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Articles 1621 - 1650 of 2452

Full-Text Articles in Geophysics and Seismology

Cretaceous/Paleogene Boundary Biostratigraphy And Palynofacies Of The Alo-1 Well, Southeastern Nigeria, Janet Diane Raymer Jan 2010

Cretaceous/Paleogene Boundary Biostratigraphy And Palynofacies Of The Alo-1 Well, Southeastern Nigeria, Janet Diane Raymer

Masters Theses

"The Cretaceous/Paleogene boundary (K/Pg) has been studied in great detail because of the fascination most people have with the extinction of the dinosaurs. The response of the vegetation to this extinction event has been studied in detail in mid to high latitudes, but little is known about what happened in the tropics. Sixty-seven samples from the Nsukka and Imo formations in the Alo-1 well in the Anambra Basin, southeastern Nigeria have been studied for their palynological contents. The aims of the study was to use spores, pollen and dispersed organic matter components to interpret biostratigraphy, and evaluate depositional conditions across …

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Calcium Carbonate Precipitation Mechanisms And Geochemical Analysis Of Particulate Material Found Within The Waters Of Maramec Spring, St. James, Missouri, Kyle Steven Rybacki Jan 2010

Calcium Carbonate Precipitation Mechanisms And Geochemical Analysis Of Particulate Material Found Within The Waters Of Maramec Spring, St. James, Missouri, Kyle Steven Rybacki

Masters Theses

"The purpose of the present study is to determine whether a mineral phase is precipitating from solution in the natural Maramec Spring system giving the spring water a milky blue color, to identify the mineral phase, and to investigate potential mechanisms for inducing precipitation. Maramec Spring is a first-order magnitude spring located 11 km southeast of St. James, Missouri. The water that expels from Maramec Spring varies between being near saturation, but undersaturated in calcium, with respect to calcite (saturation index of 0.994 mg/L). Moving downstream, away from the conduit, the spring waters increase in pH and temperature. Eh is …

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Palynology Of The Middle To Upper Eocene Esmeraldas Formation In The Nuevo Mundo Syncline Area, Middle Magdalena Valley Basin, Colombia, Guillermo Rodriguez-Forero Jan 2010

Palynology Of The Middle To Upper Eocene Esmeraldas Formation In The Nuevo Mundo Syncline Area, Middle Magdalena Valley Basin, Colombia, Guillermo Rodriguez-Forero

Masters Theses

"The palynology of the Eocene Esmeraldas Formation in the Middle Magdalena Valley Basin, Colombia was analyzed in order to constrain the age of the unit. This formation is a very important oil reservoir in the Middle Magdalena Valley Basin, which is a product of a fragmentation of a Cenozoic foreland basin by the Northern Andes. It created structural complexities and syntectonic deposition. The lateral continuity of the formation, as well as its correlations with lithostratigraphic units is adjacent basins, are not clearly understood. The Los Corros Fossil Horizon, a mollusk horizon in the upper part of the Esmeraldas Formation, is …

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Fluid Budget Of Metasedimentary Rocks From A Tertiary Accretionary Prism And Connections To Seismicity, Olympic Peninsula, Northwest Washington State, Holly Makena Macfadden Rotman Jan 2010

Fluid Budget Of Metasedimentary Rocks From A Tertiary Accretionary Prism And Connections To Seismicity, Olympic Peninsula, Northwest Washington State, Holly Makena Macfadden Rotman

All Master's Theses

Metamorphic dehydration reactions and fluid movement in accretionary prisms have been linked to the recently discovered episodic tremor and slip (ETS) earthquake events along subduction zones, but prior studies lack the detail to effectively test the hypothesis that fluid flow triggers ETS events. I conducted field work along a 52.5 km transect on the Olympic Peninsula metasedimentary accretionary prism of the Cascadia subduction zone, and collected approximately 40 representative samples of sandstone and mudrock that were buried to 6–15 km. This depth range intersects the 10–50 km depth range of ETS events. My objectives are to quantify the water flow …

