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Dissertationen zum Thema „Seismic surface waves“
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1
Carter, Andrew James. „Seismic waves from surface seismic reflection surveys : an exploration tool?“ Thesis, University of Leeds, 2003. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.633653.
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Hebeler, Gregory L. „Site characterization in Shelby County, Tennessee using advanced surface wave methods“. Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/20996.
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Ferreira, Ana Margarida Godinho. „Seismic surface waves in the laterally heterogeneous Earth“. Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426406.
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4
Ronda, Afonso Jose. „Railway formation condition assessment using seismic surface waves“. Diss., University of Pretoria, 2016. http://hdl.handle.net/2263/66239.
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The demands of railway transport have been changing over the 150 years of existence of this type of transport in South Africa, specifically the performance requirements of the formation to cater for new traffic requirements. As such, it is important to assess the condition of this vital part of a railway track. This dissertation covers a research project conducted on two railway lines in which measurements of ground vibration were conducted in order to perform geophysical analysis and characterise the formation based on the results obtained. Measurements were taken on a 26 ton axle load track (Coal line, at Bloubank) and on a 20 ton axle load track (at Amandelbult) in South Africa. Planning and implementation of several test procedures to characterise track formation require considerable effort to minimize the impact on railway operations. Coupled with track occupation and the destructive nature of some of the test procedures, it is relevant to investigate alternative testing techniques to address the issues stated above. The use of surface waves for geotechnical characterization of sites is increasing worldwide. Applications to railway engineering have so far been limited to light load, high speed lines to minimize the use of poor geomaterials with reduced Rayleigh wave velocity. Four sites were identified where trains are operated at heavy loads, with the formation condition varying from poor to good. Seismic testing (geophysical) and conventional testing (deflection measurements) were performed at the identified sites. Seismic measurements were recorded using geophones as receivers, coupled to an amplifier and a computer. The source of the seismic events was the trains operating on the track and a hammer for impact testing. For the deflection measurements, the Remote Video Monitoring (RVM) technique was adopted. Dispersion analysis of the ground vibration experimental data was conducted using the multiple receiver method. The main conclusions reached with the analysis indicated that: __ Dispersion analysis had a good correlation with the formation deflection analysis; __ Phase velocity can be used as an indicator of the quality of a certain site; __ There are limitations when using trains as the energy source in terms of the generation of excitation frequency, which greatly reduces the phase velocity information in individual layers in the formation (i.e. wavelengths are not short enough).Dissertation (MSc)--University of Pretoria, 2016.
Civil Engineering
MSc
Unrestricted
5
Malladi, Subrahmanya Sastry Venkata. „Modeling and Algorithm Performance For Seismic Surface Wave Velocity Estimation“. University of Akron / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=akron1194630399.
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6
Hwang, Sukyeon. „Acoustic seismic modeling in the slowness-time intercept domain /“. Access abstract and link to full text, 1993. http://0-wwwlib.umi.com.library.utulsa.edu/dissertations/fullcit/9318174.
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7
Fox, Benjamin Daniel. „Seismic source parameter determination using regional intermediate-period surface waves“. Thesis, University of Oxford, 2007. http://ora.ox.ac.uk/objects/uuid:6b89e41d-8dd0-4286-9bf0-d22c4a349bb7.
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In general, the depths of shallow earthquakes are poorly resolved in current catalogues. Variations in depth of ±10 km can significantly alter the tectonic interpretation of such earthquakes. If the depth of a seismic event is in error then moment tensor estimates can also be significantly altered. In the context of nuclear-test-ban monitoring, a seismic event whose depth can be confidently shown to exceed say, 10km, is unlikely to be an explosion. Surface wave excitation is sensitive to source depth, especially at intermediate and short periods, owing to the approximate exponential decay of surface wave displacements with depth. The radiation pattern and amplitude of surface waves are controlled by the depth variations in the six components of the strain tensor associated with the surface wave eigenfunctions. The potential exists, therefore, for improvements to be made to depth and moment tensor estimates by analysing surface wave amplitudes and radiation patterns. A new method is developed to better constrain seismic source parameters by analysing 100-20s period amplitude spectra of fundamental-mode surface waves. Synthetic amplitude spectra are generated for all double-couple sources over a suitable depth range and compared with data in a grid-search algorithm. Best fitting source parameters are calculated and appropriate bounds are placed on these results. This approach is tested and validated using a representative set of globally-distributed events. Source parameters are determined for 14 moderately-sized earthquakes (5.4 ≤ Mw ≤ 6.5), occurring in a variety of tectonic regimes with depths calculated between 4-39km. For very shallow earthquakes the use of surface wave recordings as short as 15s is shown to improve estimates of source parameters, especially depth. Analysis of aftershocks (4.8 ≤ Mw ≤ 6.0) of the 2004 great Sumatra earthquake is performed to study the depth distribution of seismicity in the region. Three distinct tectonic regimes are identified and depth estimates calculated between 3-61km, including the identification of one CMT depth estimate to be in error by some 27km.
8
Schlottmann, Robert Brian. „A path integral formulation of elastic wave propagation /“. Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p3004372.
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Rosenblad, Brent Lyndon. „Experimental and theoretical studies in support of implementing the spectral-analysis-of-surface-wave (SASW) method offshore /“. Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
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Gonzalez, John. „Estimating body and surface waves using virtual sources and receivers“. Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/10313.
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This research is focused on the application of both new and established seismic interferometry techniques to a single area: the Altiplano in the Andes region. This area has already been widely studied in terms of its geological evolution. Nevertheless, a single accepted theory has not yet been developed to explain why the topography of the Andes incorporates such a large area of low relief at this altitude. The Altiplano is therefore an interesting zone to study. This research introduces and analyses new concepts and methodologies, such as retrieving surface and body waves between earthquakes by using interferometry. Nevertheless, several factors, such as the quality of recordings, the separation between sources, and the velocity gradient of the medium, had to be taken into account for body and surface wave retrieval. This research also analysed the retrieval of body waves by means of seismic interferometry applied to coda wave arrivals. Results show that due to the attenuation of S waves produced by the zone of partial molten material, when using S coda waves, seismic interferometry does not achieve the objective of wave retrieval. On the other hand, P coda waves gave good results. Also, the combined methodology of interferometry by cross-correlation and convolution was shown to account for the behaviour of the retrieved waves and provided an indication of how the distribution of sources affects the Green’s functions estimates for body waves in this area. Another point covered by this research was the analysis of passive recordings in order to retrieve surface and body waves. Results indicate that surface and body waves could be retrieved. However, in order to retrieve body waves, special circumstances are required, such as lateral continuity of the Moho, a relative strong Moho impedance contrast, and simplicity of the geologic structure because these factors will contribute to a strong signal like that obtained in critical reflections making interferometry results more successful.
11
Kalinski, Michael E. „Determination of in situ V[subscript s] and G[subscript max] using surface wave measurements in cased and uncased boreholes /“. Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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Zywicki, Daren Joseph. „Advanced signal processing methods applied to engineering analysis of seismic surface waves“. Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/20232.
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Liu, Faqi. „Surface multiple attenuation operators in the plane wave domain : theory and applications /“. Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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14
Gonzalez-Huizar, Hector. „Insight into the physics of rupture dynamic triggering seismicity /“. To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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15
Pei, Donghong. „Modeling and inversion of dispersion curves of surface waves in shallow site investigations“. abstract and full text PDF (free order & download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3275830.
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16
Fenneman, Douglas. „An acoustic method for the detection of surface waves in sand“. Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/21802.
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Liu, Kui. „Surface Wave Propagation and Global Crustal Tomography“. Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/25428.
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In this thesis, a finite-frequency theory is developed to calculate Born sensitivity kernels for Rayleigh-wave phase and amplitude measurements that are valid in regions near seismic stations. Calculations of sensitivity kernels for inter-station measurements show that exact travelling-wave representation of Green tensor is necessary when station spacing is close to or smaller than the seismic wavelength. This finite-frequency theory will allow us to take advantage of dense seismic arrays to obtain high-resolution surface-wave tomography using inter-station measurements.
The non-linear dependence of surface wave phase upon large perturbations in crustal thickness as well as finite-frequency effects in global surface-wave tomography are investigated using wave propagation simulations. Calculations show that non-linearity as well as finite-frequency effects can be accounted for by using 2D phase-velocity kernels for boundary perturbations. A 3D-reference tomographic approach is developed for iterative inversions of global crustal structure where Frechet kernels are calculated in 3D reference models.
A global dataset of minor-arc and major-arc Rayleigh wave dispersion measurements at periods between 25 seconds and 100 seconds are built and global phase velocity maps based on the dataset are obtained using diffractional tomography. The phase velocity model confirms many general features associated with surface tectonics including the ocean-continent dichotomy and the signature of lithospheric cooling in oceanic plates. There are significant differences between the phase velocity model and calculations based on a current global model CRUST2.0+S20RTS in oceanic regions, Archean and Proterozoic cratons as well as orogenic belts. In addition, the high resolution phase velocity maps reveal a major change in the distribution of small scale anomalies in the Pacific at different wave periods.Ph. D.
18
Ruan, Youyi. „Surface wave propagation in 3-D anelastic media“. Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/28945.
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Lateral perturbations in anelasticity (Q) and wave speed together provide important constraints
on thermal and chemical structures in the mantle. In present-day tomography studies of global wave
speed and anelasticity, the significance of 3-D wave speed and 3-D Q structures on surface wave
travel times and amplitudes has not been well understood. In this dissertation, the effects of lateral perturbations in anelasticity (Q) and wave speed on surface wave observables are quantified based upon wave propagation simulations in 3-D earth models using a Spectral Element Method.
Comparison between phase delays caused by 3-D wave speed structures and those caused by 3-D
Q variations show that anelastic dispersion due to lateral perturbation in Q is important in long-period surface wave and can account for 15-20% observed phase delays. For amplitude perturbations, elastic focusing/defocusing effects associated with 3-D wave speed structures are dominant while energy dissipation is important in short-period (â ¼ 50 s) surface waves but decreases quickly with increasing
wave period. Anelastic focusing/defocusing associated with 3-D anelastic dispersion becomes more important than wave attenuation in longer period surface waves.
In tomography studies, ray theory breaks down and finite frequency effects become important
when the length scale of heterogenities are smaller than seismic wavelength. Finite frequency effects in 3-D earth models are investigated by comparing theoretical predictions of travel times and amplitudes with â ground truthâ measurements made on synthetic seismograms generated in SEM
simulations. The comparisons show that finite frequency effects are stronger in amplitudes than in phases, especially at long periods.Ph. D.
19
Zaccherini, Rachele. „Surface waves attenuation in granular media through a small-scale Metabarrier“. Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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The present thesis describes a small-scale experiment, carried out in the laboratory of the Swiss Federal Institute of Technology of Zurich (ETH). The research focuses on metamaterials, locally resonant structures able to affect the propagation of waves passing through them.
The present thesis investigates an innovative method to attenuate Rayleigh waves through the insertion of a barrier of scaled resonators into the soil, capable of generating a bandgap in the dispersion relation. Waves, whose frequency fall within the bandgap, cannot propagate through the resonant structure. Each resonator is constituted by a steel mass mounted on top of a spring made with 16 beams forming a truss.
Taking advantage of the results of A. Palermo et al [1] as a starting point, we carried out a small-scale experiment in a big wooden box filled with glass beads in order to investigate the effectiveness of the designed metabarrier in attenuating surface waves generated by a metal rod exciting the surface every 300 ms. We found a stop-band in the dispersion relation inside the metabarrier, generated by the coupling between the vertical component of Rayleigh waves and the longitudinal resonances of the resonators.
In parallel with the laboratory experiment, some numerical simulations have been performed with the software Comsol Multiphysics in order to compare the results obtained experimentally.
20
Kuehnert, Julian. „Simulation of High Frequency Seismic Waves generated by Rockfalls on Real Topography“. Thesis, Université de Paris (2019-....), 2019. https://theses.md.univ-paris-diderot.fr/KUEHNERT_Julian_va2.pdf.
