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Geophysics

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Articles 91 - 120 of 123

Full-Text Articles in Geophysics and Seismology

Insights Into Volcanic Processes Using Seismic Data Techniques, Ezer Patlan Jan 2016

Insights Into Volcanic Processes Using Seismic Data Techniques, Ezer Patlan

Open Access Theses & Dissertations

We present in this study numbers of technique to understand the volcanic processes using seismology. The types of techniques we used are earthquake location (double difference travel-time, cross-correlation tremor technique, and time reversal), stresses (b-values, focal mechanism), and tomography imagery (ambient noise tomography). The areas of study we focus on are in two different tectonic settings. The East Africa Rift System at Kenya, studying four volcanoes: Menengai Caldera, Silali, Paka, and Korosi volcanoes. The other area of study is located in a subduction zone in Central America, Salvador at San Miguel volcano.

In this study we aim to calculate accurate …


Integrated Geophysical Methods In Investigation Of Claiborne Aquifer Hydrostratigraphy, Jackson Purchase, Kentucky, Marie Cooper Jan 2016

Integrated Geophysical Methods In Investigation Of Claiborne Aquifer Hydrostratigraphy, Jackson Purchase, Kentucky, Marie Cooper

Theses and Dissertations--Earth and Environmental Sciences

Increased groundwater withdrawals associated with agricultural irrigation in the Jackson Purchase have prompted questions related to groundwater availability and sustainability. Key factors in addressing these questions are understanding the extent and variation in thickness of the local hydrostratigraphic system, which is the upper part of the Mississippi Embayment aquifer system. Correlations of 70 gamma-ray well logs, and 49 resistivity logs were made across parts of the Jackson Purchase in Fulton and Hickman Counties in order to delineate the upper Claiborne aquifer and middle Claiborne confining unit. Commercial software (i.e. Petra 3.8.3) was used to generate cross sections, structure and isopach …


A Geophysical Investigation At The Potrillo Maar, Manuel Moncada Gutierrez Jan 2016

A Geophysical Investigation At The Potrillo Maar, Manuel Moncada Gutierrez

Open Access Theses & Dissertations

The Potrillo Volcanic Field (PVF) is a unique geological site located in Doña Ana County the southernmost part of New Mexico, and part of northern part of Chihuahua, Mexico. The main feature of the southern PVF is Potrillo Maar. This maar-volcano straddles the international boundary between United States and Mexico and lies within the southern part of the Rio Grande Rift. The Potrillo Maar was formed about 20,000 years ago in three major events that formed basalt lava flows and ejecta deposits that consist of crustal and mantle xenoliths.

The purpose of this Thesis is to determine the area of …


Spatiotemporal Slip Rate Variations Along Surprise Valley Fault In Relation To Pleistocene Pluvial Lakes, Brian N. Marion Jan 2016

Spatiotemporal Slip Rate Variations Along Surprise Valley Fault In Relation To Pleistocene Pluvial Lakes, Brian N. Marion

All Master's Theses

Using mapped paleoshoreline features with high-resolution topographic data and obtained radiocarbon dates on paleoshoreline tufas, I documented precise fault offsets of dated features over the last 25 ka along the Surprise Valley Fault (SVF). Fault offset measured in three lake sections within Surprise Valley ranged from 3.6 m in the southern section to 14.4 m in the central section. The offset paleoshorelines are dated to the late Pleistocene (<22 >ka) and were formed during the latest impoundment of pluvial Lake Surprise since the last glacial maximum. Slip rates vary along strike, assuming a fault dip of 68° with 0.25 ± …


Spatial Scaling Of Crustal And Lithospheric Deformation In The Western United States, Cody W. Bomberger Jan 2016

Spatial Scaling Of Crustal And Lithospheric Deformation In The Western United States, Cody W. Bomberger

Graduate Student Theses, Dissertations, & Professional Papers

Deformation of continental lithosphere can extend great distances laterally from tectonic plate boundaries. This extent has been used to argue for a variety of constitutive laws for continental materials, based on the underlying principles in continuum mechanics that identify a relationship between characteristic spatial scale and material properties. Although the relationship between observed deformation and material models is always non-unique, quantifying one or more characteristic scales of deformation in a region can rule out some models of how the lithosphere deforms. In the western United States active deformation occurs at the plate boundary between North America and either the Pacific …