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Geophysical Investigation Of Paleoseismological Features In Eastern Arkansas, Usa, Okba Raad Al-Qadhi Jan 2010

Geophysical Investigation Of Paleoseismological Features In Eastern Arkansas, Usa, Okba Raad Al-Qadhi

Theses and Dissertations

Satellite images and field surveys reveal the existence of several liquefaction features in east central Arkansas on an area that is not known to have experienced major earthquakes in the past. The research of this dissertation is part of a long term comprehensive program to study and assess the seismic risk in the central United States. This research successfully showed that geophysical methods are effective and more economical than traditional drilling and trenching methods. Ground Penetrating Radar (GPR) and Capacitively Coupled Resistivity (CCR) techniques were comprehensively implemented at over 36 sites in the study area near Marianna, Arkansas, United States. …

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Studies Of Earthquakes Stress Drops, Seismic Scattering, And Dynamic Triggering In North America, Christian Rene Escudero Ayala Jan 2010

Studies Of Earthquakes Stress Drops, Seismic Scattering, And Dynamic Triggering In North America, Christian Rene Escudero Ayala

Open Access Theses & Dissertations

I use the Relative Source Time Function (RSTF) method to determine the source properties of earthquakes within southeastern Alaska-northwestern Canada in a first part of the project, and earthquakes within the Denali fault in a second part. I deconvolve a small event P-arrival signal from a larger event by the following method: select arrivals with a tapered cosine window, fast fourier transform to obtain the spectrum, apply water level deconvolution technique, and bandpass filter before inverse transforming the result to obtain the RSTF. I compare the source processes of earthquakes within the area to determine stress drop differences to determine …

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Seismic Investigation Of The Southern Rio Grande Rift, Lennox Emmanuel Thompson Jan 2010

Seismic Investigation Of The Southern Rio Grande Rift, Lennox Emmanuel Thompson

Open Access Theses & Dissertations

Competing models exist to explain what caused the Earth's crust to spread apart 29 million years ago to create a region known today as the Rio Grande Rift (RGR). The RGR extends from central Colorado through New Mexico to northern Mexico, near El Paso. The RGR has different geologic features that distinguish it from most other valleys (e.g., the RGR was not cut by a river nor does a river branch upstream). A growing body of evidence shows that geologic activity still occurs in the RGR, with a continuation of faulting, seismicity and widening at a small rate of about …

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Bagc.M: Three Dimensional Gravity Modeling Software With An Application In Death Valley, Ca, Brian Eugene Eslick Jan 2010

Bagc.M: Three Dimensional Gravity Modeling Software With An Application In Death Valley, Ca, Brian Eugene Eslick

Open Access Theses & Dissertations

Basin Anomaly Gravity Calculator (BAGC.m) is a 3D interactive gravity modeling package designed to create, edit, and calculate the gravitational attraction of basin models entirely within the MATLABTM environment. Gravity anomalies are calculated using the Rectangular Prism Method (Bott, 1960; Kane, 1962; and Plouff, 1966) which subdivides earth models into regularly spaced rectangular prisms. This approach requires large 3D matrices to store most realistic earth models. The process of model editing is simplified by storing basins as 2D gridded files which define the depth to the boundary between basement rock and sedimentary fill for each model cell. In order to …

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Investigating The Source Of Thermal Anomalies In The Northern United Arab Emirates (Uae) Desert Using Geophysical Methods, Khalid Ahmad Jan 2010

Investigating The Source Of Thermal Anomalies In The Northern United Arab Emirates (Uae) Desert Using Geophysical Methods, Khalid Ahmad

Doctoral Dissertations

"We conducted geophysical surveys to investigate the source of thermal anomalies and to delineate any potential water transport pathways from the recharge zones in the Oman Mountains to the location of the temporal thermal anomalies within the desert plain of the United Arab Emirates (UAE). In the visible region of the spectrum of both ASTER and MODIS satellite images, the desert plain of the UAE appears as a bare sandy surface. However, detailed examination of these images in the thermal bands reveal cooler thermal anomalies within the desert plain following major rainfall events. This anomaly has a cooler surface of …

