La tectonique actuelle et récente (~40 Ma) de la région Egée-Anatolie en fait un laboratoire naturel privilégié pour l'étude de la déformation continentale. L'analyse de la structure détaillée et de la déformation du manteau de cette zone de collision continentale immature constitue une étape indispensable pour comprendre les relations entre la cinématique de surface et la dynamique du manteau. La structure du manteau supérieur a été étudiée à l'échelle de la région en réalisant un modèle 3-D de la vitesse des ondes S par tomographie télésismique en ondes de surface. Les résolutions latérale (~100-200 km) et verticale (~50 km) des images obtenues, grâce à l'utilisation d'un réseau sismologique large bande composé de ~150 stations (permanentes et temporaires (expérience SIMBAAD), apporte de nouvelles contraintes sur la structure du manteau de la Grèce continentale à l'Anatolie centrale. Cette tomographie révèle notamment des corrélations verticales claires entre les géométries des déchirures affectant le slab Hellénique et celles des zones de cisaillement trans-tensives qui accommodent le mouvement rapide du bloc Egéen vers le SW. Le slab Chypriote est clairement imagé dans le modèle 3-D comme plissé et déchiré en plusieurs segments sous l'Anatolie. L'analyse de l'anisotropie azimutale par méthode de réseau sur les ondes de Rayleigh a permis de proposer l'existence de deux couches anisotropes dans le manteau supérieur. L'étude de variations latérales de l'anisotropie sous la région suggère que la déformation des slabs et la cinématique de surface sont contrôlées par des flux mantelliques toroïdaux de différentes échelles. / The last ~40 M.y. tectonics of the Aegean-Anatolia region has shaped a natural laboratory ideal to study the continental deformation processes. The detailed analysis of the mantle structure and deformation of this non-mature continental collision zone constitutes an essential step to investigate the contribution of mantle dynamics to surface kinematics. The upper mantle structure is investigated over the entire region through a new 3-D S-wave velocity model from surface-wave tomography. The model reveals remarkable vertical correlations between geometries of the Hellenic slab tears and geometries of shear zones which accommodate the rapid SW movement of the Aegean bloc. The Cyprus slab is clearly identified in the 3-D model as fold and torn in tree segments beneath Anatolia. The observed azimuthal anisotropy from Rayleigh-wave array analysis suggests the existence of two anisotropic layers in the upper mantle. The lateral variations of anisotropy beneath the region are interpreted as the indication of toroidal mantle flows at different scales governing the slabs deformation and the surface kinematics.

To determine the effect of body shape on the response of underwater vehicles to surface waves in shallow water, the wave radiation hydrodynamic forces are evaluated for a family of (i) prolate spheroidal hull forms and (ii) cylindrical bodies with hemispherical nose and conical tail sections by systematically varying the geometric parameters but keeping displacement constant. The added-mass and wave damping coefficients are determined using a frequency-domain, simple-source based boundary integral method. Results are obtained for a range of wave frequencies and depths of vehicle submergence all for a fixed water depth of 10 m. With the wave exciting force and moment determined using the Froude-Krylov theory, the response transfer functions for heave and pitch are then determined. The heave and pitch response spectra in actual littoral seas are then determined with the sea state modeled using TMA spectral relations. Results show that vehicle slenderness is a key factor affecting the hydrodynamic coefficients and response. The results show two characteristics that increase the radiation hydrodynamic forces corresponding to heave and pitch motions: namely, vehicle length and further-away from mid-vehicle location of the body shoulder. The opposite is true for the oscillatory surge motion. By utilizing these observed characteristics, one can design the lines for maximum radiation forces and consequently minimum hull response for the critical modes of rigid-body motion in given waters and vehicle missions. In the studies carried out in the thesis, a hull with a long parallel middle body with hemispherical nose and conical tail sections has better heave and pitch response characteristics compared prolate spheroid geometry of same volume. The methodology developed herein, which is computationally efficient, can be used to determine optimal hull geometry for minimal passive vehicle response in a given sea. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

