Thèses : « Seismic area »

1

Liang, Jonathan Zhongyuan. « Seismic risk analysis of Perth metropolitan area ». University of Western Australia. School of Civil and Resource Engineering, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0142.

Texte intégral

Résumé :

[Truncated abstract] Perth is the capital city of Western Australia (WA) and the home of more than three quarters of the population in the state. It is located in the southwest WA (SWWA), a low to moderate seismic region but the seismically most active region in Australia. The 1968 ML6.9 Meckering earthquake, which was about 130 km from the Perth Metropolitan Area (PMA), caused only minor to moderate damage in PMA. With the rapid increase in population in PMA, compared to 1968, many new structures including some high-rise buildings have been constructed in PMA. Moreover, increased seismic activities and a few strong ground motions have been recorded in the SWWA. Therefore it is necessary to evaluate the seismic risk of PMA under the current conditions. This thesis presents results from a comprehensive study of seismic risk of PMA. This includes development of ground motion attenuation relations, ground motion time history simulation, site characterization and response analysis, and structural response analysis. As only a very limited number of earthquake strong ground motion records are available in SWWA, it is difficult to derive a reliable and unbiased strong ground motion attenuation model based on these data. To overcome this, in this study a combined approach is used to simulate ground motions. First, the stochastic approach is used to simulate ground motion time histories at various epicentral distances from small earthquake events. Then, the Green's function method, with the stochastically simulated time histories as input, is used to generate large event ground motion time histories. Comparing the Fourier spectra of the simulated motions with the recorded motions of a ML6.2 event in Cadoux in June 1979 and a ML5.5 event in Meckering in January 1990, provides good evidence in support of this method. This approach is then used to simulate a series of ground motion time histories from earthquakes of varying magnitudes and distances. ... The responses of three typical Perth structures, namely a masonry house, a middle-rise reinforced concrete frame structure, and a high-rise building of reinforced concrete frame with core wall on various soil sites subjected to the predicted earthquake ground motions of different return periods are calculated. Numerical results indicate that the one-storey unreinforced masonry wall (UMW) building is unlikely to be damaged when subjected to the 475-year return period earthquake ground motion. However, it will suffer slight damage during the 2475-return period earthquake ground motion at some sites. The six-storey RC frame with masonry infill wall is also safe under the 475-year return period ground motion. However, the infill masonry wall will suffer severe damage under the 2475-year return period earthquake ground motion at some sites. The 34-storey RC frame with core wall will not experience any damage to the 475-year return period ground motion. The building will, however, suffer light to moderate damage during the 2475-year return period ground motion, but it might not be life threatening.

Styles APA, Harvard, Vancouver, ISO, etc.

2

Milluzzo, Vincenzo. « Seismic chacterization of Vulcano island and Aeolian area by tectonic and seismo-volcanic events ». Doctoral thesis, Università di Catania, 2013. http://hdl.handle.net/10761/1330.

Texte intégral

Résumé :

We investigated the relationship between seismo-volcanic events, recorded at La Fossa crater of Vulcano (Aeolian Islands, Italy) during 2004-2009, and the dynamics of the hydrothermal system. During the period of study, six episodes of increasing numbers of seismo-volcanic events took place at the same time as geothermal and geochemical anomalies were observed. These geothermal and geochemical anomalies have been interpreted as resulting from an increasing deep magmatic component of the hydrothermal fluids. Four classes of seismic events (long period, high frequency, monochromatic and tornillos events), characterised by different spectral content and various similarity of the waveforms, have been recognised. These events, clustered mainly below La Fossa crater area at depths of 0.5 1.1 km b.s.l., were space-distributed according to the classes. Based on their features, we can infer that such events at Vulcano are related to two different source mechanisms: (1) fracturing processes of rocks and (2) resonance of cracks (or conduits) filled with hydrothermal fluid. In the light of these source mechanisms, the increase in the number of events, at the same time as geochemical and geothermal anomalies were observed, was interpreted as the result of an increasing magmatic component of the hydrothermal fluids, implying an increase of their flux. Indeed, such variation caused an increase of both the pore pressure within the rocks of the volcanic system and the amount of ascending fluids. Increased pore pressures gave rise to fracturing processes, while the increased fluid flux favoured resonance and vibration processes in cracks and conduits. Finally, a gradual temporal variation of the waveform of the hybrid events (one of the subclasses of long period events) was observed, likely caused by heating and drying of the hydrothermal system. After careful analysis of the seismo-volcanic events of the Aeolian Islands area, the attention was paid to the tectonic events, in order to find possible relationships with the volcanic activity in the area. The aim of this part of the thesis was to identify spatial clusters of earthquakes, locate active seismogenic zone and their relationships with the volcanic activity in the Aeolian Islands. High precision locations were performed in the present thesis, by applying the concept of the velocity model-hypocentres joint inversion and earthquake relocations, along with an analysis of the fault plane solutions. In order to improve our knowledge on the active seismo-tectonics areas we exploited a dataset encompassing 351 events recorded during a 17 year period (1993-2010). Overall, our results show that part of the seismicity is clustered along active seismogenic structures that concur with the main regional tectonic trends whose activity furnishes new elements to better understand the dynamics of the area. A cluster of 24 events in the northern part of Vulcano, NE-SW oriented, marks the presence of a structure that seems to play a key role in magma uprising at Vulcano. These earthquakes suggest the existence of a seismogenic structure (passing just below Vulcanello), which could be interpreted as a discontinuity linking the two magma accumulation zones, thereby representing a possible preferential pathway along which magma may intrude as well as being responsible for fluid migration toward the surface. The results presented in this thesis suggest that the comparison of seismic, ground deformation and temperature data can be useful for better understanding the dynamics of a complex volcano-hydrothermal system, including a better definition of the origin of a volcano unrest, and hence for improving the estimation of the level of the local volcanic hazard.

Styles APA, Harvard, Vancouver, ISO, etc.

3

Miao, Xiao Gui. « Integrated seismic study of the Sudbury structure and surrounding area ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1995. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq23640.pdf.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

4

Stoch, Agnieszka. « Analysis of Seismic Data Acquired in the Hverahlíð Geothermal Area ». Thesis, Uppsala universitet, Geofysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-413199.

Texte intégral

Résumé :

Volcanic rifting environments, such as in Iceland, are challenging for conventional seismic reflection methods using active surface seismic sources. This study demonstrates the potential of a novel technique, called Virtual Reflection Seismic Profiling (VRSP) for imaging reflections in geothermal regions, like Hverahlíð, where a dense seismic array recorded a number of local microearthquakes for cross-correlation. Uppsala University, in collaboration with Reykjavik Energy, recorded seismicity in Hverahlíð using both seismometers and geophones. Acquired data were processed using the VRSP method, which applies seismic interferometry only to selected events, in this thesis local microearthquakes. Cross-correlation of the signal from a microearthquake recorded at one of the stations, which acts as a virtual source, with a ghost reflection recorded by the remaining receivers, produces a virtual shot gather. Stacking each station’s result, for all available events, and following a conventional multichannel processing sequence resulted in two stacked seismic images. Potential reflections observed in the obtained sections could be associated with major feed zones identified in the area by the borehole measurements. Eight dynamite explosions were processed with a conventional seismic reflection method, as a complementary source to the microearthquakes. In the produced stacked seismic section two potential reflections could be observed. Results from both passive and active datasets were 3D visualised to verify whether the reflections correspond to each other between sections. Two horizons were traced throughout all three stacked sections. One more interface appeared on two images obtained from processing the passive data. This study shows promising results for using natural sources to image the subsurface in a challenging environment.

Styles APA, Harvard, Vancouver, ISO, etc.

5

Abdelrahman, Wedissa. « Reprocessing of reflection seismic data from the Skåne area, southern Sweden ». Thesis, Uppsala universitet, Geofysik, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-183607.

Texte intégral

Résumé :

Seismic reflection surveying is a powerful method to explore the structures of the Earth’s crust and describe it is layers. It is also used extensively in the oil industry. Offshore seismic profiles were acquired in southern Sweden (Skane area) for petroleum exploration purposes, but no productive fields were discovered in that area. The seismic reflection data were collected and processed in the 1970s. The purpose of this thesis is to reprocess some of the seismic profiles from the 1970s with new processing programs to improve the results and compare it with the previous results. Offshore lines 208, 206, 212 have been selected in this project because they cross each other and are close to a borehole with sonic data. The borehole lies close to lines 208 and 212 as seen from the Skane area map. Also this report can be used to introduce the reader to fundamentals of seismic data processing. The processing was done using Claritas software by applying standard processing steps to produce migrated stacked sections for every line as a final product.

Styles APA, Harvard, Vancouver, ISO, etc.

6

Allen, G. F. « Interval velocities from moveout velocities over a seismic reflection survey area ». Thesis, University of Leicester, 1985. http://hdl.handle.net/2381/33751.