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Accurate Inversion Of High-Resolution Snow Penetrometer Signals For Microstructural And Micromechanical Properties, Hans-Peter Marshall, Jerome B. Johnson Nov 2009

Accurate Inversion Of High-Resolution Snow Penetrometer Signals For Microstructural And Micromechanical Properties, Hans-Peter Marshall, Jerome B. Johnson

CGISS Publications and Presentations

Measurements of snow using a high-resolution micropenetrometer can be used to discriminate between different snow types; in lower-density snow the signal is sensitive to microstructure, and micromechanical properties can be estimated. Although a physics-based snow penetration theory was first developed almost a decade ago, since that time the majority of studies using snow micropenetrometers have focused on using direct hardness measurements in statistical relationships. We use Monte-Carlo simulations to rigorously test the existing physics-based snow micropenetration theories over a wide range of parameters. These tests revealed four major sources of error in the inversion, which are corrected in this analysis. …

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Plains Co2 Reduction (Pcor) Partnership Atlas, Wesley D. Peck, Katherine K. Anagnost, Barry W. Botnen, Lisa S. Botnen, Daniel J. Daly, Charles D. Gorecki, Megan M. Grove, John A. Harju, Melanie D. Jensen, Michael L. Jones, Steven A. Smith, James A. Sorensen, Edward N. Steadman, Stephanie L. Wolfe, Andrea T. Mcnemar, John T. Litynski, Sean I. Plasynski Nov 2009

Plains Co2 Reduction (Pcor) Partnership Atlas, Wesley D. Peck, Katherine K. Anagnost, Barry W. Botnen, Lisa S. Botnen, Daniel J. Daly, Charles D. Gorecki, Megan M. Grove, John A. Harju, Melanie D. Jensen, Michael L. Jones, Steven A. Smith, James A. Sorensen, Edward N. Steadman, Stephanie L. Wolfe, Andrea T. Mcnemar, John T. Litynski, Sean I. Plasynski

EERC Maps and Infographics

The Plains CO2 Reduction (PCOR) atlas, 3rd edition, introduces global climate change and provides a regional profile of CO2 sources and potential sinks across the PCOR Partnership region. Carbon storage offers a promising set of technologies through which CO2 can be stored for long periods of time.

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Modeling Soil Depth From Topographic And Land Cover Attributes, Teklu K. Tesfa, David G. Tarboton, David G. Chandler, James P. Mcnamara Oct 2009

Modeling Soil Depth From Topographic And Land Cover Attributes, Teklu K. Tesfa, David G. Tarboton, David G. Chandler, James P. Mcnamara

Geosciences Faculty Publications and Presentations

Soil depth is an important input parameter in hydrological and ecological modeling. Presently, the soil depth data available in national soil databases (STATSGO and SSURGO) from the Natural Resources Conservation Service are provided as averages within generalized land units (map units). Spatial uncertainty within these units limits their applicability for distributed modeling in complex terrain. This work reports statistical models for prediction of soil depth in a semiarid mountainous watershed that are based upon the relationship between soil depth and topographic and land cover attributes. Soil depth was surveyed by driving a rod into the ground until refusal at locations …

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Infrasonic Ambient Noise Interferometry From Correlations Of Microbaroms, Matthew M. Haney Oct 2009

Infrasonic Ambient Noise Interferometry From Correlations Of Microbaroms, Matthew M. Haney

CGISS Publications and Presentations

We show that microbaroms, continuous infrasound fluctuations resulting from the interaction of the ocean with the atmosphere, have long-range correlation properties that make it possible to estimate the impulse response between two microphones from passive recordings. The processing is analogous to methods employed in the emerging field of ambient noise seismology, where the random noise source is the ocean coupling with the solid Earth (microseisms) instead of the atmosphere (microbaroms). We find that timedependent temperature fields and temperature inversions determine the character of infrasonic impulse responses at Fourpeaked Volcano in Alaska. Applications include imaging and monitoring the gross structure of …

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Geogram 2009, David J. Keeling Editor, Wku Department Of Geography And Geology Oct 2009

Geogram 2009, David J. Keeling Editor, Wku Department Of Geography And Geology

Earth, Environmental, and Atmospheric Sciences Publications

No abstract provided.

