Geophysics and Seismology Commons^™

Geophysical Imaging Of Karst Features In Missouri, Jeremiah Chukwunonso Obi

Doctoral Dissertations

"Automated electrical resistivity tomography (ERT) supported with multichannel analysis of surface waves (MASW) and boring data were used to map karst related features in Missouri in order to understand karst processes better in Missouri. Previous works on karst in Missouri were mostly surficial mapping of bedrock outcrops and joints, which are not enough to define the internal structure of karst system, since most critical processes in karst occur underground. To understand these processes better, the density, placement and pattern of karst related features like solution-widened joints and voids, as well as top of bedrock were mapped. In the course of …

Methodology Investigations For Shear Wave Splitting Analysis, Fansheng Kong

Doctoral Dissertations

"Over the past several decades, shear wave splitting analyses have been increasingly utilized to delineate mantle structure and probe mantle dynamics. However, the reported splitting parameters (fast polarization orientations and splitting times) are frequently inconsistent among different studies, partially due to the different techniques used to estimate the splitting parameters. Here the study conduct research on methodology investigations for shear wave splitting analysis, which are composed of two sub-topics, i.e., a systematic comparison of the transverse minimization (TM) and the splitting intensity (SI) techniques and applicability of the multiple-event stacking technique (MES). Numerical experiments are conducted using both synthetic and …

Seismic Anisotropy And Mantle Dynamics Beneath The Central And Western United States, Bin Yang

Doctoral Dissertations

"Various tectonic features and the recent availability of high-quality broadband seismic data from the USArray and other seismic stations in the central and western United States (CWUS) provide a distinct opportunity to test different anisotropy-forming mechanisms. For the first part of the study, a total of 4138 pairs of well-defined shear wave splitting (SWS) parameters observed at 445 stations on the northern Great Plains show systematic spatial variations of anisotropic characteristics. Azimuthally invariant fast orientations subparallel to the absolute plate motion (APM) direction are observed at most of the stations on the Superior Craton and the southern Yavapai province, indicating …

Palynological Studies Of Holocene Lake Sediments In The Missouri Ozarks, Robert D. Haselwander

Doctoral Dissertations

"Five small lakes in southeast Missouri (Frisco, Pine Forest, and Bray Area lakes [Phelps County], and Cypress and Blue ponds [Bollinger County]) were cored for paleolimnological studies. Cores were evaluated for their sedimentology, palynology, and geochemistry. In two of these lakes (Bray Area and Pine Forest lakes) the planktonic algae were also studied in the water column, along with ecological parameters. Algae in the sediments were compared to algae in the water to understand the resistance of different species to decay, and a suggested methodology for this work is described. Reconstructions of the past environments around each lake were created …

Identifying Shallow Subsurface Stratigraphy And Voids Using Dispersive Characteristics Of Electromagnetic And Surface Waves, Payman Hajiani

Doctoral Dissertations

"This dissertation presents the results of three manuscripts on spectral analysis of electromagnetic and seismic surface waves to detect subsurface stratigraphy and voids. In the first manuscript, a new technique was developed by utilizing spectral analysis of surface waves to detect subsurface openings. This technique applied the concept of group delay to evaluate the effects of subsurface voids on the phase shift domain. Seismic data sets were acquired at different sites where the shape, size, and depth of the void varied. In all surveys, the time delay technique precisely identified the locations of the subsurface openings. The second manuscript presents …

The Role Of Pre-Existing Basement Fabrics In The Initiation Of Continental Rifting: The Okavango Rift Zone, Botswana, Angelica Alvarez Naranjo

Doctoral Dissertations

"Integrated geophysical, remote sensing, and field investigations of the Okavango Rift Zone (ORZ), Botswana indicate that a feedback between optimum-oriented basement structures and fluid flow influence the nucleation and growth of continental rifts in their incipient stages. The ORZ, the youngest rift of the East African Rift System, occurs within a Proterozoic inter-cratonic suture zone - the NE-trending Precambrian Damara/Ghanzi-Chobe orogenic belts. The Pleistocene to Holocene ORZ forms a ~450 km long and ~100 km wide half-graben bounded by NE-trending normal faults. Basement units within the Damara/Ghanzi-Chobe orogenic belts exhibit a well-developed NE-trending linear fabric (045-065) defined by parallel limbs …

Numerical Modeling Of Ambient Noise Seismic Interferometry, Simisola M. Arogundade

Dissertations, Master's Theses and Master's Reports

CO₂ sequestration involves storing CO₂ in a deep geological formation and may help to mitigate the increasing emission of carbon. To monitor the migration of injected fluid in the reservoir, seismic observations may be used to observe changes in reflection character. Conventional methods to image the subsurface, using active seismic measurements, with man-made sources, have been applied at a few test sites, and the use of passive measurements, with natural sources, has been considered as a probable cost-efficient method to monitor CO₂ migration and leakage. This numerical modeling study examines the use of seismic interferometry to retrieve …

