Дисертації з теми "Seismology and Seismic Exploration"
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Brannon, Brittany Ann. "Faulty Measurements and Shaky Tools: An Exploration into Hazus and the Seismic Vulnerabilities of Portland, OR." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/1410.
Повний текст джерелаGillet, Kévin. "Explorer les hétérogénéités de petite échelle de la lune et de la terre." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30310/document.
Повний текст джерелаDuring their propagation, seismic waves are attenuated by two phenomena: on one hand, absorption caused by the anelastic properties of the materials, and on the other hand, scattering caused by the presence of small-scale heterogeneities in the medium. The aim of this thesis is to map the properties of scattering and absorption of seismic waves in two extreme geophysical contexts with very different spatial scales. The first part of this memoir is devoted to the stratification of heterogeneities in the Moon. We use a new diffusion model in spherical geometry to invert measurements of the time of arrival of the maximum of energy and the seismic coda decay on data from the Apollo missions. Our inversions provide evidence of a very sharp contrast of scattering properties between the highly attenuating megaregolith and the transparent deep lunar mantle. Attenuation is largerly dominated by scattering and suggests the presence of fractures down to about 100 km depth, into the mantle. A new method for estimating the depth of shallow moonquakes based on diffusive signals was developped and confirms the existence of active faults around 50 km deep. The second part of this thesis is devoted to the attenuation structure of Taiwan, a region with a wide variety of geological structures in the context of two subduction zones. We use the MLTWA (Multiple Lapse Time Window Analysis) -a method based on the ratio between the coherent and incoherent energy of the seismic signal- to image the lateral variations of attenuation. We worked first with the classical hypothesis of isotropic scattering in a half-space. Our results provide evidence for a globally high level of attenuation with sharp contrasts of scattering properties across small spatial scales, of the order of 10-20 km. Scattering is particularly strong in the basins of the west coast, southern Taiwan and the eastern Coastal Range associated with the collision with the Luzon volcanic arc. Absorption increases gradually eastwards and reaches a maximum below the volcanic arc. A posteriori examination of the fit between data and model shows unambiguously the limits of the hypothesis of isotropic scattering in a half-space for a number of stations located along the coasts. This leads us to explore the effects of anisotropic scattering in a guide for seismic waves representing the crust. Taking anisotropy into account significantly improves the fitness of the model to the data. In particular, at low frequency (1-2 Hz), our study shows the prevalence of backscattering. This result is compatible with the presence of sharp contrasts of impedance in the crust and suggests the strong presence of fluids in fault zones and volcanoes in Taiwan. The measurement of scattering anisotropy opens new perspectives for characterizing small-scale geophysical heterogeneities
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.
Повний текст джерелаThe 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
Hanson, Jeffrey Acton. "Seismic and hydroacoustic investigations near Ascension Island /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1998. http://wwwlib.umi.com/cr/ucsd/fullcit?p9823701.
Повний текст джерелаHarrigan, Edward. "Seismic event tracking." Thesis, University of Strathclyde, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267506.
Повний текст джерелаValle, G. Raul del. "Model parameterization in refraction seismology." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66057.
Повний текст джерелаSen, Vikramaditya. "A seismic survey in antarctica, parallel schemes for seismic migration and target oriented velocity analysis /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
Повний текст джерелаMorgan, Joanna Victoria. "Seismic studies over continental margins." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.279659.
Повний текст джерелаLee, Delman. "Seismic imaging through inhomogeneous media." Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305556.
Повний текст джерелаMonterroso, Juárez David Aníbal. "Statistical Seismology Studies in Central America : b-value, seismic hazard and seismic quiescence." Doctoral thesis, Uppsala University, Department of Earth Sciences, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3613.
Повний текст джерелаThe present thesis collects results of research applying theory and methods of statistical seismology to the seismicity of Central America, a region with a complex tectonic setting controlled by the interaction of four major plates, namely the Caribbean, Cocos, Nazca and North American plates.
Three different earthquake catalogues were used for studies focused on stress in a tectonic volume, seismic hazard maps and seismicity patterns (precursors), covering the region 94ºW to 81ºW and 5ºN to 20ºN.