Stabilized Least Squares Migration, Graham Ganssle Dec 2015

Stabilized Least Squares Migration, Graham Ganssle

LSU New Orleans Theses and Dissertations

Before raw seismic data records are interpretable by geologists, geophysicists must process these data using a technique called migration. Migration spatially repositions the acoustic energy in a seismic record to its correct location in the subsurface. Traditional migration techniques used a transpose approximation to a true acoustic propagation operator. Conventional least squares migration uses a true inverse operator, but is limited in functionality by the large size of modern seismic datasets. This research uses a new technique, called stabilized least squares migration, to correctly migrate seismic data records using a true inverse operator. Contrary to conventional least squares migration, this …


Analysis Of Paleokarst Sinkholes In The Arkoma Basin Using 3-D Seismic, Michael Kumbalek May 2015

Analysis Of Paleokarst Sinkholes In The Arkoma Basin Using 3-D Seismic, Michael Kumbalek

Graduate Theses and Dissertations

Paleokarst features are important to understand, both with regards to research geologists and to the petroleum industry. In terms of geology, understanding paleokarst features can yield more information about the depositional and surface environments of past times, and how diagenetic alteration affected the environment during the formation of karst features. In the petroleum industry, paleokarst features can have positive or negative consequence resulting in a potential reservoir with enhanced porosity due to the paleokarst features, or as a geo-hazard to prepare for or avoid when drilling.

Inspired by issues faced when drilling in the Ft. Worth basin, this study utilizes …


Seeing Below The Surface With Electrical Resistivity Tomography: Exploring The Deepest Reaches Of Arkansas' Tallest Prehistoric Mounds, James Robert Zimmer-Dauphinee Dec 2014

Seeing Below The Surface With Electrical Resistivity Tomography: Exploring The Deepest Reaches Of Arkansas' Tallest Prehistoric Mounds, James Robert Zimmer-Dauphinee

Graduate Theses and Dissertations

Despite decades of research and over a century of public interest, the most prominent features at Toltec Mounds Archeological State Park, Mound A and Mound B, remain virtually unexamined by modern archaeological techniques, and poorly understood. The tremendous scale and importance of these mounds makes most standard research methods difficult if not impossible. Electrical Resistivity Tomography, a geophysical technique rarely used in North America, was employed to survey both Mound A and Mound B, resulting in models of the subsurface that provide insights into the construction, modification and condition of the mounds.


Particle Swarms In Confining Geometries, Eric Robert Boomsma Oct 2014

Particle Swarms In Confining Geometries, Eric Robert Boomsma

Open Access Dissertations

The transport of micro- and nano-particles in subsurface fluid deposits is an area of increasing interest due to the rising use of these particles for consumer and industrial purposes. Subsurface particle transport is complicated by the presence of fractures and fracture networks which govern the paths that particles will be able to take. In this thesis, subsurface particle transport will be investigated using particle swarms; collections of hydro-dynamically interacting particles which exhibit group behavior. The effects of fluid viscosity, particle properties, fracture geometry, and fracture aperture on swarm behavior were experimentally investigated. ^ Swarm parameters were examined in time with …


Mechanical Stratigraphy Of The Mississippian In Osage County, Oklahoma, Caleb James Jennings May 2014

Mechanical Stratigraphy Of The Mississippian In Osage County, Oklahoma, Caleb James Jennings

Graduate Theses and Dissertations

The Mississippian formation of Oklahoma and Kansas has recently developed as a world class unconventional reservoir with wells producing up to 800 bbl/day. The Mississippian is composed of multiple distinct lithologic zones including limestone, hard chert, and soft tripolitic chert. These zones are difficult to discern with traditional log correlation, but mechanical stratigraphy has the potential to improve previous correlations of the Mississippian.