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Les risques d'éboulements doivent être évalués et surveillés afin de prévenir les pertes de vies humaines et dommages aux infrastructures. A cet égard, il est important de créer des catalogues d'événements et de comprendre la dynamique des éboulements. Les ondes sismiques peuvent être utiles à cette fin, car elles transmettent des informations précieuses sur l'événement. Elles sont générées lorsque des éboulements touchent le sol et peuvent être utilisées pour détecter, classer et localiser des événements. Plus encore, on peut déduire des propriétés des éboulements telles que leur volumes et leur comportement dynamique. Cependant, les signaux sismiques hautes fréquences (>1Hz) sont mal compris. En effet, ils sont associés à des sources sismiques complexes qui sont réparties dans l'espace et peuvent varier rapidement dans le temps. De plus, les ondes sismiques hautes fréquences sont susceptibles d'être diffusées et diffractées en raison des interactions avec les hétérogénéités du sol ou la topographie de surface. Cette thèse franchit une étape importante dans la compréhension des signaux sismiques hautes fré-quences des éboulements en simulant la propagation des ondes sismiques en utilisant la méthode des éléments spectraux (SEM) avec des profils de vitesse réalistes et des topographies de surface 3D. L'influence de la topographie sur le champ des ondes sismiques est étudiée. On constate que l'ampli-fication induite par la topographie est sensiblement différente entre les sources situées en profondeurs et celles situées en surface. En effet, les ondes de surface générées par des sources peu profondes sont exposées à une diffusion et à une diffraction constantes lorsqu'elles se déplacent le long de la surface. La désintégration de l'énergie le long de la surface est étudiée pour différents modèles de vitesse et des équations sont dérivées pour calculer rétroactivement l'énergie sismique totale rayonnée par la source. Ceci est intéressant du fait du lien entre l'énergie sismique et le volume d'éboulement. Afin de tenir compte des effets topographiques, il est proposé un facteur de correction qui peut être introduit dans le calcul de l'énergie. Les signaux sismiques générés par les éboulements du cratère Dolomieu du Piton de la Fournaise, à La Réunion, sont analysés. Les sismogrammes synthétiques sont utilisés pour identifier et interpréter les signaux observés qui sont générés par des impacts uniques. L'influence de la topographie sur les formes d'onde est démontrée et la sensibilité avec l'emplacement et la direction de la source est évaluée. Les caractéristiques du signal telles que les amplitudes et le contenu fréquentiel sont expliquées sur la base de la théorie du contact de Hertz. De plus, les rapports spectraux entre stations, calculés à partir des signaux sismiques d'éboulement, sont considérés comme caractéristiques de la position de la source. La comparaison avec les rapports spectraux simulés suggère qu'ils sont dominés par la propagation le long de la topographie plutôt que par le mécanisme de la source. Sur la base de ces résultats, une méthode est proposée pour la localisation des éboulements à l'aide de rapports énergétiques simulés entre stations. La méthode est appliquée pour localiser les éboulements dans le cratère de Dolomieu. La mise en œuvre de la méthode implique une fenêtre temporelle glissante qui permet une application simple sur des signaux sismiques continus. L'accent est mis sur la capacité de la méthode à surveiller l'activité des éboulements en temps réelRockfall hazard has to be evaluated and monitored in order to prevent loss of life and infrastructure. In this regard it is important to create event catalogs and understand rockfall dynamics. Seismic waves can help for this purpose as they carry valuable information of the event. They are generated when rockfalls impact the ground and can be used to detect, classify and locate events. Beyond that, rockfall properties such as their volume and their dynamic behavior can be inferred. Yet, high frequency seismic signals (>1Hz) are poorly understood. This is because they are associated to complex seismic sources which are spatially distributed and can rapidly vary over time. On top of this, high frequency seismic waves are prone to be scattered and diffracted due to interactions with soil heterogeneities or surface topography. This thesis takes an important step forward to enhance understanding of high frequency rockfall seismic signals by simulating seismic wave propagation on domains with realistic velocity profiles and 3D surface topographies using the Spectral Element Method (SEM). The influence of the topography on the seismic wave field is investigated. It is found that topography induced amplification is substantially different between deep sources and sources located at the surface. This is because surface waves generated by shallow sources are exposed to constant scattering and diffraction when traveling along the surface. The energy decay along the surface is investigated for different velocity models and equations are derived to back-calculate the total seismic energy radiated by the source. This is of interest as the rockfall seismic energy is related to the rockfall volume. In order to account for topography effects, a correction factor is proposed which can be introduced in the energy calculation. Observed seismic signals generated by rockfall at Dolomieu crater on Piton de la Fournaise volcano, La Réunion, are analyzed. Synthetic seismograms are used to identify and interpret observed signals generated by single impacts. The influence of topography on the waveforms is demonstrated and the sensitivity on source location as well as source direction is evaluated. Signal characteristics such as amplitudes and frequency content are explained based on Hertz contact theory. Additionally, inter-station spectral ratios computed from rockfall seismic signals are shown to be characteristic of the source position. Comparison with simulated spectral ratios suggest that they are dominated by the propagation along the topography rather than the mechanism of the source. Based on these findings, a method is proposed for the localization of rockfalls using simulated inter-station energy ratios. The method is applied to localize rockfalls at Dolomieu crater. The implementation of the method involves a sliding time window which allows a straightforward application on continuous seismic signals. The potential of the method to monitor rockfall activity in real-time is emphasized
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Bjurström, Henrik. „Non-contact surface wave measurements on pavements“. Doctoral thesis, KTH, Jord- och bergmekanik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-201147.
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In this thesis, nondestructive surface wave measurements are presented for characterization of dynamic modulus and layer thickness on different pavements and cement concrete slabs. Air-coupled microphones enable rapid data acquisition without physical contact with the pavement surface. Quality control of asphalt concrete pavements is crucial to verify the specified properties and to prevent premature failure. Testing today is primarily based on destructive testing and the evaluation of core samples to verify the degree of compaction through determination of density and air void content. However, mechanical properties are generally not evaluated since conventional testing is time-consuming, expensive, and complicated to perform. Recent developments demonstrate the ability to accurately determine the complex modulus as a function of loading time (frequency) and temperature using seismic laboratory testing. Therefore, there is an increasing interest for faster, continuous field data evaluation methods that can be linked to the results obtained in the laboratory, for future quality control of pavements based on mechanical properties. Surface wave data acquisition using accelerometers has successfully been used to determine dynamic modulus and thickness of the top asphalt concrete layer in the field. However, accelerometers require a new setup for each individual measurement and are therefore slow when testing is performed in multiple positions. Non-contact sensors, such as air-coupled microphones, are in this thesis established to enable faster surface wave testing performed on-the-fly. For this project, a new data acquisition system is designed and built to enable rapid surface wave measurements while rolling a data acquisition trolley. A series of 48 air-coupled micro-electro-mechanical sensor (MEMS) microphones are mounted on a straight array to realize instant collection of multichannel data records from a single impact. The data acquisition and evaluation is shown to provide robust, high resolution results comparable to conventional accelerometer measurements. The importance of a perfect alignment between the tested structure’s surface and the microphone array is investigated by numerical analyses. Evaluated multichannel measurements collected in the field are compared to resonance testing on core specimens extracted from the same positions, indicating small differences. Rolling surface wave measurements obtained in the field at different temperatures also demonstrate the strong temperature dependency of asphalt concrete. A new innovative method is also presented to determine the thickness of plate like structures. The Impact Echo (IE) method, commonly applied to determine thickness of cement concrete slabs using an accelerometer, is not ideal when air-coupled microphones are employed due to low signal-to-noise ratio. Instead, it is established how non-contact receivers are able to identify the frequency of propagating waves with counter-directed phase velocity and group velocity, directly linked to the IE thickness resonance frequency. The presented non-contact surface wave testing indicates good potential for future rolling quality control of asphalt concrete pavements.QC 20170209
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Casey, Thomas J. „Shear wave data collection in mid America using an automated surface source during seismic cone testing“. Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/32804.
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Chaiprakaikeow, Susit. „New Methods for Engineering Site Characterization Using Reflection and Surface wave Seismic Surveys“. DigitalCommons@USU, 2012. https://digitalcommons.usu.edu/etd/1273.
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This study presents two new seismic testing methods for engineering application, a new shallow seismic reflection method and Time Filtered Analysis of Surface Waves (TFASW). Both methods are described in this dissertation. The new shallow seismic reflection was developed to measure reflection at a single point using two to four receivers, assuming homogeneous, horizontal layering. It uses one or more shakers driven by a swept sine function as a source, and the cross-correlation technique to identify wave arrivals. The phase difference between the source forcing function and the ground motion due to the dynamic response of the shaker-ground interface was corrected by using a reference geophone. Attenuated high frequency energy was also recovered using the whitening in frequency domain. The new shallow seismic reflection testing was performed at the crest of Porcupine Dam in Paradise, Utah. The testing used two horizontal Vibroseis sources and four receivers for spacings between 6 and 300 ft. Unfortunately, the results showed no clear evidence of the reflectors despite correction of the magnitude and phase of the signals. However, an improvement in the shape of the cross-correlations was noticed after the corrections. The results showed distinct primary lobes in the corrected cross-correlated signals up to 150 ft offset. More consistent maximum peaks were observed in the corrected waveforms. TFASW is a new surface (Rayleigh) wave method to determine the shear wave velocity profile at a site. It is a time domain method as opposed to the Spectral Analysis of Surface Waves (SASW) method, which is a frequency domain method. This method uses digital filtering to optimize bandwidth used to determine the dispersion curve. Results from testings at three different sites in Utah indicated good agreement with the dispersion curves measured using both TFASW and SASW methods. The advantage of TFASW method is that the dispersion curves had less scatter at long wavelengths as a result from wider bandwidth used in those tests.
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Sullivan, Brendan. „Delayed triggering of early aftershocks by multiple surface waves circling the earth“. Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45827.
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It is well known that direct surface waves of large earthquakes are capable of triggering shallow earthquakes and deep tremor at long-range distances. Recent studies have shown that multiple surface waves circling the earth could also remotely trigger microearthquakes. However, it is still not clear whether multiple surface waves returning back to the main shock epicenters could also trigger/modulate aftershock behavior. Here we conduct a study to search for evidence of such triggering by systematically examining aftershock patterns of earthquakes with magnitude ≥ 8 since 1990 that produce observable surface waves circling the globe repeatedly. We specifically examine the 2011 M9 Tohoku-Oki event using a composite catalog of JMA, HiNet and newly detected events obtained by waveform cross correlation. We compute the magnitude of completeness for each sequence, and stack all the sequences together to compute the seismicity and moment rates by sliding data windows. The sequences are also shuffled randomly and these rates are compared to the actual data as well as synthetic aftershock sequences to estimate the statistical significance of the results. Our results suggest that there is some moderate increase of early aftershock activity after a few hours when the surface waves return to the epicentral region. However, we could not completely rule out the possibility that such an increase is purely due to random fluctuations of aftershocks or caused by missing aftershocks in the first few hours after the mainshock.
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Bailey, Jonathan Pqul. „Development of shear wave velocity profiles in the deep sediments of the Mississippi Embayment using surface wave and spectral ratio methods“. Diss., Columbia, Mo. : University of Missouri-Columbia, 2008. http://hdl.handle.net/10355/5635.
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Thesis (M.S.)--University of Missouri-Columbia, 2008.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 10, 2009 Includes bibliographical references.
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Fader, Amelia Erin. „Integration of surface seismic waves, laboratory measurements, and downhole acoustic televiewer imaging, in geotechnical characterization: Ogden, KS“. Thesis, Kansas State University, 2012. http://hdl.handle.net/2097/15118.
