Geophysics and Seismology Commons^™

Mapping Along-Strike Changes In Shallow Subduction Zone Geometry At The Alaska Subduction Zone Using Seismic Reflection And Tectono-Geomorphic Analysis, Madelyn K. Hurd

Earth and Planetary Sciences ETDs

The Alaska subduction zone, where the oceanic Pacific plate subducts beneath the continental North American plate at a rate of 60-66 mm/yr, has hosted more >M8 earthquakes over the last century than any other subduction zone globally. The largest of these, the 1964 M9.2 Alaska earthquake, ruptured 800 km of the margin, including a high slip patch near the trench offshore Kodiak Island. The 1964 rupture area may have overlapped with the 1938 M8.3 Semidi earthquake rupture zone that lies to the west. Slip propagation near the subduction trench during large earthquakes can control tsunamigenesis, and differences in wedge geometry …

Exploring The Role Of A Mushy, Crustal Compliant Region In Volcano Deformation, Grant A. Block

Physics & Astronomy ETDs

Volcanoes are both creative and destructive forces that have shaped and continue to shape our world from early geologic time to the present day. Continued study of volcanic processes not only better prepares us for monitoring volcanic hazards but also allows us to better understand processes fundamental to Earth as we know it, such as the generation of the atmosphere and accretion of the continents. This dissertation focuses on an integral part of volcanic processes: the trans-crustal magmatic transport system. Specifically, we investigate regions of these transport systems where magma pools in melt-rich lenses within broader regions of low melt-fraction, …

Marine Geophysical Studies Of Coupled Tectonic And Sedimentary Processes At Active Plate Boundaries, Sarah R. Rysanek

Earth and Planetary Sciences ETDs

Deep-sea and convergent margin sedimentary systems preserve critical records of tectonic and climatic processes that shape Earth’s surface. This dissertation investigates source-to-sink sediment routing and forearc deformation to better constrain the interplay between sedimentary and tectonic processes, through investigations of a deep-sea fan system, and the forearc geomorphology offshore Nicaragua. In the Gulf of Alaska, we integrate ultra-long-offset and regional multi-channel seismic reflection data, multi-resolution bathymetry, and plate reconstructions to remap the Baranof Fan system. Results show that the fan is larger than previously recognized and constructed by two primary depocenters linked to distinct glacial sediment pathways, with accommodation space …

Seismological Investigations Of Magmatic Systems Using Dense Nodal Arrays, Wenkai Song

Earth and Planetary Sciences ETDs

Understanding the internal architecture of magmatic systems is crucial for volcanology, yet conventional geophysical techniques often lack the resolution to image their fine-scale structures. This dissertation leverages unique datasets from dense nodal arrays to investigate the upper crustal magmatic systems beneath Yellowstone Caldera, Valles Caldera, and Mount St. Helens. At Yellowstone, I processed vibroseis data to delineate the top of the modern magma reservoir and evaluate the thermal connection between the magmatic and the overlying hydrothermal systems. At Valles, 3D radial seismic anisotropy imaging reveals strong positive radial anisotropy within the reservoir, indicating an organized structure of horizontally sill-like melt …

Integrating Satellite Observations And Modeling Approaches To Study Tectonic And Land Surface Hazards, Jeng Hann Chong

Earth and Planetary Sciences ETDs

The increasing availability of Earth observation satellites, such as SAR and optical platforms, has improved our ability to study the ground deformation processes during, after, and leading up to these natural hazards, such as earthquakes and debris flows. In this dissertation, I analyze satellite geodetic interseismic velocities across the Rakhine-Bangladesh megathrust and the influence of having realistic modeling assumptions for subduction zones to better constrain seismic hazard. I also examined changes in post-fire debris flow likelihood four years after the 2020 Lake Fire in Southern California using a suite of satellite data and field observations. Together, these studies highlight how …

Seeking Structure In Complex Systems: From Feature Analysis To Space-Time Causal Discovery With Earth Science Applications, Jeffrey J. Nichol