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Estimating Debye Parameters From Gpr Reflection Data Using Spectral Ratios, John H. Bradford Sep 2009

Estimating Debye Parameters From Gpr Reflection Data Using Spectral Ratios, John H. Bradford

Geosciences Faculty Publications and Presentations

In the GPR frequency range, electromagnetic wave attenuation is largely controlled by dielectric relaxation processes. A primary relaxation commonly occurs in the 10 – 100 MHz range for many earth materials in which the GPR signal propagates effectively. This relaxation leads to strong nonlinearity in the frequency dependent attenuation and occurs in a frequency range that is often used for groundwater investigations. This non-linearity complicates data analysis but also may provide additional material property information. I investigate inversion for Debye relaxation parameters directly from GPR reflection data, including increasing the bandwidth of the signal by summing the response from 25 …

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Improved Confidence In (U-Th)/He Thermochronology Using The Laser Microprobe: An Example From A Pleistocene Leucogranite, Nanga Parbat, Pakistan, J. W. Boyce, K. V. Hodges, D. King, James L. Crowley, M. Jercinovic, N. Chatterjee, S. A. Bowring, M. Searle Sep 2009

Improved Confidence In (U-Th)/He Thermochronology Using The Laser Microprobe: An Example From A Pleistocene Leucogranite, Nanga Parbat, Pakistan, J. W. Boyce, K. V. Hodges, D. King, James L. Crowley, M. Jercinovic, N. Chatterjee, S. A. Bowring, M. Searle

Geosciences Faculty Publications and Presentations

The newly developed laser microprobe (U-Th)/He thermochronometer permits, for the first time, the ability to generate precise (U-Th)/He cooling ages for even very young (Ma) samples with a spatial resolution on the order of tens of micrometers. This makes it possible to test the reproducibility of independent (U-Th)/He age determinations within individual crystals, further increasing the reliability of the method. As an example, we apply it here to a Pleistocene granite from Nanga Parbat, Pakistan, where previous constraints on the thermal history are consistent with rapid exhumation and cooling. Twenty-one (U-Th)/He dates determined on two monazite crystals from a single …

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Understanding Paleoclimate And Human Evolution Through The Hominin Sites And Paleolakes Drilling Project, Andrew Cohen, Ramon Arrowsmith, Anna K. Behrensmeyer, Christopher Campisano, Craig Feibel, Shimeles Fisseha, Roy Johnson, Zelalem Bedaso, Charles Lockwood, Emma Mbua, Daniel Olago, Richard Potts, Kaye Reed, Robin Renaut, Jean-Jacques Tiercelin, Mohammed Umer Sep 2009

Understanding Paleoclimate And Human Evolution Through The Hominin Sites And Paleolakes Drilling Project, Andrew Cohen, Ramon Arrowsmith, Anna K. Behrensmeyer, Christopher Campisano, Craig Feibel, Shimeles Fisseha, Roy Johnson, Zelalem Bedaso, Charles Lockwood, Emma Mbua, Daniel Olago, Richard Potts, Kaye Reed, Robin Renaut, Jean-Jacques Tiercelin, Mohammed Umer

Department of Earth, Environment and Sustainability Faculty Publications

Understanding the evolution of humans and our close relatives is one of the enduring scientific issues of modern times. Since the time of Charles Darwin, scientists have speculated on how and when we evolved and what conditions drove this evolutionary story. The detective work required to address these questions is necessarily interdisciplinary, involving research in anthropology, archaeology, human genetics and genomics, and the earth sciences. In addition to the difficult tasks of finding, describing, and interpreting hominin fossils (the taxonomic tribe which includes Homo sapiens and our close fossil relatives from the last 6 Ma), much of modern geological research …

