Geophysics and Seismology Commons^™

The First Second Of Volcanic Eruptions From The Erebus Volcano Lava Lake, Antarctica—Energies, Pressures, Seismology, And Infrasound, A. Gerst, M. Hort, R. C. Aster, J. B. Johnson, P. R. Kyle

Geosciences Faculty Publications and Presentations

[1] We describe a multiparameter experiment at Erebus volcano, Antarctica, employing Doppler radar, video, acoustic, and seismic observations to estimate the detailed energy budget of large (up to 40 m-diameter) bubble bursts from a persistent phonolite lava lake. These explosions are readily studied from the crater rim at ranges of less than 500 m and present an ideal opportunity to constrain the dynamics and mechanism of magmatic bubble bursts that can drive Strombolian and Hawaiian eruptions. We estimate the energy budget of the first second of a typical Erebus explosion as a function of time and energy type. We constrain …

Photochemical And Microbial Alteration Of Dissolved Organic Matter In Temperate Headwater Streams Associated With Different Land Use, Yuehan Lu, James E. Bauer, Elizabeth A. Canuel, Youhei Yamashita, R. M. Chambers, Rudolf Jaffe´

FCE LTER Journal Articles

[1] Photochemical and microbial transformations of DOM were evaluated in headwater streams draining forested and human-modified lands (pasture, cropland, and urban development) by laboratory incubations. Changes in DOC concentrations, DOC isotopic signatures, and DOM fluorescence properties were measured to assess the amounts, sources, ages, and properties of reactive and refractory DOM under the influence of photochemistry and/or bacteria. DOC in streams draining forest-dominated watersheds was more photoreactive than in streams draining mostly human-modified watersheds, possibly due to greater contributions of terrestrial plant-derived DOC and lower amounts of prior light exposure in forested streams. Overall, the percentage of photoreactive DOC in …

Reinterpreting The Stratigraphy Of The Florissant Fossil Beds National Monument Through Correlation By Magnetic Susceptibility And Geochemical Comparison, Lindsay Prothro

Honors Theses

No abstract provided.

On The Lack Of Stratospheric Dynamical Variability In Low‐Top Versions Of The Cmip5 Models, Andrew J. Charlton-Perez, Mark P. Baldwin, Thomas Birner, Robert X. Black, Amy H. Butler, Natalia Calvo, Nicholas A. Davis, Edwin P. Gerber, Nathan Gillett, Steven Hardiman, Junsu Kim, Kirsten Krüger, Yun-Young Lee, Elisa Manzini, Brent A. Mcdaniel, Lorenzo Polvani, Thomas Reichler, Tiffany A. Shaw, Michael Sigmond, Seok-Woo Son, Matthew Toohey, Laura Wilcox, Shigeo Yoden, Bo Christiansen, François Lott, Drew Shindell, Seiji Yukimoto, Shingo Watanabe

Faculty and Research Publications

We describe the main differences in simulations of stratospheric climate and variability by models within the fifth Coupled Model Intercomparison Project (CMIP5) that have a model top above the stratopause and relatively fine stratospheric vertical resolution (high-top), and those that have a model top below the stratopause (low-top). Although the simulation of mean stratospheric climate by the two model ensembles is similar, the low-top model ensemble has very weak stratospheric variability on daily and interannual time scales. The frequency of major sudden stratospheric warming events is strongly underestimated by the low-top models with less than half the frequency of events …

Clustering Revisited: A Spectral Analysis Of Microseismic Events, Deborah Fagan, Kasper Van Wijk, James Rutledge

CGISS Publications and Presentations

Identifying individual subsurface faults in a larger fault system is important to characterize and understand the relationship between microseismicity and subsurface processes. This information can potentially help drive reservoir management and mitigate the risks of natural or induced seismicity. We have evaluated a method of statistically clustering power spectra from microseismic events associated with an enhanced oil recovery operation in southeast Utah. Specifically, we were able to provide a clear distinction within a set of events originally designated in the time domain as a single cluster and to identify evidence of en echelon faulting. Subtle time-domain differences between events were …

Elastic Laboratory Measurements And Modeling Of Saturated Basalts, Ludmila Adam, Thomas Otheim

Geosciences Faculty Publications and Presentations

Understanding the elastic behavior of basalt is important to seismically monitor volcanoes, subsea basalts, and carbon sequestration in basalt. We estimate the elastic properties of basalt samples from the Snake River Plain, Idaho, at ultrasonic (0.8 MHz) and seismic (2–300 Hz) frequencies. To test the sensitivity of seismic waves to the fluid content in the pore structure, measurements are performed at three saturation conditions: saturated with liquid CO₂, water, and dry. When CO₂ replaces water, the P-wave velocity drops, on average, by 10%. Vesicles and cracks, observed in the rock microstructure, control the relaxation of pore-fluid pressures …

Neogene Stratigraphy Of The Eski̇şehi̇r Graben And The Investigation Of Coal Deposition By Seismic Reflection Method, İlker Şengüler, Erdener Izladi

Bulletin of the Mineral Research and Exploration

No abstract provided.

