Geophysics and Seismology Commons^™

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 …

The Impact Of Contact Geometry On Sea Ice Stress And Fracture At The Scale Of Ice Floes, Michael J. May

Dartmouth College Master’s Theses

Observations of stress and strain at the scale of ice floes are necessary to fill a gap in our understanding of sea ice mechanical behavior. Current climate and ice dynamics models represent ice mechanical properties using stress-strain relationships largely determined at laboratory-scale (<1m) or from regional-scale (10+km) deformation observations. The former scale does not include all mechanisms of deformation operating in the ice pack; the latter aggregates multiple modes of deformation into non-physical fluid analogies. The Sea Ice Dynamics Experiment (SIDEx) was run in Feb-Mar 2021 to fill this gap, observing stress and strain at the scale of sea ice failure processes. Here we present stress sensor observations. Stress gages (N=31) were deployed over a 4.5km² area in the southern Beaufort Sea to observe in-situ stress. These data were analyzed in the context of deformation observations from satellite imagery and local laser and radar interferometers to explain the drivers of sea ice stress variations before and after fracture. Three case studies between 14 March and 24 March, during which fractures propagated through …

Hydrogeologic Investigation Of A Covered Karst Terrain, Joseph Peter Honings

LSU Doctoral Dissertations

Increasing demand for water for agricultural use within the Dougherty Plain of the Southeastern United States has depleted surface water bodies. In karstic landscapes, such as the Dougherty Plain in southwest Georgia where the linkages between surface and ground waters are close, there is a need to understand the physical characteristics of the subsurface that allow these close linkages. Having a better understanding of the subsurface characteristics will aid numerical modeling efforts that underpin policy decisions and economic analyses. Two common features on this karstic landscape are draws and geographically isolated wetlands. Using LiDAR, aerial imagery, and ground-penetrating radar, this …

Approaches To Model Non-Uniqueness And Site Complexity For Non-Invasive Shear-Wave Depth Profiling, Christopher Boucher

Electronic Thesis and Dissertation Repository

Shear-wave velocity (VS) depth profiling and associated seismic site classifications were performed at 15 sites across Metro Vancouver, British Columbia using passive seismic and surface wave methods. Inversion model parameters are constrained at each site using nearby geodata in combination with developing regression models of shear-wave velocity with depth for three primary stratigraphic units. Statistical methods such as a Bayesian Information Criterion are applied post-inversion to evaluate models between and within varying parameterizations. Data evaluation metrics, including the use of microtremor horizontal-to-vertical spectral ratios (MHVSRs), are applied to identify two common deviations from the simple case of normally dispersive laterally …

Infrasonic Gliding Reflects A Rising Magma Column At Mount Etna (Italy), Mariangela Sciotto, Leighton M. Watson, Andrea Cannata, Massimo Cantarero, Emanuela De Beni, Jeffrey B. Johnson

Geosciences Faculty Publications and Presentations

Infrasound is increasing applied as a tool to investigate magma dynamics at active volcanoes, especially at open-vent volcanoes, such as Mt. Etna (Italy), which are prodigious sources of infrasound. Harmonic infrasound signals have been used to constrain crater dimensions and track the movement of magma within the shallow plumbing system. This study interprets the remarkable systematic change in monotonic infrasound signals preceding a lava fountaining episode at Mt. Etna on 20 February 2021. We model the changing tones (0.7 to 3 Hz fundamental frequency) as a rise in the magma column from 172 ± 25 m below the crater rim …

Cascadia Subduction Zone Earthquake Vertical Ground Acceleration Investigation And Potential Impact On Bridges In The Pacific Northwest, Rachel Caroline Bassil

Civil and Environmental Engineering Master's Project Reports

The effects of vertical ground accelerations during subduction zone earthquakes currently are not sufficiently understood. There are numerous case studies and evidence that effects of vertical ground accelerations can significantly impact the performance of bridges during a seismic event, but most previous research has been focused on shallow crustal earthquakes. Current bridge design codes provide little guidance for accounting for vertical ground accelerations in seismic design, in part because additional information is needed about the characteristics of vertical ground motions during Cascadia Subduction Zone (CSZ) earthquakes in the Pacific Northwest.

For this study, recorded seismic data from recent subduction zone …

Upper-Plate Structure And Tsunamigenic Faults Near The Kodiak Islands, Alaska, Usa, Marlon D. Ramos, Lee M. Liberty, Peter J. Haeussler, Robert Humphreys

Geosciences Faculty Publications and Presentations

The Kodiak Islands lie near the southern terminus of the 1964 Great Alaska earthquake rupture area and within the Kodiak subduction zone segment. Both local and trans-Pacific tsunamis were generated during this devastating megathrust event, but the local tsunami source region and the causative faults are poorly understood. We provide an updated view of the tsunami and earthquake hazard for the Kodiak Islands region through tsunami modeling and geophysical data analysis. Using seismic and bathymetric data, we characterize a regionally extensive seafloor lineament related to the Kodiak shelf fault zone, with focused uplift along a 50-km-long portion of the newly …

Review Article: Global Monitoring Of Snow Water Equivalent Using High-Frequency Radar Remote Sensing, Hans-Peter Marshall