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Geometry Of The Trachyte Mesa Intrusion, Henry Mountains, Utah: Implications For The Emplacement Of Small Melt Volumes Into The Upper Crust, Paul H. Wetmore, Charles B. Connor, Sarah E. Kruse, Sean Callihan, Geoffrey Pignotta, Ciprian Stremtan, Andrea Burke Aug 2009

Geometry Of The Trachyte Mesa Intrusion, Henry Mountains, Utah: Implications For The Emplacement Of Small Melt Volumes Into The Upper Crust, Paul H. Wetmore, Charles B. Connor, Sarah E. Kruse, Sean Callihan, Geoffrey Pignotta, Ciprian Stremtan, Andrea Burke

Geology Faculty Publications

The Trachyte Mesa intrusion is one of several small satellite bodies to the larger intrusions of the Henry Mountains, Utah. Most previous studies have worked under the assumptions that Trachyte Mesa is blister shaped and intruded into flat and gently NW dipping strata. In this study we combine structural and geophysical data sets to constrain the structural geology of the host lithologies and the unmodified geometry of the intrusion. Trachyte Mesa intrudes a series of northeast trending upright and open folds formed within the Jurassic Entrada Formation. Truncation of these folds at the contact with the overlying Curtis/Summerville formations indicates …

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Obtaining Parsimonious Hydraulic Conductivity Fields Using Head And Transport Observations: A Bayesian Geostatistical Parameter Estimation Approach, Michael Fienen, R. Hunt, D. Krabbenhoft, Tom Clemo Aug 2009

Obtaining Parsimonious Hydraulic Conductivity Fields Using Head And Transport Observations: A Bayesian Geostatistical Parameter Estimation Approach, Michael Fienen, R. Hunt, D. Krabbenhoft, Tom Clemo

CGISS Publications and Presentations

Flow path delineation is a valuable tool for interpreting the subsurface hydrogeochemical environment. Different types of data, such as groundwater flow and transport, inform different aspects of hydrogeologic parameter values (hydraulic conductivity in this case) which, in turn, determine flow paths. This work combines flow and transport information to estimate a unified set of hydrogeologic parameters using the Bayesian geostatistical inverse approach. Parameter flexibility is allowed by using a highly parameterized approach with the level of complexity informed by the data. Despite the effort to adhere to the ideal of minimal a priori structure imposed on the problem, extreme contrasts …

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Complex Dielectric Permittivity Measurements From Ground-Penetrating Radar Data To Estimate Snow Liquid Water Content In The Pendular Regime, John H. Bradford, Joel T. Harper, Joel Brown Aug 2009

Complex Dielectric Permittivity Measurements From Ground-Penetrating Radar Data To Estimate Snow Liquid Water Content In The Pendular Regime, John H. Bradford, Joel T. Harper, Joel Brown

CGISS Publications and Presentations

Monitoring the snow water equivalent (SWE) is critical to effective management of water resources in many parts of the world that depend on the mountain snowpack for water storage. There are currently no methods to remotely sense SWE with accuracy over large lateral distances in the steep and often forested terrain of mountain basins. Previous studies have shown that measurements of ground-penetrating radar (GPR) velocity can provide accurate estimates of SWE in dry snow. Introduction of liquid water into the snowpack results in a three-phase system that cannot be accurately characterized with GPR velocity alone. We show that measuring the …

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Moment Release Rate Of Cascadia Tremor Constrained By Gps, Ana C. Aguiar, Timothy I. Melbourne, Craig W. Scrivner Jul 2009

Moment Release Rate Of Cascadia Tremor Constrained By Gps, Ana C. Aguiar, Timothy I. Melbourne, Craig W. Scrivner