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Master of ScienceDepartment of Geology
Abdelmoneam Raef
Geotechnical site characteristics are a function of the subsurface elastic moduli and the geologic structures. This study integrates borehole, surface and laboratory measurements for a geotechnical investigation that is focused on investigating shear-wave velocity (Vs) variation and its implication to geotechnical aspects of the Ogden test site in eastern Kansas. The area has a potential of seismicity due to the seismic zone associated with the Nemaha formation where earthquakes pose a moderate hazard. This study is in response to recent design standards for bridge structures require integrating comprehensive geotechnical site characterization. Furthermore, evaluation of dynamic soil properties is important for proper seismic response analysis and soil modeling programs. In this study, near surface geophysical site characterization in the form of 2D shear-wave velocity (Vs) structure that is compared with laboratory measurements of elastic moduli and earth properties at simulated in situ overburden pressure conditions and synergy with downhole Acoustic Televiewer time and amplitude logs, proved very robust “validated” workflow in site characterization for geotechnical purposes. An important component of a geotechnical site characterization is the evaluation of in-situ shear modulus, Poisson’s ratio and reliable and accurate elastic modulus ([lambda]) and shear modulus ([mu]) estimates are important in a good geotechnical site characterization. The geophysical site characterization, undertaken in this study, will complement and help in extrapolating drilling and core-based properties deduced by the geotechnical engineers interested at the test site.
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Ward, Kevin Michael, und Kevin Michael Ward. „Imaging the Lithospheric Structure of the Central Andes from the Joint Inversion of Multiple Seismic Data Sets“. Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/621780.
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A lingering question in Cordilleran tectonics is how high plateaus form in the absence of continental collision. The type example of an active Cordilleran high plateau is found in the Central Andes of Peru, Bolivia, Argentina, and Chile. Along this section of the South American Cordillera, tectonics are primarily driven by subduction of the oceanic Nazca Plate beneath the continental South American Plate. Extending over 1,800 km along the active continental margin, the Central Andean Plateau (CAP) reaches a maximum width of around 400 km with several peaks in excess of 6 km. Numerous morphotectonic subdivisions of the CAP highlight the complex along-strike variability of the Plateau providing a natural laboratory for investigating the relative contribution of tectonic processes involved in building and maintaining Cordilleran high plateaus. The scale of this problem extends far beyond the scope of any one geoscientific discipline requiring a multidisciplinary approach. Our contribution to this scientific problem and the focus of the work presented in this dissertation is to better understand the current lithospheric and uppermost mantle structure along the CAP. This is achieved by integrating recent advances in seismic imaging techniques with a growing availability of high-quality seismic data into three distinct studies across the South American continent. In the first study, we present a shear-wave velocity model for the crust below the Altiplano-Puna Volcanic Complex (APVC). The target of this study is to constrain the crustal volume of a large magma reservoir inferred to exist below the APVC. When combined with geological and petrological constraints, the large-volume magma reservoir imaged in this study suggests a significant magmatic contribution to the growth of the Plateau in excess of one kilometer over the last ten million years. In addition to the tectonic contributions of this work, we introduce a new method of jointly inverting surface-wave dispersion data and receiver functions to generate a three-dimensional velocity model. In the second study, we combine Rayleigh-wave dispersion data from ambient noise and earthquake-generated surface waves to invert for a shear-wave velocity model of the lithosphere and uppermost mantle below the Bolivian Orocline. The target of this study is to identify any possible mantle contributions to the uplift history along the northern CAP. The highlight of this study is a high-velocity feature that extends from the base of the crust to ~120 km depth below the Altiplano basin. We interpret this feature using a simple isostatic model and suggest it is responsible for the relatively low topography of the Altiplano basin. In the third and final study, we extend the seismic model of the APVC crust to cover the entire Puna Plateau (southern CAP). The target of this study is to assess the uniqueness of the APMB and to look for additional magma reservoirs in the crust. A highlight of this work is the nearly one-to-one spatial correlation between the long-wavelength topography, ignimbrite deposits, long-wavelength Bouguer gravity anomalies, and four additional mid-crustal low-velocity zones imaged in the southern Puna Plateau. When placed in the context of existing geological and petrological constraints, we suggest the contribution of magmatic addition as an uplift mechanism in Cordilleran systems is much larger than is currently accepted.
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Alzawad, Ahmed. „Bedrock Fracture Zone Delineation Using Multichannel Analysis of Surface Waves in Carter Park, Bowling Green, Ohio“. Bowling Green State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1338837442.
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Asabere, Philip. „COMPARISON OF DISPERSION CURVES ACQUIRED USING MULTICHANNEL ANALYSIS OF SURFACE WAVES WITH VARIOUS STRIKER PLATE CONFIGURATIONS“. Master's thesis, Temple University Libraries, 2016. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/368445.
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Civil EngineeringM.S.C.E.
There is growing appreciation and research regarding geophysical methods to evaluate near surface soil properties in geotechnical engineering. Geophysical methods are generally non-destructive test (NDT) methods that do not necessitate traditional sampling of soils. Instead, they rely on application of input signals and deduction of soil properties from the measured response of the domain. Geophysical methods include various seismic, magnetic and nuclear techniques applied at the surface and/or subsurface within boreholes. Surface seismic methods, which include Multichannel Analysis of Surface Waves (MASW), are increasing in usage for geotechnical engineering purposes to evaluate stiffness properties of soils. MASW typically involves using a hammer to impact a base plate (also referred to as a striker plate) to transmit surface waves into the ground. These waves propagate through the underlying soils at a site and are received by an array of geophones placed on the ground surface. The manner in which the waves propagate is primarily influenced by soil stiffness, particularly against shear. Therefore, the signals recorded during an MASW survey can be analyzed to estimate the shear stiffness of the soils at a site, a parameter that is extremely important for seismic-related engineering purposes (e.g., site amplification, liquefaction, etc.). Aluminum plates are routinely used in a large number of MASW studies as a striker plate to couple the energy from a sledgehammer blow to the underlying soil layers. Various researchers have postulated that the material make-up of the striker plate has an effect on the frequency of the generated waves and, for that matter, the depth achieved with a typical MASW survey. For example, a less stiff material such as ultra-high-molecular-weight (UHMW) polyethylene is often recommended to increase low frequency energy of the input surface wave relative to aluminum. However, very limited research work has been performed in this area to systematically ascertain the effects of modifications to the striker plate material. Due to the limited direct research related to striker plates, MASW was utilized in this study to measure the dispersion curve resulting from MASW at various sites in the Philadelphia metropolitan area. Different striker plate configurations were used during testing to systematically quantify their effects on typical MASW results. The proposed striker base plate configurations included a one (1.0) inch thick aluminum plate, a one (1.0) inch thick aluminum plate over additional rubber mats of varying thickness, and multiple ultra-high-molecular-weight (UHMW) polyethylene plates of various thicknesses. The purpose of this testing was to examine the performance of each configuration, particularly at the low frequency range of the dispersion results. Also efforts were made to qualitatively access the durability of the configurations with respect to long term exposure to impact load.
Temple University--Theses
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Masoni, Isabella. „Inversion of surface waves in an oil and gas exploration context“. Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAU029/document.
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La caractérisation de la proche surface est un enjeu majeur pour l'industrie pétrolière. Lors des acquisitions terrestres et Ocean Bottom Cable (OBC), les couches superficielles généralement altérées ou peu consolidées, présentent des structures géologiques complexes et ont éventuellement des variations topographiques importantes. Les ondes de surface, énergétiques, se propagent dans ce milieu complexe et dominent les sismogrammes, ce qui masque le signal utile pour le traitement sismique classique et rend difficile l'imagerie à la profondeur du réservoir.Il est donc important de pouvoir atténuer ces ondes, éventuellement d'appliquer des corrections statiques et/ou d'amplitude. Ceci qui nécessite une connaissance précise du modèle de vitesse de la proche surface. L'étude de la dispersion des ondes de surface est couramment utilisée en sismologie globale et à l'échelle géotechnique pour évaluer les propriétés des milieux terrestres. Il existe néanmoins des limitations: la mesure de cette dispersion est souvent difficile et les profils de vitesses obtenus sont 1D. A l'échelle pétrolière, l'hypothèse 1D n'est pas toujours adaptée, ce qui motive l'utilisation d'une méthode alternative d'imagerie plus haute résolution, la méthode d'inversion de la forme d'onde (FWI). Cependant, le modèle de vitesse initial doit être assez précis pour éviter le "cycle-skipping" et permettre la convergence vers la solution optimale.Cette étude explore différentes alternatives de fonctions coûts pour résoudre le "cycle-skipping" et diminuer la dépendance de l'inversion à la qualité du modèle initial. En exprimant les fonctions coûts dans le domaine f-k (fréquence-nombre d'onde) et le domaine f-p (fréquence-lenteur), la FWI est plus robuste. A l'aide d'exemples synthétiques, nous démontrons l'efficacité de ces nouvelles approches qui permettent bien de retrouver les variations latérales de vitesses d'onde S.Dans une seconde partie, nous développons une inversion FWI en "layer stripping", adaptée spécifiquement à la physique des ondes de surface. Comme la profondeur de pénétration de ces ondes dépend de leur longueur d'onde, et donc, de leur contenu fréquentiel, nous proposons d'inverser séquentiellement des plus hautes aux plus basses fréquences de ces ondes pour contraindre successivement les couches superficielles jusqu'aux plus profondes. Un fenêtrage selon la distance source-station est également appliqué. Dans un premier temps seules les courtes distances sont inversées, au fur à mesure les données associées à des plus grandes distances sont rajoutées, plus fortement impactées par le "cycle-skipping". Nous démontrons à l'aide d'exemples synthétiques l'avantage de cette méthode par rapport aux méthodes multi-échelles conventionnelles inversant des basses vers les hautes fréquences.Enfin, l'inversion des ondes de surface pour la caractérisation de la proche surface est confrontée à un cas réel. Nous discutons la construction et la pertinence du modèle initial et les difficultés rencontrées lors de l'inversionThe characterization of the near surface is an important topic for the oil and gas industry. For land and Ocean Bottom Cable (OBC) acquisitions, weathered or unconsolidated top layers, prominent topography and complex shallow structures may make imaging at target depth very difficult. Energetic and complex surface waves often dominate such recordings, masking the signal and challenging conventional seismic processing. Static corrections and the painstaking removal of surface waves are required to obtain viable exploration information.Yet surface waves, which sample the near surface region, are considered as signal on both the engineering and geotechnical scale as well as the global seismology scale. Their dispersive property is conventionally used in surface wave analysis techniques to obtain local shear velocity depth profiles. But limitations such as the picking of dispersion curves and poor lateral resolution have lead to the proposal of Full Waveform Inversion (FWI) as an alternative high resolution technique. FWI can theoretically be used to explain the complete waveforms recoded in seismograms, but FWI with surface waves has its own set of challenges. A sufficiently accurate initial velocity model is required or otherwise cycle-skipping problems will prevent the inversion to converge.This study investigates alternative misfit functions that can overcome cycle-skipping and decrease the dependence on the initial model required. Computing the data-fitting in different domains such as the frequency-wavenumber (f-k) and frequency-slowness (f-p) domains is proposed for robust FWI, and successful results are achieved with a synthetic dataset, in retrieving lateral shear velocity variations.In the second part of this study a FWI layer stripping strategy, specifically adapted to the physics of surface waves is proposed. The penetration of surface waves is dependent on their wavelength, and therefore on their frequency. High-to-low frequency data is therefore sequentially inverted to update top-to-bottom layer depths of the shear velocity model. In addition, near-to-far offsets are considered to avoid cycle-skipping issues. Results with a synthetic dataset show that this strategy is more successful than conventional multiscale FWI in using surface waves to update the shear velocity model.Finally inversion of surface waves for near surface characterization is attempted on a real dataset at the oil and gas exploration scale. The construction of initial models and the difficulties encountered during FWI with real data are discussed
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Akhtar, Ehsan Siddique. „Seismic Characterization of the Central Iberian Zone from the Surface to the Upper Mantle“. Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/290072.
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The multi-seismic experiments carried out under the ALCUDIA research initiative include a normal incidence and a wide-angle seismic reflection datasets. These constrain the internal architecture, the detailed crustal and lithospheric structure and, provide the necessary knowledge on physical properties across the Central Iberia Zone. The normal incidence seismic images from south to north: the suture zone of Ossa-Morena Zone (the Central Unit), the undulating Central Iberian domain, the intruded granitic bodies (the Mora Granite, the Toledo Anatectic complex, etc) up to the Toledo Fault, just south of the Tajo Basin. The study area is characterized by undulating topography characterized by a series of synclines and anticlines. The image shows a weakly reflective upper crust, ~13-18 km thick. The sinusoidal topography reflects the folding, the imbricate thrust systems, and listric extensional faults imaged by the normal incidence data. At deeper levels the image reveals arcuate and laminated events suggesting boudinage like structures. These features are disrupted in the south most probably due to the existence of the suture zone. The deep expression of the outcropping suture zone, is slightly displaced to the north with respect to its surface position and, it is imaged as an under-thrusting of a thin slice of lower crust. Towards the northern end of the transect, beneath the Toledo fault, a north dipping band of reflectivity suggest a significant thinning of the lower crust to the north. The Mohorovicic discontinuity is delineated as a sharp decrease in reflectivity at the base of the lower crust, located at ~31-33 km depth (10.5 s two-way travel-time).