Comparisons Of Seismic Interferometry By Cross Correlation, Deconvolution, And Cross Coherence, Haitao Cao

Dissertations, Master's Theses and Master's Reports

Ambient noise seismic interferometry (ANSI) has been applied widely for geophysical investigations including earthquake tomography, civil engineering and seismic exploration purposes. Comparing this approach with the traditional active seismic survey, the application of ANSI is cost effective, environmentally friendly and easily repeatable. Conventional seismic interferometry by cross correlating wavefields recorded at different receivers has already obtained fruitful results.

Even though the application of seismic interferometry (SI) by cross correlation has been successful, different methods for the processing workflow such as cross coherence and deconvolution have been conducted in an effort to improve the resolution. While these three methods have been …

Can Seismic Velocity Stacking Errors Result In The Low-Frequency Shadow?, Umit Serhan Inan

Dissertations, Master's Theses and Master's Reports

The low-frequency shadow is the area on reflection seismic data, underneath gas reservoirs, that exhibits anomalously low frequency. This phenomenon has been related to the highly attenuating nature of the gas reservoir, which could explain the low-frequency shadows observed underneath extremely thick reservoirs, but not the ones underneath thin reservoirs. There are several other mechanisms that could be responsible, however detailed analysis of these possible explanations is yet to be found in the literature.

The main focus of this research is to test the possible contribution of stacking of offset seismic data, namely, their mis-stacking, to the generation of the …

Comparison Of Different Seismic Filtering Techniques On Prestack Inversion For Penobscot Area-Nova Scotia, Omer Emre Uygun

Dissertations, Master's Theses and Master's Reports

The goal of this study is to compare three different type of seismic filtering according to their inversion results and their quality of data improvements. To do this bandpass filter, Inverse Q, and Radon transform are applied to the original NMO corrected pre-stack data from Nova-Scotia offshore Canada.

The seismic data used was provided as pre-stack data of generally good quality. The test for quality of data improvement comes from the results of inversion based on different types of filtering performed on the pre-stack gathers.

Bandpass filter, Inverse Q, and Radon transform are applied to the migrated prestack data, over …

Submarine Channel Evolution Linked To Rising Salt Dome, Mississippi Canyon, Gulf Of Mexico, Rachel C. Carter

LSU New Orleans Theses and Dissertations

By examining halokinetics and channel evolution in a deep-water system, we investigate how submarine channel morphology is affected by changing seascape linked to diapirism. The study area is located in Mississippi Canyon, Gulf of Mexico (GOM), situated directly off the continental slope in a prominent salt dome region. Interactions of salt domes with submarine channels in the GOM are poorly documented. Utilizing 3D seismic data and seismic geomorphology techniques, a long-lived Plio-Pleistocene submarine channel system has been investigated to develop a relationship between variable phases of salt movement and plan-form morphology of preserved channels.

We suggest that halokinetics acts as …

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 …

Petroleum Play Study Of The Keathley Canyon, Gulf Of Mexico, Jean Pierre Malbrough

LSU New Orleans Theses and Dissertations

Beneath Keathley Canyon (KC) off the Southern Coast of Louisiana and Texas, allochthonous salt bodies have attained thicknesses of over 7620 m (25000 feet), providing excellent seals and migration pathways for hydrocarbons produced by post-rift sedimentary deposition. This study analyzes a small portion of the KC area, utilizing Petrel Seismic software and well information from the KC102 (Tiber) well.

An intra-Miocene wedge, expressed beneath salt, may provide information about movement of allochthonous salt over Wilcox sands, sediment compaction, and hydrocarbon pathways. Progradational sedimentation is the driving force which leads to faulting in the early Miocene, allowing Jurassic salt to rise, …

A Preliminary Assessment Of Water Partitioning And Ecohydrological Coupling In Northern Headwaters Using Stable Isotopes And Conceptual Runoff Models, James P. Mcnamara

Geosciences Faculty Publications and Presentations

We combined a conceptual rainfall-runoff model and input–output relationships of stable isotopes to understand ecohydrological influences on hydrological partitioning in snow-influenced northern catchments. Six sites in Sweden (Krycklan), Canada (Wolf Creek; Baker Creek; Dorset), Scotland (Girnock) and the USA (Dry Creek) span moisture and energy gradients found at high latitudes. A meta-analysis was carried out using the Hydrologiska Byråns Vattenbalansavdelning (HBV) model to estimate the main storage changes characterizing annual water balances. Annual snowpack storage importance was ranked as Wolf Creek > Krycklan > Dorset > Baker Creek > Dry Creek > Girnock. The subsequent rate and longevity of melt were reflected in calibrated parameters …

