Geophysics and Seismology Commons^™

The Mantle Transition Zone Beneath West Antarctica: Seismic Evidence For Hydration And Thermal Upwellings, E. L. Emry, Andrew A. Nyblade, J. Julia, Sridhar Anandakrishnan, R. C. Aster, Douglas A. Wiens, Audrey D. Huerta, Terry J. Wilson

Geological Sciences Faculty Scholarship

Although prior work suggests that a mantle plume is associated with Cenozoic rifting and volcanism in West Antarctica, the existence of a plume remains conjectural. Here we use P wave receiver functions (PRFs) from the Antarctic POLENET array to estimate mantle transition zone thickness, which is sensitive to temperature perturbations, throughout previously unstudied parts of West Antarctica. We obtain over 8000 high-quality PRFs using an iterative, time domain deconvolution method filtered with a Gaussian width of 0.5 and 1.0, corresponding to frequencies less than ∼0.24 and ∼0.48 Hz, respectively. Single-station and common conversion point stacks, migrated to depth using the …

Estimation Of Offsets In Gps Time-Series And Application To The Detection Of Earthquake Deformation In The Far-Field, Jean-Philippe Montillet, S. D. P. Williams, A. Koulali, S. C. Mcclusky

All Faculty Scholarship for the College of the Sciences

Extracting geophysical signals from Global Positioning System (GPS) coordinate time-series is a well-established practice that has led to great insights into how the Earth deforms. Often small discontinuities are found in such time-series and are traceable to either broad-scale deformation (i.e. earthquakes) or discontinuities due to equipment changes and/or failures. Estimating these offsets accurately enables the identification of coseismic deformation estimates in the former case, and the removal of unwanted signals in the latter case which then allows tectonic rates to be estimated more accurately. We develop a method to estimate accurately discontinuities in time series of GPS positions at …

Exploring Radioisotopic Geochronology And Astrochronology, Stephen R. Meyers, Bradley S. Singer, Mark D. Schmitz

Geosciences Faculty Publications and Presentations

Numerical dating of the geologic record provides an essential framework for interpreting the rich history of our planet. Common applications include the determination of dates for extinction events and climate reorganizations, the assessment of rates of paleoenvironmental and paleobiologic change, and the correlation of rocks across vast expanses. Such investigations have yielded crucial insight into the mechanisms that shape Earth's surface environments over geologic time. But as geologists increasingly pursue high (spatial) resolution stratigraphic analyses in "deep time," the short temporal scales (<100,000 years) of the processes investigated push the limits of high-­precision geochronology.

Petrophysical Analysis And Rock-Physics Based Prediction Of Sonic Velocities In Carbonates, Yeliz Egemen

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

This study performs a petrophysical analysis and rock-physics modeling of the Traverse Formation, using eleven different wells. In the first part of this study, well logs, crossplots, and mineral identification were used to determine the rock components, lithology, and to predict the sonic velocities of carbonate rocks using conventional methods for two of those wells.

In the second part of this study, rock-physics modeling methods were used to predict the sonic velocities using the Kuster-Toksöz equations. Sonic velocities are very difficult to predict in carbonate rock because of their complex pore systems. To overcome this difficulty, multiple aspect ratios for …

Morphological, Structural, And Spectral Characteristics Of Amorphous Iron Sulfates, Elizabeth Sklute, Heidi Jensen, Deanne Rogers, Richard Reeder

Department of Geosciences Faculty Publications

Current or past brine hydrologic activity on Mars may provide suitable conditions for the formation of amorphous ferric sulfates. Once formed, these phases would likely be stable under current Martian conditions, particularly at low- to mid-latitudes. Therefore, we consider amorphous iron sulfates (AIS) as possible components of Martian surface materials. Laboratory AIS were created through multiple synthesis routes and characterized with total X-ray scattering, thermogravimetric analysis, scanning electron microscopy, visible/near-infrared (VNIR), thermal infrared (TIR), and Mössbauer techniques. We synthesized amorphous ferric sulfates (Fe(III)2(SO4)3 · ~ 6–8H2O) from sulfate-saturated fluids via vacuum dehydration or exposure to low relative humidity (

