Geophysics and Seismology Commons^™

Towards Spatial Inversion Of Aerial Gamma-Ray Survey Data For Measurement Of Naturally Occurring Radioactivity, Daniel A. Haber

UNLV Theses, Dissertations, Professional Papers, and Capstones

Aerial gamma-ray surveying (AGRS) is used in geologic and environmental contexts to provide data on the surface spatial distribution of naturally occurring radioactive material (NORM) or other gamma-ray-emitting isotopes. The standard data reduction workflow for AGRS data involves a process whereby pointwise gamma-ray spectral data are denoised, corrected for numerous sources of background radiation and aircraft height, and are finally converted to physical values by empirical conversion factors. The reduced pointwise data are then typically spatially interpolated to form a continuous surface map.

This dissertation introduces and explores a novel spatial inversion method for reduced AGRS data that considers aircraft …

First-Principles Insights Into Binary Oxide Systems Under Extreme Pressure, Daniel Schacher

UNLV Theses, Dissertations, Professional Papers, and Capstones

Pressure is powerful tool by which one can manipulate the properties of materials. In this work we utilize pressure to explore binary oxide systems and characterize their structural and electronic properties. The observation of anomalous structural and electronic behavior in the rutile to CaCl2 phase transition in SnO2 led to the prediction that such behavior is inherent to all oxides experiencing such a phase transition sequence.[1] Here, the ultra-wide band gap semiconductor GeO2 is confirmed to exhibit anomalous behavior during the rutile to CaCl2 phase transition. A phase pure rutile GeO2 sample synthesized under high-pressure, high-temperature, conditions is probed using …

The Compositional And Dynamical Properties Of Exoplanets, Cody James Shakespeare

UNLV Theses, Dissertations, Professional Papers, and Capstones

The solid surface density profile of protoplanetary discs, and the composition of these solids, can be formed through sequential condensation models of dust precipitating from the cooling gas of the solar nebula. I continue developing a code that reproduces the chemical compositions of most chondrites as well as the bulk compositions of the rocky planets using our partial condensation model with an evolving disc. I extend this validated code to exoplanet systems with different initial elemental ratios, like the carbon-to-oxygen ratio and estimated stellar abundances over the age of the universe. I have improved this dust condensation code to include …

Α-Quartz Plastic Strength Investigation Via Diffraction Experiments On Novaculite Using A D-Dia And Elastic Plastic Self-Consistent Interpretation, Denali Jivanjee Medina

UNLV Theses, Dissertations, Professional Papers, and Capstones

The plastic response of experimentally deformed quartz provides insight into the strength of ductile shear zones that has implications for tectonic, lithospheric, and ore deposit models. We present a suite of 15 uniaxial deformation experiments on Arkansas novaculite conducted in a DDIA apparatus with in-situ synchrotron x-rays. Experimental temperatures range from 25 C to 1334 C with pressures between 1.39 GPa and 3.1 GPa, and strain rates between 1x10-5 s-1 and 9x10-6 s-1. Macroscopic sample strain ranges from 3% to 24%. d-spacings from the (101), (110), (200), (201), and (112) lattice planes were measured, producing lattice strain up to ~5%. …

Impact Of Young Biocrust On Dryland Surface Albedo, Rhynhardt Mudde, Rebekah Magness, Raul Roman, Nicole Pietrasiak

Undergraduate Research Symposium Posters

More than 40% of the Earth’s surface is covered by drylands. Due to limited availability of water, less surface area is covered by vascular plants. Instead, this space is occupied by microbial communities that exist in close contact with mineral soil, creating a living aggregate on the upper soil layer and are known collectively as biological soil crusts or “biocrusts”. Biocrusts play a vital role in ecosystem functioning in drylands specifically through their influence on hydrological processes (e.g., water retention, infiltration). However, the impact of biocrusts on evaporation is not well understood. Biocrusts have been reported to either increase or …

Examining The Spatial Periodicity Of Force Chains And Strain Localization In Polycrystal Models, Richard D. Panduro-Allanson

UNLV Theses, Dissertations, Professional Papers, and Capstones

Shear strain localization is typical in deforming rocks and is vital for developing faults and tectonic boundaries. There are various proposed drivers of shear localization (temperature, fluid, phase transformation, and microstructure); we will explore the effects of elastic heterogeneity (a microstructural influence) on shear localization in polycrystal models. Elastic heterogeneity can lead to varied stress states in material and drive shear localization. Previous simulations of elastically heterogeneous polycrystal models have shown that the stress distribution can be described as forming an anastomosing pattern of high-stress streams parallel to the compression direction. This anastomosing patterning resembles force chains; linear, high-stress features …