This study uses full wave sonic logs from Osage County, OK to analyze the elastic properties of the Mississippian. Our work computes isotropic elastic parameters in an effort to partition the Mississippian section into units that may …


Slides: Thoughts On Regulatory Mechanisms For Natural Resource Development: Alternatives To Command And Control, Including A Look At Open Source Approaches, Stanley Dempsey Feb 2014

Slides: Thoughts On Regulatory Mechanisms For Natural Resource Development: Alternatives To Command And Control, Including A Look At Open Source Approaches, Stanley Dempsey

Natural Resource Industries and the Sustainability Challenge (Martz Winter Symposium, February 27-28)

Presenter: Stanley Dempsey, Chairman, Royal Gold

17 slides


Geoelectrical Detection Of Water Table Depth At Two Locations In The Los Osos Groundwater Basin, Hallie A. Douglas Dec 2013

Geoelectrical Detection Of Water Table Depth At Two Locations In The Los Osos Groundwater Basin, Hallie A. Douglas

Natural Resources Management and Environmental Sciences

The city of Los Osos sits on top of a coastal groundwater aquifer which is the sole supplier of all its residential, agricultural, and industrial water needs. Lacking a sewer system, the upper aquifer became progressively contaminated with nitrates over several decades. Groundwater pumping eventually shifted to the lower aquifer, however seawater intrusion of the lower aquifer caused by over-pumping has further degraded water quality. The Los Osos groundwater basin provides an excellent field region to examine the utility of geophysical methods for characterizing aquifer structure. In this study shallow (<20 >m) electrical resistivity imaging methods were performed at two …


Integrated Geophysical Exploration Of A Known Geothermal Resource: Neal Hot Springs, Clinton Ryan Colwell Dec 2013

Integrated Geophysical Exploration Of A Known Geothermal Resource: Neal Hot Springs, Clinton Ryan Colwell

Boise State University Theses and Dissertations

I present an integrated geophysical characterization of the Neal Hot Springs geothermal system in eastern Oregon. This newly established 23 MW geothermal production site is located in a region of complex geology and intersecting faults associated with two major extensional systems; the Oregon-Idaho Graben and the western Snake River Plain. The intersection of two dominant fault orientations, coupled with a high geothermal gradient from relatively thin continental crust and radioactive decay from a shallow granitic body, produces the pathways and heat needed for deep water circulation at Neal Hot Springs. New geologic mapping, geochemistry, and measurements from several boreholes in …


Software Development For A 3d Gravity Inversion And Application To Study Of The Border Ranges Fault System, South-Central Alaska, Rolando Cardenas Jan 2013

Software Development For A 3d Gravity Inversion And Application To Study Of The Border Ranges Fault System, South-Central Alaska, Rolando Cardenas

Open Access Theses & Dissertations

The Border Ranges Fault System (BRFS) bounds the Cook Inlet and Susitna Basins, and is an important petroleum province within south-central Alaska. A primary goal of our research is to test several plausible models of structure along the BRFS using a novel three-dimensional inversion technique utilizing gravity data, constrained with other geophysical, borehole and surface geological information. This research involves the development of 3D inversion modeling software using C++ Builder from Embarcadero's XE2 Suite. The novel inversion approach directly models known geology with a priori uncertainties assigned to the geologic model to allow researchers to compare alternative interpretations. This technique …


Continued Mapping Of Unmarked Graves In The Mescalero Apache Indian Reservation, Ashley Galusina Nauer^, Alan C. Espino^, Alejandro Rios^, Laura Serpa* Apr 2012

Continued Mapping Of Unmarked Graves In The Mescalero Apache Indian Reservation, Ashley Galusina Nauer^, Alan C. Espino^, Alejandro Rios^, Laura Serpa*

COURI Symposium Abstracts, Spring 2012

No abstract provided.