Variations in the b-value, the parameter in Gutenberg & Richter’s equation LogN=a-bM, as a function of depth in the subduction zone were investigated. High b-values were identified in the upper part of the slab at depths of 80-110km beneath Guatemala-El Salvador and at depths 130-170km beneath Nicaragua. These anomalies may be related to the generation of volcanism occurring above them. Time dependence of the b-value was also studied. Five case studies were selected (events with MS ≥7.2) for a detailed analysis. In three out of five cases, it was possible to link b-value minima to the time of occurrence of corresponding large events.
Seismic quiescence was mapped as a function of time and space by a griding technique. The characteristics of the quiescence were calculated using the statistics Z and ß and for Time Window lengths between 1 and 5 years. Five positive anomalies were found, which can be associated with large earthquakes (MS≥7.2).
Finally, a Monte Carlo approach was utilized to evaluate the ground motion hazard and its uncertainties in northern Central America. A set of new seismic hazard maps exhibiting probabilistic values of peak ground acceleration (PGA) with 50%, 10%, and 5% probabilities of exceedance (PE) in 50 years is presented for a large area of northern Central America, including El Salvador and Guatemala.
Leipski, Elizabeth A. "Analytical investigation of In Situ Seismic methods." Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/19002.
Повний текст джерелаDemere, Judith Arlene. "Attenuation of seismic waves in Alabama." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/25957.
Повний текст джерелаBrittan, John. "Veracity of wide-angle seismic data." Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309316.
Повний текст джерелаRowbotham, Peter S. "Advances in crosshole seismic reflection processing." Thesis, Durham University, 1993. http://etheses.dur.ac.uk/5760/.
Повний текст джерелаHarith, Zuhar Zahir Tuan. "New methods in shallow seismic reflection." Thesis, University of Glasgow, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284735.
Повний текст джерелаCoates, Richard T. "On the scattering of seismic waves." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335705.
Повний текст джерелаLewis, Anthony H. J. "The deep seismic structure of northern England and adjacent marine areas from the Caledonian Suture Seismic project." Thesis, Durham University, 1986. http://etheses.dur.ac.uk/7088/.
Повний текст джерелаJones, Kevin Alun. "Crustal inferences from multi-offset seismic data." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267855.
Повний текст джерелаPortsmouth, Ian Robert. "Field studies of seismic attenuation and scattering." Thesis, Imperial College London, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296850.
Повний текст джерелаLe, Bougeant Michel. "Reflection seismic processing in transversely isotropic media." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300086.
Повний текст джерелаZolfaghari, Mohammad Reza. "GIS-based seismic hazard assessment of Iran." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299902.
Повний текст джерелаHu, Tianyue. "Decomposition of seismic wavefields and its applications." Thesis, Birkbeck (University of London), 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390193.
Повний текст джерелаDemir, Ismail. "Seismic wave modelling using finite difference methods." Thesis, University of South Wales, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284896.
Повний текст джерелаSmith, Sonya K. "Assessing the quality of deep seismic data." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361690.
Повний текст джерелаRoberts, Graham. "Shear-wave polarizations from local seismic events." Thesis, University of Edinburgh, 1985. http://hdl.handle.net/1842/14293.
Повний текст джерелаJones, Neil. "Seismic anisotropy and heterogeneity of young Atlantic crust." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240090.
Повний текст джерелаLoveridge, M. M. "Marine seismic source signatures : directivity and the ghost." Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355760.
Повний текст джерелаEddies, Roderick David. "An investigation of seismic attenuation in marine sediments." Thesis, University of Plymouth, 1994. http://hdl.handle.net/10026.1/2109.
Повний текст джерелаBrooks, S. G. "Seismic velocities from crustal sections in Northern Scandinavia." Thesis, University of East Anglia, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372358.
Повний текст джерелаHenry, William John. "A seismic investigation of the Kenya Rift Valley." Thesis, University of Leicester, 1987. http://hdl.handle.net/2381/35038.
Повний текст джерелаCraig, Mitchell Scott. "A discreet-scatterer model of the seismic P coda." Diss., Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/25858.
Повний текст джерелаAlberts, Ernst Patrick. "Horizon mapping in exploration seismology using artficial intelligence." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272160.
Повний текст джерелаWillemsen, Lucas Abraham. "Problems with a localized nature in exploration seismology." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/108840.
Повний текст джерелаThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 267-274).