Texte intégral

Résumé :

Moveout velocities sampled frequently along seismic horizons on a selection of seismic lines are used to derive interval velocities in an 'inversion' algorithm developed from work published by Hubral. This inversion is based on zero-offset raytrace modelling in a simplistic local ground model. The 'Hubral algorithm' is incorporated into a database which allows spatial smoothing of velocities. The spatial consistency of derived interval velocities can then be assessed by reference to mis-ties at line intersections, while interval velocities from well data can be used to check their validity. These principles have been used to derive interval velocities both from real data and from 'synthetic' data generated by common mid-point raytracing over schematic ground models. The latter study reveals that the procedure performs well if the local subsurface sampled by the CMP gather conforms approximately to the simplistic ground model assumed by the Hubral algorithm. The method is unsuitable in areas of faulting and interval velocity heterogeneity, and may yield spurious results over fold axes. Application of the procedure to real data indicates that it is generally desirable to smooth both moveout velocities before inversion and interval velocities after inversion. Comparison with well information shows that interval velocities derived by the Hubral algorithm are consistently higher than those measured from calibrated velocity logs. This observation is disturbing, since the derived interval velocities require a correction if they are to be used for depth conversions, but the discrepancy cannot be explained by ray theoretical considerations. No advantage appears to be gained by the 'layer-by-layer' mode of inversion over the 'direct' inversion, despite the greater potential for error propagation anticipated in the latter. Further work on different data sets is required to justify general use of the layer-by-layer mode of inversion.

Styles APA, Harvard, Vancouver, ISO, etc.

7

Ribeiro, Tiago Daniel Machado Pinto. « Multichannel seismic investigation of the Gran Burato area, off W Galicia ». Master's thesis, Universidade de Aveiro, 2011. http://hdl.handle.net/10773/7509.

Texte intégral

Résumé :

Mestrado em Engenharia Geológica
The study of offshore gas accumulation has been a key-topic over the last decades due to the importance of hydrocarbon exploration and production. The presence of free gas or gas accumulations in the sediments can also indicate hydrocarbon reservoirs in depth. This work presents the results of a geophysical survey in the Western continental Galicia margin in the scope of a research project to investigate a giant pockmark discovered in this margin, known as the Gran Burato. The main objectives of this work were the detailed re-processing and interpretation of the multichannel seismic data acquired during the BURATO4240 survey. The preliminary processing carried out onboard during the cruise was improved in the scope of this work, with a more detailed processing (detailed velocity analysis and pre-stack time migration of selected seismic lines), to better image the deeper part of the seismic sections. The application of advanced processing techniques allowed the improvement of the onboard seismic processing, in particular, the imaging of the faults and the deeper part of the seismic sections, which helped the seismic interpretation work. In this thesis, the preliminary seismic interpretation was revised, improved, the main faults were mapped, and time and depth structural and horizon maps for the main interpreted seismic stratigraphic units were produced. A preliminary structural map of the study area was obtained, which contributes to a better knowledge about the possible formation of the Gran Burato, and the underlying geology. The origin of the Gran Burato seems to be related to episodes of massive expulsions of gas which lifted the overlying sediments into the water, which then were drifted away by the currents, and created this outstanding structure. This gas probably migrated to the upper stratigraphic sequences through the extensive faults, where it was accumulated. A preliminary interpretation of possible evidences of fluids (most likely gas) accumulations and leakage were performed, and several amplitudes anomalies were identified. The weaker evidences of gas or other fluids around the Gran Burato seem to support the idea that the majority of the gas has already escaped, probably during the formation of this giant pockmark. However, possible evidences of gas accumulations were identified in areas farther away. New multichannel seismic data acquired last August in the same area, will permit to confirm better some hypothesis rose in this work, and will certainly represent a solid base to support this investigation work.
O estudo de acumulações de gás offshore tem sido um tópico chave ao longo das últimas décadas, devido à importância da produção e exploração de hidrocarbonetos. A presença de gás livre ou acumulações de gás nos sedimentos pode indicar a presença de reservatórios de hidrocarbonetos em profundidade. Este trabalho apresenta os resultados de uma campanha geofísica realizada na margem continental Oeste da Galiza, no âmbito de um projecto de investigação para estudar um pockmark gigante descoberto nesta margem, conhecido como Gran Burato. Os principais objectivos deste trabalho foram o re-processamento e interpretação dos dados sísmicos multicanal, adquiridos na campanha BURATO4240. O processamento sísmico preliminar realizado durante a campanha de aquisição foi melhorado no âmbito deste trabalho, com um fluxo de processamento mais pormenorizado (análise de velocidades detalhada e migração pré-stack em tempo dos perfis mais representativos), de modo a permitir uma melhor visualização da parte mais profunda dos perfis sísmicos. A aplicação de técnicas de processamento utilizadas na indústria melhorou a qualidade do processamento preliminar, em particular, a resolução das falhas e as partes mais profundas das secções sísmicas, o que foi essencial para a interpretação sísmica. No âmbito desta tese, a interpretação sísmica preliminar foi detalhada e melhorada, as falhas principais foram espacialmente correlacionadas, e mapas estruturais e dos horizontes interpretados foram criados em tempo e em profundidade. Foi construído um mapa estrutural preliminar para a área de estudo, o que permite um conhecimento integrado sobre possíveis mecanismos de formação do Gran Burato, e também sobre a estrutura geológica observada nesta região. A origem do Gran Burato parece estar relacionada com vários episódios de expulsão massiva de gás que remobilizaram os sedimentos, dando origem a esta impressionante estrutura. Este gás terá provavelmente migrado através de falhas para as unidades sedimentares mais superficiais, onde foi acumulado. Uma interpretação preliminar de possíveis evidências de escape e acumulações de fluidos (provavelmente gás) foi realizada, e várias anomalias de amplitudes foram identificadas. As fracas evidências de gás na zona do Gran Burato, aparentam suportar a ideia de que a maioria do gás nesta zona já terá escapado, provavelmente durante a formação desta estrutura. Contudo, possíveis evidências de gás foram detectadas em áreas vizinhas.

Styles APA, Harvard, Vancouver, ISO, etc.

8

Ozturk, Mehmet Selim. « Effects Of Masonry Infill Walls On The Seismic Performance Of Buildings ». Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606753/index.pdf.

Texte intégral

Résumé :

In Turkey, in most of the reinforced concrete buildings, hallow masonry infill walls are used as a non-structural element, during design stage, their contribution to overall building behavior is not well known. Observations made after the earthquakes revealed that these non-structural elements had beneficial effects on the lateral capacity of the building. In this study, the contribution of the hallow masonry infill walls to the lateral behavior of reinforced concrete buildings was investigated. For this purpose, two different buildings were chosen as case studies. Three and six story symmetric buildings are modeled as bare and infilled frames. The parameters that were investigated are column area, infill wall area, distribution of masonry infill walls throughout the story. To determine the effect of each parameter, global drift ratios are computed and are compared for each case.

Styles APA, Harvard, Vancouver, ISO, etc.

9

Martin, Jake Joseph. « Geophysical and geological analysis of fault activity and seismic history of the Obion River Area, New Madrid Seismic Zone (NMSZ), Western Tennessee, USA ». Thesis, Boston College, 2014. http://hdl.handle.net/2345/bc-ir:103595.

Texte intégral

Résumé :

Thesis advisor: John Ebel
The New Madrid Seismic Zone (NMSZ) is well known for producing some of the largest intra-cratonic earthquakes within the North American Plate. The common hypothesis for the geological structure within the NMSZ is that stress is released across three major faults: the Cottonwood Grove Fault, the New Madrid North Fault, and the Reelfoot Thrust Fault. Evidence exists that would suggest an alternative model of geologic deformation in the area: that stress is being released across more than these three faults. A geologic and geophysical investigation was done to investigate a hypothetical fault west of Dyersburg, TN to test the alternative multi-fault hypothesis. A seismically created sand blow was logged in close proximity to the fault projection. Weathering of the sand blow indicated that the age of the sand blow came from a seismic event prior to the 1811-1812 earthquakes. There was no evidence to confirm this sand blow was created by a hypothetical fault in close proximity. A seismic exploration of the area was done across four seismic lines, primarily mapping Quaternary-age Mississippi River flood plain deposits. These seismic surveys yielded no evidence to suggest the presence of an additional fault. Across all surveys no evidence was found to conclusively support any existing theory on fault movement in the NMSZ
Thesis (MS) — Boston College, 2014
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Earth and Environmental Sciences

Styles APA, Harvard, Vancouver, ISO, etc.

10

Nicolosi, Massimo. « Seismic analysis of inclined shallow granular deposits ». Doctoral thesis, Università di Catania, 2012. http://hdl.handle.net/10761/1158.

Texte intégral

Résumé :

In the last decades many attempts for understanding the cyclic and dynamic behaviour of soft soils have been devoted by the scientific community. The aim of this thesis consists to investigate the mechanical response of two granular material (Hostun and Toyoura sand) in cyclic/dynamic conditions. In this paper some relationships between permanent displacement, evaluated by means of the code VIBRAZIONE and the Newmark method, and earthquake parameters, such as critical acceleration ratio, Arias Intensity and Destructive Power, have been investigated.

Styles APA, Harvard, Vancouver, ISO, etc.

11

Cheraghi, Saeid. « Seismic investigations in the Brunswick No. 6 area, Canada – Imaging and heterogeneity ». Doctoral thesis, Uppsala universitet, Geofysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-190479.