Geosciences Faculty Publications and Presentations

Seasonal snow cover is the largest single component of the cryosphere in areal extent, covering an average of 46 × 10⁶ km² of Earth's surface (31 % of the land area) each year, and is thus an important expression and driver of the Earth's climate. In recent years, Northern Hemisphere spring snow cover has been declining at about the same rate (∼ −13 % per decade) as Arctic summer sea ice. More than one-sixth of the world's population relies on seasonal snowpack and glaciers for a water supply that is likely to decrease this century. Snow is also …

Nsf Supported Socio-Environmental Research: How Do Crosscutting Programs Affect Research Funding, Publication, And Citation Patterns?, Kendra E. Kaiser, Anna E. Braswell, Megan L. Fork

Geosciences Faculty Publications and Presentations

Recognizing the continued human domination of landscapes across the globe, social-ecological systems (SES) research has proliferated, necessitating interdisciplinary collaborations. Although interdisciplinary research started gaining traction in academic settings close to 50 years ago, formal frameworks for SES research did not develop until the late 1990s. The first National Science Foundation (NSF) funding mechanism specifically for interdisciplinary SES research began in 2001 and the SES-specific Coupled Natural Human (CNH) Systems program began in 2007. We used data on funded NSF projects from 2000 to 2015 to examine how SES research was funded, where the research is published, and the scholarly impact …

The Geochemical Evolution Of Santa Cruz Island, Galápagos Archipelago, E. L. Wilson, K. S. Harpp, D. M. Schwartz, R. Van Kirk

Geosciences Faculty Publications and Presentations

Understanding how ocean island volcanoes evolve provides important insight into the behavior of mantle plumes, how plumes interact with mid-ocean ridges, and potential risks posed to inhabitants as the islands age. In this field-based study of the Galápagos Islands, we use radiogenic isotope ratio, major element, and trace element analysis of >70 new lava samples to document the geochemical evolution of Santa Cruz Island over the past ∼2 million years, as it has been carried away from the plume. Currently, Santa Cruz is a dormant shield volcano in the central archipelago. Previous work indicates that exposed lavas preserve >1 million …

Diverse Magmatic Evolutionary Trends Of The Northern Andes Unraveled By Paleocene To Early Eocene Detrital Zircon Geochemistry, James L. Crowley

Geosciences Faculty Publications and Presentations

The Paleocene-early Eocene continental magmatic arc (PECMA) in the Northern Andes is an example of arc magmatism following a major collisional event. This arc formed after the arc-continent collision between the Caribbean Plate and the South American continental margin at ca. 72 Ma. We used detrital zircon LA-ICP-MS and CA-ID-TIMS geochronology and geochemistry to complement the limited plutonic record of the PECMA and better characterize the PECMA's magmatic evolution. Zircon geochronology and their respective trace element geochemistry were analyzed from Paleocene-early Eocene strata of the Bogotá Formation in the foreland region. Our results show that after the collision of the …

Relative Timing Of Off-Axis Volcanism From Sediment Thickness Estimates On The 8°20’N Seamount Chain, East Pacific Rise, Andrea Fabbrizzi, Ross Parnell-Turner, Patricia M. Gregg, Daniel J. Fornari, Michael R. Perfit, V. Dorsey Wanless, Molly Anderson

Geosciences Faculty Publications and Presentations

Volcanic seamount chains on the flanks of mid-ocean ridges record variability in magmatic processes associated with mantle melting over several millions of years. However, the relative timing of magmatism on individual seamounts along a chain can be difficult to estimate without in situ sampling and is further hampered by Ar⁴⁰/Ar³⁹ dating limitations. The 8°20’N seamount chain extends ∼170 km west from the fast-spreading East Pacific Rise (EPR), north of and parallel to the western Siqueiros fracture zone. Here, we use multibeam bathymetric data to investigate relationships between abyssal hill formation and seamount volcanism, transform fault slip, and …

Low-Volume Magmatism Linked To Flank Deformation On Isla Santa Cruz, Galápagos Archipelago, Using Cosmogenic 3He Exposure And 40Ar/39Ar Dating Of Fault Scarps And Lavas, D. M. Schwartz, K. Harpp, M. D. Kurz, E. Wilson, R. Van Kirk

Geosciences Faculty Publications and Presentations

Isla Santa Cruz is a volcanic island located in the central Galápagos Archipelago. The island’s northern and southern flanks are deformed by E–W-trending normal faults not observed on the younger Galápagos shields, and Santa Cruz lacks the large summit calderas that characterize those structures. To construct a chronology of volcanism and deformation on Santa Cruz, we employ ⁴⁰Ar/³⁹Ar geochronology of lavas and ³He exposure dating of fault scarps from across the island. The combination of Ar–Ar dating with in situ-produced cosmogenic exposure age data provides a powerful tool to evaluate fault chronologies. The ^{40 …}

Airborne Snowsar Data At X And Ku Bands Over Boreal Forest, Alpine And Tundra Snow Cover, Hans-Peter Marshall

