Earth Sciences Commons^™

Seismic Field Survey Of The Ground Of The National Research Institute Of Astronomy And Geophysics, Mohamed Said Hanno

Archived Theses and Dissertations

No abstract provided.

High-Resolution Stratigraphy At A Coastal Drillhole, Beth Wrege

All Theses

Lithologic descriptions of continuous core interpreted in conjunction with borehole geophysical logs were used to determine thicknesses of hydrologic and geologic units at CR-622 in the coastal plain of North Carolina. Borehole geophysics was used to adjust the position of core loss within each cored interval and to supplement lithology to determine the stratigraphy of missing segments of core. Although some geophysical logs produce non-unique lithologic solutions, a complete normal stratigraphic profile may be obtained with the addition of continuous core. Curve characteristics within geophysical logs provide precise identification of transitional sequences and can be used to calibrate lithostratigraphy. The …

Episodic Tremor And Slip In The Pacific Northwest, Kenneth C. Creager, Timothy I. Melbourne

Geological Sciences Faculty Scholarship

Every 14 months the Pacific Northwest experiences slow slip on a fault that is the equivalent of about a magnitude 6.5 earthquake. While a typical earthquake of this magnitude happens in less than 10 seconds, the duration of these slip events is two to several weeks. The most recent event occurred from January 14 through February 1, 2007.

Frequency-Dependent Attenuation Analysis Of Ground-Penetrating Radar Data, John H. Bradford

CGISS Publications and Presentations

In the early 1990s, it was established empirically that, in many materials, ground-penetrating radar (GPR) attenuation is approximately linear with frequency over the bandwidth of a typical pulse. Further, a frequency-independent Q* parameter characterizes the slope of the band-limited attenuation versus frequency curve. Here, I derive the band-limited Q* function from a first-order Taylor expansion of the attenuation coefficient. This approach provides a basis for computing Q* from any arbitrary dielectric permittivity model. For Cole-Cole relaxation, I find good correlation between the first-order Q* approximation and Q* computed from linear fits to the attenuation coefficient …

Modified Kubelka-Munk Equations For Localized Waves Inside A Layered Medium, Kasper Van Wijk

CGISS Publications and Presentations

We present a pair of coupled partial differential equations to describe the evolution of the average total intensity and intensity flux of a wave field inside a randomly layered medium. These equations represent a modification of the Kubelka-Munk equations, or radiative transfer. Our modification accounts for wave interference (e.g., localization), which is neglected in radiative transfer. We numerically solve the modified Kubelka-Munk equations and compare the results to radiative transfer as well as to simulations of the wave equation with randomly located thin layers.

High Crystallinity Si-Ferrihydrite: An Insight Into Its Neel Temperature And Size Dependence Of Magnetic Properties, Thelma S. Berquo, Subir K. Banerjee, Robert G. Ford, R. Lee Penn, Thomas Pichler

Geology Faculty Publications

Ferrihydrite, an antiferromagnetic iron oxyhydroxide with resulting magnetization due to uncompensated spins, is of great importance for the cycling of many trace metals in the environment. Four ferrihydrite samples prepared with 1.3 to 3.5 wt% of Si at different synthesis temperatures (7.5°C, 22°C, 50°C, and 75°C) were studied by temperature-dependent hysteresis loops, ZFC/FC susceptibility curves, ac susceptibility and Mössbauer spectroscopy. The incorporation of Si into the ferrihydrite during synthesis changed the properties of this mineral. Interestingly, seven sharp lines were observed in the X-ray diffraction pattern of the ferrihydrite samples prepared at 50°C and 75°C. In general, both XRD and …

A Field Comparison Of Fresnel Zone And Ray-Based Gpr Attenuation-Difference Tomography For Time-Lapse Imaging Of Electrically Anomalous Tracer Or Contaminant Plumes, Timothy C. Johnson, Partha S. Routh, Warren Barrash, Michael D. Knoll