A wide range of problems in seismology have a localized nature. Examples include inversion for time-lapse change, salt boundary position and Amplitude or Phase Versus Angle (AVA/PVA). With increasing computational power, many inversion procedures have transitioned away from forward models with simplified physics and now simulate synthetic wavefields on a model representation of the Earth. These simulated wavefields form the basis for the model updates in the inversion. Usually these wavefields are simulated on the entire computational model, even though the region of interest and the associated updates of the computational model are localized. In this thesis I explore ways of making use of the localized nature of the inversion by limiting the wavefield generation to the region of interest. This shrinking of the computational domain leads to faster solutions, reducing the time between the start and finish of the local inversion. This shorter turn-around time facilitates decision making and improves the interactivity of the inversion procedure. I first introduce a frequency domain local solver which can generate exactly the same wavefields as a full domain solver. I then apply this local solver to both a time-lapse problem and to salt boundary inversion. I then take a step back and look at time-lapse inversion outside the scope of local solvers. By looking at differences in the Full Waveform Inversion (FWI) gradient obtained from baseline and monitor datasets I compute a confidence map of locations likely to contain time-lapse change. This confidence map is then used to regularize a joint inversion for both the baseline and monitor datasets. I compare this methodology to other existing time-lapse algorithms on a synthetic North Sea model. In this study I notice the importance of post-critical reflections and become aware of their potential for reservoir characterization. Motivated by this observation I introduce a local solver for simulating elastic reflections in a region of interest. These elastic reflections can then be used for AVA and PVA to for instance invert for reservoir characteristics. The wavefield is efficiently propagated through the overburden using precomputed acoustic Green's functions obtained from a cheap acoustic solver.
by Lucas Abraham (Bram) Willemsen
Ph. D. in Geophysics
Williamson, P. R. "Tomographic inversion of traveltime data in reflection seismology." Thesis, University of Cambridge, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383956.
Повний текст джерелаHenton, Joseph Alan. "GPS studies of crustal deformation in the northern Cascadia subduction zone." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0020/NQ48226.pdf.
Повний текст джерелаScott, James B. "Seismic noise in the shallow subsurface methods for using it in earthquake hazard assessment /." 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:3258847.
Повний текст джерелаKirk, Wayne John. "Seismic and potential field studies over the East Midlands." Thesis, University of Leicester, 1989. http://hdl.handle.net/2381/35054.
Повний текст джерелаWang, Yanghua. "Co-operative inversion of seismic traveltime and amplitude data." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267299.
Повний текст джерелаTotterdell, Ian John. "Lower-crustal velocities from long-offset seismic reflection data." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259655.
Повний текст джерелаLinneman, Dorothy. "The EGS Collab Hydrofracture Experiment: Seismic Velocity and Elastic Moduli Characterization." Scholarship @ Claremont, 2019. https://scholarship.claremont.edu/scripps_theses/1240.
Повний текст джерелаLi, Dekun. "Seismic hazard analysis for bridge design in the Hong Kong region /." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B23436049.
Повний текст джерелаHerrmann, Felix J. "Seismology meets compressive sampling." Institute for Pure & Applied Mathematics. University of California, Los Angeles, 2007. http://hdl.handle.net/2429/603.
Повний текст джерелаZheng, York Yao. "Time-lapse seismic imaging using elastic full waveform inversion of ocean-bottom cable data." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648657.
Повний текст джерелаStek, Ivan. "Frequency domain seismic forward modelling : a tool for waveform inversion." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267748.
Повний текст джерелаHerwanger, Jorg. "Seismic and electric crosshole tomography for fracture detection and characterization." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367577.
Повний текст джерелаMcDonald, Robert John. "The application of shallow seismic reflection to onshore quaternary studies." Thesis, Cardiff University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250747.
Повний текст джерелаPowell, C. M. R. "A wide-angle, multichannel seismic study of the continental lithosphere." Thesis, University of Cambridge, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233313.
Повний текст джерелаPotts, C. G. "Anomalous seismic structure of the Tydeman and Vema fracture zones." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332744.
Повний текст джерелаButcher, J. A. "Seismic stratigraphy of shallow water Quaternary sediments around the UK." Thesis, Bangor University, 1997. https://research.bangor.ac.uk/portal/en/theses/seismic-stratigraphy-of-shallow-water-quaternary-sediments-around-the-uk(0103ae6b-808e-491e-b207-74e648b5ddee).html.
Повний текст джерелаTie, An. "On scattering of seismic waves by a spherical obstacle." Diss., Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/27988.
Повний текст джерела