Texte intégral

Résumé :

The Brunswick No. 6 area, which is located in the Bathurst Mining Camp, New Brunswick, Canada, is the focus of this thesis. Almost a decade ago, in order to improve the understanding of the crustal structures and explore for new mineral deposits at depth, three 2D seismic profiles totaling about 30 km and 3D seismic data covering an area of about 38 km2 were acquired from the study area. Petrophysical properties including compressional-wave velocity and density were also measured in two deep boreholes in the area. These data were recovered and reanalyzed, and the improved seismic images interpreted as the main part of this PhD thesis. A prestack DMO and poststack migration algorithm was considered for processing both 2D and 3D data. Processing of 2D data revealed shallow and deep reflections, which correlate well with surface geology. Steeply-dipping reflections, some of which could host mineral deposits, were imaged down to a depth of 6-7 km. Processing of 3D data showed similar results to the processed 2D profiles. Nevertheless, the non-orthogonal nature of the 3D survey, combined with irregular distribution of offsets, azimuths and trace midpoints, caused a severe acquisition footprint masking reflections in the DMO-corrected unmigrated stacked cube. An FK-dip filter in the wavenumber domain was designed to reduce the effects of the acquisition footprint. To better understand wave propagation and scattering effects, calculated acoustic impedance log from the available borehole data was used to estimate vertical scale length using a von Karman autocorrelation function. 2D synthetic models representative of heterogeneity in the area were generated accounting for the estimated scale length. Numerical modeling was used to study the scattering effects on the synthetic models, where some predefined targets were superimposed in the provided 2D heterogeneous medium. The effects of variable source frequency, longer horizontal scale length and petrophysical fluctuations of heterogeneous medium were also investigated. The modeling results indicate that, in the presence of large horizontal, but small vertical scale lengths (structural anisotropy), the identification of mineral deposits is possible in the unmigrated stacked sections, but can be challenging in the migrated sections.

Styles APA, Harvard, Vancouver, ISO, etc.

12

Bian, Hanbing. « Numerical model for unsaturated sandy soils in seismic area : application to liquefaction ». Lille 1, 2007. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2007/50376-2007-Bian.pdf.

Texte intégral

Résumé :

Ce travail comporte la formulation d'un modèle numérique pour les sols sableux partiellement saturés et son application à l'analyse de la liquéfaction de ces sols. La liquéfaction est un phénomène important qui peut se produire sous sollicitation sismique. Depuis le séisme de Niigata en 1964, des recherches importantes ont été menées sur ce phénomène. La plupart de ces recherches ont été consacrée aux sols saturés. Cependant, les observations montrent qu'une légère diminution de la saturation en eau engendre une augmentation significative de la résistance des sols à la liquéfaction. A noter que dans le domaine de la géotechnique, les sols sont souvent en condition partiellement saturée. Les couches des sols liquéfiables qui sont situées au-dessous de la nappe sont dans un état quasi-saturé. Il est donc nécessaire d'étudier la liquéfaction des sols sableux en condition partiellement saturée. A partir des observations expérimentales, des hypothèses sont proposées dans ce travail pour la construction d'un modèle numérique: égalité de la pression de l'air et celle de l'eau dans l'espace poreux; absence d'interaction entre ces deux phases; absence du flux d'air. Un modèle est formulé pour les sols partiellement saturés dans le cadre de la théorie de la poromécanique fondée par Coussy. Le modèle proposé est adapté aux problèmes des sols en condition saturée ou partiellement saturée. Les sols saturés sont considérés comme un cas particulier. Les analyses du module de compressibilité et du coefficient de Skempton confirment les fondements théoriques du modèle proposé. Enfin, le modèle est validé sur des observations expérimentales. Dans la dernière partie, un modèle élastoplastique cyclique est utilisé dans le cadre du modèle proposé pour étudier l'influence de la saturation sur la liquéfaction des sables. Les résultats montrent que la diminution de la saturation en eau conduit à une augmentation de la résistance des sables à la liquéfaction. L'étude de la réponse en champ libre montre que la saturation initiale influence d'une manière significative la liquéfaction de sols. Elle conduit à réduire le risque de liquéfaction de ces sols. Le tassement pendant la phase de chargement (avant la dissipation de la surpression) augmente avec la diminution de la saturation en eau. L'influence de la perméabilité des sols partiellement saturés est moins significative que celle en condition saturée.

Styles APA, Harvard, Vancouver, ISO, etc.

13

Raffaele, Rosario Mario. « Seismic strutture of subduction zone of the lesser antille ». Doctoral thesis, Università di Catania, 2012. http://hdl.handle.net/10761/1256.

Texte intégral

Résumé :

In this work, in order to study the relationship between tectonic structures and seismicity, we show results of the experiment SISMANTILLES I on the central Lesser Antilles Subduction Zone where the North and South American plates converge with the Caribbean in a roughly ENE direction, at a rate of about 2 cm/yr. This motion is responsible for volcanic and seismic activity of the Lesser Antilles region. We analyzed local seismicity by using the data recorded, from November 1999 to January 2002, by a temporary combined on/offshore network. A data-set of 155 well located earthquakes, with a total of 4054 and 2617 pickings for P- S-waves respectively, was used to compute first a minimum 1-D velocity model which served as starting model for the subsequent 3-D inversion. To partly estimate the huge structural heterogeneity, the minimum 1-D model is complemented by station corrections that take into account near surface velocity heterogeneity and the geometry of the crust. In particular, the OBS station-terms are in general positive with respect to land stations indicating late arrivals, consistently with the presence of soft mud and sediments at the sea-bottom. The OBS station-terms vary with the thickness of sediments as can be derived here from multi-channel reflection seismic profiles shot over them. The inversion for 3-D P-velocity crustal structure was performed by iteratively solving the coupled hypocentre-velocity problem in a least-squares sense. Careful analysis of the resolution capability of our data set outlines the well-resolved features for interpretation. The resulting 3-D velocity model of the Lesser Antilles region shows that, in the investigated area, the island arc is divided into three layers (upper, middle and lower crust) characterized by a total average thickness of 23-24 km. P-wave velocities between sedimentary values and 6.0 km/s mark the upper crust that is interpreted to consist mainly of volcaniclastics and igneous rocks. Instead the bulk composition of the middle crust (Vp <6.8 km/s) is interpreted to be felsic to intermediate. Finally a plutonic lower crust, that shows P-wave velocities increasing from 7.1 km/s to 7.3 km/s, forms a layer extending from the forearc to the backarc domain. With regards earthquake locations, we observe a very low seismic activity beneath OBS stations that, on the contrary, is mainly concentrated east of the island arc. During the 13-month observation period available, hypocentral distribution highlights earthquakes mostly located between the island arc backstop and the subducting oceanic crust. At depth greater than 50 km we detect earthquakes that can be linked to dehydration of sepertinized slab mantle. In the centre of the arc near 15° 30 , beneath Dominique island, there is a clear concentration of deep events. It is in this area that on November 29, 2007 a 7.4 Mw intraplate earthquake occurred at 150 km depth. A first observation from earthquake locations map suggests that certain seismicity coincides with the extrapolated surface trace of the Tiburon ridge that several authors considered aseismic. Another remark is the no significant seismicity detected either in the accretionnary prism or in the outer forearc region. In our study area we may assume that the inner forearc controls the seismicity since the main seismic activity begins at its eastern border. The occurrence of a high seismicity level far from the backstop position and locate in the slab could be explained by slab bending.

Styles APA, Harvard, Vancouver, ISO, etc.

14

Gunel, Orhun Ahmet. « Influence Of The Shear Wall Area To Floor Area Ratio On The Seismic Performance Of Existing Reinforced Concrete Buildings ». Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615678/index.pdf.

Texte intégral

Résumé :

An analytical study is performed to evaluate the influence of shear wall area to floor area ratio on the behavior of existing mid-rise reinforced concrete buildings under earthquake loading. The seismic performance of five existing school buildings with shear wall ratios between 0.00% and 2.50% in both longitudinal and transverse directions and their strengthened counterparts are evaluated. Based on the structural properties of the existing buildings, additional buildings with varying shear wall ratios are designed. Consequently, twenty four buildings with different floor plans, number of stories, cross-sectional properties of the members and material strengths are acquired. Nonlinear time-history analyses are performed for all buildings by utilizing the software program, SAP2000 v14.2.0. under seven different ground motion records. The results indicated that roof drifts and plastic deformations reduce with increasing shear wall ratios, but the rate of decrease is lower for higher shear wall ratios. Buildings with 1.00% shear wall ratio have significantly lower roof drifts and plastic deformations when compared to buildings with 0.00% or 0.50% shear wall ratio. Roof drifts and plastic deformations are minimized when the shear wall ratio is increased to 1.50%. After this limit, addition of shear walls has only a slight effect on the seismic performance of the analyzed buildings.

Styles APA, Harvard, Vancouver, ISO, etc.

15

Janiszewski, Frank David. « Seismic reflection and gravity constraints on the bedrock configuration in the greater East Missoula area ». CONNECT TO THIS TITLE ONLINE, 2007. http://etd.lib.umt.edu/theses/available/etd-05232007-120605/.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

16

Panzera, Francesco. « Approaches to earthquake scenarios validation using seismic site response ». Doctoral thesis, Università di Catania, 2012. http://hdl.handle.net/10761/1084.

