Geophysics and Seismology Commons^™

New Magnetic Field Models Of The Moon, Dhananjay Ravat, Michael E. Purucker, Nils Olsen

Earth and Environmental Sciences Research Data

We use L1-norm model regularization of |B_r| component at the surface on magnetic monopoles bases and along-track magnetic field differences alone (without vector observations) to derive high quality global magnetic field models at the surface of the Moon. The practical advantages to this strategy are: monopoles are more stable at closer spacing in comparison to dipoles, improving spatial resolution; L1-norm model regularization leads to sparse models which may be appropriate for the Moon which has regions of localized magnetic field features; and along-track differences reduce the need for ad-hoc external field noise reduction strategies. We examine also the …

Orogenic Link ∼41°N–46°N: Collisional Mountain Building And Basin Closure In The Cordillera Of Western North America, Keith D. Gray, V. Isakson, D. Schwartz, Jeffrey D. Vervoort

Geosciences Faculty Publications and Presentations

Polyphase structural mapping and mineral age dating across the Salmon River suture zone in west-central Idaho (Riggins region; ∼45°30′N, ∼117°W–116°W) support a late Mesozoic history of penetrative deformation, dynamothermal metamorphism, and intermittent magmatism in response to right-oblique oceanic-continental plate convergence (Farallon–North America). High-strain linear-planar tectonite fabrics are recorded along an unbroken ∼48 km west-to-east transect extending from the Snake River (Wallowa intra-oceanic arc terrane; eastern Blue Mountains Province) over the northern Seven Devils Mountains into the lower Salmon River Canyon (ancestral North America; western Laurentia). Given the temporally overlapping nature (ca. 145–90 Ma) of east-west contraction in the Sevier fold-and-thrust …

Co-Eruptive Tremor From Bogoslof Volcano: Seismic Wavefield Composition At Regional Distances, Matthew M. Haney, David Fee, Kathleen F. Mckee, John J. Lyons, Robin S. Matoza, Aaron G. Wech, Gabrielle Tepp, Cheryl Searcy, T. Dylan Mikesell

Geosciences Faculty Publications and Presentations

We analyze seismic tremor recorded during eruptive activity over the course of the 2016–2017 eruption of Bogoslof volcano, Alaska. Only regional recordings of the tremor wavefield exist for Bogoslof, making it a challenge to place the recordings in context with other eruptions that are normally captured by local seismic data. We apply a technique of time-frequency polarization analysis to three-component seismic data to reveal the wavefield composition of Bogoslof eruption tremor.We find that at regional distances, the tremor is dominated by P-waves in the band from 1.5 to 10 Hz. Using this information, along with an enriched Bogoslof earthquake catalog, …

High-Velocity Surface Layer Effects On Rayleigh Waves: Recommendations For Improved Shear-Wave Velocity Modeling, Gabriel Gribler, Lee M. Liberty, T. Dylan Mikesell

Geosciences Faculty Publications and Presentations

Soil stiffness estimates are critical to geologic hazard and risk assessment in urban centers. Multichannel analysis of surface-wave (MASW) data collection along city streets is now a standard, cost-effective, and noninvasive soil stiffness approximation tool. With this approach, shear-wave velocities (V_S) are derived from Rayleigh-wave signals. Although the current MASW practice is to neglect the effect of a high-velocity road layer on soil V_S estimates, our models show measurable impacts on Rayleigh-wave amplitudes and phase velocities when seismic data are acquired on a road surface. Here, we compare synthetic models with field MASW and downhole V …

Mantle Structure And Flow Beneath An Early-Stage Continental Rift: Constraints From P Wave Anisotropic Tomography, Youqiang Yu, Stephen S. Gao, Dapeng Zhao, Kelly H. Liu

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

To explore 3-D seismic velocity and radial anisotropy structures of the upper mantle and mantle transition zone beneath the Malawi and Luangwa rift zones of the East African Rift System, we conduct the first study of P wave anisotropic tomography using data recorded at 75 seismic stations including 34 stations that we installed along two profiles as part of the Seismic Arrays for African Rift Initiation experiment. Both rift zones are revealed to have normal or slightly low velocity anomalies in the lithosphere and upper asthenosphere. The surrounding cratonic lithosphere is characterized by high-velocity anomalies with amplitudes ranging from +1.0% …