O método da análise multicanal de ondas superficiais foi empregado em um estudo de caso no sítio controlado do Instituto de Astronomia, Geofísica e Ciências Atmosféricas da Universidade de São Paulo - IAG-USP, localizado no campus Butantã, São Paulo, em terrenos da bacia sedimentar de São Paulo. O estudo visou à investigação geológica rasa, ou seja, ao mapeamento dos estratos sedimentares presentes e do contato sedimentos-embasamento. Além disso, procurou-se, através de testes de diversos parâmetros de aquisição, chegar-se a uma rotina para a aquisição e tratamento dos dados provenientes de fontes ativas (marreta e queda de peso) e passivas (tráfego de veículos) que possa ser indicada para ensaios em outras áreas da cidade de São Paulo que apresentem condições semelhantes às da área estudada. Na aquisição com fontes ativas foram registrados dados com diversos offsets mínimos e na passiva foi aplicada a técnica Passive Roadside com o arranjo de geofones disposto próximo e paralelamente à via de tráfego. Foram realizadas as etapas de pré-processamento dos dados, geração das imagens de dispersão, extração das curvas de dispersão e inversão. A combinação de imagens geradas a partir de dados adquiridos com diferentes fontes resultou numa imagem com melhor razão sinal-ruído, e consequentemente na produção de melhores curvas que foram invertidas para a geração dos perfis 1D das velocidades da onda S. De modo geral, os perfis de velocidades obtidos a partir dos dados obtidos com o emprego de uma marreta para geração da onda mapearam as interfaces geológicas mais superficiais, já os perfis resultantes dos dados adquiridos com o uso de uma fonte tipo queda de peso alcançaram profundidades maiores, por vezes amostrando o embasamento. No caso das fontes passivas, as principais interfaces de contato foram imageadas, conseguindo-se com sucesso o mapeamento do embasamento, que na área está a mais de 50 metros de profundidade. Correlações com o perfil litológico e de dados de ensaios SPT de um furo de sondagem localizado no centro do arranjo revelaram que as diferenças na determinação da profundidade das interfaces foram menores do que 10%. Desta forma, o método mostrou ser uma ferramenta prática e eficiente nas aplicações geotécnicas, principalmente em ix áreas urbanas onde o ruído é elevado, o que muitas vezes inviabiliza o uso da investigação sísmica convencional (refração ou reflexão). / The multichannel analysis of surface waves (MASW) method was employed in a case study on the controlled site in the Institute of Astronomy, Geophysics and Atmospheric Sciences (IAG), University of São Paulo (USP), located on the campus Butantã, São Paulo, in the grounds of the sedimentary basin São Paulo. The study aimed to shallow geological investigation, in other words, mapping of sedimentary strata present and the sediment-basement contact. In addition, It is sought to, by testing with different acquisition parameters, to get a routine for the acquisition and processing of data from active sources (sledgehammer and drop weight) and passive (vehicle traffic) that can be suitable for testing in other areas of the city of São Paulo who have similar conditions of the study area. In the acquisition with active sources were registered data with many different offsets and passive acquisition has been applied to the Passive Roadside MASW technique with the conventional linear receiver array disposed near and parallel to the traffic lane. Were performed, pre-processing of the data, generation of images of dispersion, extraction of dispersion curves and inversion. The combination of images generated based on data acquired from various sources resulted in image with improved signal to noise ratio and consequently in the production of finest curves that have been inverted to generate the 1D shear-wave velocities profiles. In general, the velocity profiles obtained from the data were acquired with the use of a sledgehammer to the wave generation mapped shallowest geological interfaces, but the resulting profiles of the acquired data using a font type \"drop weight\" reached greater depths, sometimes sampling the basement. In the case of passive sources, the main contact interfaces were imaged, achieving successful mapping of the basement, which in this area is over 50 meters deep. Correlations with the lithological profile and SPT data from a borehole located in the center of the array revealed that the differences in the depth determination of the interfaces was less than 10%. Thus, the method showed to be an efficient and practical tool in geotechnical applications, especially in urban areas where the noise is high, which often prevents the use of conventional seismic survey (reflection or refraction).