Texte intégral

Résumé :

A seismic hazard assessment was carried out for the Catania and Siracusa towns providing a comprehensive re-examination and re-processing of all the available seismic data. The site approach and the seismotectonic one were used and compared. The hazard assessment, using both methods, was performed following a logic-tree approach in order to consider and reduce the epistemic uncertainties. The combined use and comparison of these approaches is recommended since it allows to verify the robustness of the hazard estimates and allowed us to obtain useful elements to define the seismic hazard in Catania and Siracusa. Experimental data and numerical modeling were used to study the effect of local geology on the seismic response in the Catania area. Available boreholes data and elastic parameters were used to reconstruct a geotechnical model in order to perform 1D numerical modeling. Seismic urban scenarios were simulated considering destructive (Mw=7.0), strong (Mw=6.2) and moderate (Mw=5.7) earthquakes. PGA and spectral acceleration at different periods were obtained in the urban area through the equivalent linear numerical code EERA, and contour maps of different levels of shaking were drawn. Standard and horizontal-to-vertical spectral ratios were achieved making use of a dataset of 172 seismic events recorded at ten stations located on the main outcropping lithotypes. Spectral ratios inferred from earthquake data were compared with theoretical transfer functions. Both experimental and numerical results confirm the role of the geologic and morphologic setting of Catania. A study aimed to investigate on the dynamic properties of main lithotypes outcropping in the Siracusa area and their relationships with the local seismic response was performed. Non-invasive seismic prospecting techniques using the vertical component of surface waves (MASW and ReMi) were adopted, as well as ambient noise measurements, processed through the Nakamura technique. Moreover, a cluster analysis was performed to subdivide into homogeneous groups the experimentally obtained noise spectral ratios. Results pointed out that the use of combined different methods provides a more robust way to characterized the investigated soils and to reduce the problems linked to the non-uniqueness of solutions during the interpretation of geophysical data. The role of local geology and topography on the site response of a small hill, located in the northern part of Catania, was investigated. Ambient noise and earthquake data were processed through standard and horizontal-to-vertical spectral ratios. Directional effects were also investigated by computing the spectral ratios after rotating the horizontal components of motion and performing polarization analysis. Results of noise and earthquakes analysis, although show significant differences in amplitude, are comparable in frequency, especially in the sedimentary terrains. Pronounced directional effects are mostly observed on the slopes rather than at the hill top. Our findings appear linked to the complex wavefield generated by the lithologic heterogeneities existing in the area which seem to have a stronger influence with respect to the simple topographic effect. Seismic noise recorded by mobile stations in the Ortigia peninsula (downtown Siracusa) was analyzed through H/V spectral ratios, to investigate local site effects. Moreover, shear wave velocities were investigated through non-invasive techniques (MASW and ReMi) in order to assess the theoretical resonant frequency of the hill. Experimental results coming out from the spectral ratios show peaks in the frequency range 1.0-3.0 Hz which are consistent with the theoretical resonance frequency at Ortigia. The H/V azimuthal spectral analysis shows a clearly predominant E-W directional effect, transversal to the main axis of the peninsula, which is also confirmed by the polarization analysis in the time domain.

Styles APA, Harvard, Vancouver, ISO, etc.

17

Pearson, Eric Wesely. « Seismic modeling of thrust sheets in the Wildcat Hills area, Southern Alberta Foothills ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq24691.pdf.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

18

Castillo, Felix Vicente 1952. « Structural and stratigraphic interpretation of seismic reflection data from the North Barinas area, Venezuela ». Thesis, The University of Arizona, 1993. http://hdl.handle.net/10150/558222.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

19

De, Francesco Giovanni. « Advanced Seismic Design of Innovative Precast Systems for Structural Response Control ». Doctoral thesis, Università di Catania, 2013. http://hdl.handle.net/10761/1275.

Texte intégral

Résumé :

Emerging Design Philosophy. In current design philosophy a key concept is ductility, a parameter that reflect intrinsic energy dissipation capacity of structural elements. The key concept is the reduction of the structural cost, from the point of view of the initial cost, for design under moderate or important earthquake levels assuming possible damages at structural and non structural elements but ensuring the Life Safety. However, when the ductility of the elements is activated damage is introduced. Since, the described philosophy has been introduced, a lot of buildings have been designed and constructed. They have been subjected to various earthquakes and the obtained performances make evident the limits of this design philosophy. The considered arguments require the development of structural systems able to realize higher structural performances under level of the earthquakes moderate or severe. The most serious obstruction is the increase in cost. If substantial increase in cost is not required, compared with those required in ordinary buildings then, it is rational to design buildings characterized by absence of damage even for very rare earthquakes and a such design will be accepted by the society. Therefore, we should changeover the direction of technology development from cost reduction keeping same performance level to higher performance level without cost increase. Advanced Seismic Design Methodologies and Procedures. The characterization of systems with higher structural performances calls for the introduction of design methodologies able to defie the structural response in a more efficient and detailed. In the cost analysis, costs related to Non Structural component and contents (NCs) are usually dominant, especially for buildings with relevant impact for society. The response of NCs must be carefully characterized, and must be taken into account. In particular, the interaction between structural and non structural components must be properly investigated. Evidently, Performance based seismic Design Methodologies largely developed in the research field, are necessary and should be apply, even by practitioners engineers. In the comparison with Strength Based Seismic Design Procedures, Displacement Based Seismic Design Procedures appear to be more appropriate to better achieved the performance objectives. A displacement Based Seismic Design Procedure via Inelastic Displacement Ratio is highlighted and an analysis of Inelastic Displacement Ratio-key aspect in the mentioned procedure-is developed. Innovative Systems applied to Precast Concrete Structures. The introduction of innovative structural systems for seismic response control is particularly effective for precast prestressed concrete structures. Precast structural elements, produced in the factory and trucked in the construction site, must be appropriately connected. The necessity to realize appropriate connections and to introduce a dissipation capacity not involving damage to structural elements make attractive the introduction of new systems, not based on the cast in place emulation, where connections are designed to develop a specific deformation pattern, independent from the large seismic action variability. The displacement capacity is basically related to the deformability in post-tensioned partially unbounded steel strands that, provided the elastic behavior, guarantee re-centering capacity, removing any residual deformation. The well-defined deformation pattern and the dissipation capacity concentration in external metallic energy dissipators give to the structure a reliable dissipation capacity, easily replaceable without relevant additional costs. Thanks to the introduced characteristics the conceived structural system improves performances of traditional precast concrete buildings without a sensible variation in the cost production.

Styles APA, Harvard, Vancouver, ISO, etc.

20

Hardy, Anna Corella. « Hypocenter Locations and Focal Mechanism Solutions of Earthquakes in the Epicentral Area of the 1886 Charleston, SC, Earthquake ». Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/51252.

Texte intégral

Résumé :

The Charleston earthquake of 1886 was one of the largest shocks to occur on the eastern coast of North America. The geological cause has long been a controversial issue and a variety of source models have been proposed. Previous potential field modeling and reinterpretation of seismic reflection and well data collected in the early 1980s indicate that the crust between approximately 1 and 4.5 km depth is comprised primarily of Mesozoic mafic rocks, with extensive faulting that is spatially coincident with modern seismicity in the epicentral area (Chapman and Beale, 2010). This thesis proposes a new and testable hypothesis concerning the fault source of the 1886 shock that is very different from all previous interpretations. It is based on data collected during 2011-2012 from a local seismic network deployment in the immediate epicentral area. The 8-station temporary network was designed to better constrain earthquake hypocenter locations and focal mechanisms. Hypocenter locations of 134 earthquakes indicate a south-striking, west-dipping seismogenic zone in the upper 12 km of the crust. Over 40% of the 66 well-constrained focal mechanisms show reverse faulting on approximately north-south trending nodal planes, consistent with the orientation of the tabular hypocenter distribution. I offer the following hypothesis: The 1886 shock occurred by compressional reactivation of a major, south-striking, west-dipping early Mesozoic extensional fault. The modern seismicity can be regarded as a long-term aftershock sequence that is outlining the 1886 damage zone. Variability of shallow focal mechanisms is due to the complex early Mesozoic fault structure in the upper 4-5 km.
Master of Science

Styles APA, Harvard, Vancouver, ISO, etc.

21

Abdi, Amir. « Re-processing of reflection seismic data from line V2 of the HIRE Seismic Reflection Survey in the Suurikuusikko mining and exploration area, northern Finland ». Thesis, Uppsala universitet, Geofysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-156975.

