The National Science Foundation has announced a plan to establish a Deep Underground Science and Engineering Laboratory (DUSEL) for interdisciplinary research in physics, geosciences, biosciences and engineering. The proposed laboratory will extend to a depth of about 2200 meters and will consist of research facilities for long term study. To date, eight sites in North America have been proposed to host DUSEL. One of these sites, known as Kimballton, is located near Butt Mountain in Giles County in southwestern Virginia. Two seismic lines were acquired along the top of Butt Mountain in June of 2004 to support the ongoing integrated site characterization effort by the Kimballton Science Team. Both lines, approximately 3 km in length, are standard multifold seismic reflection data aimed at imaging faults, thrust sheets, and repeated sections of Paleozoic rocks in the vicinity of the proposed Kimballton site. Crooked line geometry, irregular geophone spacing, ground roll, and poor impedance contrasts between juxtapositioned rock units were challenges in processing the data. Non-standard processing techniques included the use of travel time tomography to accurately constrain near surface velocities, the use of 2D median filters to remove ground roll, and stacking only offsets exceeding 500 m. Interpretation of seismic data supports a triplicated stratigraphic section caused by the stacking of the the St. Clair and Narrows thrust sheets. The St. Clair and Narrows faults are interpreted as shear zones within ductile units of the Martinsburg Formation. 3D travel time tomography was used to build a near surface velocity model of Lines 1 and 2 for the purposes of imaging near surface structure and constraining the extent of topographic lineaments, which are interpreted as bedrock joint systems. Interpretation of the velocity models suggests that the broadly folded strata of the Butt Mountain synclinorium dip gently to the east along the hinge surface. The surface extrapolation of the Lookout Rock fault and the intersection of topographic lineaments with the seismic lines are expressed as low velocity zones that extend to depths of 150 m. This may be related to accelerated weathering along jointed rock surfaces. Results of this study have already been incorporated into the NSF proposal submitted by the Kimballton Science Team (http://www.phys.vt.edu/~kimballton/s2p/b2.pdf). / Master of Science

A relocation study is made for 50 Virginia earthquakes (1959-1981) using a variation (JED/SE77) of the Joint Hypocenter Determination (JHD) method. Joint Epicenter Determinations (JED) were used in conjunction with a companion single event location program (SE77) to relocate hypocenters from data sets in the Giles County seismic zone (GCSZ) in southwestern Virginia and the central Virginia seismic zone (CVSZ). In the GCSZ six earthquakes, recorded both regionally and teleseismically and previously relocated jointly by Dewey and Gordon (1980), and nine earthquakes, recorded by a local network and individually located using the HYPOELLIPSE program (Lahr, 1979), were relocated. The JED/SE77 relocated hypocenters virtually all fall within the 70% confidence ellipses of the corresponding original hypocenters. In the CVSZ 25 events, originally located individually using HYPOELLIPSE, were relocated. The JED/SE77 relocations produce, for the most part, only small changes in epicenters (<5 km average displacement) and comparably small changes in focal depths. Geometrically, they can be grouped into three planes and one cluster of events. The majority (17/25) of the events are contained in two of the planes, both of which have an ENE trend and a 45° southerly dip. The JED/SE77 results: 1) indicate that the original HYPOELLIPSE hypocenters are quite accurate and should constitute the preferred hypocenters; 2) give added confidence to the instrumental definition of the GCSZ and the CVSZ; and 3) show by the depth distribution of foci that the entire upper portion of the crust is involved in the release of seismic energy. / Master of Science