The wide-angle seismic reflection data acquired in early May 2012, was aimed to provide the distributions of the physical properties (P- and and S-wave velocities, densities, and Poisson’s ratio) of the crust beneath the study area. It was designed to be nearly coincident with the normal incidence profile. The obtained P- and S- wave velocity models reveal significant lateral velocity variations in the upper crust, which are consistent with the observation from the surface outcrops. The lower crust is identified by a sharp increase in velocity at ~13 km and ~20 km beneath the Central Iberian Zone and the Tajo Basin, respectively. The base of the crust is strongly constrained by the high amplitude PmP and SmS arrivals and it is located at ~31 km in the southern end and at ~35.5 km below the northern end of the wide-angle transect. The wide-angle was also used to produce low-fold P- and S-wave wide-angle stacks. This was done to take a closer look to the Moho discontinuity, and to be able to estimate the internal structure and generate synthetic seismograms in which the PmP and SmS would be qualitatively comparable to the phases observed in the shot records. This place key constraints on the structure of the Moho discontinuity beneath the Central Iberian Zone and the Tajo Basin in the Variscan orogen of the central Iberian Massif. The images reveal gradual deepening from ~31 km (10.2 s) in the Central Iberian Zone to ~35.5 km (11.8 s) beneath the Tajo Basin for the Moho discontinuity. The wide-angle seismic data and the results derived from it are compatible with the normal incidence images.Los experimentos de multi-sísmicas realizados en el marco de la iniciativa del proyecto ALCUDIA incluyen una incidencia normal y sísmica gran angular de los conjuntos de datos de reflexión sísmica. Estos limitan las estructuras internas, la estructura detallada de la corteza y litosfera y, proporcionan el conocimiento necesario de las propiedades físicas a lo largo de la Zona Central Ibérica. Las imágenes sísmicas de incidencia normal se presentan de Sur a Norte: las estructuras de la Zona Ossa-Morena (Unidad Central), el ondulante domino Ibérico Central, los cuerpos intrusivos graníticos (Granitos de Mora, complejo Anatético de Toledo, etc.) hasta la falla de Toledo, justo al Sur de la cuenca del Tajo. La zona de estudio está caracterizada por una topografía ondulada debido a una serie de sinclinales y anticlinales. La imagen muestra una corteza inferior débilmente reflectante, ~13-18 km de espesor. La topografía sinodal refleja los pliegues, los sistemas de cabalgamientos imbricados, y fallas extensionales lístricas observados por los datos de sísmica de incidencia normal. A niveles más profundos las imágenes revelan estructuras arqueadas y laminares que sugieren estructuras como boundinage. Estas características son interrumpidas hacia el Sur, muy probablemente debido a la existencia de la zona de sutura. La expresión más profunda del afloramiento de la zona de sutura, está ligeramente desplazada hacia el Norte con respecto a su localización en superficie y, esta es vista como un cabalgamiento profundo de una fina capa de corteza inferior. Hacia el límite norte del perfil, debajo la falla de Toledo, una banda de reflectividad buzando hacia norte sugiere un adelgazamiento de la corteza inferior hacia el Norte. La discontinuidad de Mohorovicic se delimita como una fuerte disminución de la reflectividad a la base de la corteza inferior, localizada a unos ~31-33 km de profundidad (10.5 s tempo doble). Los datos de gran ángulo de sísmica de reflexión adquiridos a principios de mayo de 2012, tenían como objetivo proporcionar las distribuciones de las propiedades físicas (velocidades P y S, densidades, y el coeficiente de Poisson) de la corteza bajo la zona de estudio. Este perfil fue diseñado para ser casi coincidente con el perfil de incidencia normal. Los modelos de velocidad de P y S obtenidos revelan importantes variaciones laterales de velocidad en la corteza superior, que son coherentes con la observación de los afloramientos en superficie. La corteza inferior se identifica por un fuerte aumento de la velocidad a ~13 km y ~20 km de profundidad en Zona Central Ibérica y en la Cuenca del Tajo, respectivamente. La base de la corteza está fuertemente limitada por grandes amplitud de las llegadas de PmP y SmS y se encuentra a ~31 km en el extremo sur y a ~35,5 km por debajo del extremo norte del perfil de sísmica de gran ángulo. La sísmica de gran ángulo también se utilizó para producir low-fold stacks para las ondas P y las S. Esto se hizo para tomar una mirada más cercana a la discontinuidad de Moho, y para ser capaces de estimar la estructura interna y generar sismogramas sintéticos donde las fases PmP y SmS serían cualitativamente comparables a las fases observadas en los registros sísmicos. Esto dio lugar restricciones clave en la estructura de la discontinuidad de Moho bajo la Zona Central Ibérica y la Cuenca del Tajo en el orógeno Varisco del Macizo Central Ibérico. Las imágenes revelan una profundización gradual de ~31 km (10,2 s) en la Zona Central Ibérica a ~35,5 km (11,8 s) debajo de la cuenca del Tajo para la discontinuidad de Moho. Los datos sísmicos de gran ángulo y los resultados derivados de ellos son compatibles con las imágenes de incidencia normal.
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Alder, Chloé. „Etude de la déformation de la croûte et du manteau terrestres à partir de l'anisotropie sismique des modèles tomographiques“. Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEN021.
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L’anisotropie est souvent utilisée en sismologie comme proxy de la déformation des roches. Elle se développe lorsque des minéraux acquièrent une orientation préférentielle. C’est le cas de l’olivine des péridotites du manteau qui s’aligne selon la direction des flux de matière. Néanmoins, l’anisotropie observée en tomographie peut aussi provenir d’hétérogénéités chimiques non résolues par les ondes sismiques longues périodes : elle s’apparente alors à̀ de l’anisotropie artificielle. Les théories et développements méthodologiques actuels ne permettent pas de distinguer l’anisotropie réelle de l’anisotropie artificielle dans les signaux sismiques. Dans cette thèse nous avons utilisé des modèles simples de manteau terrestre pour étudier théoriquement et numériquement le lien entre le niveau d’hétérogénéités non résolues et l’anisotropie radiale artificielle. Nous en avons conclu que l’anisotropie est proportionnelle au carré des hétérogénéités et que 10% de contraste de vitesse sismique peut engendrer plus de 3% d’anisotropie, un niveau non négligeable au regard des observations tomographiques. Une tomographie 3-D anisotrope de l’Europe, centrée sur les Alpes et les Apennins, a également enté réalisée. Les données d’ondes de surface utilisées sont issues de corrélations de bruit sismique et permettent d’imager la croûte et le manteau supérieur. La structure isotrope de notre modelé illumine particulièrement bien la plaque adriatique en subduction sous les Apennins ainsi qu’une rupture de ce panneau située au sud de la chaîne. Par ailleurs, la méthode d’inversion en profondeur utilisée prend en compte le biais entre anisotropie et hétérogénéités. Nous présentons ainsi le premier modelé 3-D d’anisotropie radiale en Europe réalisé pour des profondeurs aussi faibles. Nos résultats suggèrent que la croûte inférieure est marquée par une structuration horizontale dans les Apennins, probablement en lien avec la déformation extensive actuelle observée dans la régionSeismic anisotropy is often used as a proxy for rock deformation. It arises from the preferred orientation of anisotropic minerals. For instance, olivine in mantellic peridotites align according to mantle flow. However, anisotropy in tomographic models can be the result of small scale heterogeneities unresolved by long period seismic waves. It is thus considered as artificial. Theories and methodological developments do not allow to distinguish the relative contributions of real and artificial anisotropy in seismic signals. In this thesis, we used simple models of the Earth’s mantle to analytically and numerically study the link between unresolved heterogeneities and the level of artificial radial anisotropy. We concluded that anisotropy is proportional to the square of heterogeneities and that 10% of velocity contrast can be responsible for 3% of anisotropy, which is non negligible compared to the observed anisotropy in tomography. A 3-D anisotropic model of Europe, focusing on the Alps and Apennines, was constructed from surface waves data. The dispersion measurements were made from noise correlation and allow to image the crust and uppermost mantle. The isotropic structure of the model shows particularly well the Adriatic plate subducting under the Apennines, as well as a slab break-off in the Southern part of the chain. The method used for the depth inversion takes into account the trade-off between layering and anisotropy. Our model is therefore the first 3-D model of radial anisotropy built at shallow depths in Europe. Our results suggest that the lower crust has a horizontal organization in the Apennines, probably related to the extensive regime observed in the area
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Montagner, Jean-Paul. „Etude de la structure profonde de la terre a partir des ondes de surface de longue periode“. Paris 6, 1986. http://www.theses.fr/1986PA066188.
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Differentes methodes d'inversion de la vitesse de ces ondes sont appliquees a plusieurs regions du globe: ocean pacifique, afrique, ocean indien. La regionalisation suivant l'age du fond oceanique montre que des heterogeneites laterales de vitesse existent jusqu'a au moins 400 km de profondeur et que la correlation entre la tectonique de surface et la structure profonde est meilleure sous l'ocean pacifique que sous l'ocean indien
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Pérez, Solano Carlos Andrés. „Imagerie sismique de la proche sub-surface : modification de l'inversion des formes d'onde pour l'analyse des ondes de surface“. Phd thesis, Ecole Nationale Supérieure des Mines de Paris, 2013. http://pastel.archives-ouvertes.fr/pastel-00932790.
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L'amélioration des images sismiques peut aider à mieux contraindre l'exploration deshydrocarbures. Les ondes élastiques qui se propagent dans la Terre peuvent être classifiéescomme ondes de volume et ondes de surface. Si ces dernières sont les plus énergétiques,seules les ondes de volume sont couramment considérées comme des signaux utiles.Cependant, les ondes de surface sont utiles pour caractériser la proche sub-surface.Classiquement, les ondes de surface sont analysées dans des contextes de propriétésélastiques localement 1D.Nous proposons une modification de l'inversion des formes d'onde classique pourreconstruire des profils de propriétés 2D (la windowed-Amplitude Waveform Inversion, w-AWI). La w-AWI est spécialement robuste en ce qui concerne le choix du modèle initial.Nous appliquons la w-AWI aux données synthétiques ainsi qu'aux données réelles, montrantque cette approche permet de récupérer des propriétés 2D.
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Duffy, Brendan Gilbert. „Development of Multichannel Analysis of Surface Waves (MASW) for Characterising the Internal Structure of Active Fault Zones as a Predictive Method of Identifying the Distribution of Ground Deformation“. Thesis, University of Canterbury. Geological Sciences, 2008. http://hdl.handle.net/10092/2051.