Texte intégral

Résumé :

The Suurikuusikko gold deposit is located in northern Finland; it is the largest known gold resource in northern Europe. The acquired high resolution reflection seismic data along the c.30 km long profile V2 of the HIRE reflection survey in the Surrikuusikko gold mining and exploration area have been re-processed. A 15.4 ton Geosvip was used as the source, with a receiver spacing of 12.5 m and source spacing of 25 or 50 m. It was aimed to obtain more detailed structural information of the upper 5 – 6 km crust, and to study the seismic response of the important geological and tectonic structures (e.g. Suasselkä PG fault) along the line V2. The line V2 runs from south to north; in the north, it cuts the mafic graphitic tuffic rocks, which are buried under a layer of tholeiite. It is almost perpendicular to the surface trace of the Suasselkä PG fault in the north. The obtained seismic image showed significant improvements compared with the previous work. The seismic response of the major rock units generated strong reflections, and they can be traced down to at least 3 km depth; the reflections correlate well with the surface geology. The moderately dipping reflections from the PG fault are clearly imaged; the dip direction of the fault is towards the SE with a dip of about 50o, possibly decreasing with depth down to about 35o, the fault can be traced down to about 3 km depth. The reverse movement of the fault most probably caused the neighboring sub-horizontal layers to be folded and generated a duplex structure. The dip direction of the major structures in the southern parts is towards NE; this together with the mentioned information about the fault, can be utilized in order to define the major geological structures and most importantly the tectonic evolution of the area; such information can be used in many crucial aspects such as prediction of the future movements of the bedrock and discovery of new resources.

Styles APA, Harvard, Vancouver, ISO, etc.

22

Angelica, Carmelo. « Potenziale sismogenetico dell'Italia, da dati sismici e geodetici ». Doctoral thesis, Università di Catania, 2012. http://hdl.handle.net/10761/1085.

Texte intégral

Résumé :

L' Italia rappresenta una zona chiave per capire la complessa dinamica dell'Area Mediterranea. La disponibilità di reti GPS sempre più dense e dati sismici precisi, permette di avere informazioni sul campo di deformazione asismica, che è l'elemento principale per capire il potenziale sismico delle strutture sismogenetiche.

Styles APA, Harvard, Vancouver, ISO, etc.

23

Ehsan, Siddique Akhtar. « Re-processing and Interpretation of 2D Seismic Line in the Kristineberg Mining Area, Northern Sweden ». Thesis, Uppsala universitet, Geofysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-179533.

Texte intégral

Résumé :

The Skellefte district, 1.90 to 1.80 Ga, is one of the most important base metal mining districts of Sweden with over 85 volcanic-hosted massive sulfide (VHMS) deposits. The study area focuses on the western part of the Skellefte district which contains volcanic, metasedimentary and intrusive rocks. In 2003, seismic data acquisition was carried out in the western part of the Skellefte district in the vicinity of the Kristineberg mine. Two parallel seismic lines were acquired about 8 km apart from each other. Profile 1 is about 22 km long and selected for the re-processing and interpretation in this thesis. The acquisition geometry, low fold coverage, the complex tectonic history and fewer outcrops in the area make the data processing and interpretation quite challenging and required a careful processing design to obtain interpretable seismic image. The re-processed Profile 1 is correlated with two other newly acquired seismic lines in the area for the purpose of possible 3D visualization and interpretation. The re-processing work includes a careful velocity analysis along with a series of iterations in residual statics, poststack and prestack migrations and cross dip analysis. The re-processed seismic section clearly shows a north dipping reflector which truncates against the Revsund Granites at depth. The possible interpretation for this reflector is a structural basement to the Skellefte Group constituting Bothnian Basin or a fault zone within the Viterliden intrusion. The Kristineberg mine is situated on the northern limb of a synform structure with prominent southwards dipping reflections. The major lithological contacts between different rock units are series of latest thrust faults. The prominent reflectivity within and at the contact with the Viterliden intrusion may suggest deep seated mineralized horizons. The cross dip analysis helps finding the eastward dipping component for the shallow horizons. The re-processed image is also compared with the previous processed seismic section and improvements in reflectors are evident.
VINNOVA 4D

Styles APA, Harvard, Vancouver, ISO, etc.

24

Semmens, Stephen Bradley. « An Engineering Geological Investigation of the Seismic Subsoil Classes in the Central Wellington Commercial Area ». Thesis, University of Canterbury. Geological Sciences, 2010. http://hdl.handle.net/10092/4287.

Texte intégral

Résumé :

The city of Wellington has a high population concentration and lies within a geologically active landscape at the southern end of the North Island, New Zealand. Wellington has a high seismic risk due to its close proximity to several major fault systems, with the active Wellington Fault located in the north-western central city. Varying soil depth and properties in combination with the close proximity of active faults mean that in a large earthquake rupture event, ground shaking amplification is expected to occur in Thorndon, Te Aro and around the waterfront. This thesis focuses on the area bounded by Thorndon Overbridge in the north, Wellington Hospital in the south, Kelburn in the west, and Oriental Bay in the east. It includes many of the major buildings and infrastructural elements located within the central Wellington commercial area. The main objectives were to create an electronic database which allows for convenient access to all available data within the study area, to create a 3D geological model based upon this data, and to define areas of different seismic subsoil class and depth to rock within the study area at a scale that is useful for preliminary geotechnical analysis (1:5,000. Borelogs from 1025 holes with accompanying geological and geotechnical data obtained from GNS Science and Tonkin & Taylor were compiled into a database, together with the results from SPAC microtremor testing at 12 sites undertaken specifically for this study. This thesis discusses relevant background work and defines the local Wellington geology. A 3D geological model of the central Wellington commercial area, along with ten ArcGIS maps including surficial, depth to bedrock, site period, Vs30, ground shaking amplification hazard and site class (NZS 1170.5:2004) maps were created. These outputs show that a significant ground shaking amplification risk is posed on the city, with the waterfront, Te Aro and Thorndon areas most at risk.

Styles APA, Harvard, Vancouver, ISO, etc.

25

Hess, Clarion Hadleigh. « Geologic interpretations of seismic scattering and attenuation for the Cianten Caldera and the surrounding area ». Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82302.

Texte intégral

Résumé :

Thesis (S.M. in Geophysics)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 77-80).
The Cianten Caldera in Indonesia is immediately adjacent to the producing portion of the Awibengkok geothermal field. The Cianten Caldera contains rocks similar to those in the Awibengkok field, however, the Cianten Caldera is not capable of producing geothermal power on a commercial scale. The Cianten Caldera has been microseismically monitored along with the producing Awibengkok field as injections and fracing in that field have occurred. This microseismic data is analyzed with Multi Window Time Lapse Analysis (MWTLA) to find values for the scattering coefficient, go, and the seismic albedo, [Beta]o, of the Cianten Caldera. The scattering coefficient describes the amount of seismic energy that is attenuated due to the wave scattering off of heterogeneities and the seismic albedo is the ratio of the amount of scattering to the total amount of attenuation that includes both scattering and intrinsic attenuation. This information has been combined with the geology of the Cianten Caldera to define the interior features of the Cianten Caldera and which of these features are preventing the Cianten Caldera from being a productive geothermal energy source
by Clarion Hadleigh Hess.
S.M.in Geophysics

Styles APA, Harvard, Vancouver, ISO, etc.

26

Spina, Laura. « Investigation on Mt. Etna dynamics by seismic and acoustic signals (August 2007 December 2010) ». Doctoral thesis, Università di Catania, 2014. http://hdl.handle.net/10761/1566.

Texte intégral

Résumé :

In order to shed light on the dynamics of the plumbing system, and define the source-mechanism of acoustic events at Mt. Etna, infrasound signals-continuously recorded by Istituto Nazionale di Geofisica and Vulcanologia- were analyzed in this thesis, jointly with some seismic signals. In particular, we focused on the period comprised between August 2007 and December 2010, during which a wide spectrum of eruptive activity occurred. Until the activation of Bocca Nuova (BN), on August 2010, the three main vents radiating infrasound were North East Crater (NEC), South East Crater (SEC), and the Eruptive Fissure of the 2008-2009 eruption (EF). Location and spectral analyses carried out on the infrasound signals, revealed the numerical dominance and the steadiness of NEC events, radiating almost continuously acoustic energy, oppositely to SEC and EF. Furthermore, NEC events most relevant changes (spectral and amplitude variation) occurred systematically after the renewal of activity at SEC or at the EF. This evidence led us to infer the existence of a persistent link among their feeding system, and confirm the presence of a double resonance model for NEC events. Successively, events from EF were gathered and analyzed in detail through high precision location methods, allowing to define the cyclic activation of an highest altitude vent along the fissure, likely corresponding to the arrival of new batch of magma, rich in volatiles. During 2010, instead, Mt. Etna eruptive style was different, being characterized by a total number of roughly 35 minor ash emissions from SEC, BN and NEC. Three main episodes are here analyzed, by studying the morphological and compositional features of the sampled ash and the seismic and acoustic signals radiated during those events. Different conditions were deduced for the craters. In particular, for SEC and BN the presence of material plugging the upper conduit was inferred, while data shows that NEC was characterized by open conduit conditions. Finally, a dataset of acoustic signals, regarding few days of explosive activity occurring at Mt. Yasur (Vanuatu) was analyzed. Indeed, the comparison with other volcanic environments is fundamental in order to widen the knowledge on the volcanic phenomena. Mt. Yasur data, revealed completely different features, suggesting that different source dynamics were active. Furthermore, the existence of propagation effects, affecting the signals´ characteristics and due to the topography is discussed.

Styles APA, Harvard, Vancouver, ISO, etc.