Transportation facilities and services provide the cornerstones to the rescue and response operations after a big earthquake. This study appraises the transportation actions taken by the authorities in the immediate aftermath of the Loma Prieta Earthquake of October 17, 1989. The failure of several transportation structures had a significant impact on rescue operations, traffic congestion and change in travel patterns in the San Francisco Bay Area. Emphasis is placed on travel demand management strategies adopted to meet the travel needs in the Bay Area and to return traffic to normalcy. The short-term and long-term impacts of closures of certain highways due to a 7.5 magnitude earthquake are also addressed in this research. Recent predictions by the United States Geological Survey show that there is a 67 percent chance of a big earthquake of 7.5 magnitude happening in the Bay Area before the year 2020. Therefore, there is a dire need to look at the transportation problems that the Bay Area might face if the "Big One" really hits. It is also important to note that certain bridges play a major role in the cross-bay transportation. Hence, the failure of such critical links would greatly influence the mobility of the citizens in the region. A macro-level measure referred to as "Weighted Roadway Congestion index" (RCIW) is developed to assess the severity of the closures of these links. To fulfill this objective, scenario analysis is performed for the expected closures in the San Francisco Bay Area. It is important to note that the macro-level measure developed is applicable only to urban areas. This research also aims at identifying the key network parameters, such as number of lane-miles per freeway exit and freeway network connectivity that impact roadway congestion after earthquakes. / Master of Science

An inversion method is developed to estimate the P- and S-wave velocities and density ratio of two elastic, isotropic, and homogeneous media separated by a plane, horizontal boundary from P-wave reflection amplitude-versus-offset (AVO) data recorded at the surface. The method has for its basis the inversion of the plane wave Zoeppritz. equations by generalized linear inversion (GLI) and bootstrapping. The Zoeppritz equations are converted into the time-offset domain by using Snell’s law, common mid-point (CMP) geometry, and two-way travel (twt) time. The equations in the time-offset domain have five independent variables that enable estimation of P- and S-wave velocities and density ratio for the upper and lower layers. The linearity and uniqueness of the inversion are investigated by residual function maps (RFMs). The RFMs show closed elliptical contours around the true values of the seismic parameter pairs except in the case of S-wave velocity pair for which the open contours imply a linear correlation. However, the RFMs of S-wave velocities with the other model parameters show well defined minima, indicating the uniqueness of the inverse problem in the absence of noise. The estimation of seismic parameters is constrained by physical considerations and the results are enhanced statistically by bootstrapping to obtain the most likely solutions, i.e., the mode values of the distribution functions of solutions, and the confidence limits of the most likely solutions. The inversion method is tested using model AVO data with and without random noise. The tests show that the model parameters are exactly recovered when offset-to-depth (O/D) ratio 1s about 2 or larger, depending on the contrast among the seismic parameters of the media. The results for small O/D ratios (< 1) diverge from the true values, especially for S-wave velocities, and indicate the importance of the O/D ratio in the AVO data inversion. The parameters are not recovered correctly in the case of noisy model AVO data because of the degrading effect of noise in the inversion. However, the model parameters fall into the confidence limits of the estimated parameters when tight constraints are imposed on the solutions, and the signal to noise (S/N) ratio is high. The inversion method is sensitive to auxiliary parameters such as the root-mean-square (rms) velocity and zero-offset twt time which are used in the adjustments of observed or calculated reflection amplitudes to compensate for the effects of wave propagation. Because the plane wave Zoeppnitz equations define the variation in reflection amplitude with offset for a single boundary, the method is limited to isolated reflections in the CMP gathers. The AVO inversion is applied to field data from the Atlantic Coastal Plain in South Carolina to show the feasibility of the method. The first example is from Charleston, S.C. where the estimated seismic parameters from adjacent CMP gathers are in close agreement demonstrating the stability of the AVO inversion. The second example is a data set that crosses the border fault of the Dunbarton Triassic basin, S.C. For this data set common offset stacked CMP gathers are used to increase the S/N ratio and minimize the surface coupling effects. The inversion results show that the seismic parameters are greater north of the border fault indicating crystalline basement while smaller parameters to the south represent the Triassic basin. P-wave velocities estimated for the crystalline basement (6.4 km/s) and the Triassic basin (4.8 km/s) are in good agreement with the computed refraction velocities and support the interpreted location of the Dunbarton Triassic border fault. / Ph. D.