Steel Module-To-Concrete Core Connection Methods In High Rise Modular Buildings: A Critical Review, Bishal Poudel, Seungtaek Lee, Jin Ouk Choi

Civil and Environmental Engineering and Construction Faculty Research

Modularization in a high-rise building is different from a small building, as it is exposed to more lateral forces like wind and earthquakes. The integrity, robustness, and overall stability of the modules and their performance is based on the joining techniques and strong structural systems. High lateral stiff construction structures like concrete shear walls and frames, braced steel frames, and steel moment frames are used for the stability of high-rise modular buildings. Similarly, high-rise stick-built buildings have concrete cores and perimeter frames for lateral load strength and stiffness. Methods for general steel-concrete connections are available in many works of literature. …

Shallow Rupture Propagation Of Pleistocene Earthquakes Along The Hurricane Fault, Ut, Revealed By Hematite (U-Th)/He Thermochronometry And Textures, Madison P. Taylor, Alexis K. Ault, Margaret L. Odlum, Dennis L. Newell

Geoscience Faculty Research

The material properties and distribution of faults above the seismogenic zone promote or inhibit earthquake rupture propagation. We document the depths and mechanics of fault slip along the seismically active Hurricane fault, UT, with scanning and transmission electron microscopy and hematite (U-Th)/He thermochronometry. Hematite occurs as mm-scale, striated patches on a >10 m2 thin, mirror-like silica fault surface. Hematite textures include bulbous aggregates and cataclasite, overlain by crystalline Fe-oxide nanorods and an amorphous silica layer at the slip interface. Textures reflect mechanical, fluid, and heat-assisted amorphization of hematite and silica-rich host rock that weaken the fault and promote rupture propagation. …

Initial Measurements On The Effect Of Stress On P- And S-Wave Velocities In Olivine, Taryn Traylor

UNLV Theses, Dissertations, Professional Papers, and Capstones

It is well known that elasticity is a key physical property in the determination of the structure and composition of the Earth and provides critical information for the interpretation of seismic data. This study investigates the stress-induced variation in elastic wave velocities, known as the acoustoelastic effect, in San Carlos olivine. A recently developed experimental ultrasonic acoustic system, the Directly Integrated Acoustic System Combined with Pressure Experiments (DIASCoPE), was used with the D-DIA multi-anvil apparatus to transmit ultrasonic sound waves and collect the reflections. We use the DIASCoPE to obtain longitudinal (P) and shear (S) elastic wave velocities from the …

Experimental Polycrystal Stress Mapping Using Raman Spectroscopy, Genevieve C. Kidman

UNLV Theses, Dissertations, Professional Papers, and Capstones

Stress conditions leading to rock deformation influence how a rock will ultimately deform. However, the internal distribution of stress in an elastically anisotropic rock under load, a precursor to rock deformation, is not well understood. Two models that may describe the distribution of stress in polycrystals include the Reuss bound and stress percolation. The Reuss bound, when applied to a polycrystal, describes isostress on each grain resulting in homogeneous intragranular strain and heterogeneous intergranular strain. The stress percolation model involves a network of strong contacts or force chains containing domains of high stress interwoven through areas of lower stress that …

Arc‐Type Magmatism Due To Continental‐Edge Plowing Through Ancient Subduction‐Enriched Mantle, Douwe J.J. Van Hinsbergen, Wim Spakman, Hugo De Boorder, Michiel Van Dongen, Simon M. Jowitt, Paul R.D. Mason

Geoscience Faculty Research

The puzzling... (See article for full abstract).

Thermal Analysis, Compressibility, And Decomposition Of Synthetic Bastnäsite-(La) To Lanthanum Oxyfluoride, Richard L. Rowland, Barbara Lavina, Kathleen E. Vander Kadeen, Lisa R. Danielson, Pamela C. Burnely

Geoscience Faculty Research

Understanding basic material properties of rare earth element (REE) bearing minerals such as their phase stability and equations of state can assist in understanding how economically viable deposits might form. Bastnäsite is the most commonly mined REE bearing mineral. We synthesized the lanthanum-fluoride end member, bastnäsite-(La) (LaCO3F), and investigated its thermal behavior and decomposition products from 298 K to 1173 K under ambient pressure conditions through thermogravimetric analysis, differential scanning calorimetry, evolved gas analysis, and high temperature powder X-ray diffraction. We also investigated the compressibility of bastnäsite-(La) via single crystal X-ray diffraction in diamond anvil cells at an ambient temperature …