CGISS Publications and Presentations

Ground-penetrating radar (GPR) attenuation-difference tomography is a useful tool for imaging the migration of electrically anomalous tracer or contaminant plumes. Attenuation-difference tomography uses the difference in the trace amplitudes of tomographic data sets collected at different times to image the distribution of bulk-conductivity changes within the medium. The most common approach for computing the tomographic sensitivities uses ray theory, which is well understood and leads to efficient computations. However, ray theory requires the assumption that waves propagate at infinite frequency, and thus sensitivities are distributed along a line between the source and receiver. The infinite-frequency assumption in ray theory leads …

Geodetic Monitoring Of The Yucca Mountain Region Using Continuous Gps Measurements, Geoff Blewitt, Jonathan Price, Nevada Geodetic Laboratory, Nevada Bureau Of Mines & Geology

Publications (YM)

What Task 3 is About:

Monitor current crustal deformation at YM
– In the broader tectonic context of the NA-Pacific plate boundary
– In the regional context of the East California Shear Zone (ECSZ)
– In the geological context of specific fault activity
– Vertical motion associated with geophysical fluids

Using geodetic methods
– GPS – mature, proven
track the 3-D point-positions of 47 stations with < 1 mm precision
– InSAR – new, experimental
regional map of displacement along the line-of-sight (accuracy??)
proven capability: (1) co-seismic deformation; (2) local instabilities

Longbase Laser Strainmeter Measurements At Yucca Mountain, James N. Brune

Publications (YM)

Why Operate a Strainmeter?

To monitor strain over a broader bandwidth and with much higher sensitivity than GPS (or other instruments):
– Measure strain from seismic, earth-tide, temperature and air pressure inputs--gives local rock properties, and changes in them.
– Independently constrains GPS results.

To directly measure in the Yucca Mountain Block:
– Sensitive to potential very local tectonic events, (including any triggered slip), or volcanic events.

To establish a baseline for future strain changes:
– E.g., events developing from loading and heating of the repository

Southern Great Basin Seismic Network Operations, John G. Anderson, Glenn Biasi, Ken Smith, Nevada Seismological Laboratory, University Of Nevada, Reno

Publications (YM)

Subtasks

1. Record and archive data from the permanent seismic network.
2. Process seismic data into a preliminary earthquake bulletin.
3. Maintain the seismic stations, the strong-motion stations, the telemetry network, and the computing lab.
4. Prepare and submit a seismicity report on a yearly basis
5. Maintain and collect data from 3 north-portal boreholes.
6. Report on borehole accelerometers.
7. Estimate Kappa at network stations.
8. Implement a recording system at borehole UZ16.
9. Prepare and submit high-quality papers to peer-reviewed journals on seismic data and interpretations in the YM region.
10. Perform a multi-year telemetry and station upgrade.

Extreme Ground Motion Studies, James N. Brune, John G. Anderson

Publications (YM)

Subtasks: 1. Constraints on Yucca Mountain extreme ground motion based on precariously balanced rocks, unstable precipitous cliffs, and un-fractured sandstone along the San Andreas fault. 2. Prepare summary report on large recorded ground motions.

Guide To Participation For The Andrill Southern Mcmurdo Sound Project, Andrill Science Management Office, Mcmurdo-Andrill Science Implementation Committee

ANDRILL Project Information

Purpose of This Document

This document is a guide to participation for Science Team members involved in the Southern McMurdo Sound (SMS) Project of the ANDRILL Program. The document provides the following information: 1) Overview of the ANtarctic geologic DRILLing (ANDRILL) Program; 2) Overview of expected individual involvement in and commitment to the SMS Project; and 3) Logistical information most relevant to onice participants. Information provided in this document will be supplemented by the publication of the SMS Science and Logistics Implementation Plan (SLIP).The SLIP will be available to all SMS ANDRILL participants prior to commencement of drilling.