Identification And Quantification Of Diffuse Fresh Submarine Groundwater Discharge Via Airborne Thermal Infrared Remote Sensing, Joseph T. Tamborski, A Deanne Rogers, Henry J. Bokuniewicz, J Kirk Cochran, Caitlin R. Young

Department of Geosciences Faculty Publications

Airborne thermal infrared (TIR) overflights were combined with shoreline radionuclide surveys to investigate submarine groundwater discharge (SGD) along the north shore of Long Island, NY between June 2013 and September 2014. Regression equations developed for three distinct geomorphological environments suggest a positive linear relationship between the rate of diffuse SGD and the spatial extent of the observed coastal TIR anomalies; such a relationship provides quantitative evidence of the ability to use TIR remote sensing as a tool to remotely identify and measure SGD. Landsat TIR scenes were unable to resolve any of the 18 TIR anomalies identified during the various …

Feldspathic Rocks On Mars: Compositional Constraints From Infrared Spectroscopy And Possible Formation Mechanisms, Deanne Rogers, Hanna Nekvasil

Department of Geosciences Faculty Publications

Rare feldspar-dominated surfaces on Mars were previously reported based on near-infrared (NIR) spectral data and were interpreted to consist of anorthosite or felsic rocks. Using thermal infrared (TIR) data over the feldspar detections with the largest areal extent in Nili Patera and Noachis Terra, we rule out felsic interpretations. Basaltic or anorthositic compositions are consistent with TIR measurements, but the geologic contexts for these regions do not support a plutonic origin. Laboratory NIR spectral measurements demonstrate that large plagioclase crystals (>~840 μm) can be detected in mixtures with as much as 50 vol % mafics, which is higher than …

Examination Of Geophysical Signatures Of Ethanol-Water Mixtures In A Homogeneous Sand Column Using Ground Penetrating Radar And Time-Domain Reflectometry, Angelo Lampousis, Neil Terry, Lee Slater

Publications and Research

In recent years there has been an increase in the frequency of incidents involving ethanol-blended gasoline affecting the groundwater. Near-surface geophysical methods hold promise for site characterization at ethanol contaminated sites. We attempted to record the broadband dielectric properties of ethanol at various concentrations as it was circulating through a closed tank containing either sand or a sand-clay mixture. Two high frequency GPR antennas were positioned symmetrically on either side of the sample holder to obtain transmission measurements. In the first part of the experiment we used a sample consisting of sand. In the second part of the experiment we …

Geophysical Explorations On And Near The Ismenion Hill, Thebes, Greece, 2011, Robert W. Jacob, Stephanie Larson, Kevin Daly, Emily Bitely

Faculty Journal Articles

Το άρθρο αυτό παρουσιάζει τις πρώτες κοινές έρευνες στη Θήβα, στην περιοχή του ναού του Απόλλωνος Ισμηνίου, που κρίθηκαν επιβεβλημένες, πριν από την υποβολή μιας ολοκληρωμένης και τεκμηριωμένης πρότασης Συνεργασίας, για τη διενέργεια εργασιών πεδίου και πιό συγκεκριμένα ανασκαφών. Οι έρευνες αυτές έλαβαν χώρα το καλοκαίρι του 2011, μετά από ευγενική πρόσκληση του Διευθυντή τότε ένατης Εφορείας, Καθηγητή κυρίου Βασίλειου Αραβαντινού, που χρονολογείται το 2010. Σκοπός μας ήταν ωα αναλάβουμε μαζί την προσπάυεια διερεύνησης τοπογραφικών και αρχαιολογικών ζητημάτων, σχετικών με την παλαιά ανασκαφή του Ισμηνίου και τη νεώτερη του Ηρακλείου των Θηβών.