2012 Haida Gwaii Quake: Insight Into Cascadia's Subduction Extent, Walter Szeliga

Geological Sciences Faculty Scholarship

The limits of Cascadia were first defined to contain nearly the entire margin of the Pacific Northwest, from Cape Mendocino through the Alaska Panhandle [Schuchert, 1910; Schuchert and Barrell, 1914]. Since that time, the boundary of Cascadia has shrunk to become essentially synonymous with the region where the Juan de Fuca plate subducts beneath the North American plate. As a consequence, seismic hazard assessments in the Pacific Northwest have conventionally focused on the potential for large megathrust earthquakes along the interface of the Juan de Fuca and North American plates.

Recognizing And Modeling Variable Drawdown Due To Evapotranspiration In A Semiarid Riparian Zone Considering Local Differences In Vegetation And Distance From A River Source, Brady Johnson, Bwalya Malama, Warren Barrash, Alejandro N. Flores

CGISS Publications and Presentations

Riparian zones in semiarid regions often exhibit high rates of evapotranspiration (ET) in spite of low-soil moisture content due to the presence of phreatophytic vegetation that is able to withdraw water from shallow aquifers. This work seeks to better define the relationship between ET, the saturated zone and the river boundary by comparing observed water table drawdown records to analytically modeled drawdown in fully penetrating wells of an unconfined aquifer in response to daily ET flux. ET at the Boise Hydrogeophysical Research Site (BHRS), a riparian zone in a temperate, semiarid environment, is calculated using a radiation-based method to provide …

Nucleation And Seismic Tremor Associated With The Glacial Earthquakes Of Whillans Ice Stream, Antarctica, J. Paul Winberry, Sridhar Anandakrishnan, Douglas A. Wiens, Richard B. Alley

All Faculty Scholarship for the College of the Sciences

The ability to monitor transient motion along faults is critical to improving our ability to understand many natural phenomena such as landslides and earthquakes. Here, we usedata from a GPS and seismometer network that were deployed to monitor the regularly repeating glacial earthquakes of Whillans Ice Stream, West Antarctica to show that a unique pattern of precursory slip precedes complete rupture along the bed of the ice stream. Additionally, we show that rupture can be independently tracked by increased levels of microseismic activity, including harmonic tremor, that are coincident with the onset of slip at any location, thus providing a …

Comparison Of Earthquake Source Models For The 2011 Tohoku Event Using Tsunami Simulations And Near‐Field Observations, Breanyn T. Macinnes, Aditya Riadi Gusman, Randall J. Leveque, Yuichiro Tanioka

All Faculty Scholarship for the College of the Sciences

Selection of the earthquake source used in tsunami models of the 2011 Tohoku event affects the simulated tsunami waveform across the near field. Different earthquake sources, based on inversions of seismic waveforms, tsunami waveforms, and Global Positioning System (GPS) data, give distinguishable patterns of simulated tsunami heights in many locations in Tohoku and at near‐field Deep‐ocean Assessment and Reporting of Tsunamis (DART) buoys. We compared 10 sources proposed by different research groups using the GeoClaw code to simulate the resulting tsunami. Several simulations accurately reproduced observations at simulation sites with high grid resolution. Many earthquake sources produced results within 20% …

Validation Of A 'Displacement Tomography' Inversion Method For Modeling Sheet Intrusions, Sarah J. Menassian

Dissertations, Master's Theses and Master's Reports - Open

The study of volcano deformation data can provide information on magma processes and help assess the potential for future eruptions. In employing inverse deformation modeling on these data, we attempt to characterize the geometry, location and volume/pressure change of a deformation source. Techniques currently used to model sheet intrusions (e.g., dikes and sills) often require significant a priori assumptions about source geometry and can require testing a large number of parameters. Moreover, surface deformations are a non-linear function of the source geometry and location. This requires the use of Monte Carlo inversion techniques which leads to long computation times. Recently, …

Amplitude-Versus-Angle Analysis And Wide-Angle-Inversion Of Crosswell Seismic Data In A Carbonate Reservoir, Mohamed S. Ibrahim

Dissertations, Master's Theses and Master's Reports - Open

Crosswell data set contains a range of angles limited only by the geometry of the source and receiver configuration, the separation of the boreholes and the depth to the target. However, the wide angles reflections present in crosswell imaging result in amplitude-versus-angle (AVA) features not usually observed in surface data. These features include reflections from angles that are near critical and beyond critical for many of the interfaces; some of these reflections are visible only for a small range of angles, presumably near their critical angle.