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Bulk rock strength is greatly dependent on fracture density, so that reductions in rock strength associated with faulting and fracturing should be reflected by reduced shear coupling and hence S-wave velocity. This study is carried out along the Canterbury rangefront and in Otago. Both lie within the broader plate boundary deformation zone in the South Island of New Zealand. Therefore built structures are often, , located in areas where there are undetected or poorly defined faults with associated rock strength reduction. Where structures are sited near to, or across, such faults or fault-zones, they may sustain both shaking and ground deformation damage during an earthquake. Within this zone, management of seismic hazards needs to be based on accurate identification of the potential fault damage zone including the likely width of off-plane deformation. Lateral S-wave velocity variability provides one method of imaging and locating damage zones and off-plane deformation. This research demonstrates the utility of Multi-Channel Analysis of Surface Waves (MASW) to aid land-use planning in such fault-prone settings. Fundamentally, MASW uses surface wave dispersive characteristics to model a near surface profile of S-wave velocity variability as a proxy for bulk rock strength. The technique can aid fault-zone planning not only by locating and defining the extent of fault-zones, but also by defining within-zone variability that is readily correlated with measurable rock properties applicable to both foundation design and the distribution of surface deformation. The calibration sites presented here have well defined field relationships and known fault-zone exposure close to potential MASW survey sites. They were selected to represent a range of progressively softer lithologies from intact and fractured Torlesse Group basement hard rock (Dalethorpe) through softer Tertiary cover sediments (Boby’s Creek) and Quaternary gravels. This facilitated initial calibration of fracture intensity at a high-velocity-contrast site followed by exploration of the limits of shear zone resolution at lower velocity contrasts. Site models were constructed in AutoCAD in order to demonstrate spatial correlations between S-wave velocity and fault zone features. Site geology was incorporated in the models, along with geomorphology, river profiles, scanline locations and crosshole velocity measurement locations. Spatial data were recorded using a total-station survey. The interpreted MASW survey results are presented as two dimensional snapshot cross-sections of the three dimensional calibration-site models. These show strong correlations between MASW survey velocities and site geology, geomorphology, fluvial profiles and geotechnical parameters and observations. Correlations are particularly pronounced where high velocity contrasts exist, whilst weaker correlations are demonstrated in softer lithologies. Geomorphic correlations suggest that off-plane deformation can be imaged and interpreted in the presence of suitable topographic survey data. A promising new approach to in situ and laboratory soft-rock material and mass characterisation is also presented using a Ramset nail gun. Geotechnical investigations typically involve outcrop and laboratory scale determination of rock mass and material properties such as fracture density and unconfined compressive strength (UCS). This multi-scale approach is espoused by this study, with geotechnical and S-wave velocity data presented at multiple scales, from survey scale sonic velocity measurements, through outcrop scale scanline and crosshole sonic velocity measurements to laboratory scale property determination and sonic velocity measurements. S-wave velocities invariably increased with decreasing scale. These scaling relationships and strategies for dealing with them are investigated and presented. Finally, the MASW technique is applied to a concealed fault on the Taieri Ridge in Macraes Flat, Central Otago. Here, high velocity Otago Schist is faulted against low velocity sheared Tertiary and Quaternary sediments. This site highlights the structural sensitivity of the technique by apparently constraining the location of the principal fault, which had been ambiguous after standard processing of the seismic reflection data. Processing of the Taieri Ridge dataset has further led to the proposal of a novel surface wave imaging technique termed Swept Frequency Imaging (SFI). This inchoate technique apparently images the detailed structure of the fault-zone, and is in agreement with the conventionally-determined fault location and an existing partial trench. Overall, the results are promising and are expected to be supported by further trenching in the near future.
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Imtiaz, Afifa. „Champ d'ondes, variabilité spatiale et cohérence des mouvements sismiques : effets en champ proche et en vallée alluviale“. Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GRENU002/document.
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La variation spatiale du mouvement sismique a des effets significatifs sur la réponse dynamique des structures de génie civil de grandes dimensions. Dans la pratique courante, l'excitation du mouvement sismique le long de la fondation de la structure est considérée uniforme, approche cependant inadéquate pour les structures de large portance au sol localisées à proximité des failles ou sur des sites présentant une structure du sous-sol latéralement hétérogène. Cette thèse se propose donc de comprendre les facteurs clefs contrôlant localement la variabilité spatiale du mouvement sismique, avec en ligne de mire la mise en place de recommendations en vue d'incorporer ces effets dans l'estimation de l'aléa sismique et le dimensionnement des structures. La première partie de cette thèse s'intéresse à la composante intra-évènement de l'écart-type de la distribution du mouvement sismique en champ proche à l'aide de simulations numériques du mouvement sismique pour des sources étendues présentnat une cinématique de rupture réaliste. Les résultats suggèrent que la variabilité intra-évènement dépend significativement du type de rupture, cette variabilité augmentant avec la distance pour les ruptures bilatérales et diminuant pour les ruptures unilatérales. La seconde partie traite de la caractérisation de la composition du champ d'onde dans la vallée de Koutavos-Argostoli, qui est une vallée de petite dimension et d'épaisseur sédimentaire faible, située sur l'île – sismiquement active - de Céphalonie en Grèce. Les champs d'onde générés par 46 séismes, ayant des magnitudes variant entre 2 et 5 et des distances épicentrales jusqu'à 200 km, ont été analysés à partir de l'enregistrement par deux réseaux denses de capteurs sismologiques. L'algorithme de traitement d'antenne MUSIQUE est utilisé pour extraire la vitesse, l'azimut, le type et la polarisation des ondes dominantes se propageant à travers le réseau. Les résultats montrent clairement d'importantes diffractions d'ondes de surface aux bords de vallée au-delà de la fréquence de résonance de la vallée. Tandis que les ondes de Love dominent clairement le champ d'ondes proche de la fréquence de résonance, les ondes de Rayleigh dominent à plus haute fréquence dans des gammes de fréquences étroites. Par ailleurs, un excellent accord est observé entre les champs d'onde de surface diffractés localement et les caractéristiques d'amplification du site. La “cohérence décalée” de la partie la plus énergétique du signal a été quantifiée pour chaque paire de stations du réseau. En général, la cohérence calculée sur les composantes horizontales diminue avec la distance entre stations et la fréquence. La cohérence sur la composante verticale indique des valeurs relativement fortes à haute fréquence. Les valeurs de cohérence apparaissent très faiblement corrélées à la magnitude, l'azimut et la distance épicentrale du séisme, mais sont au contraire liées aux caractéristiques géométriques de la vallée. La coherence est systématiquement plus forte pour les couples de capteurs orientés selon la direction parallèle à l'axe de la vallée, et moins forte pour des couples de capteurs orientés dans la direction perpendiculaires. Cette observation est en accord avec les résultats du traitement d'antenne: la prédominance d'ondes de surface diffractées sur les bords de la vallée conduit à des mouvements en phase le long de la direction parrallèle à l'axe de la vallée. Les résultats de cette thèse apporte des elements de compréhension sur la variabilité spatiale du movement sismique et ouvrent de nombreuses perspectives d'applicationSpatial variation of earthquake ground motion over short distances significantly affects the dynamic response of engineered structures with large dimensions. In current practices, the ground motion excitation across the foundation of a structure is assumed to be spatially uniform, which becomes inadequate for spatially extended structures in the near-fault region or on sites with lateral inhomogeneity. This PhD thesis seeks to understand the key parameters that locally control the ground motion spatial variability with the intent of putting forth practical propositions for incorporating such effects in seismic design and hazard assessment. The first part of the thesis addresses the within-event component of the standard deviation of ground-motion distribution in near source region by means of numerical simulation of ground motions for extended sources with realistic rupture kinematics. The results suggest that the within-event variability significantly depends on the rupture type, depicting an increase with distance for bilateral ruptures and a decrease for unilateral ruptures. The second part deals with the characterization of seismic wave field at the Koutavos-Argostoli site, a small-size, shallow, alluvial valley located in the seismically active Cephalonia Island in Western Greece. The seismic wave field was investigated from the recordings of a dense seismological array for a set of 46 earthquakes, with magnitude 2 to 5 and epicentral distance up to 200 km. The MUSIQUE array analysis algorithm was used to extract the phase velocity, back-azimuth, type and polarization of the dominant waves crossing the array. The results clearly indicate dominant scattering of seismic surface waves, mainly from the valley-edge directions, beyond the fundamental frequency of the valley. While Love surface waves clearly dominate the wave field close to the resonance frequency, Rayleigh waves strongly dominate only in relatively narrow frequency bands at higher frequency. Besides, an excellent consistency is observed between the dominance of the identified surface wave type in the wave field and the site amplification. The "lagged coherency" of the most energetic part of the ground motion has been quantified for each station-pair within the array. In general, spatial coherency estimated from the horizontal components exhibit decays with frequency and interstation distance. Estimates from the vertical component exhibit rather larger values at some higher frequencies. Although coherency does not show any consistent trend indicating dependence on the magnitude, back-azimuth or site-to-source distance of the event, it seems to be primarily controlled by the site geometry. Larger coherency is systematically observed when the station pair is oriented parallel to the valley axis, while lower values are observed in the perpendicular direction. This observation proves to be consistent with the MUSIQUE analysis results: the predominance of scattered surface waves propagating across the valley implies an in-phase motion along valley-parallel direction and out-of-phase motion along valley-perpendicular direction. The findings of the present research are expected to contribute in enhancing our understanding of spatial variability of ground motion and improving the coherency models used in engineering. This work also opens up new insights and many questions in need of further investigation
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Maupin, Valérie. „Etude des caracteristiques des ondes de surface en milieu anisotrope : application a l'analyse d'anomalies de polarisation a la station de port-aux-francais“. Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13035.
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Dispersion et polarisation des ondes de surface dans des structures anisotropes lateralement homogenes. L'equation des ondes elastiques dans des structures planes isotropes est perturbee par l'introduction de coefficients elastiques anisotropes. On en deduit l'anomalie de vitesse de phase et l'anomalie de polarisation decomposee sur les modes propres de la structure isotrope de reference. Ces resultats sont illustres par le calcul d'anomalies de vitesse et de polarisation dans des modeles oceaniques ou l'anisotropie est cree par orientation de fissures dans la croute ou de cristaux d'olivine dans le manteau
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Forissier, Delphine. „Caractérisation de la compacité du ballast ferroviaire par méthodes sismiques“. Thesis, Paris Est, 2015. http://www.theses.fr/2015PESC1184/document.
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Les voies ferrées, construites pour la plupart depuis plus d'une centaine d'années, sont des ouvrages vieillissants. Elles nécessitent une maintenance et un entretien accrus, ce qui constitue un enjeu technique et économique majeur pour les années à venir. Jusqu'à l'ouverture des marchés à la concurrence, la mise en œuvre des voies nouvelles était vérifiée empiriquement par la SNCF. Du fait de la mise en œuvre de la directive européenne 91/440/10, l'exploitant historique se tourne d'un objectif de moyen vers un objectif de résultat. Cela nécessite donc de disposer de méthodes d'auscultation non destructives, permettant de vérifier que le compactage du ballast est correctement réalisé, avant de faire circuler le trafic voyageurs, en vue de garantir un niveau de sécurité élevé. Cette première approche pourrait être poursuivie pour assurer une auscultation à grand rendement. Cependant, les méthodes existantes permettant d'obtenir l'état de compactage du ballast à la mise en œuvre sont ponctuelles et difficiles à mettre en place; elles ne répondent pas à la problématique de doublement de la maintenance des voies des prochaines années. L'étude de la propagation d'ondes vibratoires dans le ballast est une alternative à ces méthodes qui peut permettre de répondre à ces contraintes. Le ballast est un milieu discontinu complexe pour la compréhension des ondes car elles se propagent dans un chaînon de force. Il présente une grande difficulté dans la modélisation du fait de la taille élevée des éléments et doit être traité comme un milieu discret ne répondant pas à une mécanique élastique de milieu continu. Étant donné la difficulté de modéliser cette couche discrète, il convient de traiter le problème par l'expérimentation. L'objectif de cette thèse est donc d'orienter la recherche vers l'utilisation de la propagation des ondes vibratoires dans la structure de la voie. Ce mémoire est organisé comme suit :- un premier chapitre détaille la structure de la voie ferrée et le matériau granulaire qu'est le ballast, ainsi que les méthodes de diagnostic des voies ferrées existantes.- le deuxième chapitre décrit les différents types d'ondes vibratoires se propageant dans un milieu élastique homogène, puis dans le ballast, et étudie la réponse du ballast à travers celle de la traverse ferroviaire.- Ces deux chapitres, issus de l'état de l'art, permettent de définir dans le chapitre trois les expérimentations réalisées dans le cadre de ce travail sur une structure ferroviaire en vraie grandeur : mise en œuvre, instrumentation, résultats. Ce chapitre s'attache particulièrement à décrire la vitesse des ondes et leur amortissement dans le ballast, les courbes de dispersion mesurées.- Enfin, la propagation d'une onde vibratoire dans le ballast est étudiée dans le chapitre quatre par le biais d'une simulation numérique, avec la comparaison de deux modélisations discrète et continue avec l'expérimentationRailways, most of them built for over one hundred years, are old structures. They require increasing maintenance, a major technical and economic challenge for the coming years. Until the opening of markets to competition, the implementation of new railroads was empirically controlled by SNCF. Because of the application of the European directive 91/440/10, the historical operator turns from a goal of means to a goal of results. This calls for non-destructive highly efficient auscultation methods to check the right compaction of the ballast. However, existing methods for obtain ballast compaction assessment during implementation stage are surface-limited and difficult to apply; they do not respond to the issue of the doubling of track maintenance. Thus the study of the propagation waves in the ballast is an alternative to these methods and may allow to answer these requirements. The ballast is a discontinuous medium, complex for the understanding of waves, as they propagate in a force link. Modelling ballast is especially difficult because of the large size of its components and because it should be treated as a discrete environment, not following the elastic mechanics of continuous media. Given the difficulty to model this discrete layer, it is necessary to undertake the problem with experimentation. The aim of this thesis is to focus on the use of the propagation of vibration waves in the railroad structure. This work is organized as follows : the first chapter details the structure of the railroad and the ballast as a granular material, and the existing assessment methods for railroad. The second chapter describes the different types of vibration waves that propagate, first, in an elastic homogeneous medium, second in the ballast, and presents the answer of ballast through the answer of the sleeper. The two previous chapters, derived from the state of the art, allow to define in chapter three the experiments implemented as part of this work on a full scale railroad structure : realization, instrumentation, results. This chapter especially endeavours to describe the waves celerity, their damping in ballast and the measured dispersion curves. Finally, the propagation of a vibration wave in the ballast is studied in chapter four and a numerical simulation, compares with a disctete model and a continuous model with experimental results
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Carcolé, Carrubé Eduard. „Three-dimensional spatial distribution of scatterers in the crust by inversion analysis of s-wave coda envelopes. A case study of Gauribidanur seismic array site (Southern india) and Galeras volcano (South-western Colombia)“. Doctoral thesis, Universitat Ramon Llull, 2006. http://hdl.handle.net/10803/9321.