Commercialization Of A Small, Lightweight, Low-Cost Seismic Borehole Receiver, Rachel Adams

Theses and Dissertations--Civil Engineering

Herein, conceptualization of a recently patented seismic borehole receiver and its components is developed for commercialization. The device is significantly cheaper, lighter, and smaller than existing technologies on the market. Additionally, it has the potential to achieve better seismic readings than its competitors via patented sensor-to-borehole coupling mechanism. It is the hope that the commercialization of this device will not only provide a more affordable alternative to engineers and geophysicists in the existing market, but the significant cost difference may open new seismic measurement opportunities in the developing world. Its compact size and light weight will increase mobility, allowing investigators …

Evidence For A Far-Traveled Thrust Sheet In The Greater Himalayan Thrust System, And An Alternative Model To Building The Himalaya, S. Khanal, D. M. Robinson, M. J. Kohn, S. Mandal

Geosciences Faculty Publications and Presentations

The Galchhi shear zone underlies the Kathmandu klippe in central Nepal and has emerged as a key structure for discriminating competing models for the formation of the Himalayan orogenic wedge. New chronologic data from the Galchhi area suggest a new structural and orogenic interpretation. Zircons from quartzites and an orthogneiss restrict protolith deposition to between 467+7/ – 10 Ma and ~570 Ma, with metamorphic zircon growth at 23-29 Ma. Comparable data from the Greater Himalayan Sequence (GHS) at the intra-GHS Langtang thrust, north of Galchhi, similarly restrict GHS deposition to between 475+7/ – 3 and ~660 Ma. Undeformed pegmatites near …

Early Permian Conodont Fauna And Stratigraphy Of The Garden Valley Formation, Eureka County, Nevada, Bruce R. Wardlaw, Dora M. Gallegos, Valery V. Chernykh, Walter S. Snyder

Geosciences Faculty Publications and Presentations

The lower part of the Garden Valley Formation yields two distinct conodont faunas. One of late Asselian age dominated by Mesogondolella and Streptognathodus and one of Artinskian age dominated by Sweetognathus with Mesogondolella. The Asselian fauna contains the same species as those found in the type area of the Asselian in the southern Urals including Mesogondolella dentiseparata, described for the first time outside of the Urals. Apparatuses for Sweetognathus whitei, Diplognathodus stevensi, and Idioprioniodus sp. are described. The Garden Valley Formation represents a marine pro-delta basin and platform, and marine and shore fan delta complex deposition. …

Magmatic Plumbing At Lucky Strike Volcano Based On Olivine-Hosted Melt Inclusion Compositions, V. D. Wanless, A. M. Shaw, M. D. Behn, S. A. Soule, J. Escartín, C. Hamelin

Geosciences Faculty Publications and Presentations

Here we present volatile, major, and trace element concentrations of 64 olivine-hosted melt inclusions from the Lucky Strike segment on the mid-Atlantic ridge. Lucky Strike is one of two locations where a crustal melt lens has been seismically imaged on a slow-spreading ridge. Vapor-saturation pressures, calculated from CO₂ and H₂O contents of Lucky Strike melt inclusions, range from approximately 300-3000 bars, corresponding to depths of 0.5-9.9 km below the seafloor. Approximately 50% of the melt inclusions record crystallization depths of 3-4 km, corresponding to the seismically imaged melt lens depth, while an additional ∼35% crystallize at depths …

Comparison Of The Ground-Motion Attenuation Relationship Between The Wenchuan, China, Area And The Central And Eastern United States, Jiwei Feng, Zhenming Wang, Edward W. Woolery, Shanyou Li

Report of Investigations--KGS

An M_w-7.9 earthquake occurred in Wenchuan, China, in 2008, along the Longmenshan Fault, which is located on the western border of the South China stable continental region. A detailed comparison of the Wenchuan ground-motion attenuation relationships with the relationships for the central and eastern United States (also a stable continental region) showed that the ground-motion prediction equation for the Wenchuan area is similar to those for the central and eastern United States. Thus, the strong-motion records from the Wenchuan earthquake can be used for constraining the ground-motion prediction equation and engineering analysis for the central and eastern United …

Keflavík On Hegranes: Cemetery Excavation—Interim Report2015, Guðný Zoega, Douglas J. Bolender, Brian N. Damiata, John M. Steinberg