27

Van, Avendonk Hermanus Josephus Antonius. « An investigation of the crustal structure of the Clipperton transform fault area using 3D seismic tomography / ». 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?p9823314.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

28

Yoshikawa, Miyuki. « Seismic velocity structure beneath Otake-Hatchobaru geothermal area at Kuju Volcano in the central Kyusyu, Japan ». 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/147827.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

29

VALAGUSSA, ANDREA. « Relationships between landslides size distribution and earthquake source area in a perspective of seismic hazard zoning ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2015. http://hdl.handle.net/10281/68458.

Texte intégral

Résumé :

Gli eventi sismici sono riconosciuti come una delle maggiori cause per l’innesco di frane (Keefer, 1984). Le frane sismo-indotte sono documentate sin dal IV secolo (Seed, 1968). È stata condotta un’analisi sulla distribuzione spaziale delle frane sismo-indotte nell’area circostante la sorgente sismogenetica per meglio comprendere il loro innesco in aree sismiche e per delimitare la massima distanza alla quale un sisma con data magnitudo possa indurre frane. Tuttavia, quando si applicano tali approcci a eventi storici si pone un problema legato al sottocampionamento delle frane più piccole, che possono essere obliterate dall'erosione e dall'evoluzione del paesaggio. Per questo motivo è importante caratterizzare accuratamente la distribuzione delle frane, in termini di dimensione, in funzione della distanza dalla sorgente sismica. Sono stati analizzati sei terremoti in tutto il mondo che hanno innescato un significativo numero di frane (Finisterre 1993, Northridge 1994, Niigata 2004, Wenchuan 2008, Iwate 2008 and Tohoku 2011) per meglio comprendere le relazioni esistenti tra la distribuzione spaziale delle frane, l’accelerazione di picco al suolo (PGA), la distanza dalla sorgente, il relief e le litologie presenti nell’area. Si è osservata una forte relazione tra la PGA e la dimensione delle frane, mentre una la relazione tra la loro dimensione e la distanza dalla sorgente non è altrettanto chiara, ciò legato all’interazione tra diversi fattori quali ad esempio il relief e la litologia. Sono state realizzate e analizzate le curve magnitudo-frequenza (MFC) per differenti distanze dall’area sorgente attraverso varie metodologie: stimatore di massima verosimiglianza per distribuzioni di tipo potenza cumulate (Clauset et al, 2009), stimatore di massima verosimiglianza per distribuzioni di tipo potenza non cumulate, regressione ai minimi quadrati per funzioni di tipo potenza non cumulate in scala logaritmica e stimatore di massima verosimiglianza per la distribuzione Double Pareto. Dalle analisi si è potuto osservare un decrescere della densità spaziale delle frane con la distanza, ma un basso impatto della dimensione delle frane. Inoltre la funzione Double Pareto è stata scelta come miglior strumento per il fittaggio dei dati (Valagussa et al, 2014). Allo scopo di definire il rischio legato alle frane sismo-indotte è stata sviluppata una metodologia per la zonazione probabilistica quantitativa del rischio da frane da crollo (Valagussa et al, 2014). Il metodo è stato applicato e dimostrato nell’area del Friuli (Apli orientali) colpita da un terremoto di magnitudo 6.4 nel 1976. Quattro inventari sono stati realizzati sia tramite attività di terreno che da dati storici. La metodologia si basa sul vettore di rischio tridimensionale (RHVmod) le cui componenti includo l’energia cinetica, l’altezza di volo e la frequenza annua. I primi due valori sono calcolati per ogni cella del versante per mezzo del programma Hy-STONE. La frequenza annua è invece determinata moltiplicando la frequenza d’innesco annua per il numero di transiti simulati in ogni cella. La frequenza d’innesco annua è calcolata combinando l’area instabile, calcolata per 10 differenti scenari con differente frequenza annua di occorrenza sulla base di caratteristiche morfometriche e sismiche, e la curva magnitudo-frequenza relativa dei blocchi identificati da attività di terreno. Una serie di analisi discriminanti sono state condotte per determinare le variabili che controllano l’area in frana, sulla base degli inventari redatti e di DEMs a differenti risoluzioni (1 e 10m). L’analisi ha dimostrato il ruolo rilevante della curvatura nella definizione dell’area instabile. Per verificare la validità della mappa di PGA utilizzata nelle analisi, una nuova mappa è stata redatta sulla base delle Precarious Balanced Rocks identificate sul terreno.
Earthquakes have been recognized as a major cause of landsliding (Keefer, 1984), and landslides triggered by earthquakes have been documented since the IV century (Seed, 1968). The spatial distribution of earthquake-induced landslides around the seismogenetic source has been analysed to better understand the triggering of landslides in seismic areas and to forecast the maximum distance at which an earthquake, with a certain magnitude, can trigger landslides. However, when applying such approaches to old earthquakes one should be concerned about the undersampling of smaller landslides, which can be cancelled, by erosion and landscape evolution. For this reason, it is important to characterize carefully the size distribution of landslides as a function of distance from the earthquake source. I analysed six earthquakes in the world that triggered significant amount of landslides (Finisterre 1993, Northridge 1994, Niigata 2004, Wenchuan 2008, Iwate 2008 and Tohoku 2011) to better understand the relation between the spatial distribution of the landslides, the peak ground acceleration (PGA), the distance from the sources, the relief and the lithologies of the area. I observed a strong relationship between landslides size and PGA, while the relationship between the distance from the source and the landslide size distribution is not clear, due to the interaction of different factors such as relief and lithology. I also developed magnitude frequency curves (MFC) for different distances from the source area by using different methods, such as: the maximum likelihood estimator of cumulative power-law distribution (Clauset et al, 2009); the maximum likelihood estimator of non-cumulative power-law function; the least square regression of non-cumulative log power-law function and the maximum likelihood estimator of Double Pareto distribution. I observed a decrease of the spatial density of landslides with distance, with a small effect of the size of these landslides. I also identify the Double Pareto function as the best tool for the fitting of the data (Valagussa et al., 2014a). In order to define the hazard due to earthquake-induced landslides, I developed a methodology for quantitative probabilistic hazard zonation for rockfalls (Valagussa et al., 2014b). I applied and demonstrated the method in the area of Friuli (Eastern Italian Alps) that was affected by the 1976 Mw 6.5 earthquake. Four rockfall datasets have been prepared from both historical data and field surveys. The methodology relies on a three-dimensional hazard vector (RHVmod), whose components include the rockfall kinetic energy, the fly height, and the annual frequency. The values of the first two components are calculated for each location along the slope using the 3D rockfall runout simulator Hy-STONE. The rockfall annual frequency is assessed by multiplying the annual onset frequency by the simulated transit frequency. The annual onset frequency is calculated 2 through a procedure that combines the extent of unstable areas, calculated for 10 different seismichazard scenarios with different annual frequencies of occurrence, and the magnitude relativefrequency relationship of blocks as derived from the collected field data. For each annual frequency of occurrence, the unstable area is calculated as a function of morphometric and earthquake characteristics. A series of discriminant-analysis models, using the rockfall datasets and DEMs of different resolution (1 and 10 m), identified the controlling variables and verified the model robustness. In contrast with previously published research, I show that the slope curvature plays a relevant role in the computation of the unstable area. To ensure the validity of the peak ground acceleration used as seismic parameter in the discriminant function, I also try to define a map of PGA based on the precarious balanced rocks surveyed on the field.

Styles APA, Harvard, Vancouver, ISO, etc.

30

Martin, James R. « Implications from a geotechnical investigation of liquefaction phenomena associated with seismic events in the Charleston, SC area ». Diss., This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-06062008-172159/.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

31

Arzuman, Sadun. « 3-D structural and seismic stratigraphic interpretation of the Guasare-Misoa Interval, VLE 196 Area, Block V, Lamar Field, Lake Maracaibo, Venezuela ». Texas A&M University, 2002. http://hdl.handle.net/1969/557.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

32

Barbagallo, Francesca. « An overdamped multimodal adaptive nonlinear static procedure for seismic assessment of rc infilled frames ». Doctoral thesis, Università di Catania, 2018. http://hdl.handle.net/10761/3752.