Examination Of Maskelynite Through Static Recompression And Dynamic Compression, Justin James Reppart

UNLV Theses, Dissertations, Professional Papers, and Capstones

This is an experimental study that aims to clarify the possible formation mechanisms of maskelynite. Maskelynite is a diaplectic glass, that forms during shock compression of feldspar far below the melting point, and without fusion. Maskelynite also paramorphises precursor feldspar grains. Maskelynite is an important probe of shock-pressures at terrestrial impact sites and in many meteorites. Two mechanisms of formation of maskelynite are examined here: 1) maskelynite is result of a pressure-induced amorphization of feldspar compressed beyond its mechanical stability where the formation of thermodynamically stable phases is kinetically inhibited [1, 2]. 2) Feldspar transforms upon dynamic compression into a …

Shergottite Northwest Africa 6963: A Pyroxene‐Cumulate Martian Gabbro, Justin Filiberto, Juliane Gross, Arya Udry, Jarek Trela, Axel Wittmann, Kevin M. Cannon, Sarah Penniston-Dorland, Richard Ash, Victoria E. Hamilton, Andrea L. Meado, Paul Carpenter, Brad Jolliff, Eric C. Ferré

Geoscience Faculty Research

Northwest Africa (NWA) 6963 was found in Guelmim‐Es‐Semara, Morocco, and based on its bulk chemistry and oxygen isotopes, it was classified as a Martian meteorite. On the basis of a preliminary study of the textures and crystal sizes, it was resubclassified as a gabbroic shergottite because of the similarity with terrestrial and lunar gabbros. However, the previous work was not a quantitative investigation of NWA 6963; to supplement the original resubclassification and enable full comparison between this and other Martian samples; here we investigate the mineralogy, petrology, geochemistry, quantitative textural analyses, and spectral properties of gabbroic shergottite NWA 6963 to …

Postaragonite Phases Of Caco3 At Lower Mantle Pressures, Dean Smith, Keith V. Lawler, Miguel Martinez-Canales, Austin W. Daykin, G. Alexander Smith, Christian Childs, Jesse S. Smith, Chris J. Pickard, Ashkan Salamat

Chemistry and Biochemistry Faculty Research

The stability, structure, and properties of carbonate minerals at lower mantle conditions have significant impact on our understanding of the global carbon cycle and the composition of the interior of the Earth. In recent years there has been significant interest in the behavior of carbonates at lower mantle conditions, specifically in their carbon hybridization, which has relevance for the storage of carbon within the deep mantle. Using high-pressure synchrotron x-ray diffraction in a diamond anvil cell coupled with direct laser heating of CaCO3 using a CO2 laser, we identify a crystalline phase of the material above 40 GPa—corresponding to a …

Evaluation Of Earthquake Hazard For Las Vegas Valley, Nevada Incorporating Probabilistic Hazard Assessment And Non--Linear Site Response, Suchan Lamichhane

UNLV Theses, Dissertations, Professional Papers, and Capstones

Abstract from Manuscript 1, "An alternative analysis of the probabilistic seismic hazard for Las Vegas Valley, Nevada": Probabilistic seismic hazard calculations relevant for rock-site conditions in the Las Vegas Valley, Nevada (LVV) have been computed that account for seismic sources that are not included in the current (2008) USGS national seismic hazard model (NSHM) because of insufficient knowledge or documentation, using the commercial software package EZ-FRISK. The LVV is underlain by a system of mapped, active normal faults that comprise the Las Vegas Valley Fault System (LVVFS), with maximum potential earthquakes to M6.8. The 2008 NSHM explicitly includes only one …

Finite Difference Modeling Of Surface-~Wave Scattering For Shallow Cavity Detection, Heston Travis Norcott

UNLV Theses, Dissertations, Professional Papers, and Capstones

Data collection and analysis of scattering of Rayleigh-type surface waves are investigated for locating shallowly buried cavities. Surface-based seismic experiments conducted by others at the University of Nevada, Las Vegas (UNLV) Engineering Geophysics Test Site (EGTS) demonstrate scattering of Rayleigh waves caused by buried empty barrels (essentially air-filled cavities). The interpretation of the data is complicated by factors such as the presence of a high-velocity geologic layer just below the cavity.