High-resolution crosswell seismic surveys were conducted over a Silurian (Niagaran) reef at two fields …

Seismic Velocity Database For The New Madrid Seismic Zone And Its Vicinity, Qian Li, Edward W. Woolery, Matthew M. Crawford, David M. Vance

Information Circular--KGS

Over the last 20 years, researchers at the University of Kentucky have collected seismic-reflection and refraction data to characterize seismic velocity models of the soil-sediment overburden throughout the central United States. The data are in different forms, such as published reports, theses, and journal articles, and in digital form. In order to construct a unified database for easier management, access, and use, Microsoft Access was used to design the data structure and field properties. The database consists of four tables with unified field names, data type, and units. An ArcGIS geodatabase with the same data structure as the Access database …

Post-Caledonian Brittle Fault Zones On The Hyperextended Sw Barents Sea Margin: New Insights Into Onshore And Offshore Margin Architecture, Kjetil Indrevær, Steffen G. Bergh, Jean-Baptiste Koehl, John-Are Hansen, Elizabeth R. Schermer, Arild Ingebrigtsen

Geology Faculty Publications

Onshore-offshore correlation of brittle faults and tectonic lineaments has been undertaken along the SW Barents Sea margin off northern Norway. The study has focused on onshore mapping of fault zones, the mapping of offshore fault complexes and associated basins from seismic interpretation, and the linkage of fault complexes onshore and offshore by integrating a high-resolution DEM, covering both onshore and offshore portions of the study area, and processed magnetic anomaly data. This study shows that both onshore and offshore brittle faults manifest themselves mainly as alternating NNE–SSW- and ENE–WSW-trending, steeply to moderately dipping, normal fault zones constituting at least two …

On Different Techniques For The Calculation Of Bouguer Gravity Anomalies For Joint Inversion And Model Fusion Of Geophysical Data In The Rio Grande Rift, Azucena Zamora

Open Access Theses & Dissertations

Density variations in the Earth result from different material properties, which reflect the tectonic processes attributed to a region. Density variations can be identified through measurable material properties, such as seismic velocities, gravity field, magnetic field, etc. Gravity anomaly inversions are particularly sensitive to density variations but suffer from significant non-uniqueness. However, using inverse models with gravity Bouguer anomalies and other geophysical data, we can determine three dimensional structural and geological properties of the given area. We explore different techniques for the calculation of Bouguer gravity anomalies for their use in joint inversion of multiple geophysical data sets and a …

Predicting Anthropogenic Streambed Shifts In Beckley, West Virginia, Modeled Over 15 Years Using Landsat Tm And Dems, Andrew D. Reinhardt

Theses, Dissertations and Capstones

Anthropogenic change of streambeds in the Beckley, West Virginia watershed region was modeled using Landsat 5 TM satellite data from 1988 and 2003, and Digital Elevation Model (DEM) data for 1969 and 2005. Comparing the 15 year land cover changes and the 36 year elevation shifts, and using a modified Universal Soil Loss Equation (USLE), in ESRI ArcMap and ERDAS Imagine, a streambed shift model was created. The model predicted land cover and elevation changes for 2018, using inputs from geospatial differencing of 2003 and 1988 land cover as well as 2003 and 1969 DEM data. Further analysis using hydrodynamic …

Formation Of Sprite Streamers At Subbreakdown Conditions From Ionospheric Inhomogeneities Resembling Observed Sprite Halo Structures, Burcu C. Kosar, Ningyu Liu, Hamid K. Rassoul

Aerospace, Physics, and Space Science Faculty Publications

Modeling results of sprite streamer formation from large ionospheric inhomogeneities or patches (several tens to hundreds of meter wide) indicate that positive streamers can be initiated at subbreakdown conditions from the inhomogeneities with a density comparable to sprite halo densities. For spherical patches with a given radius, the minimum density required for streamer initiation decreases with increasing ambient field. For a given density, the minimum size of the inhomogeneity decreases with increasing ambient field. The modeling results on the associated optical emissions show that a luminous spherical-like cap appears around the lower tip of the ionization patch before streamer initiation, …

Callovian (Upper Middle Jurassic) Magnetostratigraphy: A Composite Polarity Pattern From France, Britain And Germany, And Its Correlation To The Pacific Marine Magnetic Anomaly Model, Rachel Anne Gipe

Open Access Theses

Callovian strata from sixteen exposures across western Europe produced a nearly continuous composite geomagnetic polarity reference sequence spanning the latest Bathonian (Clydoniceras discus Zone) through the entire Callovian and into the earliest Oxfordian (Quenstedtoceras mariae zone). This sequence is compiled from multi-section sequences from France and England, a section in southern Germany, and a section on the Isle of Skye (Scotland). These sections are calibrated with ammonite biostratigraphy, brachiopod associations and sequence stratigraphy. Over 400 oriented core samples were subjected to progressive thermal demagnetization and filtered according to magnetic behavior; the highest quality suite produced mean paleopoles of 67.3°N, 174.8°E …

Shear-Wave Imaging And Birefringence In A Complex Near-Surface Geological Environment, Ali Z. Almayahi

Theses and Dissertations--Earth and Environmental Sciences

Multiple geophysical and geological data sets were compiled, reprocessed, and interpreted using state-of-the-art signal processing and modeling algorithms to characterize the complex post-Paleozoic geology that overlies the southwestern projection of the Fluorspar Area Fault Complex (FAFC) in western Kentucky. Specific data included 21.5 km of SH-wave seismic reflection, 1.5 km of P-wave seismic reflection, 2 km of electrical resistivity, vertical seismic profiles, Vp and Vs sonic-suspension logs, and 930 lithologic borehole logs. The resultant model indicates three general northeast–southwest-oriented fault zones pass through the study area as southwestern extensions of parts of the FAFC. These fault zones form two significant …