Use Of Georphysics To Map Subsurface Features At Levee Seepage Locaitons, Thomas Chapman Brackett Jan 2012

Use Of Georphysics To Map Subsurface Features At Levee Seepage Locaitons, Thomas Chapman Brackett

Electronic Theses and Dissertations

The Great Flood of 2011 caused moderate to severe seepage and piping along the Mississippi River levees in Northwest Mississippi. The aim of this thesis was to implement geophysical techniques at two seepage locations in order to give a better understanding of the causes of underseepage and information on how to mitigate the problem. Sites near Rena Lara in Coahoma County and near Francis in Bolivar County were chosen to conduct this survey. Electrical Resistivity Tomography (ERT) and Electromagnetic Induction (EM) surveys were conducted on and adjacent to levees to identify seepage pathways and any dominant geological features at the …


Numerical Modeling Of Tectonics And Fault Activity Of Icy Satellites, John Olgin Jan 2012

Numerical Modeling Of Tectonics And Fault Activity Of Icy Satellites, John Olgin

Open Access Theses & Dissertations

Enceladus, one of the satellites of Saturn, exhibits evidence of recent fault activity, which may be due to gravitational fluctuations, or tidal stresses, generated by its orbit around Saturn. Recent Cassini spacecraft observations of Enceladus reveal water-ice plume activity at the south polar region, originating from locations that correlate with four geologically young, linear fracture-like features, named the "tiger stripes". It is the goal of this investigation to determine the ideal geophysical and geological factors (e.g., fault depths, frictional coefficients, ice layer thickness, ocean layer thickness, tidal stress sources) that support fault activity on Enceladus. The core of this work …


2d And 3d Imaging Of The Metamorphic Carbonates At Omalos Plateau/Polje, Crete, Greece By Employing Independent And Joint Inversion On Resistivity And Seismic Data, Hamdan Ali Hamdan Dr, Nikos Economou, Giorgos Kritikakis, Nikos Andronikidis, Emmanuil Manoutsoglou, Antonis Vafidis, Pangratis Pangratis, Georgina Apostolidou Jan 2012

2d And 3d Imaging Of The Metamorphic Carbonates At Omalos Plateau/Polje, Crete, Greece By Employing Independent And Joint Inversion On Resistivity And Seismic Data, Hamdan Ali Hamdan Dr, Nikos Economou, Giorgos Kritikakis, Nikos Andronikidis, Emmanuil Manoutsoglou, Antonis Vafidis, Pangratis Pangratis, Georgina Apostolidou

International Journal of Speleology

A geophysical survey carried out at Omalos plateau in Chania, Western Crete, Greece employed seismic as well as electrical tomography methods in order to image karstic structures and the metamorphic carbonates (Tripali unit and Plattenkalk group) which are covered by post-Mesozoic deposits (terra rossa, clays, sands and gravels). The geoelectrical sections image the metamorphic carbonates which exhibit a highly irregular relief. At the central part of the plateau the thickness of post-Mesozoic deposits (terra rossa, clays, sands and gravels) ranges from 40-130 m. A 3D resistivity image was generated by inverting resistivity data collected on a grid to the south …


Quasi 3-Dimensional Electrical Resistivity Mapping Of Air-Filled Karst Conduits And Policy Implications, Charles W. Mccrackin Oct 2011

Quasi 3-Dimensional Electrical Resistivity Mapping Of Air-Filled Karst Conduits And Policy Implications, Charles W. Mccrackin

USF Tampa Graduate Theses and Dissertations

This study assesses the capability and practical applications of quasi 3-Dimensional (3D) electrical resistivity surveying (ER) for mapping air-filled karst conduits. Vadose zone caves within the Brooksville Ridge of West Central Florida are relatively similar in architecture, with N-S elongation, and do not consist of an interconnected network of conduits. A high resolution quasi-3D ER survey was performed over two mapped cave systems on the Brooksville Ridge. The resultant survey verified the general effectiveness of quasi-3D ER in locating the two known near-surface cave features. Several other locations in the survey show similar or stronger resistivity anomalies trending in a …


Sensitivity Analysis Of Empirical Parameters In The Ionosphere-Plasmasphere Model, Janelle V. Jenniges Mar 2011

Sensitivity Analysis Of Empirical Parameters In The Ionosphere-Plasmasphere Model, Janelle V. Jenniges

Theses and Dissertations

A sensitivity analysis of empirical parameters used in physics-based models was completed in this study to determine their effect on electron densities and total electron content (TEC) in the ionosphere. The model used was the Ionosphere-Plasmasphere Model (IPM) developed by Utah State University. The empirical parameters studied include the O+/O collision frequency, zonal wind, secondary electron production, nighttime ExB drifts, and tidal structure. The sensitivity analysis was completed by comparing a default run of the IPM to a run with the parameter adjusted for three geophysical cases. Many of the comparisons resulted in nonlinear changes to the model …