Microwave Brightness Temperature Characteristics Of Three Strong Earthquakes In Sichuan Province, China, Feng Jing, Ramesh P. Singh, Yueju Cui, Ke Sun

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Passive microwave remote sensing technology is an effective means to identify the thermal anomalies associated with earthquakes due to its penetrating capability through clouds compared with infrared sensors. However, observed microwave brightness temperature is strongly influenced by soil moisture and other surface parameters. In the present article, the segmented threshold method has been proposed to detect anomalous microwave brightness temperature associated with the strong earthquakes occurred in Sichuan province, China, an earthquake-prone area with high soil moisture. The index of microwave radiation anomaly (IMRA) computed by the proposed method is found to enhance prior to the three strong earthquakes, 2008 …

Mapping Snowmelt Progression In The Upper Indus Basin With Synthetic Aperture Radar, Jewell Lund, Richard R. Forster, Summer B. Rupper, Elias J. Deeb, H.P. Marshall, Muhammad Zia Hashmi, Evan Burgess

Geosciences Faculty Publications and Presentations

The Indus River is a vital resource for food security, ecosystem services, hydropower, and economy for millions of people living in Pakistan, India, China, and Afghanistan. Glacier and snowmelt from the high altitude Himalaya, Karakoram, and Hindu Kush mountain ranges are the largest drivers of discharge in the upper Indus Basin (UIB), and contribute significantly to Indus flows. Complex climatology and topography, coupled with the challenges of field study and meteorological measurement in these rugged ranges, elicit notable uncertainties in predicting seasonal runoff as well as cryospheric response to changes in climate. Here we utilize Sentinel-1 synthetic aperture radar (SAR) …

Glacial Earthquakes And Precursory Seismicity Associated With Thwaites Glacier Calving, J. Paul Winberry, Audrey D. Huerta, Sridhar Anandakrishnan, Richhard C. Aster, Andrew A. Nyblade, Douglas A. Wiens

All Faculty Scholarship for the College of the Sciences

We observe two (~M_S 3) long‐period (10–30 s) seismic events that originate from the terminus of Thwaites Glacier, Antarctica. Serendipitous acquisition of satellite images confirm that the seismic events were glacial earthquakes generated during the capsizing of icebergs. The glacial earthquakes were preceded by 6 days of discrete high‐frequency seismic events that can be observed at distances exceeding 250 km. The high‐frequency seismicity displays an increasing rate of occurrence, culminating in several hours of sustained tremor coeval with the long‐period events. A series of satellite images collected during this precursory time period show that the high‐frequency events and …

Lunar Magnetic Field Models From Lunar Prospector And Selene/Kaguya Along‐Track Magnetic Field Gradients, Dhananjay Ravat, M. E. Purucker, N. Olsen

Earth and Environmental Sciences Faculty Publications

We use L1‐norm model regularization of |Br | component at the surface on magnetic monopoles bases and along‐track magnetic field differences alone (without vector observations) to derive high quality global magnetic field models at the surface of the Moon. The practical advantages to this strategy are the following: monopoles are more stable at closer spacing in comparison to dipoles, improving spatial resolution; L1‐norm model regularization leads to sparse models which may be appropriate for the Moon which has regions of localized magnetic field features; and along‐track differences reduce the need for ad‐hoc external field noise reduction strategies. We examine also …

Crustal Composition And Moho Variations Of The Central And Eastern United States: Improving Resolution And Geologic Interpretation Of Earthscope Usarray Seismic Images Using Gravity, H. L. Zhang, Dhananjay Ravat, A. R. Lowry

Earth and Environmental Sciences Faculty Publications

EarthScope's USArray Transportable Array has shortcomings for the purpose of interpreting geologic features of wavelengths less than the Transportable Array station spacing, but these can be overcome by using higher spatial resolution gravity data. In this study, we exploit USArray receiver functions to reduce nonuniqueness in the interpretation of gravity anomalies. We model gravity anomalies from previously derived density variations of sedimentary basins, crustal V p /V s variation, Moho variation, and upper mantle density variation derived from body wave imaging informed by surface wave tomography to estimate V p/V s. Although average densities and density contrasts for these seismic …