The reader …

I Sinkholes Nella Letteratura Scientifica Internazionale: Una Breve Rassegna, Con Particulare Riferimento Agli Stati Uniti D'America, Lee J. Florea, Mario Parise

Earth, Environmental, and Atmospheric Sciences Faculty Publications

Fenomeni di sinkholes sono diffusi in moltissimi paesi del mondo, in ambiti geologici e morfologici alquanto differenziati, e coinvolgono svariate litologie, sia nelle successioni di copertura che in quelle direttamente affioranti alla superficie. Il presente contributo intende fornire una breve rassegna, certamente non esaustiva, sullo stato dell’arte delle ricerche relative ai sinkholes in ambito internazionale. Esso consiste in una descrizione della più aggiornata e diffusa classificazione dei sinkholes e, a seguire, in descrizioni delle più tipiche casistiche di sinkholes nei vari paesi. Tra questi, viene dato particolare risalto agli Stati Uniti d’America (e, più in particolare, alla Florida), dove le …

International, Cooperative Research In The Apuseni Mountains Of Western Romania, Lee J. Florea, Bogdan P. Onac

Earth, Environmental, and Atmospheric Sciences Faculty Publications

In May of 2006, nine American scientists and cavers from the Karst Research Group at the University of South Florida traveled to western Romania to attend and present at an international conference on records of climate change in caves in the historic Roman town of Baile Hurculane. The conference, co-sponsored by the “Emil Racoviţă” Speleological Institute of Romania and the Karst Waters Institute, drew more than 100 experts in the field of climate change and karst, and was a wonderful time spent alongside the thermal springs and Austro-Hungarian bathhouses nestled within the massive limestone canyon of the Cerna River.

Following …

Sinkhole Distribution Based On Pre-Development Mapping In Urbanized Pinellas County, Florida, Usa, Robert Brinkmann, Kelly Wilson, Nichole Elko, Larry D. Seale, Lee J. Florea, H L. Vacher

Earth, Environmental, and Atmospheric Sciences Faculty Publications

Locating sinkholes in Pinellas County, Florida, is confounded by the presence of a cover of Quaternary sediments that mute the surface appearance of these sinkholes. As a first step in addressing the sinkhole hazard in the county, we analysed aerial photographs from 1926 and 1995 that covered the entire county. We digitized all identifiable sinkholes in each set of photographs in a GIS (Geographical Information System) using a set of criteria established to differentiate between karst depressions and depressions resulting from other geological processes. The 1926 photographs, although of low quality, helped to establish a baseline prior to urbanization. The …

Physical Modeling And Analysis Of P-Wave Attenuation Anisotropy, Kasper Van Wijk

CGISS Publications and Presentations

Anisotropic attenuation can provide sensitive attributes for fracture detection and lithology discrimination. This paper analyzes measurements of the P-wave attenuation coefficient in a transversely isotropic sample made of phenolic material. Using the spectral-ratio method, we estimate the group (effective) attenuation coefficient of P-waves transmitted through the sample for a wide range of propagation angles (from 0° to 90°) with the symmetry axis. Correction for the difference between the group and phase angles and for the angular velocity variation help us to obtain the normalized phase attenuation coefficient A governed by the Thomsen-style attenuation-anisotropy parameters ε_Q and δ_Q. …

An Investigation Of Lead And Other Metal Contaminants In The Sediments Of Clearwater Lake, Missouri, Gary W. Krizanich

Doctoral Dissertations

"The purpose of this investigation is to characterize the spatial and temporal distribution and concentration of trace metals in sediments of Clearwater Lake. Understanding how trace metals are released to and transported in aquatic environments is important to the overall understanding of the impacts of mining on the natural environment. The main focus of this research will be on historic sedimentation within Clearwater Lake, which may act as a sink where mining related trace metals are stored. Because of their high preservation rates in basins, sediments can provide detailed chronostratigraphic histories of trace metal inputs in lakes. Sediment records can …

Seismic Constraints On Slow Slip Events Within The Cascadia Subduction Zone, Ana Cristina Aguiar

All Master's Theses

Reanalysis of geodetic GPS time series from the Cascadia subduction zone have revealed at least 30 resolvable slow slip events along the megathrust, ranging from northern California to southern British Columbia, since 1997. Many of the smaller and more recent events are barely resolvable with GPS, but stand out clearly as tremor sequences. Since tremor bursts lasting less than 10-seconds are often visible across multiple stations, they offer the highest resolution for studying moment release through time. To test the hypothesis that tremor and transient deformation are two manifestations of the same faulting process, and to quantify the relative contribution …

Late Holocene Uplift Of The Chihshang Segment Of The Longitudinal Valley Fault At Fuli, Eastern Taiwan, Brian Thomas Gray