Texte intégral

Résumé :

The seismic assessment of existing structures is considered the fundamental step to (i) estimate the seismic capacity of the initial structure (ii) predict the collapse mechanism and the structural weakness, (iii) select the most appropriate seismic retrofitting technique and determine the improved capacity of the upgraded building. Nonlinear dynamic analysis is widely recognised as the most accurate tool to predict the seismic behaviour of structures. However, this type of analysis has a high computational cost, and it is not an approach that can be extensively applied for professional purposes yet. To provide a tool that predicts the seismic behaviour of structures with a good accuracy but with a lower computational burden, nonlinear static methods of analysis were developed. The Capacity Spectrum Method (CSM) proposed by Freeman and the N2 Method proposed by Fajfar were pioneering methods and were recommended by the American and the European seismic code, respectively. Although these methods of analysis are generally reliable for the assessment of plane frames, however they neglect the contribution of higher modes of vibration to the seismic response and do not consider the progressive reduction of the structural stiffness due to the nonlinear behaviour of the structure. To improve the level of accuracy, advanced nonlinear static methods of analysis were developed, such as the Multimodal Pushover Analysis by Chopra et al., the Displacement Adaptive Puhover by Pinho et al. and the Advanced N1 method by Ghersi et al. Despite the innovative character of these methods, however they still present shortcomings. Another important aspect regarding existing structures is the presence of infill panels. Although infill panels provide the structure with a much larger stiffness and their location and mechanical properties influence the dissipative mechanism of the structure, however they are considered nonstructural elements, and their contribution to the seismic response is neglected. This thesis aims at the development of a nonlinear static method of analysis that can accurately estimate the seismic response of RC frames, with and without infill panels, keeping acceptable computation costs. To this end, the thesis proposes a multimodal adaptive procedure named overDamped Displacement Adaptive Procedure (D-DAP). This method has been developed from the combination of the approaches proposed by Pinho et al. and by Ghersi et al. The multimodal adaptive procedure to update the load vector is taken from the first, while the method for the association of the peak ground acceleration to the displacement demand without the SDOF approximation is drawn from the second. In addition, the D-DAP is equipped with an equivalent damping to consider the increase of the energy dissipation due the cumulated damage in the structure. To this end, the value of the equivalent damping is updated at each step according to a new damping law that has been properly calibrated in this work for RC frames with and without infill panels. The accuracy of the D-DAP in the seismic assessment of rc frames was compared to that of the DAP by Pinho, the MPA by Chopra, the N2 method (EC8) and the CSM (FEMA 440). To this end, a set of 54 RC frames was designed to be representative of existing buildings with various levels of seismic deficiencies, and their seismic responses were predicted by those aforementioned methods of analysis. These comparisons showed that the D-DAP applied with the proposed damping law demonstrated an accuracy in predicting the seismic response of RC frames, with and without infills, generally higher than the other nonlinear static methods of analysis. In particular, the D-DAP provided a significant improvement with respect to the other existing methods in the prediction of the response of RC frames with infill panels.

Styles APA, Harvard, Vancouver, ISO, etc.

33

Occhipinti, Giuseppe. « Seismic Assessment and Rehabilitation of existing RC Buildings not designed to withstand earthquakes ». Doctoral thesis, Università di Catania, 2017. http://hdl.handle.net/10761/3979.

Texte intégral

Résumé :

This thesis presents a high fidelity numerical model developed to investigate the seismic performance and structural robustness of an original and retrofitted 10-storey reinforced concrete (RC) framed building. The analysed structure represents a typical existing building in Catania, Italy, that was designed to resist only gravity and wind loading according to the design regulation allowed until the 1981 in that area. The proposed numerical description adopts beam-column elements for beams and columns and special purpose shell elements for modelling RC floor slabs, both allowing for geometric and material nonlinearity. In order to model masonry infills, a novel macro-element is implemented within a FE framework based on an already published discrete formulation. 3D nonlinear dynamic simulations are performed considering sets of natural accelerograms acting simultaneously along all the three space directions and compatible with the design spectrum for the Near Collapse Limit State. To improve computational efficiency, which is critical when investigating the nonlinear dynamic behaviour of large structures, the partitioning approach previously developed at Imperial College is adopted, enabling effective parallelisation on HPC systems. The numerical results obtained from the 3D nonlinear dynamic simulations are presented and discussed, focusing on the variation in time of the deformed shape, inter-storey drifts, plastic deformations and internal force distribution, considering or neglecting the infill panel contribution. The original structure showed a very poor seismic performance, even though the infill panel contribution leads to significant variation in the response it is not sufficient to preserve the structure from the collapse. A never adopted strengthening solution that utilises the synergetic contribution of concentric steel bracing and eccentric steel bracings with dissipative shear links is illustrated and employed to retrofit the original structure. A detailed model of the retrofitting components is implemented within the detailed model for the original building. The results of numerical simulations for the retrofitted structure confirm that the proposed solution significantly enhances the response under earthquake loading, allowing the structure to resist the design earthquake with only limited damage in the original RC beams and columns, highlighting the feasibility of retrofitting for this typical multi-storey RC building structure.

Styles APA, Harvard, Vancouver, ISO, etc.

34

Sciotto, Mariangela. « Insights into eruption dynamics and shallow plumbing system of MT. Etna by infrasound and seismic signals ». Doctoral thesis, Università di Catania, 2013. http://hdl.handle.net/10761/1327.

Texte intégral

Résumé :

The success in eruption forecasting needs the knowledge of the eruptive processes and the plumbing system of the volcano. Indeed, the eruptive styles are controlled by the interplay between magma dynamics and the plumbing system. In multi-vent volcanoes, such as Mt. Etna, where volcanic activity can rapidly vary over time and be simultaneously at the different craters, the shallow plumbing system is quite complex. For forecasting purposes, volcano monitoring measures many geophysical parameters and interprets sub-aerial volcanic phenomena. Lots of volcanic processes occur at or near the boundary between the earth and the atmosphere, thus, beside seismic signal, acoustic waves mainly in the range of infrasound are generated. In particular, infrasound activity is usually evidence of open conduit conditions and its quantification can provide information on explosive phenomena and source mechanism. A more comprehensive knowledge of the source mechanism, as well as of the source depth into the conduit, can be achieved by exploring seismo-acoustic sources, exciting mechanical waves both in the volcano edifice and in the atmosphere. The aim of the thesis is to look closely at the eruption dynamics at Mt. Etna, with a focus on explosive activity, and at the shallow plumbing system by means of analysis of infrasound and seismo-acoustic signals.

Styles APA, Harvard, Vancouver, ISO, etc.

35

Herrera, Fabiola, Flaby Mamani et Victor Arana. « Admissible height and urban density of buildings for the Prospective Management of Seismic Risk in residential areas ». Institute of Electrical and Electronics Engineers Inc, 2020. http://hdl.handle.net/10757/656562.

Texte intégral

Résumé :

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado.
This research proposes limit values of height and population density of buildings for a Prospective Management of Seismic Risk in residential areas. The analysis of an efficient evacuation of buildings to the street or refuge area was carried out, evaluating human behavior with models based on the agent, the influence of buildings and the urban parameters of the city with three-dimensional models (BIM) for a severe seismic scenario. The present article establishes that the maximum permissible height of buildings projected in a residential avenue is directly related to the width of the available refuge zone to guarantee the correct evacuation of said zone during a severe seismic event. In addition, an evaluation of a real existing scenario is made in a section of a residential avenue.

Styles APA, Harvard, Vancouver, ISO, etc.

36

Pilz, Marco. « A comparison of proxies for seismic site conditions and amplification for the large urban area of Santiago de Chile ». Phd thesis, Universität Potsdam, 2010. http://opus.kobv.de/ubp/volltexte/2011/5296/.

Texte intégral

Résumé :