Joint Geophysical Data Analysis For Geothermal Energy Exploration, Antony Munika Wamalwa Jan 2011

Joint Geophysical Data Analysis For Geothermal Energy Exploration, Antony Munika Wamalwa

Open Access Theses & Dissertations

Geophysical data modelling often yields non-unique results and hence the interpretation of the resulting models in terms of underlying geological units and structures is not a straightforward problem. However, if multiple datasets are available for a region of study, an integrated interpretation of models for each of the geophysical data may results to a more realistic geological description. This study not only demonstrates the strength of resistivity analysis for geothermal fields but also the gains from interpreting resistivity data together with other geophysical data such as gravity and seismic data. Various geothermal fields have been examined in this study which …


Applications Of Geophysical Analysis For Environmental And Geotechnical Problems, Basil Miller Sep 2010

Applications Of Geophysical Analysis For Environmental And Geotechnical Problems, Basil Miller

Theses and Dissertations

Geophysical investigative techniques including Magnetic, Electric, Ground Penetrating Radar (GPR), and Geochemistry become increasingly essential to study near surface setting as well as deep earth structure. A model was developed of the hot water system in southwest Arkansas using Geochemistry, Magnetic, and Ground Penetrating Radar (GPR) data. The model was constructed using the data collected at the Caddo Gap and Little Missouri Hot Springs in Southeast Arkansas, USA. Understanding the mechanism of the transition from slow flow in porous media to fast flow in a fracture is critical in understanding the hot water flow of the hot spring. The geochemistry …


Interpreting Surface-Wave Data For A Site With Shallow Bedrock, Daniel W. Casto, Barbara Luke, Carlos Calderon-Macias, Ronald Kaufmann Jan 2009

Interpreting Surface-Wave Data For A Site With Shallow Bedrock, Daniel W. Casto, Barbara Luke, Carlos Calderon-Macias, Ronald Kaufmann

Civil and Environmental Engineering and Construction Faculty Research

The inversion of dispersive Rayleigh-wave data has been shown to be successful in providing reliable estimated shear-wave velocities within unconsolidated materials in the near surface. However, in a case where the multi-channel analysis of surface waves method was applied to a site consisting of clay residuum overlying basalt bedrock, inversion for the fundamental-mode Rayleigh wave resulted in shear-wave velocities within the rock that are less than half of expected values. Forward modeling reveals that the fundamental-mode dispersion curve is hardly sensitive to bedrock velocity perturbations over a practical range of wavelengths, leading to poorly constrained solutions. Standard surface-wave methods can …


Understanding Wavelet Analysis And Filters For Engineering Applications, Chethan Bangalore Parameswariah Apr 2003

Understanding Wavelet Analysis And Filters For Engineering Applications, Chethan Bangalore Parameswariah

Doctoral Dissertations

Wavelets are signal-processing tools that have been of interest due to their characteristics and properties. Clear understanding of wavelets and their properties are a key to successful applications. Many theoretical and application-oriented papers have been written. Yet the choice of a right wavelet for a given application is an ongoing quest that has not been satisfactorily answered. This research has successfully identified certain issues, and an effort has been made to provide an understanding of wavelets by studying the wavelet filters in terms of their pole-zero and magnitude-phase characteristics. The magnitude characteristics of these filters have flat responses in both …


Present Day Kinematics Of The Eastern California Shear Zone From A Geodetically Constrained Block Model, S. C. Mcclusky, S. C. Bjornstad, B. H. Hager, R. W. King, B. J. Meade, M. Meghan Miller, F. C. Monastero, B. J. Souter Sep 2001

Present Day Kinematics Of The Eastern California Shear Zone From A Geodetically Constrained Block Model, S. C. Mcclusky, S. C. Bjornstad, B. H. Hager, R. W. King, B. J. Meade, M. Meghan Miller, F. C. Monastero, B. J. Souter