All Master's Theses

Uplifted Holocene strath terraces of the Bieh River drainage, eastern Taiwan, were analyzed in order to determine millennial-scale uplift and horizontal shortening rates of the Longitudinal Valley fault. Detrital charcoal fragments collected from three terraces within the Bieh River drainage yield ages between 1395 and 555 cal. yr B.P, suggesting an average uplift rate of 11.3 ± 3.6 mm yr^-1 for the last 1400 cal. yr B.P. The average horizontal shortening rate of 19.7 ± 9.5 mm yr^-1 was within error of present-day conventional geodetic measurements, but near the lower limit of the geodetic measurements. This suggests that …

Integrated Geophysical Data Processing And Interpretation Of Crustal Structure In Ethiopia With Emphasis On The Ogaden Basin And Adjacent Areas, Ketsela Tadesse

Open Access Theses & Dissertations

The combined effects of magmatism and stretching due to asthenosphere upwelling modifies the crustal structure of the Earth as seen in the Ethiopian rift and adjacent areas. The Ethiopian rift provides unique opportunities to understand the nature of rifted crust and the intensity of its modification by magmatic processes. I used geological and geophysical data to conduct an integrated study in and around the Ethiopian rift including the northern Kenyan rift and the northern part of the Kenyan dome. New gravity, controlled source seismic, and teleseismic data from the EAGLE (Ethiopia-Afar Geoscientific Lithospheric Experiment) were used as additional constraints in …

Impacts Of Acid Mine Drainage On Carbon Cycling In Receiving Streams, Ernest W. Fonyuy

Doctoral Dissertations

"Field and laboratory investigations of acid mine drainage (AMD) contaminated and uncontaminated waters were conducted in order to determine and model processes and reaction mechanisms that control dissolved inorganic carbon (DIC) transformation and shifts in isotope ratio of DIC (Δ¹³C_DIC). The results show that AMD caused variable pH changes, overall decreases in Fe²⁺, alkalinity, and DIC, and increases in (Δ¹³C_DIC) in receiving streams. AMD caused more than 50 to > 98% seasonal DIC loss in stream water through CO₂ degassing. High DIC losses corresponded to high Fe²⁺ and lower or no HCO₃⁻ in the water samples, because …

Incipient Continental Rifting: Insights From The Okavango Rift Zone, Northwestern Botswana, Baraka D. Kinabo

Doctoral Dissertations

"In this dissertation aeromagnetic, gravity, and Shuttle Radar Topography Mission Digital Elevation Model (SRTM DEM) data from the Okavango Rift Zone in northwest Botswana are used to map the distribution of rift and basement structures. The distribution of these structures provide useful insights into the early stages of continental rifting. The objectives of this study are (1) assessing the role of pre-existing structures on rift basin development, (2) characterizing the geometry of the nascent rift basins, (3) documenting fault growth and propagation patterns, and (4) investigating the border fault development"--Abstract, page iv.

Issues During The Inversion Of Crosshole Radar Data: Can We Have Confidence In The Outcome?, William P. Clement

Geosciences Faculty Publications and Presentations

One method of assessing the confidence in modeled features is to compare the results from different inversion schemes. I use synthetic traveltimes calculated from a model of an unconfined aquifer to determine the reliability of crosshole tomography. I compare the inverted models from straight and curved ray approximations to wave propagation. I investigate the effects of added random noise, regularization, the starting model, and the reference model on the curved ray inversion method. I also investigate the effects of different grid sizes for the forward model and of limited ray coverage through the earth model. Understanding the effects of these …

Geogram 2006, David J. Keeling Editor, Wku Department Of Geography And Geology

Earth, Environmental, and Atmospheric Sciences Publications

No abstract provided.