Early Triassic Conchostracans From The Tiryakh-Kobyume Section (Southern Verkhoyansk Region, Republic Of Sakha (Yakutia)), V. V. Zharinova, F. Scholze, V. I. Davydov, R. V. Kutygin

Geosciences Faculty Publications and Presentations

Conchostracans (Crustacea) from the Induan deposits of the Tiryakh-Kobyume section (southern Verkhoyansk region) were studied. We identified the following seven conchostracan species belonging to five genera: Pseudestheria Raymond, 1946; Euestheria Deperet et Mezeran, 1912; Sphaerestheria Novojilov, 1954; Lioestheria Deperet et Mezeran, 1912; Wetlugites Novojilov, 1958. Most of the previously identified species in the Tiryakh-Kobyume region (“Pseudestheria sibirica”, “Ps. tumaryana”, “Ps. kashirtzevi”, and “Sphaeres­theria aldanensis”) were described in the middle of the 20th century from the basal Triassic in the western Verkhoyansk region (Balbuk section). Revision of these species with the use …

Lévy Processes: Characterizing Volcanic And Financial Time Series, Peter Kwadwo Asante

Open Access Theses & Dissertations

In this work, we use the Diffusion Entropy Analysis (DEA) to analyze and detect the scaling properties of time series from both emerging and well established markets as well as volcanic eruptions recorded by a seismic station, both financial and volcanic time series data are known to have high frequencies (i.e they are collected at an extremely fine scale). The objective is to determine the characterization i.e whether they follow a Gaussian or Lévy distribution. If they do follow a Lévy distribution we are then interested in finding if they are characterized by a Lévy walk which has a finite …

Shallow Seismic Modeling Of The Hydrothermal Plumbing System Beneath Old Faithful Geyser In The Upper Geyser Basin Of Yellowstone National Park, Jordan Rigdon Caylor

Open Access Theses & Dissertations

In November 2016, a 2-D and 3-D seismic survey was performed around Old Faithful Geyser in the southeastern portion of the Upper Geyser Basin in Yellowstone National Park. The survey consisted of 521 3-component seismic receiver locations including 39 receivers on a ~1km NE-SW trending line crossing Old Faithful Geyser. A 5.4kg sledgehammer striking a metal plate was our source with a dominant frequency of ~40Hz. Our 2-D line crosses Old Faithful in a NE-SW direction with station spacing at 25-30m with ~100m spacing on either side of Old Faithful and a total length of 1024m. Our 3-D seismic grid …

Physical Modeling Of The Krauklis Waves: Insights From Two Experimental Apparatuses, Haitao Cao

Dissertations, Master's Theses and Master's Reports

Fractures play an important role in the geological related processes such as hydraulic fracturing, water-water disposal, and volcanic earthquake. Seismic waves can provide useful information from fractures at a relatively low cost. In particular, the acoustic property of fractures containing magmatic or hydrothermal fluids can provide useful information about the fracture size and the fluid composition within the fracture. For instance, in volcanology, the resonant frequency of long-period events that are linked to crack interface waves is used to obtain fluid properties of cracks in magmatic systems. However, in order to rely on seismic data, they should be precisely characterized …

Exploring Effects Of Gps Processing On Atmospheric And Hydrologic Pressure-Induced Crustal Responses, Cody T. Norberg

Undergraduate Theses, Professional Papers, and Capstone Artifacts

The Earth’s crust is in continuous motion from changes in fluid pressures associated with the redistribution of mass at the surface. These forces, known as surface mass loading, make up a significant amount of signal within GPS time series. This thesis is broken up into two projects exploring atmospheric and hydrologic pressure-induced crustal responses. The first project focuses on effects of GPS processing on corrections of atmospheric loading. We use data from over 1100 GPS stations within the Western US to investigate crustal displacements from atmospheric surface pressure variations. We find that modeling and removing atmospheric mass loading reduces root …