We formulate a model for acoustic excitations in a magnetorheological fluid. Constitutive equations are derived for Navier-Stokes flow coupled with Maxwell's Equations. The viscosity of the fluid is modified to reflect the dependence of waves propagating within the fluid itself and in the case where they propagate along the network of particles.

Thesis. 1977. Elec.E.--Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / Elec.E.

Thesis. 1975. Ph.D.--Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. / Vita. / Includes bibliographical references. / Ph.D.

O método da análise multicanal de ondas superficiais foi empregado em um estudo de caso no sítio controlado do Instituto de Astronomia, Geofísica e Ciências Atmosféricas da Universidade de São Paulo - IAG-USP, localizado no campus Butantã, São Paulo, em terrenos da bacia sedimentar de São Paulo. O estudo visou à investigação geológica rasa, ou seja, ao mapeamento dos estratos sedimentares presentes e do contato sedimentos-embasamento. Além disso, procurou-se, através de testes de diversos parâmetros de aquisição, chegar-se a uma rotina para a aquisição e tratamento dos dados provenientes de fontes ativas (marreta e queda de peso) e passivas (tráfego de veículos) que possa ser indicada para ensaios em outras áreas da cidade de São Paulo que apresentem condições semelhantes às da área estudada. Na aquisição com fontes ativas foram registrados dados com diversos offsets mínimos e na passiva foi aplicada a técnica Passive Roadside com o arranjo de geofones disposto próximo e paralelamente à via de tráfego. Foram realizadas as etapas de pré-processamento dos dados, geração das imagens de dispersão, extração das curvas de dispersão e inversão. A combinação de imagens geradas a partir de dados adquiridos com diferentes fontes resultou numa imagem com melhor razão sinal-ruído, e consequentemente na produção de melhores curvas que foram invertidas para a geração dos perfis 1D das velocidades da onda S. De modo geral, os perfis de velocidades obtidos a partir dos dados obtidos com o emprego de uma marreta para geração da onda mapearam as interfaces geológicas mais superficiais, já os perfis resultantes dos dados adquiridos com o uso de uma fonte tipo queda de peso alcançaram profundidades maiores, por vezes amostrando o embasamento. No caso das fontes passivas, as principais interfaces de contato foram imageadas, conseguindo-se com sucesso o mapeamento do embasamento, que na área está a mais de 50 metros de profundidade. Correlações com o perfil litológico e de dados de ensaios SPT de um furo de sondagem localizado no centro do arranjo revelaram que as diferenças na determinação da profundidade das interfaces foram menores do que 10%. Desta forma, o método mostrou ser uma ferramenta prática e eficiente nas aplicações geotécnicas, principalmente em ix áreas urbanas onde o ruído é elevado, o que muitas vezes inviabiliza o uso da investigação sísmica convencional (refração ou reflexão). / The multichannel analysis of surface waves (MASW) method was employed in a case study on the controlled site in the Institute of Astronomy, Geophysics and Atmospheric Sciences (IAG), University of São Paulo (USP), located on the campus Butantã, São Paulo, in the grounds of the sedimentary basin São Paulo. The study aimed to shallow geological investigation, in other words, mapping of sedimentary strata present and the sediment-basement contact. In addition, It is sought to, by testing with different acquisition parameters, to get a routine for the acquisition and processing of data from active sources (sledgehammer and drop weight) and passive (vehicle traffic) that can be suitable for testing in other areas of the city of São Paulo who have similar conditions of the study area. In the acquisition with active sources were registered data with many different offsets and passive acquisition has been applied to the Passive Roadside MASW technique with the conventional linear receiver array disposed near and parallel to the traffic lane. Were performed, pre-processing of the data, generation of images of dispersion, extraction of dispersion curves and inversion. The combination of images generated based on data acquired from various sources resulted in image with improved signal to noise ratio and consequently in the production of finest curves that have been inverted to generate the 1D shear-wave velocities profiles. In general, the velocity profiles obtained from the data were acquired with the use of a sledgehammer to the wave generation mapped shallowest geological interfaces, but the resulting profiles of the acquired data using a font type \"drop weight\" reached greater depths, sometimes sampling the basement. In the case of passive sources, the main contact interfaces were imaged, achieving successful mapping of the basement, which in this area is over 50 meters deep. Correlations with the lithological profile and SPT data from a borehole located in the center of the array revealed that the differences in the depth determination of the interfaces was less than 10%. Thus, the method showed to be an efficient and practical tool in geotechnical applications, especially in urban areas where the noise is high, which often prevents the use of conventional seismic survey (reflection or refraction).

