished near-surface winds should have resulted in a reduction in near-surface ocean circulation. One check on this deduction is the delineation of biogenic sediments associated with an equatorial current system of the early Eocene Pacific. A latitudinal seismic reflection transect across the tropical Pacific along early Paleogene ocean crust reveals a basal high-amplitude reflection package that we take to be the lower Eocene section. This unit varies in thickness by a factor of about two, with the thickest portion forming a low mound some 3˚–4˚ north of the 56 Ma …
Depth Characterization Of Shallow Aquifers With Seismic Reflection, Part Ii—Prestack Depth Migration And Field Examples, John H. Bradford, D. S. Sawyer
Depth Characterization Of Shallow Aquifers With Seismic Reflection, Part Ii—Prestack Depth Migration And Field Examples, John H. Bradford, D. S. Sawyer
CGISS Publications and Presentations
It is common in shallow seismic studies for the compressional-wave velocity in unconsolidated sediments to increase by a factor of four or more at the transition from dry or partial water saturation to full saturation. Under these conditions, conventional NMO velocity analysis fails and leads to large depth and layer thickness estimates if the Dix equation is assumed valid. Prestack depth migration (PSDM) is a means of improving image accuracy. A comparison of PSDM with conventional NMO processing for three field examples from differing hydrogeologic environments illustrates that PSDM can significantly improve image quality and accuracy.
Detection Of Iapetan Rifting (Rome Trough Tectonism) By Quaternary Karstification: Pulaski County, Kentucky, Lee J. Florea
Detection Of Iapetan Rifting (Rome Trough Tectonism) By Quaternary Karstification: Pulaski County, Kentucky, Lee J. Florea
Earth, Environmental, and Atmospheric Sciences Faculty Publications
No abstract provided.
Aftershocks And Pore Fluid Diffusion Following The 1992 Landers Earthquake, William Bosl, A Nur
Aftershocks And Pore Fluid Diffusion Following The 1992 Landers Earthquake, William Bosl, A Nur
Nursing and Health Professions Faculty Research and Publications
We model the evolution of regional stress following the 1992 Landers earthquake in order to test the importance of pore fluid flow in producing aftershocks. Rising fluid pressure due to pore fluid flow and the resulting Coulomb stress changes were found to be strongly correlated with the time and location of aftershock events. Regional aftershock frequencies computed by integrating pore pressure decay rates also agreed quite well with aftershock data. Calculations show that regions of rising postseismic poroelastic Coulomb stress overlap considerably with regions of positive coseismic Coulomb stress. Thus pore fluid flow, which affects pore pressure within faults and …
Detection Of Iapetan Rifting (Rome Trough Tectonism) By Quaternary Karstification: Pulaski County, Kentucky, Lee J. Florea
Detection Of Iapetan Rifting (Rome Trough Tectonism) By Quaternary Karstification: Pulaski County, Kentucky, Lee J. Florea
Lee J Florea, PhD, P.G.
No abstract provided.
Geologic And Tectonic History Of The Western Snake River Plain, Idaho And Oregon, Spencer H. Wood, Drew M. Clemens
Geologic And Tectonic History Of The Western Snake River Plain, Idaho And Oregon, Spencer H. Wood, Drew M. Clemens
Geosciences Faculty Publications and Presentations
The western Snake River Plain is a Neogene-aged intracontinental rift basin, about 70 km wide and 300 km long, trending northwest across the southern Idaho batholith. Its southeastern end merges with the northeast-trending eastern plain, a structural downwarp associated with extension along the track of the Yellowstone hot spot. Orientation of the western plain rift is parallel to several regional northwest-trending crustal discontinuities, such as the Olympic-Wallowa lineament and the Brothers fault zone, suggesting that the rift failed along zones of lithospheric weakness, as the lithosphere was softened by the passing hot spot. Crustal refraction data and gravity show that …
Identification Of Subsonic P-Waves, Paul Michaels
Identification Of Subsonic P-Waves, Paul Michaels
CGISS Publications and Presentations
A field trial was conducted to test the existence of subsonic (Vp <331 m>/s) P-waves previously reported in the literature. A 1-m-long reverse profile was acquired with three-component (3C) geophones on a sandy silt (unified classification ML). The silt had a porosity of 54%, a degree of water saturation of 63%, and a plasticity index of 10. No subsonic P-waves were observed, although high frequency (up to 1200 Hz) Rayleigh waves were identified by hodogram analysis. These surface waves were observed with horizontal velocities that varied from 40 to 200 m/s. Hodogram observations and theory suggest that …
Depth Characterization Of Shallow Aquifers With Seismic Reflection, Part I—The Failure Of Nmo Velocity Analysis And Quantitative Error Prediction, John H. Bradford
Depth Characterization Of Shallow Aquifers With Seismic Reflection, Part I—The Failure Of Nmo Velocity Analysis And Quantitative Error Prediction, John H. Bradford
CGISS Publications and Presentations
As seismic reflection data become more prevalent as input for quantitative environmental and engineering studies, there is a growing need to assess and improve the accuracy of reflection processing methodologies. It is common for compressional-wave velocities to increase by a factor of four or more where shallow, unconsolidated sediments change from a dry or partially watersaturated regime to full saturation. While this degree of velocity contrast is rare in conventional seismology, it is a common scenario in shallow environments and leads to significant problems when trying to record and interpret reflections within about the first 30 m below the water …
Stratigraphy And Diagenesis Of The Paleoproterozoic Bushy Park Zinc-Lead Deposit, South Africa, William Daniel Baugaard
Stratigraphy And Diagenesis Of The Paleoproterozoic Bushy Park Zinc-Lead Deposit, South Africa, William Daniel Baugaard
Masters Theses
“The Bushy Park zinc-lead deposit is located in the Northern Cape Province, South Africa. The sulfides are hosted by karst-related breccias that were formed in carbonate shelf deposits of the Neoarchean (2.55 Ga) Campbellrand Subgroup. These rocks are dolomitized completely and silicified partially but have not undergone major metamorphism and thus display remarkable preservation of depositional fabrics. The stratigraphic interval includes the Papkuil and Klippan Formations (> 210 m), a sequence of cyclic microbial laminates interbedded with domed and columnar stromatolites. The Klippan is distinguished from other formations b intense silicification and brecciation. These strata are overlain by the Kogelbeen …
Wide Plate Margin Deformation, Southern Central America And Northwestern South America, Casa Gps Observations, James Kellogg
Wide Plate Margin Deformation, Southern Central America And Northwestern South America, Casa Gps Observations, James Kellogg
James N Kellogg
Global Positioning System (GPS) data from southern Central America and northwestern South America were collected during 1991, 1994, 1996, and 1998 in Costa Rica, Panama, Ecuador, Colombia and Venezuela. These data reveal wide plate boundary deformation and escape tectonics occurring along an approximately 1400 km length of the North Andes; locking of the subducting Nazca plate and strain accumulation in the Ecuador-Colombia forearc; ongoing collision of the Panama arc and Colombia; and convergence of the Caribbean plate with Panama and South America. Elastic modeling of observed horizontal displacements in the Ecuador forearc is consistent with partial locking (50%) in the …