Precarious Rock Methodology For Seismic Hazard: Physical Testing, Numerical Modeling, And Coherence Studies, Rasool Anooshehpoor, James N. Brune, Amy J. Smiecinski, Raymond E. Keeler

Publications (YM)

The precarious rock methodology used for seismic hazard assessment includes location, age dating, field measurements of the quasi-static toppling acceleration of balanced rocks, and study of their dynamic response to realistic strong motion seismograms using numerical modeling. The work scope is contained in the task description issued by the DOE to the Seismology Laboratory of the University of Nevada, Reno and is itemized in section 2.3 below. In addition, measurement of the coherence of seismic energy at high frequencies, critical to the understanding of the variability of high frequency ground motions at the repository level, will be estimated based on …

Imaging Complex Structure In Shallow Seismic-Reflection Data Using Prestack Depth Migration, John H. Bradford, Lee M. Liberty, Mitchell W. Lyle, William P. Clement, Scott Hess

CGISS Publications and Presentations

Prestack depth migration (PSDM) analysis has the potential to significantly improve the accuracy of both shallow seismic reflection images and the measured velocity distributions. In a study designed to image faults in the Alvord Basin, Oregon, at depths from 25–1000 m, PSDM produced a detailed reflection image over the full target depth range. In contrast, poststack time migration produced significant migration artifacts in the upper 100 m that obscured reflection events and limited the structural interpretation in the shallow section. Additionally, an abrupt increase from ~2500 to >3000 m/s in the PSDM velocity model constrained the interpretation of the transition …

Crosshole Radar Tomography In A Fluvial Aquifer Near Boise, Idaho, William P. Clement, Warren Barrash

Geosciences Faculty Publications and Presentations

To determine the distribution of heterogeneities in the saturated zone of an unconfined aquifer in Boise, ID, we compute tomograms for three adjacent well pairs. The fluvial deposits consist of unconsolidated cobbles and sands. We used a curved-ray, finite-difference approximation to the eikonal equation to generate the forward model. The inversion uses a linearized, iterative scheme to determine the slowness distribution from the first arrival traveltimes. The tomograms consist of a layered zone representing the saturated aquifer. The velocities in this saturated zone range between 0.06 to 0.10 m/ns. We use a variety of methods to assess the reliability of …

Precarious Rock Methodology For Seismic Hazard: Physical Testing, Numerical Modeling And Coherence Studies, Rasool Anooshehpoor, Matthew D. Purvance, James N. Brune, Leiph A. Preston, John G. Anderson, Ken Smith, Amy J. Smiecinski

Publications (YM)

This report covers the following projects: Shake table tests of precarious rock methodology, field tests of precarious rocks at Yucca Mountain and comparison of the results with PSHA predictions, study of the coherence of the wave field in the ESF, and a limited survey of precarious rocks south of the proposed repository footprint. A series of shake table experiments have been carried out at the University of Nevada, Reno Large Scale Structures Laboratory. The bulk of the experiments involved scaling acceleration time histories (uniaxial forcing) from 0.1g to the point where the objects on the shake table overturned a specified …

Sinkhole Structure Imaging In Covered Karst Terrain, Sarah E. Kruse, M. Grasmueck, Matthew Weiss, D. Viggiano

Geology Faculty Publications

Ground penetrating radar (GPR) and resistivity techniques have been widely used to map the locations of sinkholes in covered karst terrain. To determine whether a sinkhole is a likely preferential conduit for groundwater flow, however, requires higher-resolution imaging than that used in conventional sinkhole mapping surveys. Field observations combined with simulated surveys for a 15-m diameter 3-m deep sinkhole in west-central Florida are used to assess the resolution of GPR and resistivity surveys targeting the semiconfining unit that floors the sinkhole depression. 2D resistivity surveys clearly show the central depression as well as resistivity contrasts between the cover sediments within …

Maximum A Posteriori Resampling Of Noisy, Spatially Correlated Data, John A. Goff, Chris Jenkins, Brian R. Calder

Center for Coastal and Ocean Mapping

In any geologic application, noisy data are sources of consternation for researchers, inhibiting interpretability and marring images with unsightly and unrealistic artifacts. Filtering is the typical solution to dealing with noisy data. However, filtering commonly suffers from ad hoc (i.e., uncalibrated, ungoverned) application. We present here an alternative to filtering: a newly developed method for correcting noise in data by finding the “best” value given available information. The motivating rationale is that data points that are close to each other in space cannot differ by “too much,” where “too much” is governed by the field covariance. Data with large uncertainties …