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.

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.

Mechanical waves provide information about the stiffness and the condition of a medium; thus, changes in medium conditions can be inferred from changes in wave velocity and attenuation. Non-destructive testing (NDT) methods based on ultrasonic waves are often more economical, practical and faster than destructive testing. Multichannel analysis of surface waves (MASW) is a well-established surface wave method used for determination of the shear-wave profile of layered medium. The MASW test configuration is also applicable to assess the condition of concrete elements using appropriate frequency range. Both attenuation and dispersion of ultrasonic waves can be evaluated by this technique. In ultrasonic testing, the characterization of a medium requires the precise measurement of its response to ultrasonic pulses to infer the presence of defects and boundary conditions. However, any ultrasonic transducer attached to a surface affects the measured response; especially at high frequencies. On the other hand, ultrasonic transducers available for engineering application are mostly used to measure wave velocities (travel time method). Therefore, these transducers do not have a flat response in the required frequency range. Moreover, in the case of full-waveform methods, the recorded signals should be normalized with respect to the transfer functions of the transducers to obtain the real response of the tested specimen. The main objective of this research is to establish a comprehensive methodology based on surface wave characteristics (velocity, attenuation and dispersion) for condition assessment of cemented materials with irregular defects. To achieve the major objective, the MASW test configuration is implemented in the ultrasonic frequency range. The measured signals are subjected to various signal processing techniques to extract accurate information. In addition, a calibration procedure is conducted to determine the frequency response functions (FRF) of the piezoelectric accelerometers outside their nominal frequency range. This calibration is performed using a high-frequency laser vibrometer. This research includes three main studies. The first study introduces the calibration approach to measure the FRFs of the accelerometers outside of their flat frequency range. The calibrated accelerometers are then used to perform MASW tests on a cemented-sand medium. The original signals and the corrected ones by eliminating the effect of the FRFs are used to determine material damping of the medium. Although, the damping ratios obtained from different accelerometers are not same, the values from the corrected signals are found closer to the characteristic damping value compared to those from the uncorrected signals. The second study investigates the sensitivity of Rayleigh wave velocity, attenuation coefficient, material damping and dispersion in phase velocity to evaluate the sensitivity of these characteristics to the damage quantity in a medium. The soft cemented-sand medium is preferred as the test specimen so that well-defined shaped defects could be created in the medium. MASW test configuration is implemented on the medium for different cases of defect depth. The recorded signals are processed using different signal processing techniques including Fourier and wavelet transforms and empirical mode decomposition to determine the surface wave characteristics accurately. A new index, ‘dispersion index’, is introduced which quantifies the defect based on the dispersive behaviour. All surface wave characteristics are found capable of reflecting the damage quantity of the test medium at different sensitivity levels. In the final study, the condition assessment of six lab-scale concrete beams with different void percent is performed. The beam specimens involving Styrofoam pellets with different ratios are tested under ultrasonic and mechanical equipment. The assessment produce established in the second study with well-defined defects is pursed for the beams with irregular defects. Among the characteristics, attenuation, P and R-wave velocities and dispersion index are found as the promising characteristics for quantifying the defect volume.