Stochastic Inversion Integrating Seismic Data, Litho-Facies Physical Properties, And Multiple-Point Geostatistics For Reservoir Characterization, Mohamed Mohamed

Dissertations, Master's Theses and Master's Reports

We proposed a novel seismic inversion approach that integrates the physical properties of litho-facies, and geophysical data, within the multiple-point geostatistical frameworks to reduce the uncertainty in predictions of litho-facies spatial arrangement away from wells or control points. The litho-facies groups (rock-type) in the well locations are defined and conditioned to the distribution of elastic properties, including P-wave velocity (Vp) and facies density (ρ) in the well locations. A conceptual geological model (training image) is utilized within a wavelet-based multiple-point geostatistical simulation (WAVESIM) algorithm to generate litho-facies realizations. In our inversion algorithm, the forward model is created by implementing the …

Microseismic Evidence For Bookshelf Faulting In Western Montana, Ellen Mcgough Smith

Graduate Student Theses, Dissertations, & Professional Papers

One of the most seismically active regions in the western United States, far from any major plate boundary, is the Intermountain Seismic Belt (ISB). On 6 July 2017, a M5.8 earthquake occurred 11 km southeast of Lincoln, Montana within the ISB. This was the largest earthquake to occur in the state of Montana since the 1959 M7.3 Hebgen Lake earthquake. Data from the University of Montana Seismic Network (UMSN), the Montana Regional Seismic Network (MRSN), and the United States Geological Survey (USGS) were used to investigate the aftershock sequences following the M5.8 Lincoln event. We have manually picked P- and …

A Machine Learning And Data-Driven Prediction And Inversion Of Reservoir Brittleness From Geophysical Logs And Seismic Signals: A Case Study In Southwest Pennsylvania, Central Appalachian Basin, Tobi Micheal Ore

Graduate Theses, Dissertations, and Problem Reports (ETD)

In unconventional reservoir sweet-spot identification, brittleness is an important parameter that is used as an easiness measure of production from low permeability reservoirs. In shaly reservoirs, production is realized from hydraulic fracturing, which depends on how brittle the rock is–as it opens natural fractures and also creates new fractures. A measure of brittleness, brittleness index, is obtained through elastic properties of the rock. In practice, problems arise using this method to predict brittleness because of the limited availability of elastic logs.

To address this issue, machine learning techniques are adopted to predict brittleness at well locations from readily available geophysical …

Onset And Cause Of Increased Seismic Activity Near Pecos, West Texas, United States, From Observations At The Lajitas Txar Seismic Array, Clive Frohlich, Chris Hayward, Julia Rosenblit, Chastity Aiken, Peter Henning, Alexandros Savvaidis, Casee Lemons, Elizabeth Horne, Multiple Additional Authors

Geology Faculty Publications and Presentations

In recent years, numerous small earthquakes have occurred near the town of Pecos in West Texas; however, when this activity began and whether it was caused by increased petroleum industry activity has been uncertain because prior to 2017 there were few permanent seismograph stations in the region. We identify and locate earthquakes using data recorded since 2000 at TXAR, a sensitive 10‐station seismic array situated about 240 km south of Pecos. We thus show that in 2007, one earthquake occurred near Pecos, in 2009 several more occurred, and subsequently, activity has increased considerably, with more than 2000 events identified in …

A Broad Iceland Plume Associated With Two Phase Transitions At The 660 Km Discontinuity: Constraints From Receiver Functions, Dan Wang

Doctoral Dissertations

"In spite of the fact that Iceland is frequently regarded as the archetypal example of mantle plumes, the existence, depth extent, origin, dimension and excess temperature of the hypothesized plume remain enigmatic and hotly debated. The controversy mostly originates from the limited vertical resolution of seismic tomography techniques and the associated uncertainty in the depth and lateral extents of the lower wavespeed anomaly. Here we utilize a robust receiver-function-based technique to image the topography of the 410 and 660 km discontinuities bordering the mantle transition zone beneath Iceland and surrounding oceanic regions, and construct thermal and seismic wavespeed models of …