All Faculty Scholarship for the College of the Sciences

A comparison of GPS and seismic analyses of 23 distinct episodic tremor and slip events, located throughout the Cascadia subduction zone over an 11-year period, yields a highly linear relationship between moment release, as estimated from GPS, and total duration of nonvolcanic tremor, as summed from regional seismic arrays. The events last 1–5 weeks, typically produce ~5 mm of static forearc deformation, and show cumulative totals of tremor that range from 40 to 280 h. Moment released by each event is estimated by inverting GPS-measured deformation, which is sensitive to all rates of tremor-synchronous faulting, including aseismic creep, for total …

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Seismic Observations Of Transient Subglacial Water-Flow Beneath Macayeal Ice Stream, West Antarctica, J. Paul Winberry, Sridhar Anandakrishnan, Richard B. Alley Jun 2009

Seismic Observations Of Transient Subglacial Water-Flow Beneath Macayeal Ice Stream, West Antarctica, J. Paul Winberry, Sridhar Anandakrishnan, Richard B. Alley

All Faculty Scholarship for the College of the Sciences

New seismic observations of harmonic tremors beneath MacAyeal Ice Stream, West Antarctica are reported. Each of the two tremor events that we recorded during a six week period had sustained arrival of 3 Hz energy for approximately 10 minutes. During that time the source location migrated a few kilometers. The harmonic nature of the tremors is interpreted as the result of resonance in subglacial water-filled cracks and conduits. The duration, monochromatic nature, and movement of the tremor indicate that the source mechanism is likely flow in the subglacial water system resulting from the discharge from a small subglacial lake. Our …

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Seismic Wave Attenuation In Carbonates, Ludmila Adam, M. Batzle, K. T. Lewallen, Kasper Van Wijk Jun 2009

Seismic Wave Attenuation In Carbonates, Ludmila Adam, M. Batzle, K. T. Lewallen, Kasper Van Wijk

CGISS Publications and Presentations

The effect of pore fluids on seismic wave attenuation in carbonate rocks is important for interpreting remote sensing observations of carbonate reservoirs undergoing enhanced oil recovery. Here we measure the elastic moduli and attenuation in the laboratory for five carbonate samples with 20% to 30% porosity and permeability between 0.03 and 58.1 mdarcy. Contrary to most observations in sandstones, bulk compressibility losses dominate over shear wave losses for dry samples and samples fully saturated with either liquid butane or brine. This observation holds for four out of five samples at seismic (10–1000 Hz) and ultrasonic frequencies (0.8 MHz) and reservoir …

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Mantle Transition Zone Structure Beneath Kenya And Tanzania: More Evidence For A Deep-Seated Thermal Upwelling In The Mantle, Audrey D. Huerta, Andrew A. Nyblade, Angela M. Reusch Jun 2009

Mantle Transition Zone Structure Beneath Kenya And Tanzania: More Evidence For A Deep-Seated Thermal Upwelling In The Mantle, Audrey D. Huerta, Andrew A. Nyblade, Angela M. Reusch

Geological Sciences Faculty Scholarship

Here we investigate the thermal structure of the mantle beneath the eastern Branch of the East African Rift system in Kenya and Tanzania. We focus on the structure of the mantle transition zone, as delineated by stacking of receiver functions. The top of the transition zone (the 410 km discontinuity) displays distinctive topography, and is systematically depressed beneath the rift in Kenya and northern Tanzania and adjacent volcanic fields. This depression is indicative of a localized ∼350 °C thermal anomaly. In contrast, the bottom of the transition zone (the 660 km discontinuity) is everywhere depressed. This region-wide depression is best …

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Observation And Modeling Of Source Effects In Coda Wave Interferometry At Pavlof Volcano, Matthew M. Haney, Kasper Van Wijk, Leiph A. Preston, David F. Aldridge May 2009

Observation And Modeling Of Source Effects In Coda Wave Interferometry At Pavlof Volcano, Matthew M. Haney, Kasper Van Wijk, Leiph A. Preston, David F. Aldridge