A Seismic Transect Across West Antarctica: Evidence For Mantle Thermal Anomalies Beneath The Bentley Subglacial Trench And The Marie Byrd Land Dome, Andrew J. Lloyd, Douglas A. Wiens, Andrew A. Nyblade, Sridhar Anandakrishnan, Richard C. Aster, Audrey D. Huerta, Terry J. Wilson, Ian W. D. Dalziel, Patrick J. Shore, Dapeng Zhao

All Faculty Scholarship for the College of the Sciences

West Antarctica consists of several tectonically diverse terranes, including the West Antarctic Rift System, a topographic low region of extended continental crust. In contrast, the adjacent Marie Byrd Land and Ellsworth-Whitmore mountains crustal blocks are on average over 1km higher, with the former dominated by polygenetic shield and stratovolcanoes protruding through the West Antarctic ice sheet and the latter having a Precambrian basement. The upper mantle structure of these regions is important for inferring the geologic history and tectonic processes, as well as the influence of the solid earth on ice sheet dynamics. Yet this structure is poorly constrained due …

Inverse Modelling Of The Reversely Magnetized, Shallow Plumbing System Hosting Oil Reservoirs Of The Auca Mahuida Volcano (Payeina Retroarc, Neuquén Basin, Argentina), John Paine, Riccardo De Ritis, Guido Ventura, Mariana Longo, Dhananjay Ravat, Fabio Speranza, Massimo Chiappini

Earth and Environmental Sciences Faculty Publications

The Auca Mahuida volcano (2.03–0.88 Ma) located east of the Andean thrust front in the Neuquén basin (Argentina) hosts an oil system of thermogenic origin and is affected by the NW–SE striking-faults. Intrusive bodies and the underlying Jurassic sediments constitute the reservoir rocks. Aeromagnetic data collected in the Auca Mahuida area detected multiple dipolar magnetic anomalies, many of which have reverse polarity. Palaeomagnetic measurements on rock samples collected in the field together with available age determinations indicate that the reversely magnetized sources were mainly emplaced during the Matuyama reverse polarity chron while the normal polarity sources were emplaced during the …

Natural Degradation Of Earthworks, Trenches, Walls And Moats, Northern Thailand, Spencer H. Wood, Layle R. Wood, Alan D. Ziegler

Geosciences Faculty Publications and Presentations

“………..structures of this kind are hidden away securely under the thick overgrowth: thus does nature preserve what man would surely destroy” (from Sumet Jumsai, 1970)

We investigate the geometry, age, and history of several enigmatic northern Thailand earthwork entrenchments that are mostly located on hills and could not have held water to form moats. The earthworks are either oval or rectangular in map view; and they typically encircle 0.3-to-1-km² areas that do not have potsherd debris indicative of former towns. Most trenches are 3-5 m deep with inner walls 4.5-8 m high. Some encircling earthworks are concentric double trenches …

Infrasound From Volcanic Rockfalls, Jeffrey B. Johnson, Timothy J. Ronan

CGISS Publications and Presentations

Proximal infrasound arrays can robustly track rapidly moving gravity-driven mass wasting, which occurs commonly at erupting volcanoes. This study reports on detection, localization, and quantification of frequent small rockfalls and infrequent pyroclastic density currents descending the southeast flanks of Santiaguito’s active Caliente Dome in January of 2014. Such activities are identified as moving sources, which descend several hundred meters at bulk flow speeds of up to ~10 m/s, which is considerably slower than the descent velocity of individual blocks. Infrasound rockfall signal character is readily distinguishable from explosion infrasound, which is manifested by a relatively fixed location source with lower …

Validation Of The Global Distribution Of Co2 Volume Mixing Ratio In The Mesosphere And Lower Thermosphere From Saber, L. Rezac, Y. Jian, J. Yue, J. M. Russell Iii, A. Kutepov, R. Garcia, K. Walker, P. Bernath

Chemistry & Biochemistry Faculty Publications

The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite has been measuring the limb radiance in 10 broadband infrared channels over the altitude range from ~ 400 km to the Earth's surface since 2002. The kinetic temperatures and CO₂ volume mixing ratios (VMRs) in the mesosphere and lower thermosphere have been simultaneously retrieved using SABER limb radiances at 15 and 4.3 μm under nonlocal thermodynamic equilibrium (non-LTE) conditions. This paper presents results of a validation study of the SABER CO₂ VMRs obtained with a two-channel, self-consistent …

Using Foraminifera Shell Geochemistry To Test Proxies For Paleoenvironmental Reconstruction, Catherine Hudson

Honors Capstones

No abstract provided.