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In this thesis, coda waves recorded by local seismographic networks will be analyzed to estimate the three-dimensional spatial distribution of scatterers (SDS). This will be done by using the single scattering approximation. This approach leads to a huge system of equations that can not be solved by traditional methods. For the first time, we will use the Simultaneous Iterative Reconstructive Technique (SIRT) to solve this kind of system in seismological applications. SIRT is slow but provides a means to carry out the inversion with greater accuracy. There is also a very fast non-iterative method that allows to carry out the inversion 102 times faster, with a higher resolution and reasonable accuracy: the Filtered Back-Projection (FBP). If one wishes to use this technique it is necessary to adapt it to the geometry of our problem. This will be done for the first time in this thesis. The theory necessary to carry out the adaptation will be developed and a simple expression will be derived to carry out the inversion.FBP and SIRT are then used to determine the SDS in southern India. Results are almost independent of the inversion method used and they are frequency dependent. They show a remarkably uniform distribution of the scattering strength in the crust around GBA. However, a shallow (0-24 km) strong scattering structure, which is only visible at low frequencies, seems to coincide with de Closepet granitic batholith which is the boundary between the eastern and western parts of the Dharwar craton.
Also, the SDS is estimated for the Galeras volcano, Colombia. Results reveal a highly non-uniform SDS. Strong scatterers show frequency dependence, which is interpreted in terms if the scale of the heterogeneities producing scattering. Two zones of strong scattering are detected: the shallower one is located at a depth from 4 km to 8 km under the summit whereas the deeper one is imaged at a depth of ~37 km from the Earth's surface. Both zones may be correlated with the magmatic plumbing system beneath Galeras volcano. The second strong scattering zone may be probably related to the deeper magma reservoir that feeds the system.
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Lucena, Rodrigo Ferreira de. „Avaliações e testes dos métodos MASW e ReMi por meio do tratamento de dados empíricos e sintéticos em um programa de processamento e inversão desenvolvido em MATLAB e sua implicação em um problema geológico na Bacia de Taubaté“. Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/44/44138/tde-17062016-135652/.
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Os métodos de ondas superficiais com ênfase nas ondas Rayleigh foram utilizados como o núcleo desse trabalho de Doutorado. Inicialmente, as ondas Rayleigh foram modeladas permitindo o estudo de sensibilidade de suas curvas de dispersão sob diferentes configurações de parâmetros físicos representando diversos modelos de camadas, em que pôde ser observado parâmetros com maior e menor sensibilidade e também alguns efeitos provocados por baixas razões de Poisson. Além disso, na fase de inversão dos dados a modelagem das ondas Rayleigh foi utilizada para a construção da função objeto, que agregada ao método de mínimos quadrados, a partir do método de Levenberg-Marquardt, permitiu a implementação de um algoritmo de busca local responsável pela inversão de dados das ondas superficiais. Por se tratar de um procedimento de busca local, o algoritmo de inversão foi complementado por uma etapa de pré-inversão com a geração de um modelo inicial para que o procedimento de inversão fosse mais rápido e eficiente. Visando uma eficiência ainda maior do procedimento de inversão, principalmente em modelos de camadas com inversão de velocidades, foi implementado um algoritmo de pós-inversão baseado em um procedimento de tentativa e erro minimizando os valores relativos da raiz quadrada do erro quadrático médio (REQMr) da inversão dos dados. Mais de 50 modelos de camadas foram utilizados para testar a modelagem, a pré-inversão, inversão e pós-inversão dos dados permitindo o ajuste preciso de parâmetros matemáticos e físicos presentes nos diversos scripts implementados em Matlab. Antes de inverter os dados adquiridos em campo, os mesmos precisaram ser tratados na etapa de processamento de dados, cujo objetivo principal é a extração da curva de dispersão originada devido às ondas superficiais. Para isso, foram implementadas, também em Matlab, três metodologias de processamento com abordagens matemáticas distintas. Essas metodologias foram testadas e avaliadas com dados sintéticos e reais em que foi possível constatar as virtudes e deficiências de cada metodologia estudada, bem como as limitações provocadas pela discretização dos dados de campo. Por último, as etapas de processamento, pré-inversão, inversão e pós-inversão dos dados foram unificadas para formar um programa de tratamento de dados de ondas superficiais (Rayleigh). Ele foi utilizado em dados reais originados pelo estudo de um problema geológico na Bacia de Taubaté em que foi possível mapear os contatos geológicos ao longo dos pontos de aquisição sísmica e compará-los a um modelo inicial existente baseado em observações geomorfológicas da área de estudos, mapa geológico da região e informações geológicas globais e locais dos movimentos tectônicos na região. As informações geofísicas associadas às geológicas permitiram a geração de um perfil analítico da região de estudos com duas interpretações geológicas confirmando a suspeita de neotectônica na região em que os contatos geológicos entre os depósitos Terciários e Quaternários foram identificados e se encaixaram no modelo inicial de hemi-graben com mergulho para Sudeste.The surface wave methods to Rayleigh waves were used as the center of this Doctoral work. Initially, the Rayleigh waves were modeled, what enabled the study of the sensitivity of dispersion curves about different sets of physical parameters representing several layer models, wherein it could be observed parameters with higher and lower sensitivity and also some effects caused by low Poisson ratios. Moreover, in the data inversion step the Rayleigh modeling was used for the construction of the object function, that aggregate to the least-squares method, by Levenberg-Marquardt, allowed the implementation of a local search algorithm responsible for data inversion of the surface waves. By reason of being a local search procedure, the data inversion algorithm was complemented with a pre-inversion step wherein an initial model was generated so that the inversion procedure was faster and efficient. Seeking a more efficiency of the inversion procedure, mainly to layer models with velocities inversion, it was implemented a post-inversion algorithm based in a trial and error procedure minimizing the values of the relative Root Mean Squared Error (rRMSE) of the data inversion. More than 50 layer models were used to test the data modeling, pre-inversion, inversion and post-inversion allowing the precise fit of the mathematical and physical parameters present in the several scripts implemented in Matlab. Before to invert the field-acquired data, they need to be treated in the data processing step, whose main aim is the extraction of the dispersion curve caused due the surface waves. For this, three processing methodologies with different mathematical approaches were implemented, also in Matlab. These methodologies were tested and evaluated with synthetic and real data and it was possible to find their strengths and weaknesses, as well as the limitations caused by discretization of the field data. Lastly, the data processing, pre-inversion, inversion and post-inversion steps were unified to form a complete data treatment program of surface waves (Rayleigh). It was used to real data originated by study of a geological problem in the Bacia de Taubaté wherein it was possible to map the geologic contacts along of the seismic acquisition points. The results were compared to an existing initial model based in geomorphological observations of the study area, geological map and global and local geologic information of the tectonic movements in the region. The geophysical The surface wave methods to Rayleigh waves were used as the center of this Doctoral work. Initially, the Rayleigh waves were modeled, what enabled the study of the sensitivity of dispersion curves about different sets of physical parameters representing several layer models, wherein it could be observed parameters with higher and lower sensitivity and also some effects caused by low Poisson ratios. Moreover, in the data inversion step the Rayleigh modeling was used for the construction of the object function, that aggregate to the least-squares method, by Levenberg-Marquardt, allowed the implementation of a local search algorithm responsible for data inversion of the surface waves. By reason of being a local search procedure, the data inversion algorithm was complemented with a pre-inversion step wherein an initial model was generated so that the inversion procedure was faster and efficient. Seeking a more efficiency of the inversion procedure, mainly to layer models with velocities inversion, it was implemented a post-inversion algorithm based in a trial and error procedure minimizing the values of the relative Root Mean Squared Error (rRMSE) of the data inversion. More than 50 layer models were used to test the data modeling, pre-inversion, inversion and post-inversion allowing the precise fit of the mathematical and physical parameters present in the several scripts implemented in Matlab. Before to invert the field-acquired data, they need to be treated in the data processing step, whose main aim is the extraction of the dispersion curve caused due the surface waves. For this, three processing methodologies with different mathematical approaches were implemented, also in Matlab. These methodologies were tested and evaluated with synthetic and real data and it was possible to find their strengths and weaknesses, as well as the limitations caused by discretization of the field data. Lastly, the data processing, pre-inversion, inversion and post-inversion steps were unified to form a complete data treatment program of surface waves (Rayleigh). It was used to real data originated by study of a geological problem in the Bacia de Taubaté wherein it was possible to map the geologic contacts along of the seismic acquisition points. The results were compared to an existing initial model based in geomorphological observations of the study area, geological map and global and local geologic information of the tectonic movements in the region. The geophysical information associated with geological information allowed the generation of an analytical profile of the study region with two geological interpretation confirming the suspect of neotectonic movements in the region wherein the geological contacts between the quaternary and tertiary deposits were identified and they agreed with the initial model of a hemi-graben with dip to Southeast.
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Moueddene, Kada. „Analyse d'images en sismique : pretraitement et extraction d'informations par la morphologie mathematique“. Toulouse 3, 1987. http://www.theses.fr/1987TOU30006.
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Techniques de traitement d'images appliquees aux diagraphies sismiques. En particulier, utilisation des operateurs de morphologie mathematique pour les problemes de pretraitement et d'extraction d'informations. Deux exemples d'application sont presentes: tir de bruits pour l'extraction des spectres de vitesses et tir au centre pour le filtrage des ondes de surface et des arrivees refractees
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Lehujeur, Maximilien. „Étude d'un réservoir géothermique profond par corrélation de bruit sismique ambiant“. Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAH013/document.