First-hand accounts of sand boils and other liquefaction-related phenomena associated with the Charleston, SC earthquake of 1886 provide clear evidence that liquefaction was common in this event. Recent geologic investigations in the Charleston area have found evidence for the repeated liquefaction of sandy soils in the Charleston area due to recurring large seismic events. Although this information has led to an improved understanding of seismicity in the Charleston region, little hard data exists in terms of ground motion characteristics or levels of seismic loading. A two-year field investigation was undertaken by Virginia Tech to study the liquefaction findings associated with the 1886 event from the perspective of geotechnical engineering. This involved defining the engineering parameters of the Charleston soils on the basis of in-situ and laboratory tests, and estimating the levels of seismic loading required to produce the observed liquefaction phenomena. Of the sites where field tests were performed, the surficial soils were largely formed from ancient beach ridge deposits. The findings showed that soil conditions within these deposits are appropriate for liquefaction. Also, there is clear evidence that soils as old as 230,000 years have liquefied multiple times in the past 10,000 years. Many of these soils remain susceptible to liquefaction at relatively low levels of seismic shaking, although there is some evidence for progressive densification. With respect to the seismic loadings, evidence is presented which suggests that both the magnitude and peak acceleration of the 1886 earthquake were less than what has been proposed by the seismological community (M = 7.7 and 0.5 - 0.6g peak acceleration). The findings of this study indicate that for an M = 7.5 event, peak accelerations in the 0.3 to 0.4g range would serve to explain the observed 1886 liquefaction phenomena. If it is assumed that the magnitude of the 1886 earthquake was less than 7.5, then the estimated peak accelerations increase. / Ph. D.

First-hand reports on the 1886 Charleston earthquake contain numerous accounts for the widespread occurrence of liquefaction related features in and near the meizoseismal zone. Recent geologic studies have found evidence for the repeated liquefaction of sandy soils in the Charleston area due to recurring large seismic events. In the course of this investigation 24 mini-cone penetration tests were performed at seven sites in or near the meizoseismal zone of the 1886 earthquake to determine the factors influencing ground failures due to liquefaction. These tests were supplemented with soil borings, sieve tests and a limited number of standard penetration tests to aid in characterization of the sandy soils. Additionally, soil boring records in Charleston were obtained which provided in-situ testing data in an area with documented historical damage. The range of sites at which testing was done, or information was available, represent locations experiencing various levels of liquefaction and distances from the zone of seismic energy release. Penetration data were used to evaluate resistance of the sandy soil to cyclic loading and fonned the basis for assessing the effects that the lateral extent and distribution of loose sand layers has on the surficial manifestation of liquefaction. With the absence of cementation and extensive soil development, soils as old as late Pleistocene age have been found to be very susceptible to liquefaction. At several sites these soils have undergone at least three episodes of liquefaction and presently exhibit low penetration resistances, indicating that the progressive densification of a liquefiable soil layer can be minor unless it is in very close proximity to a large venting feature. The size and density of occurrence of vents and sand blows has been found to be primarily dependent on the extent of both the liquefiable layer and any overlying resistant layers. Layered system relations utilized with field performance data, and historical and geologic evidence for the occurrence of liquefaction features to suggest that the near surface peak horizontal accelerations induced by the 1886 earthquake were approximately O.3g in the meizoseismal zone and O.2g in the city of Charleston. This is in contrast with previous estimates of seismic shaking all of which point toward values in the range of 0.5 to O.6g. The reason for the different acceleration estimates is not clear at this time, and will be further studied in future extension of this work. / Master of Science