This research uses a finite-difference seismic wave propagation code to compute time histories for a model that represents the Engineering Geophysics Test Site. By adding cavities to a background …

Using Seismic Reflection To Locate A Tracer Testing Complex South Of Yucca Mountain, Nye County, Nevada, Levi Kryder

UNLV Theses, Dissertations, Professional Papers, and Capstones

Tracer testing in the fractured volcanic aquifer near Yucca Mountain, and in the alluvial aquifer south of Yucca Mountain, Nevada has been conducted in the past to determine the flow and transport properties of groundwater in those geologic units. However, no tracer testing has been conducted across the alluvium/volcanic interface. This thesis documents the investigative process and subsequent analysis and interpretations used to identify a location suitable for installation of a tracer testing complex, near existing Nye County wells south of Yucca Mountain.

The work involved evaluation of existing geologic data, collection of wellbore seismic data, and a detailed surface …

Assessing The Impact Of Additional Seismic Sources On The Probabilistic Seismic Hazard Assessment For The Las Vegas Valley, Nevada, Suchan Lamichhane, Barbara Luke, Wanda Taylor, William Savage

College of Engineering: Graduate Celebration Programs

• The densely populated (~2M) Las Vegas Valley, Nevada (LVV) is underlain by sediments that are cut by six mapped, active normal faults that comprise the Las Vegas Valley Fault System (LVVFS). Recent research indicates that these faults have the potential to generate earthquakes up to a maximum magnitude of 6.8.
• The current (2008) USGS national seismic hazard model (NSHM) explicitly considered only the Eglington fault of the LVVFS (the remaining 5 LVVFS sources were classified as "Class B" in the USGS fault and fold database and effectively given a weight of zero in the 2008 NSHM) and also did not …

Determining The Motion And Location Of The Frenchman Mountain Fault, Las Vegas, Nevada: A Paired Basin Analysis And Structural Analysis, Laura Margaret Eaton

UNLV Theses, Dissertations, Professional Papers, and Capstones

Understanding the evolution of large-scale fault systems remains a challenge to geologists and is of critical importance in understanding the dynamics of larger plate tectonic interactions. I mapped the southwestern Frenchman Mountain Fault (FMF), conducted a basin analysis of units in the footwall of the fault, and measured kinematic indicators along the fault zone in order to constrain fault offset, magnitude, and timing in an attempt to further our understanding of these systems.

My findings include: 1) the presence of vertical and sub-vertical slickenlines on southwest dipping fault surfaces indicative of normal sense offset; 2) relatively little lateral variation in …

Paleoseismic Study Of The Stewart Valley And Northern Pahrump Segments Of The Stateline Fault System, Nevada, Jonathan Carter

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Stateline fault system (SFS) is a ~200 km long zone of dextral faults running NW along the NV/CA border from Primm, Nevada to Amargosa Valley in the western Central Basin and Range province (CBR). Because of size and proximity, the SFS poses a hazard to the 2.5 million people, most of who live within 10 km, in Pahrump, Nevada and within 40 km, in Las Vegas, Nevada. The goals of this thesis are to (1) understand if the SFS is accommodating faulting slip change in the CBR; (2) test the along strike continuity of the SFS in Pahrump and …

Effects Of High-Impedance-Contrast Boundary Upon Multi-Modal Seismic Surface Wave Data, Prajwol Tamrakar

UNLV Theses, Dissertations, Professional Papers, and Capstones

Synthetic studies and analyses of an experimental dataset were conducted to address the use of Rayleigh-type surface waves for estimation of shear wave velocity (VS) profiles of shallow bedrock sites. The shallow bedrock presents a high impedance contrast boundary which causes surface wave energy to be partitioned to higher modes. Idealized studies of hypothetical datasets and root-mean-squared calculations of error surfaces showed that if reliable dispersion data are available over a broad frequency spectrum, the VS profile can be recovered using the fundamental mode alone. However, when dispersion data are limited to a relatively narrow frequency band representing what might …

Complex Vs Profiles To 100 M Depth From Rayleigh Waves And 3-D Vs Model For Las Vegas Valley, Helena Murvosh

UNLV Theses, Dissertations, Professional Papers, and Capstones

A three-dimensional (3-D) shear wave velocity (VS) model was developed for the heterogeneous shallow sediments (to nearly 400 m) of the Las Vegas Valley (LVV), Nevada. The model was based on more than 200 VS profiles and 1400 geologic well logs. Five sediment units including a cemented unit were defined from geologic log descriptions. A characteristic VS profile for four of the units was obtained by correlating between closely spaced pairs of VS and sediment data; a constant VS was assigned to the cemented unit. VS profiles were then assigned to each well location based on type of sediment according …