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Cette thèse porte sur l’application de la technique de corrélation de bruit sismologique ambiant pour l'imagerie et le suivi des réservoirs géothermiques de Rittershoffen (ECOGI) et de Soultz-sous-Forêts (GEIE-EMC). La forte variabilité spatio-temporelle des sources du bruit de fond sismologique dans la gamme de période 0.2-7s limite la reconstruction des fonctions de Green. Cela induit des erreurs dans la construction des modèles de vitesse. Deux approches sont proposées pour s’affranchir des effets de la non-uniformité spatiale du bruit. Par ailleurs, la variabilité temporelle des sources de bruit est un facteur limitant pour le suivi du réservoir. On estime que les perturbations de vitesse doivent être de l’ordre de 0.1% à 1% pour pouvoir être détectées par les réseaux disponibles. Ce seuil n’a pas été franchi lors de la construction du site Rittershoffen mais une modification probable des propriétés diffractantes du milieu a été observée à la suite d’une stimulationThis work focuses on the application of the ambient seismic noise correlation technique for the imaging and monitoring of deep geothermal reservoirs near Rittershoffen (ECOGI) and Soultz-sous-Forêts (GEIE-EMC). The strong spatial and temporal variability of the noise sources in the period range 0.2-7s limits the reconstruction of the Green’s functions. This results in significant errors in the velocity models. Two approaches are proposed to overcome the spatial non-uniformity of the noise and to improve the quality of the velocity models. Besides that, the temporal variability of the noise sources is a limiting factor for monitoring purposes. We estimate that the speed variations should be larger than 0.1% to 1% to be detected by the available networks. This threshold was not reached at Rittershoffen during the drillings or the stimulations. However, a probable change of the diffracting properties of the medium was observed following a hydraulic stimulation
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Almayahi, Ali Z. „SHEAR-WAVE IMAGING AND BIREFRINGENCE IN A COMPLEX NEAR-SURFACE GEOLOGICAL ENVIRONMENT“. UKnowledge, 2013. http://uknowledge.uky.edu/ees_etds/12.
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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 subparallel grabens with ancillary substructures. The geometry of the interpreted fault zones indicates that they have undergone episodic tectonic deformation since their first formation. Evidence of thickening and steeply dipping reflectors within Tertiary and Quaternary sediment in the downthrown blocks indicate syndepositional movement. Subtle thickening and lack of steeply dipping intraformational reflectors in the Cretaceous suggest a more quiescent period, with sediment deposition unconformably draping and filling the earlier Paleozoic structural surface. There is also evidence that the Tertiary and early Quaternary reactivation was associated with an extensional to compressional regional stress reversal, as manifested by the antiformal folds seen in the hanging wall reflectors and the potential small-amplitude force folds in the Quaternary alluvium, as well as a clear displacement inversion along the Metropolis-loess seismic horizon in two high-resolution reflection images.
A surface shear-wave splitting experiment proved to be an efficient and effective tool for characterizing shallow subsurface azimuthally anisotropic geologic inclusions in low-impedance water-saturated sediment environments. The measured azimuthal anisotropy across a well-constrained N60ºE-striking fault exhibited a natural coordinate system that had a fast direction coincident with the fault strike and an orthogonal slow direction. This is also one indicator that faults inactive during significant geologic intervals (i.e., Holocene) do not "heal". Integrated shear-wave velocity models and electrical resistivity tomography profiles across the fault zones exhibit lower shear-wave velocities and resistivities within the deformation zones compared with values outside the boundaries. This is additional evidence that the deformed sediment does not reconsolidate or heal, but that the sediment particle configuration remains more loosely packed, providing an increase in the overall porosity (i.e., hydraulic conductivity). This can wholly or in large part explain the anomalous contaminant plume migration path that is coincident with the deformed zones of the regional gravel groundwater aquifer.
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Frontera, Genovard Joana Tànit. „Estudis de soroll sísmic ambiental amb registres de sismòmetres de fons marí. Tomografia d'ones superficials al NE de la Península Ibèrica“. Doctoral thesis, Universitat Ramon Llull, 2009. http://hdl.handle.net/10803/9319.
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L'estiu de 2005, es varen instal·lar un sismòmetre de fons marí (OBS, sigles en anglès d'Ocean Bottom Seimometer) permanent, de tres components i banda ampla, i un sensor diferencial de pressió, a les immediacions de la plataforma petrolífera Casablanca (Repsol Investigaciones Petrolíferas S.A.), a uns 150 m de fondària i 50 km de la costa de Tarragona. Aquesta iniciativa, pionera a l'Estat espanyol, es va portar a terme en el marc del projecte Casablanca (REN2003-06577), concedit pel Ministerio de Educación y Ciencia a l'Institut Geològic de Catalunya (IGC) i l'Observatori de l'Ebre, amb l'objectiu de caracteritzar la detectabilitat de l'OBS i millorar el coneixement de la sismicitat i el risc sísmic a la zona. L'any 2007, després d'una reinstal·lació dels sensors en què es varen introduir millores, la transmissió satèl·lit en temps real del senyal al centre de recepció de dades sísmiques a l'IGC de Barcelona va possibilitar la integració de l'OBS a la xarxa sísmica de Catalunya.L'anàlisi de soroll sísmic ambiental a l'emplaçament de l'OBS Casablanca mostra nivells alts als tres components, especialment a baixes freqüències i a la banda microsísmica. Així mateix, s'observen variacions estacionals i la influència de les condicions meteorològiques i oceanogràfiques. La comparació dels nivells de soroll a l'OBS Casablanca amb el d'un altre OBS situat a la mar de Ligúria, amb una instrumentació semblant, però instal·lat a una fondària de 2500 m, mostra un comportament més sorollós a Casablanca, probablement a causa de la menor profunditat a què està situat.
Tot i el seu comportament sorollós, l'OBS Casablanca ha enregistrat diversos sismes locals, regionals i telesismes. Malgrat la petita magnitud i l'escassesa de terratrèmols locals succeïts durant el període de funcionament de l'OBS, l'estació ha mostrat la seva utilitat de cara a la millora de les localitzacions hipocentrals dels sismes propers amb epicentre a la mar. Noves dades permetran la validació d'aquest resultat.
El senyal de l'OBS Casablanca, juntament amb el d'estacions situades a la Península Ibèrica, el nord d'Àfrica i les Illes Balears, s'ha pogut utilitzar amb èxit en un estudi de tomografia d'ones superficials amb soroll sísmic ambiental realitzat al NE de la Península. El procediment de l'estudi tomogràfic ha inclòs un tractament del senyal a fi de minimitzar l'energia aportada pels terratrèmols i normalitzar les amplituds a totes les freqüències. Mitjançant el càlcul de la correlació creuada per a tots els parells d'estacions disponibles durant un període de més d'un any, s'ha trobat un senyal equivalent a la funció de Green del medi, que ha possibilitat la mesura de la velocitat de grup i de fase. La representació dels resultats en forma de mapes de dispersió mostra zones d'altes i baixes velocitats, coherents amb les principals estructures geològiques de l'escorça i part del mantell superior.
Durante el verano de 2005, se instalaron un sismómetro de fondo marino (OBS, siglas en inglés de Ocean Bottom Seismometer) permanente, de tres componentes y banda ancha, y un sensor diferencial de presión, en las inmediaciones de la plataforma petrolífera Casablanca (Repsol Investigaciones Petrolíferas S.A.), a unos 150 m de profundidad y 50 km de la costa de Tarragona. Esta iniciativa, pionera en España, se llevó a cabo en el marco del proyecto Casablanca (REN2003-06577), concedido por el Ministerio de Educación y Ciencia al Institut Geològic de Catalunya (IGC) y al Observatori de l'Ebre, con el objetivo de caracterizar la detectabilidad del OBS y mejorar el conocimiento de la sismicidad y el riesgo sísmico en la zona. En el año 2007, después de una reinstalación en la que se introdujeron mejoras, la transmisión satélite en tiempo real de la señal al centro de recepción de datos sísmicos del IGC en Barcelona posibilitó la integración del OBS a la red sísmica de Cataluña.
El análisis del ruido sísmico ambiental en el emplazamiento del OBS Casablanca muestra niveles altos en las tres componentes, especialmente a bajas frecuencias y en la banda microsísmica. También se observan variaciones estacionales y la influencia de las condiciones meteorológicas y oceanográficas. La comparación de los niveles de ruido en el OBS Casablanca con los de otro OBS situado en el mar de Liguria, de instrumentación similar, pero instalado a 2500 m de profundidad, muestra un comportamiento más ruidoso en Casablanca, probablemente a causa de la menor profundidad a la que está situado.
Aunque de comportamiento ruidoso, el OBS Casablanca ha registrado numerosos seísmos locales, regionales y teleseísmos. A pesar de la pequeña magnitud y la escasez de terremotos locales durante el periodo de funcionamiento del OBS, la estación ha mostrado su utilidad de cara a la mejora de las localizaciones hipocentrales de los seísmos cercanos con epicentro en el mar. Nuevos datos permitirán la validación de este resultado.
La señal del OBS Casablanca, junto con la de estaciones situadas en la Península Ibérica, el norte de África y las Islas Baleares, se ha podido utilizar con éxito en un estudio de tomografía de ondas superficiales con ruido sísmico ambiental realizado al NE de la Península. El procedimiento del estudio tomográfico ha incluido el tratamiento de la señal para minimizar la energía aportada por los terremotos y normalizar las amplitudes para todas las frecuencias. Mediante el cálculo de la correlación cruzada para todos los pares de estaciones disponibles durante un periodo de más de un año, se ha obtenido una señal equivalente a la función de Green del medio, que ha posibilitado la medida de la velocidad de grupo y de fase. La representación de los resultados en forma de mapas de dispersión muestra zonas de altas y bajas velocidades, coherentes con las principales estructuras geológicas de la corteza y parte del manto superior.
During the summer of 2005, a three-component broad-band permanent ocean bottom seismometer (OBS) and a differential pressure gauge were deployed near the Casablanca oil platform (Repsol Investigaciones Petrolíferas S.A.) at a depth of about 150 m and 50 km away from the Tarragona coast (NE Iberian Peninsula). This initiative, pioneer in Spain, was carried out within the framework of the Casablanca project (RES2003-06577), given by the Ministerio de Educación y Ciencia to the Institut Geològic de Catalunya (IGC) and to the Observatori de l'Ebre. The aim of this project was to characterize the OBS detection threshold and to improve the knowledge of the seismicity and seismic risk in the area around. In 2007 satellite transmission was implemented to have continuous and real time data, which allowed integrating the OBS into the Catalan Seismic Network.
A seismic ambient noise analysis at the Casablanca OBS site shows high levels on the three components, especially at low frequencies and at the microseismic band. Seasonal variations and the meteorological and oceanographic conditions influence are also observed. The comparison between Casablanca OBS noise levels and those from another OBS placed at the Ligurian Sea, equipped with similar instrumentation but installed at a depth of 2500 m, shows that the Casablanca site is noisier, probably due to its shallower deployment.
Despite its noisy behaviour, the Casablanca OBS has recorded a number of local and regional earthquakes and teleseisms. Only few close small events have occurred during the OBS running period. Nevertheless, the station has shown its utility to improve hipocentral locations of close earthquakes with the epicentre offshore.
The Casablanca OBS signal, together with that from stations placed at the Iberian Peninsula, northern Africa and Balearic Islands, has been successfully used in a surface wave tomographic study from ambient noise in the NE Iberian Peninsula. The tomographic study includes a signal processing to minimize the energy from earthquakes and to normalize the amplitudes for all frequencies. A signal equivalent to the Green function has been obtained through the cross-correlation between all the possible station pairs during a period longer than one year, allowing the measurement of group and phase velocities. The results, which are presented as dispersion maps, show areas of high and low velocities that are coherent with the main crust and upper mantle geological structures.
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Baumann-Wilke, Maria. „Combining body wave tomography, surface wave inversion, seismic interferometry and laboratory measurements to characterize the black shales on Bornholm at different scales“. Phd thesis, Universität Potsdam, 2013. http://opus.kobv.de/ubp/volltexte/2013/6900/.
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Black shales are sedimentary rocks with a high content of organic carbon, which leads to a dark grayish to black color. Due to their potential to contain oil or gas, black shales are of great interest for the support of the worldwide energy supply. An integrated seismic investigation of the Lower Palaeozoic black shales was carried out at the Danish island Bornholm to locate the shallow-lying Alum Shale layer and its surrounding formations and to characterize its potential as a source rock. Therefore, two seismic experiments at a total of three crossing profiles were carried out in October 2010 and in June 2012 in the southern part of the island. Two different active measurements were conducted with either a weight drop source or a minivibrator. Additionally, the ambient noise field was recorded at the study location over a time interval of about one day, and also a laboratory analysis of borehole samples was carried out. The seismic profiles were positioned as close as possible to two scientific boreholes which were used for comparative purposes.