Andrew Fiske Memorial Center for Archaeological Research Publications

The summer of 2015 was the first of three planned years of excavations at the early Christian cemetery at farm Keflavík on Hegranes in the region of Skagafjörður, North Iceland. The excavation is the third phase of Skagfirska kirkjurannsóknin (Skagafjörður Church Project) and is a collective effort of the Skagafjörður Heritage Museum and the Fiske Center of the University of MassachusettsBoston. The collective project goes by the name Skagafjörður Church and Settlement Survey (SCASS). The excavation season started on the 6thof July and finished on the 14thof August. The first two weeks were spent cleaning the surface and removing a …

Effects Of Small Thundercloud Electrostatic Fields On The Ionospheric Density Profile, Mohammad A. Salem, Ningyu Liu, Hamid K. Rassoul

Aerospace, Physics, and Space Science Faculty Publications

Small electrostatic fields of values not strong enough to activate electron impact ionization, attachment, and detachment processes can be established in the upper atmosphere by underlying thunderstorms. This paper investigates their effects on the ionospheric densities by using a simplified ion chemistry model. The modeling results indicate that under the steady state condition, the nighttime electron density profile can be reduced by up to ∼40% or enhanced by a factor of up to ∼6 because of the variation of the three-body electron attachment rate constant with the electric field.

First Images Of Thunder: Acoustic Imaging Of Triggered Lightning, M. A. Dayeh, R. Lucia, Hamid K. Rassoul

Aerospace, Physics, and Space Science Faculty Publications

An acoustic camera comprising a linear microphone array is used to image the thunder signature of triggered lightning. Measurements were taken at the International Center for Lightning Research and Testing in Camp Blanding, FL, during the summer of 2014. The array was positioned in an end-fire orientation thus enabling the peak acoustic reception pattern to be steered vertically with a frequency-dependent spatial resolution. On 14 July 2014, a lightning event with nine return strokes was successfully triggered. We present the first acoustic images of individual return strokes at high frequencies (>1kHz) and compare the acoustically inferred profile with optical …

Spectral Properties Of Titan’S Impact Craters Imply Chemical Weathering Of Its Surface, Catherine D. Neish

Aerospace, Physics, and Space Science Faculty Publications

We examined the spectral properties of a selection of Titan's impact craters that represent a range of degradation states. The most degraded craters have rims and ejecta blankets with spectral characteristics that suggest that they are more enriched in water ice than the rims and ejecta blankets of the freshest craters on Titan. The progression is consistent with the chemical weathering of Titan's surface. We propose an evolutionary sequence such that Titan's craters expose an intimate mixture of water ice and organic materials, and chemical weathering by methane rainfall removes the soluble organic materials, leaving the insoluble organics and water …

Field Measurements For Remote Sensing Of The Cryosphere, Hans-Peter Marshall, Robert L. Hawley, Marco Tedesco

CGISS Publications and Presentations

Remote sensing observations of the cryosphere, like any other target of interest, require ground-based measurements for both calibration and validation, as inversion algorithms are usually underdetermined and uncertainties in the retrieval are needed for application. Field-based observations are performed in selected representative locations, and typically involve both direct in situ measurements of the physical properties of interest, as well as ground-based remote sensing techniques.

New state-of-the-art modern techniques for measuring physical properties rapidly and at high spatial resolution have recently given us a new view of spatiotemporal variability. These are important, as large variability at scales below the typical footprint …

Theoretical Foundation Of Cyclostationary Eof Analysis For Geophysical And Climatic Variables: Concepts And Examples, Kwang-Yul Kim, Benjamin Hamlington, Hanna Na

CCPO Publications

Natural variability is an essential component of observations of all geophysical and climate variables. In principal component analysis (PCA), also called empirical orthogonal function (EOF) analysis, a set of orthogonal eigenfunctions is found from a spatial covariance function. These empirical basis functions often lend useful insights into physical processes in the data and serve as a useful tool for developing statistical methods. The underlying assumption in PCA is the stationarity of the data analyzed; that is, the covariance function does not depend on the origin of time. The stationarity assumption is often not justifiable for geophysical and climate variables even …