<p>In 2009, the Regional Municipality of Halton and McMaster University initiated a 2-year collaborative study (Georgetown Aquifer Characterization Study-GACS) of the groundwater resource potential of Quaternary sediments near Georgetown, Ontario. As part of that study, this thesis investigated the Quaternary infill stratigraphy of the Middle Sixteen Mile Creek (MSMC) and Cedarvale (CV) buried valley systems using newly acquired core and borehole geophysical data. Multi-parameter geophysical log suites (natural gamma, EM conductivity, resistivity, magnetic susceptibility, full-waveform sonic, caliper) were acquired in 16 new boreholes (16 m to 55 m depth), pre-existing monitoring wells and from archival data. Characteristic log responses (electrofacies) were identified and correlated with core to produce a detailed subsurface model of a 20-km² area to the southwest of Georgetown. Nine distinctive lithostratgraphic units were identified and their geometry mapped across the study area as structure contour and isochore thickness maps. The subsurface model shows that the CV valley truncates the Late Wisconsin MSMC stratigraphy along a channelized erosional unconformity and is a younger (post-glacial?) sediment-hosted valley system. Model results demonstrate the high level of stratigraphic heterogeneity and complexity that is inherent in bedrock valley systems and provides a geological framework for understanding groundwater resource availability.</p> <p>Principal component analysis (PCA) was applied to selected log suites to evaluate the potential for objective lithologic classification using log data. Gamma, resistivity and conductivity logs were most useful for lithologic typing, while p-wave velocity and resistivity logs were more diagnostic of compact diamict units. Cross plots of the first and second principal components of log parameters discriminated silts and clays/shales from sand/gravel and diamict lithofacies. The results show that PCA is a viable method for predicting subsurface lithology in un-cored boreholes and can assist in the identification of hydrostratigraphic units.</p> / Master of Science (MSc)

Dans l'histoire des éruptions volcaniques, le Papandayan à l'Ouest de Java est considéré comme l'un des plus meurtriers après avoir causé la mort de 2957 personnes et des dégâts sérieux en 1772. L'éruption la plus récente de ce volcan a eu lieu en 2002 et était de type phréatique. Cette éruption a été précédée d'une augmentation soudaine de l'activité sismique moins de deux jours avant l'éruption. Aucune victime n'a été déplorée. La nature de cette éruption est indéfinie. Cette thèse regroupe plusieurs études utilisant différentes techniques en vue d'améliorer la prédictibilité des éruptions du volcan Papandayan, principalement via l'interprétation des signatures sismiques.<p>Le monitoring sismique passif a débuté en décembre 2009 par l'installation d'une station sismique permanente à large bande dans le cratère du Papandayan. L'année suivante, une station météorologique a été installée pour compléter les mesures. La troisième année, 8 stations sismiques temporaires ont été déployées autour du volcan en réponse à une augmentation de l'activité sismique en 2011.<p>Nous avons conduit différentes études; (1) Nous avons examiné l'évolution de l'activité volcanique par réalisation d'une revue complète de l'histoire éruptive du volcan, autant pour la période préhistorique qu'historique. (2) Nous avons réalisé une analyse temps-fréquence des événements sismiques, étudié leurs caractéristiques et proposé une nouvelle classification avec une description des processus physiques supposés les générer. (3) Nous avons étudié les signatures sismiques précurseur de l'éruption de 2002 et pendant la crise volcanique de 2011 en implémentant différentes méthodologies, dont: la détection automatique d'événements sismiques à l'aide de filtres récursifs STA/LTA, l'analyse spectrale des formes d'onde, la mesure continue de l'amplitude spectrale du signal (SSAM), la polarisation des ondes et l'analyse de la distribution fréquence/magnitude (b-value). Nous avons alors réalisé un modèle chronologique des séquences sismiques du Papandayan. (4) Pour améliorer la compréhension de la dynamique des fluides sous le volcan Papandayan, nous avons réalisé une analyse des fréquences complexes des événements longue période (LP) et leurs variations temporelles peuvent être utilisées pour estimer (a) la composition des fluides présents dans les fractures sous le volcan et/ou (b) l'évolution des dimensions de ces fractures. Ces variations des fréquences complexes des événements LP peuvent être interprétées comme les réponses dynamiques du système hydrothermal à des changements d'impulsions de chaleur transférées par les flux de gaz volcaniques du magma sous le volcan. (5) nous avons calculé l'évolution temporelle du rapport spectral horizontal-sur-vertical (HVSR) en utilisant le bruit sismique ambiant enregistré par une station unique pour estimer les variations de vitesse de propagation des ondes de cisaillement en lien avec l'activité dynamique du volcan. Nous avons trouvé une corrélation claire entre les variations de fréquence de résonnance HVSR et l'augmentation de la sismicité.<p>Enfin, nous proposons des hypothèses sur les processus physiques qui se produisent sous le Papandayan. Cette étude est une première tentative d'utilisation de cette méthode pour surveiller l'activité volcanique en continu.<p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