The seismic field data was analyzed with traveltime tomography, surface wave inversion and seismic interferometry to obtain the P-wave and S-wave velocity models of the subsurface. The P-wave velocity models which were determined for all three profiles clearly locate the Alum Shale layer between the Komstad Limestone layer on top and the Læså Sandstone Formation at the base of the models. The black shale layer has P-wave velocities around 3 km/s which are lower compared to the adjacent formations. Due to a very good agreement of the sonic log and the vertical velocity profiles of the two seismic lines, which are directly crossing the borehole where the sonic log was conducted, the reliability of the traveltime tomography is proven. A correlation of the seismic velocities with the content of organic carbon is an important task for the characterization of the reservoir properties of a black shale formation. It is not possible without calibration but in combination with a full 2D tomographic image of
the subsurface it gives the subsurface distribution of the organic material.
The S-wave model obtained with surface wave inversion of the vibroseis data of one of the profiles images the Alum Shale layer also very well with S-wave velocities around 2 km/s. Although individual 1D velocity models for each of the source positions were determined, the subsurface S-wave velocity distribution is very uniform with a good match between the single models. A really new approach described here is the application of seismic interferometry to a really small study area and a quite short time interval. Also new is the selective procedure of only using time windows with the best crosscorrelation signals to achieve the final interferograms. Due to the small scale of the interferometry even P-wave signals can be observed in the final crosscorrelations.
In the laboratory measurements the seismic body waves were recorded for different pressure and temperature stages. Therefore, samples of different depths of the Alum Shale were available from one of the scientific boreholes at the study location. The measured velocities have a high variance with changing pressure or temperature. Recordings with wave propagation both parallel and perpendicular to the bedding of the samples reveal a great amount of anisotropy for the P-wave velocity, whereas the S-wave velocity is almost independent of the wave direction. The calculated velocity ratio is also highly anisotropic with very low values for the perpendicular samples and very high values for the parallel ones. Interestingly, the laboratory velocities of the perpendicular samples are comparable to the velocities of the field experiments indicating that the field measurements are sensitive to wave propagation in vertical direction.
The velocity ratio is also calculated with the P-wave and S-wave velocity models of the field experiments. Again, the Alum Shale can be clearly separated from the adjacent formations because it shows overall very low vP/vS ratios around 1.4. The very low velocity ratio indicates the content of gas in the black shale formation. With the combination of all the different methods described here, a comprehensive interpretation of the seismic response of the black shale layer can be made and the hydrocarbon source rock potential can be estimated.Schwarzschiefer sind Sedimentgesteine, die einen hohen Gehalt an organischem Kohlenstoff aufweisen, was zu einer dunkelgrauen bis schwarzen Färbung führt. Da Schwarzschiefer das Potenzial besitzen, Öl oder Gas zu enthalten und somit zur weltweiten Energieversorgung beitragen könnten, sind sie von großem Interesse. Mit Hilfe der Kombination verschiedener seismischer Messverfahren wurden die Schwarzschiefer des Unteren Paläozoikums auf der dänischen Insel Bornholm untersucht um den oberflächennahen Alaunschiefer und dessen Umgebungsgestein dort zu lokalisieren und sein Potenzial als Muttergestein abzuschätzen. Dafür wurden im Oktober 2010 und im Juni 2012 im südlichen Teil der Insel zwei seismische Experimente auf insgesamt drei sich kreuzenden Profilen durchgeführt. Für zwei aktive seismische Messungen wurden ein Fallgewicht und ein Minivibrator als Quellen genutzt. Zusätzlich wurde im Messgebiet noch das Wellenfeld des umgebenden Rauschens über einen Zeitraum von etwa einem Tag aufgezeichnet. Außerdem wurden Labormessungen an Bohrkernen aus dem Alaunschiefer durchgeführt. Die seismischen Messprofile befanden sich so nah wie möglich an zwei wissenschaftlichen Bohrungen, die für Vergleichszwecke genutzt wurden. Um die P- und S-Wellengeschwindigkeitsmodelle des Untergrundes zu erhalten wurden die seismischen Felddaten mittels Laufzeittomographie, Oberflächenwelleninversion und seismischer Interferometrie ausgewertet. Die P-Wellenmodelle, die für alle drei seismischen Profile erstellt wurden, zeigen den Alaunschiefer zwischen dem Komstad Kalkstein, der den Alaunschiefer überdeckt, und der Læså Sandsteinformation, die die Basis der Modelle bildet. Für die Schwarzschieferschicht ergeben sich mit rund 3 km/s deutlich geringere P-Wellengeschwindigkeiten als für die umgebenden Gesteine. Zwei seismische Profile liegen direkt an einer der Bohrungen, für die verschiedene Bohrloch-Logs durchgeführt wurden. Der Vergleich des Sonic-Logs mit den vertikalen Geschwindigkeitsprofilen beider Modelle am Bohrpunkt zeigt eine sehr gute übereinstimmung aller Geschwindigkeiten. Dies ist ein Indiz für die Plausibilität der durchgeführten Laufzeittomographie. Um die Reservoireigenschaften der Schwarzschieferschicht einordnen zu können, wurde versucht, die seismischen Geschwindigkeiten mit dem Gehalt an organischem Material zu korrelieren. Ohne geeignete Kalibrierung ist diese Korrelation schwierig, kann aber mit Hilfe der Tomographieergebnisse ein zweidimensionales Abbild der Verteilung des organischen Materials im Untergrund liefern. Auch das S-Wellengeschwindigkeitsmodell, welches mit der Oberflächenwelleninversion der Vibroseisdaten erstellt wurde, bildet den Alaunschiefer gut ab. Hierbei zeigen sich S-Wellengeschwindigkeiten um 2 km/s. Obwohl jeweils nur 1D-Modelle für jede Quellposition bestimmt wurden, ergibt sich für die gesamte Untergrundstruktur des untersuchten Profils ein einheitliches Bild der Geschwindigkeiten. Einen sehr neuen Ansatz bildet die Anwendung der seismischen Interferometrie auf ein sehr kleines Untersuchungsgebiet und über einen sehr kurzen Zeitraum. Neu ist außerdem, dass für die Bestimmung der endgültigen Interferogramme nur Zeitfenster der Kreuzkorrelationen ausgewählt werden, in denen die Signalqualität hinreichend gut ist. In den berechneten Kreuzkorrelationen sind sogar P-Wellen enthalten, was auf die geringen Abstände der seismischen Rekorder zurück zu führen ist. Bei den Labormessungen wurden die Raumwellen für verschiedene Drücke und Temperaturen aufgezeichnet. Die Messungen der Geschwindigkeiten sowohl parallel als auch senkrecht zur Schichtung der Proben zeigen eine starke Anisotropie für die P-Welle. Dagegen scheint die S-Wellengeschwindigkeit fast unabhängig von der Ausbreitungsrichtung der Wellen zu sein. Auch das Verhältnis der Geschwindigkeiten weist starke Anisotropie auf. Für die Wellenausbreitung senkrecht zur Schichtung zeigen sich sehr niedrige Werte, die Werte für die Messungen parallel zur Schichtung sind dagegen deutlich erhöht. Ein interessanter Aspekt der aus den Labormessungen resultiert ist, dass die Geschwindigkeit der Messungen senkrecht zur Schichtung mit den Geschwindigkeitswerten der Feldmessungen übereinstimmen. Damit scheinen die Feldmessungen besonders die Ausbreitung der Wellen in vertikaler Richtung zu registrieren. Das Geschwindigkeitsverhältnis wurde auch mit den P- und S-Wellenmodellen der Feldexperimente berechnet. Auch hier hebt sich der Alaunschiefer mit deutlich verringerten Werten um 1.4 vom Umgebungsgestein ab. Solch geringe Werte für das Verhältnis der Geschwindigkeiten deutet auf den Gehalt von Gas im Schwarzschiefer. Mit der Kombination der verschiedenen Methoden ist es möglich, die seismische Antwort der Schwarzschieferschicht umfassend zu beschreiben und Schlussfolgerungen darüber zu ziehen, ob die hier untersuchte Schwarzschieferschicht das Potenzial hat als Kohlenwasserstofflagerstätte zu fungieren.
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Martin, Brian E. „Seismic surface-wave ray tracing for anisotropic and laterally varying Earth models“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq20671.pdf.
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Sadeghisorkhani, Hamzeh. „Analyses and Application of Ambient Seismic Noise in Sweden : Source, Interferometry, Tomography“. Doctoral thesis, Uppsala universitet, Geofysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-320169.
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Ambient seismic noise from generation to its application for determination of sub-surface velocity structures is analyzed using continuous data recordings from the Swedish National Seismic Network (SNSN). The fundamental aim of the thesis is to investigate the applicability of precise velocity measurements from ambient noise data. In the ambient noise method, a form of interferometry, the seismic signal is constructed from long-term cross correlation of a random noise field. Anisotropy of the source distribution causes apparent time shifts (velocity bias) in the interferometric signals. The velocity bias can be important for the study area (Sweden) which has relatively small velocity variations. This work explores the entire data path, from investigating the noise-source distribution to a tomographic study of southern Sweden. A new method to invert for the azimuthal source distribution from cross-correlation envelopes is introduced. The method provides quantitative estimates of the azimuthal source distribution which can be used for detailed studies of source generation processes. An advantage of the method is that it uses few stations to constrain azimuthal source distributions. The results show that the source distribution is inhomogeneous, with sources concentrated along the western coast of Norway. This leads to an anisotropic noise field, especially for the secondary microseisms. The primary microseismic energy comes mainly from the northeast. The deduced azimuthal source distributions are used to study the level of expected bias invelocity estimates within the SNSN. The results indicate that the phase-velocity bias is less than 1% for most station pairs but can be larger for small values of the ratio of inter-station distance over wavelength. In addition, the nature of velocity bias due to a heterogeneous source field is investigated in terms of high and finite-frequency regimes. Graphical software for phase-velocity dispersion measurements based on new algorithms is presented and validated with synthetic data and by comparisons to other methods. The software is used for phase-velocity measurements, and deduced azimuthal source distributions are used for velocity-bias correction. Derived phase-velocity dispersion curves are used to construct two-dimensional velocity maps of southern Sweden at different periods based on travel-time tomography. The effect of the bias correction is investigated, and velocity maps are interpreted in comparison to previous geological and geophysical information.
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Sabey, Lindsay Erin. „Body and surface wave ambient noise seismic interferometry across the Salton Sea Geothermal Field, California“. Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/51185.
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Virtual source gathers were generated using the principles of seismic interferometry from 135 hours of ambient noise recorded during a controlled-source survey across the Salton Sea Geothermal Field in southern California. The non-uniform nature of the noise sources violated a primary assumption of the method and generated artifacts in the data. The artifacts generated by the high-energy impulsive sources (e.g. earthquakes, shots) were removable using traditional methods of amplitude normalization prior to cross-correlation. The continuous source artifacts generated by the geothermal wells and highways required an unconventional approach of utilizing only normalized impulsive sources to successfully reduce the artifacts. Virtual source gathers were produced successfully that contained strong surface waves at 0.4-2.5 Hz, an order of magnitude below the corner frequency of the geophones, and modest body waves at 22-30 Hz, which are generally more difficult to obtain due to the need for many large, well-distributed subsurface sources. The virtual source gathers compare well to nearby explosive shots and are more densely spaced, but have a much lower signal-to-noise ratio. Analysis of the surface waves was complicated by strong higher-order modes. Spectral analysis of virtual source gathers required utilization of the geothermal plant energy, which produced usable signal at offsets required for mode separation. The virtual source dispersion curve compared well to a dispersion curve from a nearby explosive shot. P-waves were observed on the virtual source gathers. Creation of a low-quality multichannel reflection stack revealed two weak reflectors in the upper 2 km.Master of Science
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van, Heijst Hendrik Jan. „New constraints on the seismic structure of the earth from surface wave overtone phase velocity measurements“. Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242041.
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Winsborrow, G. „The estimation of shear wave statics using in situ seismic measurements in near-surface marine sediments“. Thesis, Bangor University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275155.
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