Computer Science ETDs

Complex systems are difficult to study because of their many interacting parts, emergent phenomena, and feedback loops. These systems underpin all life on Earth. We need improved tools for seeking an understanding of them. This body of research presents my investigations into data-driven methods for understanding complex systems, including my invention of a novel causal discovery meta-algorithm for space-time gridded data. I demonstrated machine learning feature importance and causal discovery capabilities for comparing simulated and observed climate data. I developed a new benchmark for modeling space-time dynamics of locally driven phenomena and examined a prominent causal discovery algorithm. Finding that …

Seismological Applications To Crustal Deformation And Explosion Discrimination, Olumide Adedeji

Earth and Planetary Sciences ETDs

There are many outstanding questions in seismology and plate tectonics that remain unresolved due to the complexity of seismic wave propagation, fault system evolution, and sedimentary-tectonic interactions. In this dissertation, I analyze seismic and acoustic data to improve event discrimination, understand strain partitioning along a transpressive plate boundary, and investigate the influence of tectonic deformation on sedimentary processes. Using seismic arrays, I assess the detectability of Ground Coupled Airwaves (GCA) generated by shallow borehole explosions and earthquakes, demonstrating that GCA detections are highly dependent on source type, environmental conditions and sensor distribution. Along the Queen Charlotte Plate Boundary, I analyze …

Ambient Noise Tomography Of The Southern M9.2 1964 Great Alaska Earthquake Rupture Area, Joshua Ojuoluwa Osasona

Earth and Planetary Sciences ETDs

We used data from a densely spaced node array to investigate seismic velocity structure within the southern rupture area of the M9.2 1964 Great Alaska earthquake. The node array was deployed along a ~50 km section of the road system on Kodiak Island as part of the Alaska Amphibious Community Seismic Experiment (AACSE). The full ~400-node array was active for 25 days in May-June 2019. We extracted Rayleigh wave dispersion curves from ambient noise cross-correlations between station pairs in the node array to compute phase velocity maps from 2-8 s periods. Using these phase velocity maps, we performed a Bayesian …

Crustal Structure And Evolution Of The Queen Charlotte Plate Boundary, Collin C. Brandl

Earth and Planetary Sciences ETDs

There are many outstanding questions in plate tectonics that remain unanswered because large regions of the Earth are unexplored, both at the surface and in the subsurface. In this dissertation, I processed and analyzed active source seismic reflection data from the historically understudied Queen Charlotte transform plate boundary. Using this dataset, I found that the southern segment of the plate boundary has active underthrusting, is analogous to subduction zone crustal slivers, and is a site of early subduction initiation. Along the entire plate boundary, I constrained the near-surface thermal gradient using the stability of gas hydrate, finding that it is …

Gnss And Insar Observations Of Vertical Motion In The Valles Caldera, Nm, Savannah Chase Devine

Earth and Planetary Sciences ETDs

The Valles caldera is a rhyolitic “supervolcano” formed 1.231 Ma. An understanding of whether Valles caldera is currently deforming is needed to inform volcanic hazard estimates for northern New Mexico and will allow for a better understanding of the hazards presented by other rhyolitic caldera systems. Here, we present an InSAR time series of the Valles Caldera using 37 interferograms, spanning 2014 to 2022, which show a small but consistent signal of broad pattern subsidence/yr. We also present GNSS observations from a survey conducted in October 2022 and compare the results to surveys in 2002 and 2003 to estimate the …

Online Temporal Data Mining And Learning: Pursuing Enhanced Efficiency And Robust Algorithms, Sheng Zhong

Computer Science ETDs

Time series data mining and learning serve as a cornerstone across various domains, including finance, healthcare, and science. Recent advancements in network and sensor technologies have ignited an increasing interest in real-time temporal data mining and learning techniques. Various tasks benefit from these techniques, such as environmental monitoring, event detection, anomaly identification, and forecasting. However, these techniques still face significant challenges in the online environment settings, encompassing aspects like efficiency, accuracy, robustness, and scarcity of labeled data. This dissertation presents four innovative solutions: FilCorr, DCT-MASS, FewSig, and BitLINK to overcome these challenges. We evaluate each method and showcase their practical …

Applications Of Observational Seismology: Insights Into Volcanic And Near Surface Processes, Justin T. Wilgus

Earth and Planetary Sciences ETDs

The field of observational seismology has made tremendous progress in the past two decades. This progress has been multi-faceted in form, but significant contributions emanated from 1) increases in both the quality and the quantity of seismic data 2) advances in computational power 3) advances in algorithmic capability, including machine learning. In this dissertation I report on three distinctly different seismic applications made possible by the aforementioned progress and discuss the insights these applications have provided in understanding volcanic and near surface processes of the Earth.