Elastic Plastic Self Consistent (Epsc) Modeling Of Plastic Deformation In Fayalite Olivine, Christopher J. Cline Ii, Pamela Burnley

Festival of Communities: UG Symposium (Posters)

We are using an Elastic Plastic Self Consistent Model (a type of numerical simulation) to study deformation of olivine. Olivine is one of the major constituents of the Earth’s upper mantle and its deformation properties have an important influence on how the Earth’s crust deforms. For example, the flow strength of olivine limits the size of the largest earthquakes and the heights of the tallest mountains on Earth. By comparing the results of our simulations with data from olivine deformation experiments we are able to better interpret the experimental data.

In-Situ Synchrotron X-Ray Diffraction Study Of Quartz Deformation Using The D-Dia Apparatus, May Sas, Dawn Pape, Brian Erickson, Sylvia-Monique Thomas, Pamela Burnley

Festival of Communities: UG Symposium (Posters)

Deformation is a rock’s mechanical response to external parameters such as temperature and pressure. Knowledge of deformation is necessary to understand geodynamic processes. The behavior of rocks and minerals during deformation depends on the behavior of individual grains within those minerals as they interact. The mineral we are studying is quartz, which we chose since it is very well studied and is highly abundant. We use high-pressure high temperature experiments to simulate conditions of Earth’s interior and the D-DIA apparatus combined with synchrotron x-ray diffraction allows us to record data directly during the process of deformation. The data we collect …

Arima Model For Forecasting Poisson Data: Application To Long-Term Earthquake Predictions, Wangdong Fu

UNLV Theses, Dissertations, Professional Papers, and Capstones

Earthquakes that occurred worldwide during the period of 1896 to 2009 with magnitude greater than or equal to 8.0 on the Richter scale are assumed to follow a Poisson process. Autoregressive Integrated Moving Average models are presented to fit the empirical recurrence rates, and to predict future large earthquakes. We show valuable modeling and computational techniques for the point processes and time series data. Specifically, for the proposed methodology, we address the following areas: data management and graphic presentation, model fitting and selection, model validation, model and data sensitivity analysis, and forecasting.

Role Of Forward Model In Surface-Wave Studies To Delineate A Buried High-Velocity Layer, Xiaohui Jin, Barbara Luke, Carlos Calderon-Macias

Civil and Environmental Engineering and Construction Faculty Research

Procedures are tested and compared for processing Rayleigh surface wave data to obtain one-dimensional shear wave velocity profiles for a hypothetical site that contains a buried high-velocity layer (HVL). The main purpose of such an investigation would be to discriminate and characterize the HVL. When target dispersion curves are derived from synthetic time histories, for the most part, the HVL is better identified when profiles are inverted using only the fundamental mode of Rayleigh wave propagation, rather than a more compatible but more complex forward model. The outcomes imply that in practice, a simple forward model might be more successful …

Geoelectrical Response Of Surfactant Solutions In A Quartzitic Sand Analog Aquifer, Meghan Therese Magill

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this project, the resistivity and phase shift of ten surfactant aqueous solutions in a sand matrix were measured using spectral induced polarization (SIP). In addition, specific conductivity, pH, dissolved oxygen, and dielectric constant measurements of the solutions were also evaluated. The frequency range assessed was 0.091-12000Hz. The surfactants, which are typically used in the remediation of tetrachloroethylene, were Aerosol MA 80-I, Dowfax 8390, and Steol CS-330. The surfactants were mixed into solutions of both deionized and tap water at varying concentrations and injected into a closed system of silica sand. The surfactant treatments altered resistivity, specific conductivity, and pH …

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 …

Final Report: Task 22 — Extreme Ground Motion Studies, John G. Anderson, James N. Brune, Jaak J.K. Daemen, Matthew Purvance

Publications (YM)

TASK 22 consisted of two separate investigations into extreme ground motions due to seismic events, Subtask 1 and Subtask 2. Subtask 1 included field studies of geological formations that should put an upper bound on extreme ground motions that have happened at the site of the formations. The locations are critically selected to provide the most effective constraints possible on the validity of the probabilistic seismic hazard analysis for Yucca Mountain. Subtask 2 surveyed recorded ground motions from around the world, with the aim to draw general conclusions from these as to the conditions where extreme ground motions are observed. …