CGISS Publications and Presentations

We examine seismic records of repeating explosions from Pavlof volcano, Alaska, during its 2007 eruption. Repetitive explosions are typical of Strombolian-style eruptions and allow measurement of relative time shifts between similar late-arriving phases using the technique called coda wave interferometry (Snieder et al., 2002). The measurements enable the detection of small changes in the volcanic interior of Pavlof. We are able to resolve an increase in the relative traveltime change of late-arriving seismic waves on the order of 0.3% over the course of two weeks. Based on the spectra of the explosions, their location inside the magma conduit, previous studies …

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Numerical Modeling Of Time-Lapse Seismic Experiments To Monitor Co2 Sequestration In A Layered Basalt Reservoir, Murari Khatiwada May 2009

Numerical Modeling Of Time-Lapse Seismic Experiments To Monitor Co2 Sequestration In A Layered Basalt Reservoir, Murari Khatiwada

Boise State University Theses and Dissertations

Instead of allowing carbon dioxide (CO2) generated from the burning of hydrocarbons to escape into the atmosphere, CO2 can be captured and stored. For the long term mitigation of the increasing amount of CO2 emissions, its sequestration in geological formations is promising. As a measure, its short and long term monitoring is equally important for environmental and health safety issues. The seismic method is proposed as a non-invasive monitoring technique for geological sequestration of CO2. Based on the positive results obtained from reservoir monitoring during enhanced oil recovery with CO2 floods, geoscientists plan …

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Eastern Mediterranean Pore Waters: Clues Into The Geochemical Pathways From Evaporated Seawater To Basinal Brines, Jessica A. Mumphrey May 2009

Eastern Mediterranean Pore Waters: Clues Into The Geochemical Pathways From Evaporated Seawater To Basinal Brines, Jessica A. Mumphrey

Honors Capstones

No abstract provided.

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Capacitive Conductivity Logging And Electrical Stratigraphy In A High-Resistivity Aquifer, Boise Hydrogeophysical Research Site, C. Jonathan Mwenifumbo, Warren Barrash, Michael D. Knoll Apr 2009

Capacitive Conductivity Logging And Electrical Stratigraphy In A High-Resistivity Aquifer, Boise Hydrogeophysical Research Site, C. Jonathan Mwenifumbo, Warren Barrash, Michael D. Knoll

CGISS Publications and Presentations

We tested a prototype capacitive-conductivity borehole tool in a shallow, unconfined aquifer with coarse, unconsolidated sediments and very-low-conductivity water at the Boise Hydrogeophysical Research Site (BHRS). Examining such a high-resistivity system provides a good test for the capacitive- conductivity tool because the conventional induction- conductivity tool (known to have limited effectiveness in high-resistivity systems) did not generate expressive well logs at the BHRS. The capacitive-conductivity tool demonstrated highly repeatable, low-noise behavior but poor correlation with the induction tool in the lower-conductivity portions of the stratigraphy where the induction tool was relatively unresponsive. Singular spectrum analysis of capacitive- conductivity logs reveals …

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The Virtual Refraction: Useful Spurious Energy In Seismic Interferometry, Dylan Mikesell, Kasper Van Wijk, Alexander Calvert, Matthew M. Haney Apr 2009

The Virtual Refraction: Useful Spurious Energy In Seismic Interferometry, Dylan Mikesell, Kasper Van Wijk, Alexander Calvert, Matthew M. Haney

CGISS Publications and Presentations

Seismic interferometry is rapidly becoming an established technique to recover the Green’s function between receivers, but practical limitations in the source-energy distribution inevitably lead to spurious energy in the results. Instead of attempting to suppress all such energy, we use a spurious wave associated with the crosscorrelation of refracted energy at both receivers to infer estimates of subsurface parameters. We named this spurious event the virtual refraction. Illustrated by a numerical two-layer example, we found that the slope of the virtual refraction defines the velocity of the faster medium and that the stationary-phase point in the correlation gather provides the …

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The Storm 2.0 Project Next Generation Hurricane Data Collection, Santhana Krishnan Balaji Apr 2009

The Storm 2.0 Project Next Generation Hurricane Data Collection, Santhana Krishnan Balaji

Honors Capstones

No abstract provided.

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