In the first chapter titled, “Shear Velocity Evidence of Upper Crustal Magma Storage Beneath …

Seismic Analysis Of The Upper & Lower Falls Of The Yellowstone River, Loring Schaible

Earth and Planetary Sciences ETDs

Twelve years of concurrent hydrologic and continuous seismic data along with temporary seismic data demonstrate that the Upper and Lower Falls of the Grand Canyon of the Yellowstone River comprise a highly localized source of 0.5-5 Hz seismic energy that overwhelms anthropogenic contributions. In aggregate, seismic amplitude from 2008-2019 is linearly related to discharge with a correlation coefficient of 0.96. Repeated deviations from this linear relationship persist for 1-2 weeks prior to the date that Yellowstone Lake becomes clear of winter ice coverage. Seismic efficiency increases by ~50-250% during this period of ice-breakup, during which lake ice flows into the …

Seismic Shadow Zone Investigation In The Upper Magma Reservoir Of The Yellowstone Caldera, Sarah Nolt-Caraway

Earth and Planetary Sciences ETDs

This study investigates whether the Yellowstone Caldera has enough melt to mute S-waves, creating a seismic shadow zone. Using a dense nodal deployment of ~650 stations, 7-9 earthquakes during the nodal deployment, and 21 broadband stations with 3,000-4,000 events per station; amplitude and noise maps, seismograms, and automatic phase picks probabilities from a deep learning model were analyzed to assess the potential role of melt, crustal attenuation, and noise in affecting body waves, particularly S-phases. The results are inconclusive, with unclear evidence whether observed amplitude decay is normal signal decay due to distance, noise-related, melt, or from scattering and intrinsic …

Single-Crystal Elasticity Of Earth’S Mantle Transition Zone Minerals And High Pressure-Temperature Phase Equilibrium Experiments On Martian Basalts, Wenyi Zhou

Earth and Planetary Sciences ETDs

Wadsleyite and ringwoodite are major minerals in the Earth’s Mantle Transition Zone. Global and local seismic studies have detected strong lateral variations in seismic velocity and anisotropy in the Mantle Transition Zone, reflecting temperature and possible composition variations. Interpretation of these seismic observations requires knowledge of thermoelastic properties of wadsleyite and ringwoodite with different compositions (water and Fe contents) under high pressure-temperature conditions. In this dissertation, we have measured single-crystal elastic properties of wadsleyite and ringwoodite under high pressure-temperature conditions by Brillouin spectroscopy. Based on our measurements and previous experimental results, we further model the effects of water and Fe …

Induced Seismicity In The Raton Basin And Global Variability Of The 410-Km Discontinuity, Margaret E. Glasgow

Earth and Planetary Sciences ETDs

Natural processes like mantle convection and plate tectonics dominate Earth’s seismic structure. Recently human activities have increasingly influenced the deformation of the shallow crust. In this dissertation, passive source seismology was used to constrain seismic discontinuities in the mantle transition zone and seismogenic structures in induced earthquake settings. Using a novel sampling method and uniform processing approach, I found the 410-km discontinuity is thermally and compositionally variable. Using a machine- learning approach, I found the three main zones of seismicity in the Raton Basin consist of short faults or fault segments with variable orientations. The zone that hosted a Mw …

Dense Array Seismic Imaging Of Earth's Crust Using Active And Passive Sources, Evans Awere Onyango