The Big Clifty (Jackson) Sandstone Member of the Golconda Formation is the most important of the Mississippian (Chesterian) heavy-oil reservoirs in the southeastern Illinois Basin. Heavy oil reservoirs, or asphalt rock deposits, have been studied extensively in south central and western Kentucky, and ~2 billion barrels of original oil in place (OOIP) have been proposed to occur in the Big Clifty Sandstone. Despite high OOIP estimates, heterogeneities in the reservoir negatively impact the production of heavy oil deposits. Heterogeneities related to depositional facies changes are poorly understood in the Big Clifty Sandstone of Kentucky, where it has been mostly described as a 60-120 feet thick sandstone unit. In some locations, the Big Clifty occurs as two distinct sand bodies with intercalated mud-rich units and, most typically, with the greatest clay- and silt-rich units present between sandstone bodies. Questions exist as to how such muddy facies occur in the reservoir. This study couples sedimentary facies analysis with sequence stratigraphy to assess how lithological factors affect the occurrence of petroleum in Big Clifty reservoirs. Multiple datasets were integrated to develop a depositional model for lithologic facies observed in this study. Datasets include core, exposure descriptions, petrographic analysis, bitumen concentrations, electrical resistivity tomography (ERT), and borehole geophysical analysis. This study occurred in Logan, Warren, and Butler counties, with emphasis on an active asphalt-rock mine in Logan County. Surface geophysical methods aided in demarcating Chesterian limestones, sandstone bodies and, in particular, highly resistive heavy-oil laden Big Clifty channel bodies. In Warren County, located E-NE of the Stampede Mine, the Big Clifty coalesces into a single amalgamated sandstone channel or a series of superimposed stacked channels as observed in outcrop along Indian Creek at McChesney Field Station and at Jackson’s Orchard. In these locations, the tidal influence is subtle with large-scale trough cross bedding dominating, and the contact on the Beech Creek Limestone is sharp. Facies changes related to the environment of deposition greatly impact the quality of heavy-oil reservoirs and must be taken into consideration during exploration and siting of asphalt rock mines.

Increased groundwater withdrawals associated with agricultural irrigation in the Jackson Purchase have prompted questions related to groundwater availability and sustainability. Key factors in addressing these questions are understanding the extent and variation in thickness of the local hydrostratigraphic system, which is the upper part of the Mississippi Embayment aquifer system. Correlations of 70 gamma-ray well logs, and 49 resistivity logs were made across parts of the Jackson Purchase in Fulton and Hickman Counties in order to delineate the upper Claiborne aquifer and middle Claiborne confining unit. Commercial software (i.e. Petra 3.8.3) was used to generate cross sections, structure and isopach maps of the upper Claiborne aquifer, middle Claiborne confining unit, and middle Claiborne aquifer. The structure and isopach maps show the upper Claiborne aquifer and middle Claiborne confining unit thickening and dipping southwest into the embayment. In an effort to test different methods for mapping these hydrostatic units in the shallow sub-surface, surface electrical resistivity and a seismic walkaway sounding were acquired and compared with downhole geophysical logs at two well-constrained sites to test their limits for resolving these hydrostratigraphic units. Both electric resistivity and seismic geophysical methods were best able to image the Claiborne aquifer system when used together.