All Faculty Scholarship for the College of the Sciences

We use Global Positioning System (GPS) data from 1993–2000 to determine horizontal velocities of 65 stations in eastern California and western Nevada between 35° and 37° N. We relate the geodetic velocities to fault slip rates using a block model that enforces path integral constraints over geologic and geodetic time scales and that includes the effects of elastic strain accumulation on faults locked to a depth of 15 km. The velocity of the Sierra Nevada block with respect to Nevada is 11.1±0.3 mm/yr, with slip partitioned across the Death Valley, (2.8±0.5 mm/yr), Panamint Valley (2.5±0.8 mm/yr), and Airport Lake/Owens Valley …


Refined Kinematics Of The Eastern California Shear Zone From Gps Observations, 1993-1998, M. Meghan Miller, Timothy H. Dixon, Roy K. Dokka Feb 2001

Refined Kinematics Of The Eastern California Shear Zone From Gps Observations, 1993-1998, M. Meghan Miller, Timothy H. Dixon, Roy K. Dokka

All Faculty Scholarship for the College of the Sciences

Global Positioning System (GPS) results from networks spanning the Eastern California shear zone and adjacent Sierra Nevada block, occupied annually between 1993 and 1998, constrain plate margin kinematics. We use an elastic block model to relate GPS station velocities to long‐term fault slip rate estimates. The model accounts for elastic strain accumulation on the San Andreas fault, as well as faults of the Eastern California shear zone. South of the Garlock fault, 14 mm/yr of dextral shear is distributed across the Eastern California shear zone. Some of this slip penetrates eastward into the Basin and Range, and a collective budget …


Chemical Signals From Submarine Fluid Advection Onto The Continental Shelf, W. S. Moore, Timothy J. Shaw Sep 1998

Chemical Signals From Submarine Fluid Advection Onto The Continental Shelf, W. S. Moore, Timothy J. Shaw

Faculty Publications

No abstract provided.


Basement Structure Of The Northern Ontong Java Plateau, Rick A. Hagen, Larry A. Mayer, David Mosher, Loren W. Kroenke, Tom H. Shipley, Edward L. Winterer Jan 1993

Basement Structure Of The Northern Ontong Java Plateau, Rick A. Hagen, Larry A. Mayer, David Mosher, Loren W. Kroenke, Tom H. Shipley, Edward L. Winterer

Affiliate Scholarship

Site surveys conducted in conjunction with Leg 130 on the Ontong Java Plateau reveal a strong seismic reflector at 0.8 to 1.0 s below the seafloor that drilling at Sites 803 and 807 confirmed is Cretaceous basalt. This reflector is generally smooth, except for the northeastern margin of the plateau, where it forms a series of small, irregularly shaped depressions. Correlatable reflectors present at the bottom of the depressions are also present on the adjacent highs, suggesting that these depressions are original volcanic topography. A strong sub-basalt reflector occurs on many seismic profiles on the northeastern portion of the plateau. …


Manual Of Field Techniques In Hydrology, Department Of Agriculture, Western Australia. Division Of Resource Management Jan 1991

Manual Of Field Techniques In Hydrology, Department Of Agriculture, Western Australia. Division Of Resource Management

Agriculture reports

No abstract provided.


Hydrothermal Alteration At The Roosevelt Hot Springs Thermal Area, Utah: Petrographic Characterization Of The Alteration To 2 Kilometers Depth, J. M. Ballantyne, W. T. Parry Apr 1978

Hydrothermal Alteration At The Roosevelt Hot Springs Thermal Area, Utah: Petrographic Characterization Of The Alteration To 2 Kilometers Depth, J. M. Ballantyne, W. T. Parry

All U.S. Government Documents (Utah Regional Depository)

Hydrothermal alteration in drill cuttings from Thermal Power drillhole 14-2, Roosevelt Hot Springs Thermal area, has been studied petrographically. The hole is sited in alluvium approximately 1.6 km southeast of the old Resort and was rotary drilled to a depth of 1866.0 m. The exact hole location is 2310 FNL, 350 FWL, Sec. 2, Twp 27S, Rge 9W, elevation 1908.5 m. Core was extracted from 792.5 to 795.5 m. Thin sections were made from samples 15.2 m intervals of drill cuttings collected at 1.5 or 3.0 m intervals during drilling. Thin sections were made of 1.5 or 3.0 m intervals …