Earth and Planetary Sciences ETDs

Imaging Earth’s crust is critical to understanding processes in the near-surface that affect civilization such as the interaction of seismic waves with the near-surface to generate natural or man-made hazards or investigating how the shallow crust affects the distribution of resources. In chapter 1, I processed and analyzed active source seismic data recorded by ~1000 geophones that were acquired over the legacy HADDOCK nuclear test at the Nevada National Security Site. Using seismic reflection and refraction methods, we image the partially collapsed post-detonation structure to better understand the velocity structure in and around the HADDOCK chimney. Results from this work …

Observational Constraints On The 520 Km Mantle Discontinuity, Mantle Transition Zone Anisotropy, And Local Seismicity At Mount St. Helens, Han Zhang

Earth and Planetary Sciences ETDs

Seismology provides valuable observational constraints to thermal and compositional states at inaccessible depths via understanding how elastic wave propagating through them. While many of fundament questions regarding solid Earth structures have been addressed during its more than 100 years history, some details remain unfilled and carefully designed approaches are needed to complete the pictures. This dissertation contributes observational constraints on three topics with newly developed methods. 1) We detected a controversial mantle discontinuity at about 520 km and concluded a mean mantle composition close to the Pyrolite model based on its seismic properties. 2) We isolated anisotropic effects in mantle …

An Interdisciplinary Approach To Understanding Volcanoes And Their Processes, Katherine Cosburn

Physics & Astronomy ETDs

To better understand volcanoes and their processes is important from both a fundamental science perspective and for hazard monitoring purposes. The complexity and limitations we face in pursuing such a science are numerous and this dissertation explores how an interdisciplinary approach combining physics, computer science, and volcanology can address this complexity in a straightforward and meaningful way. This is achieved through various modelling techniques across three studies: (1) a first-order analytic modelling of stratovolcano topographic shape, (2) the use of a Bayesian joint inversion on gravity and novel cosmic-ray muon measurements for imaging flat-lying subsurface density anomalies, and (3) the …

Ultralow Velocities Of Caco3 And The Origin Of Seismic Anomalies In The Earth's Upper Mantle, Mingqiang Hou, Ming Hao, Jin Liu, Xiaowan Su, Wen-Yi Zhou, Rostislav Hrubiak, Jin S. Zhang

Earth and Planetary Sciences Faculty and Staff Publications

Calcium carbonate (CaCO₃) is a major host for CO₂ in the deep Earth. The physical and chemical properties of CaCO₃ at extreme pressure-temperature (P-T) conditions are indispensable to decipher the circulation of carbon between the Earth's interior and surface via volcanism and subduction. Using the pulse-echo-overlap method combined with Paris-Edinburgh press, we measured velocities of CaCO₃ and observed an anomalous drop associated with the amorphization of aragonite under upper mantle conditions. The compressional (V_P) and shear (V_S) wave velocities of the partially amorphized CaCO₃ are reduced …

Quaternary Shelf-Slope Development In The Northern Gulf Of Alaska From Combined Geophysical And Geomorphologic Analysis, Wesley A. Clary

Earth and Planetary Sciences ETDs

This dissertation follows the hybrid format as defined by the Office of Graduate Studies at the University of New Mexico. The three chapters defined herein were prepared as manuscripts to be submitted for publication in peer reviewed journals in the field of Earth sciences. A version of chapter 1 was published in Proceedings of the Integrated Ocean Drilling Program, 2017, Volume 41. Chapter 2 was submitted to Marine Geology in Feb 2020, and is under revision as of this date. A version of chapter 3 will be submitted to the Journal of Geophysical Research. In chapter 1, I …

Nonlinear Least Squares 3-D Geolocation Solutions Using Time Differences Of Arrival, Michael V. Bredemann

Mathematics & Statistics ETDs

This thesis uses a geometric approach to derive and solve nonlinear least squares minimization problems to geolocate a signal source in three dimensions using time differences of arrival at multiple sensor locations. There is no restriction on the maximum number of sensors used. Residual errors reach the numerical limits of machine precision. Symmetric sensor orientations are found that prevent closed form solutions of source locations lying within the null space. Maximum uncertainties in relative sensor positions and time difference of arrivals, required to locate a source within a maximum specified error, are found from these results. Examples illustrate potential requirements …

