The Karhunen-Loève transform, which optimally extracts coherent information from multichannel data, has been applied to several problems in reflection seismic data processing. The transform is derived by a least-squares construction of an orthogonal set of principal components and eigenvectors, with corresponding eigenvalues. Data are reconstructed as a linear combination of the principal components. The mathematical properties of the Karhunen-Loève transform which render it applicable to problems in seismic data processing are reviewed, and a number of new algorithms developed. Most algorithms are tested on synthetic and real data examples, and 'production-line' industrially viable versions of some of the programs have been developed. A new signal-to-noise ratio enhancement technique, based on reconstruction of stacked seismic sections, has proved to be successful on real data. Reconstruction of less coherent information to emphasize anomalous features in stacked seismic data ("misfit" reconstruction) shows some promise. Diffraction hyperbolae isolated by misfit reconstruction are used to estimate residual migration velocities with some success. And, the ability of the transform to segregate coherent information is used successfully as the basis of a new multiple suppression technique. An anomaly identification scheme, based on cluster analysis of the eigenvectors of the transform, works well on the synthetic data used, and gives promising results when applied to real data. A new velocity analysis method, utilizing a ratio of the eigenvalues, works well for good data at early travel times, and offers a potential for high resolution velocity inversion studies. Use of the eigenvalues in evaluation of a constant phase approximation to dispersion for synthetic data provides promising results, leading to quantification of dispersion in terms of relative phase shifts. As part of this development, an analysis of the effect of dispersion on Vibroseis© data acquisition, which represents an original investigation, is presented. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1979. / Microfiche copy available in Archives and Science. / Bibliography: leaves 163-173. / by Kenneth Robert Anderson. / Ph.D.

To understand better the faulting process in the Southern Appalachians, eleven single event focal mechanisms (SEFM) and seven composite focal mechanisms (CFM) are determined from 37 events that occurred in eastern Tennessee between September 1981 and July 1983. Both P-wave polarities and (Sv/P)z amplitude ratios are input to a computer program that systematically searches the focal sphere for solutions acceptable within pre-set error limits. Hypocenter locations, azimuth and departure angles are taken from locations obtained by the Tennessee Earthquake Information Center (TEIG) with a four layer velocity model (GCOl). A second velocity model (STEP2), developed to improve focal depth estimates and to acquire continuously varying departure angles, is used to relocate events for which SEFM and CFM solutions are obtained. The two different velocity models produced focal mechanisms with similar nodal plane and P-axis orientations, indicating stable and reliable results; the differences between average strike, dip, and rake angles of the two data sets range from 2° to 11°. Both SEFM and CFM solutions exhibit predominantly strike-slip motion along nearly vertical north-south (right-lateral) or east-west (left-lateral) oriented nodal planes. Standard deviations for average strike, dip, and rake angles are generally less than 20°. P-axis trends average about N50°E, with a nearly horizontal average plunge, and both have standard deviations of 25° or less. Except for three events in the northernmost region, all earthquakes in the study area result from a maximum compressive stress trending between N40°E and N70°E and plunging between 10° and -30°. / Master of Science

Orientador: Sueli Yoshinaga Pereira, Rodrigo de Souza Portugal / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-27T02:27:34Z (GMT). No. of bitstreams: 1 Vinhas_MariaCeciliaSodero_D.pdf: 6306176 bytes, checksum: 930cddf48712d9d8f841ea47190c1beb (MD5) Previous issue date: 2014 / Resumo: Essa pesquisa objetivou a aplicação e o entendimento da relação de três métodos geofísicos: eletrorresistividade, sísmica de refração e sismoelétrica; em pontos selecionados no Estuário do Rio Itanhaém e se eles podem ser validados pelas informações geológicas e hidrogeológicas da região. Os levantamentos foram realizados em duas etapas. A primeira etapa foi o de reconhecimento de campo, realizado no período de 21 a 26 de setembro/2009 que é considerado um período menos chuvoso. Os pontos escolhidos foram denominados de Ponto Praia, Ponto Chácara, Ponto Lixão e Ponto Country Club. A segunda etapa consistiu na coleta de dados propriamente dita nos pontos Chácara, Lixão e Country Club; o ponto Praia foi excluído por estar próximo às grandes torres de transmissão de energia, fazendo com que houvesse interferência nos dados. No ponto Lixão foi verificada a existência de gás metano, na superfície, através das bolhas de ar nas poças de água, no Ponto Country se localizava próximo a dois brejos e um pequeno córrego, e por fim o Ponto Chácara se localizava próximo ao Rio Branco, onde foi possível perceber a influência do aquífero livre na coleta dos dados. O período da segunda etapa dos levantamentos de dados ocorreu entre setembro de 2010 e agosto de 2011. Os levantamentos resultaram em um perfil vertical central, dos pontos selecionados, onde foram encontrados os seguintes materiais: areia, sedimentos arenosos, areia argilosa, argila seca, dois tipos de aquífero (de água doce e de água salobra), além de solos saturados e não saturados, e lixo. Em alguns levantamentos atingiram a rocha sã. Os levantamentos eletrorresistivos foram os que tiveram melhor resultado, os levantamentos de sísmica obtiveram uma camada apenas em quase todos os levantamentos, sendo que em um deles, o segundo campo do Ponto Country Club, se obteve mais de uma camada de material. Os levantamentos sismoelétricos não tiveram seus tratamentos finalizados, pois se percebeu que era necessária a utilização pré-amplificador; sua ausência no levantamento no campo, aliado a presença de linhas elétricas nos locais do levantamento, prejudicou nos resultados dos dados coletados, fato indicado pela presença das linhas harmônicas nos dados, e consequentemente não ter finalizado o algoritmo de tratamento desses dados / Abstract: This research intended the application and understanding about connexion among three geophysical methods: eletrical resistivity, refraction seismic and eletrical seismic; in selected places along Itanhaem River Estuary and if they can be accepted by geological and hydrogeological information of the region. The survey was accomplished in two phases. The first one was to recognize field of study, which was realized from 21st to 26th of September 2009, that is considered a less rainy season. The chosen sites were: Praia Point, Chácara Point, Lixão Point and Country Club Point. The second phase was the data collection, at these chosen sites, Chácara, Lixão and Country Club; The Praia Point was excluded because it was very near of large power transmission towers and it was causing interference in the collected information, at the Lixão Point was verified existence of methane, on the surface, through the air bubbles in puddles, in the case of Country Club Point was located near two swamps and a small stream, the Ranch Point was located near the river called Branco, and it was possible to realized the free influence of this aquifer in data collection. The second phase period of data collection, occurred between September 2010 and August 2011. The surveys resulted in a central vertical shape of the selected sites, where the following materials were found sand, sandy sediments, clayey sand, dry clay, two types of groundwater (freshwater and brackish water), and saturated and unsaturated soils and waste. In some surveys reached the bedrock. The electrical resistivity surveys were those who obtained better results, the seismic surveys obtained only a layer in almost all surveys, and in one of them, the second Country Club Point, got more than one layer of material. The electrical seismic surveys were not their treatments finalized, because it was realized the need to use a preamplifier; its absence in the field survey, combined with the presence of power lines in the survey sites, affected the collected data results, condition indicated by the presence of harmonic lines in the data, and consequently have not finalized these data processing algorithm / Doutorado / Geologia e Recursos Naturais / Doutora em Ciências