Geosciences Faculty Publications and Presentations

The European Space Agency SnowSAR instrument is a side-looking, dual-polarised (VV/VH), X/Ku band synthetic aperture radar (SAR), operable from various sizes of aircraft. Between 2010 and 2013, the instrument was deployed at several sites in Northern Finland, Austrian Alps and northern Canada. The purpose of the airborne campaigns was to measure the backscattering properties of snow-covered terrain to support the development of snow water equivalent retrieval techniques using SAR. SnowSAR was deployed in Sodankylä, Northern Finland, for a single flight mission in March 2011 and 12 missions at two sites (tundra and boreal forest) in the winter of 2011–2012. Over …

Regolith And Host Rock Influences On Co2 Leakage: Active Source Seismic Profiling Across The Little Grand Wash Fault, Utah, Lee M. Liberty, Jonathan Yelton, Elin Skurtveit, Alvar Braathen, Ivar Midtkandal, James P. Evans

Geosciences Faculty Publications and Presentations

Understanding carbon dioxide (CO₂) reservoir to surface migration is crucial to successful carbon capture and sequestration approaches; especially fault/reservoir interactions under injection pressure. Through seismic imaging, we explore regolith and shallow stratigraphy across the Little Grand Wash fault. The presence of natural CO₂ seeps, travertine and tufa deposits confirm modern and ancient fault-controlled CO₂ leakage. We consider this an analogue for a long-failed sequestration site. We estimate bulk porosity and fracture density for host rock, regolith, and fault zone from petrophysical relationships. When combined with existing geochemical and geological data, we characterize a 60 m wide …

A Transformer-Based Classification System For Volcanic Seismic Signals, Anthony P. Rinaldi, Cindy Mora Stock, Cristián Bravo Roman, Alexander Hemming

Undergraduate Student Research Internships Conference

Monitoring volcanic events as they occur is a task that, to this day, requires significant human capital. The current process requires geologists to monitor seismographs around the clock, making it extremely labour-intensive and inefficient. The ability to automatically classify volcanic events as they happen in real-time would allow for quicker responses to these events by the surrounding communities. Timely knowledge of the type of event that is occurring can allow these surrounding communities to prepare or evacuate sooner depending on the magnitude of the event. Up until recently, not much research has been conducted regarding the potential for machine learning …

Geomechanical Modeling Of A Fault During Fluid Injection, Charles Kw Hulls

Electronic Thesis and Dissertation Repository

The injection of fluid into rock masses as a part of industrial processes, such as hydraulic fracturing, can lead to an increase in seismic activity. The movement of the injected fluid and resulting stresses can be simulated and analyzed. One aspect of this analysis is the predicted rate of seismic activity, obtained via the Dietrich rate-and-state law and the Coulomb Failure Stress. This work produces simulations for two fracturing scenarios in the Duvernay Shale region. Model parameters, such as layer permeability and timing of fault slip, are varied to determine their impact on the model results. The simulated results show …

Development Of Deep Shear Wave Velocity Profiles And An Approach To Generate Site Signature Consistent Pseudo Shear Wave Velocity Profiles In The Mississippi Embayment, Ashraf Kamal Himel

Graduate Theses and Dissertations

This dissertation details the development of a surface wave method (SWM) technique to generate deep shear wave velocity profiles (VS profiles), applying this technique at 24 sites across the Mississippi embayment and developing an approach to generate pseudo site signature consistent VS profiles from velocity functions and fundamental frequency. In the presented SWM technique, active and passive source surface wave measurements are inverted along with fundamental frequency to develop a site signature consistent VS profile. Multiple transformation methods, including MSPAC, HRFK and FK are used to resolve experimental dispersion data from surface wave measurements. SWM VS profile at the Central …

Coastal Geomorphic Response To Sea-Level Rise, Storms, And Antecedent Geology: Examples From The Northern Gulf Of Mexico, Clayton Dike

Dissertations

Sea-level rise and tropical cyclone activity are threatening coastlines around the world. Past geologic coastal responses can be used to inform future scenarios. This three-part study examines the response of coastal systems to sea-level rise, storms, sediment supply, and antecedent geology over the past ~ 140 ka.

The first study is of the Bay St. Louis, Mississippi, coastal system along the northern Gulf of Mexico incorporating sediment supply, subsidence, and antecedent topography paired with an examination of geologic response to sea-level fall and rise. I used core and geophysical data that resolve incised valleys and other subsurface deposits from ~ …

Advancements In Measuring And Modeling The Mechanical And Hydrological Properties Of Snow And Firn: Multi-Sensor Analysis, Integration, And Algorithm Development, Tate G. Meehan

Boise State University Theses and Dissertations

Estimating snow mechanical properties – such as elastic modulus, stiffness, and strength – is important for understanding how effectively a vehicle can travel over snow-covered terrain. Vehicle instrumentation data and observations of the snowpack are valuable for improving the estimates of winter vehicle performance. Combining in-situ and remotely-sensed snow observations, driver input, and vehicle performance sensors requires several techniques of data integration. I explored correlations between measurements spanning from millimeter to meter scales, beginning with the SnowMicroPenetrometer (SMP) and instruments applied to snow that were designed for measuring the load bearing capacity and the compressive and shear strengths of roads …