Using Archaeological Remote Sensing To Evaluate Land Use And Constructed Space In Chaco Canyon, Jennie Odessa Sturm

Anthropology ETDs

Archaeological remote sensing includes a suite of non-invasive methods that can be used to study elements of the archaeological record that may not be achievable otherwise. Using primarily geophysical remote sensing, and especially ground-penetrating radar (GPR), three studies involving questions of “use” were conducted in Chaco Canyon, New Mexico. The first used GPR to study the built interior features of a single room in Pueblo Bonito to evaluate use and function of that room. Three categories of features were identified in the GPR data and confirmed with subsequent excavation. The second study used GPR to re-evaluate an enigmatic land use …

Crustal Structure Beneath The East Coast Magnetic Anomaly From Seismic Refraction Tomography, Collin C. Brandl

Earth and Planetary Sciences ETDs

Syn-rift igneous addition is necessary for successful continental breakup. Past investigations of passive margins have focused on strike perpendicular structure, but potential field anomalies indicate that significant crustal variations may be present. Data from 21 ocean bottom seismometers was acquired as part of the Eastern North American Margin Community Seismic Experiment and was used for tomographic inversion to create 2D velocity models of the margin that are representative of crustal structure. Crustal thickness varies along-strike from ~20 km to ~24 km and a high velocity (Vp > 7 km/s) layer is present at the base of the crust above the Moho. …

How To Celebrate 24 New Year's Eves In A Single Year!, Florentin Smarandache

Branch Mathematics and Statistics Faculty and Staff Publications

New Year's Eve 2018 reaches me on Jeju Island, South Korea, in the East China Sea. While I had spent New Year's Eve 2017 in Galapagos Islands, in the Pacific. We can celebrate 24 New Year's Eves in a single year, moving to the West – for example in an orbital spacecraft - (in the reverse sense of Earth's rotation around its axis) at a faster angular speed than Earth's rotation, jumping from one time-zone to another, and starting from the International Date Line. { In this paper we are referring to the solar day, hence to the angular speed …

Crustal Seismic Anisotropy Of The Ruby Mountains Core Complex And Surrounding Northern Basin And Range, Justin T. Wilgus

Earth and Planetary Sciences ETDs

Metamorphic core complexes (MCC) are distinctive uplifts that expose deeply exhumed and deformed crustal rocks due to localized extensional deformation. Consequently, their detailed structure provide a window into deep crustal mechanics. The North American Cordillera contains numerous MCC, one of which is the Ruby Mountains core complex (RMCC) located in the highly extended northern Basin and Range. To constrain the extent to which anisotropy below the RMCC deviates from the regional Basin and Range average and test the depth dependence of crustal anisotropy we conduct a radial anisotropy investigation below the RMCC and surrounding northern Basin and Range. Data from …

Dense-Array Teleseismic Imaging Of The Southern Albuquerque Basin, Tori S. Finlay

Earth and Planetary Sciences ETDs

The southern Albuquerque basin is a complex area of high extension, multiple orogenies, and ongoing uplift from a midcrustal magma body in which geophysical coverage is sparse. In this thesis, I capitalize on recent innovations in dense-array processing techniques to create virtual source reflection profiles from five teleseismic events during the deployment of the Sevilleta array. The Sevilleta array consisted of ~800 vertical component nodes with ~300 m spacing deployed for 10 days in February of 2015. Virtual source reflection profiles are created by using the free surface of the earth as a virtual seismic source, yielding profiles that mimic …

Classifying Microseismicty At Mount St. Helens Using A Large-N Array, Margaret E. Glasgow

Earth and Planetary Sciences ETDs

A dense array of ~1,000 continuously recording, short-period geophones was deployed in the summer of 2014 within ~15 km of Mount St. Helens. Two earthquake catalogs created using reverse time imaging and template detection techniques, increase the detection rate and completeness of the earthquake catalog when compared to the permanent network, Pacific Northwest Seismic Network, catalog. An investigation into event type for ~200 of the earthquake detections leads to the discrimination of two major classification groups, volcano-tectonic and long period. Previous to this study, long period earthquakes had not been identified in the upper crust during a volcanically inactive period …