Situated in an active tectonic region, Santiago de Chile, the country´s capital with more than six million inhabitants, faces tremendous earthquake hazard. Macroseismic data for the 1985 Valparaiso and the 2010 Maule events show large variations in the distribution of damage to buildings within short distances indicating strong influence of local sediments and the shape of the sediment-bedrock interface on ground motion. Therefore, a temporary seismic network was installed in the urban area for recording earthquake activity, and a study was carried out aiming to estimate site amplification derived from earthquake data and ambient noise. The analysis of earthquake data shows significant dependence on the local geological structure with regards to amplitude and duration. Moreover, the analysis of noise spectral ratios shows that they can provide a lower bound in amplitude for site amplification and, since no variability in terms of time and amplitude is observed, that it is possible to map the fundamental resonance frequency of the soil for a 26 km x 12 km area in the northern part of the Santiago de Chile basin. By inverting the noise spectral rations, local shear wave velocity profiles could be derived under the constraint of the thickness of the sedimentary cover which had previously been determined by gravimetric measurements. The resulting 3D model was derived by interpolation between the single shear wave velocity profiles and shows locally good agreement with the few existing velocity profile data, but allows the entire area, as well as deeper parts of the basin, to be represented in greater detail. The wealth of available data allowed further to check if any correlation between the shear wave velocity in the uppermost 30 m (vs30) and the slope of topography, a new technique recently proposed by Wald and Allen (2007), exists on a local scale. While one lithology might provide a greater scatter in the velocity values for the investigated area, almost no correlation between topographic gradient and calculated vs30 exists, whereas a better link is found between vs30 and the local geology. When comparing the vs30 distribution with the MSK intensities for the 1985 Valparaiso event it becomes clear that high intensities are found where the expected vs30 values are low and over a thick sedimentary cover. Although this evidence cannot be generalized for all possible earthquakes, it indicates the influence of site effects modifying the ground motion when earthquakes occur well outside of the Santiago basin. Using the attained knowledge on the basin characteristics, simulations of strong ground motion within the Santiago Metropolitan area were carried out by means of the spectral element technique. The simulation of a regional event, which has also been recorded by a dense network installed in the city of Santiago for recording aftershock activity following the 27 February 2010 Maule earthquake, shows that the model is capable to realistically calculate ground motion in terms of amplitude, duration, and frequency and, moreover, that the surface topography and the shape of the sediment bedrock interface strongly modify ground motion in the Santiago basin. An examination on the dependency of ground motion on the hypocenter location for a hypothetical event occurring along the active San Ramón fault, which is crossing the eastern outskirts of the city, shows that the unfavorable interaction between fault rupture, radiation mechanism, and complex geological conditions in the near-field may give rise to large values of peak ground velocity and therefore considerably increase the level of seismic risk for Santiago de Chile.
Aufgrund ihrer Lage in einem tektonisch aktiven Gebiet ist Santiago de Chile, die Hauptstadt des Landes mit mehr als sechs Millionen Einwohnern, einer großen Erdbebengefährdung ausgesetzt. Darüberhinaus zeigen makroseismische Daten für das 1985 Valparaiso- und das 2010 Maule-Erdbeben eine räumlich unterschiedliche Verteilung der an den Gebäuden festgestellten Schäden; dies weist auf einen starken Einfluss der unterliegenden Sedimentschichten und der Gestalt der Grenzfläche zwischen den Sedimenten und dem Festgestein auf die Bodenbewegung hin. Zu diesem Zweck wurde in der Stadt ein seismisches Netzwerk für die Aufzeichnung der Bodenbewegung installiert, um die auftretende Untergrundverstärkung mittels Erdbebendaten und seismischem Rauschen abzuschätzen. Dabei zeigt sich für die Erdbebendaten eine deutliche Abhängigkeit von der Struktur des Untergrunds hinsichtlich der Amplitude der Erschütterung und ihrer Dauer. Die Untersuchung der aus seismischem Rauschen gewonnenen horizontal-zu-vertikal-(H/V) Spektral-verhältnisse zeigt, dass diese Ergebnisse nur einen unteren Grenzwert für die Bodenverstärkung liefern können. Weil jedoch andererseits keine zeitliche Veränderung bei der Gestalt dieser Spektralverhältnisse festgestellt werden konnte, erlauben die Ergebnisse ferner, die Resonanzfrequenz des Untergrundes für ein 26 km x 12 km großes Gebiet im Nordteil der Stadt zu bestimmen. Unter Zuhilfenahme von Informationen über die Dicke der Sedimentschichten, welche im vorhinein schon durch gravimetrische Messungen bestimmt worden war, konnten nach Inversion der H/V-Spektralverhältnisse lokale Scherwellengeschwindigkeitsprofile und nach Interpolation zwischen den einzelnen Profilen ein dreidimensionales Modell berechnet werden. Darüberhinaus wurde mit den verfügbaren Daten untersucht, ob auf lokaler Ebene ein Zusammenhang zwischen der mittleren Scherwellengeschwindigkeit in den obersten 30 m (vs30) und dem Gefälle existiert, ein Verfahren, welches kürzlich von Wald und Allen (2007) vorgestellt wurde. Da für jede lithologische Einheit eine starke Streuung für die seismischen Geschwindigkeiten gefunden wurde, konnte kein Zusammenhang zwischen dem Gefälle und vs30 hergestellt werden; demgegenüber besteht zumindest ein tendenzieller Zusammenhang zwischen vs30 und der unterliegenden Geologie. Ein Vergleich der Verteilung von vs30 mit den MKS-Intensitäten für das 1985 Valparaiso-Erdbeben in Santiago zeigt, dass hohe Intensitätswerte vor allem in Bereichen geringer vs30-Werte und dicker Sedimentschichten auftraten. Weiterhin ermöglichte die Kenntnis über das Sedimentbeckens Simulationen der Bodenbewegung mittels eines spektralen-Elemente-Verfahrens. Die Simulation eines regionalen Erdbebens, welches auch von einem dichten seismischen Netzwerk aufgezeichnet wurde, das im Stadtgebiet von Santiago infolge des Maule-Erdbebens am 27. Februar 2010 installiert wurde, zeigt, dass das Modell des Sedimentbeckens realistische Berechnungen hinsichtlich Amplitude, Dauer und Frequenz erlaubt und die ausgeprägte Topographie in Verbindung mit der Form der Grenzfläche zwischen den Sedimenten und dem Festgestein starken Einfluss auf die Bodenbewegung haben. Weitere Untersuchungen zur Abhängigkeit der Bodenerschütterung von der Position des Hypozentrums für ein hypothetisches Erdbeben an der San Ramón-Verwerfung, welche die östlichen Vororte der Stadt kreuzt, zeigen, dass die ungünstige Wechselwirkung zwischen dem Verlauf des Bruchs, der Abstrahlung der Energie und der komplexen geologischen Gegebenheiten hohe Werte bei der maximalen Bodengeschwindigkeit erzeugen kann. Dies führt zu einer signifikanten Zunahme des seismischen Risikos für Santiago de Chile.

Styles APA, Harvard, Vancouver, ISO, etc.

37

Chapman, Timothy Ray. « Seismic tectono-stratigraphic study of the Pleistocene in the Sunrise/Troubadour area in relation to development of future infrastructure / ». Title page, abstract and summary only, 1998. http://web4.library.adelaide.edu.au/theses/09SB/09sbc466pdf.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

38

Nugraha, Andri Dian. « Seismic velocity, attenuation, and thermal structures in the Shikoku and Kyushu area of Japan : Relationship to low-frequency earthquakes ». 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/124423.

Texte intégral

Résumé :

Kyoto University (京都大学)
0048
新制・課程博士
博士(理学)
甲第14395号
理博第3392号
新制||理||1496(附属図書館)
UT51-2009-D107
京都大学大学院理学研究科地球惑星科学専攻
(主査)教授 Mori James Jiro, 教授川崎一朗, 教授平原和朗
学位規則第4条第1項該当

Styles APA, Harvard, Vancouver, ISO, etc.

39

Cultrera, Matteo. « HYDROGEOLOGICAL SURVEYS AND ANALYTICAL APPLICATIONS OF THE VENETIAN AQUIFER SYSTEM. IMPLEMENTATIONS OF SAFETY MEASURES FOR THE VENICE LAGOON AREA ». Doctoral thesis, Università degli studi di Padova, 2010. http://hdl.handle.net/11577/3422386.

Texte intégral

Résumé :

In the study area (Venetian hinterland, Porto Marghera) there is an average of a few hundred artesian wells (80-350 m in depth) drilled between 1910-1970 and later abandoned. These wells represent a means through which the artesian waters rise; therefore a dispersion process takes place between the groundwaters in the Shallow Aquifer System (0-80 m) and those in the deep artesian aquifers (Artesian Aquifer System, 80-350 m below ground level), in which the hydraulic head has steadily risen for the last 40 years. In this instance the shallow aquifers (about 0-30 m) could be subjected to a recharge through the abandoned wells. This recharge effect adds itself to a hydro-geological system greatly influenced by anthropic activities, such as: safety measures by means of a drainage system made up of many pumping stations which guard both the phreatic level in wide-spread areas and the hydraulic head; diaphragm walls in the whole area of Porto Marghera both near the lagoon border and the inland. The diaphragm wall goes down to 15-20 m in depth. These diaphragm walls should remove the superfluous groundwaters that – by passing through highly polluted lands – must necessarily be dealt with and treated in suitable plants. The spontaneous rise of the groundwaters through abandoned wells due to the increase of the hydraulic head in the deep aquifers has not been studied in depth from a scientific point of view. The analytical and numerical models available in scientific literature mainly deal with the definition of a system made up of abandoned deep wells, through which fluids may run because of the injection of fluid waste or carbon dioxide through injection wells. Starting from the analytical solutions suggested by different authors new ones have been achieved which may be more effectively adapted to the unusual problems occurred in defining the vertical flow through abandoned wells. The use of these solutions requires the analysis of a series of hydrogeological parameters. The most important is the geometrical reconstruction of the aquifers involved. An updated hydro-geological model of the whole study area is necessary. As there is no data on explorations at such depths, an updated hydrostratigraphic reconstruction has been developed of the only core drilling on which there is a lot of information: the Ve-1 drilled at 951 m in 1971. The reference hydrostratigraphic sequence required an analysis of the earliest scientific publications on Ve-1 on a sedimen-tological, palynological and magnetostratigraphic level. The data from the stratigraphies of some wells built through full drilling has been used in a new software package completed in this paper (modalstrata). Modalstrata allows the establishment of a mean stratigraphy from a series of reference verticals in a certain area. In the areas in which there is not much stratigraphic data, the geophysical method of passive seismic was used which allows the identification of lateral continuity in the main reflectors. This hydrostratigraphic model is confirmed by the comparison of a first hydrostratigraphic series developed for Ve-1. Therefore the updated hydrostratigraphic model of the study area allowed the definition of the geometries included in the analytical solutions in order to identify the leakage rates in the spe-cific instance a sufficient number of hydrogeological parameters are known. The GIS environment manages a great amount of data and information. The use of GIS means also allows the development of further geostatistical assessments.
Nell’area di studio (hinterland veneziano, Porto Marghera) si segnala la presenza di alcune centinaia di pozzi artesiani (80-350 m di profondità) realizzati nel periodo 1910-1970, successiva-mente dismessi. Tali pozzi rappresentano un possibile passaggio di risalita delle acque artesiane; processo, può innescarsi pertanto un di miscelazione tra le acque sotterranee del Sistema Acquifero Superficiale (0-80 m) con quelle contenute negli acquiferi artesiani profondi (Sistema Acquifero Artesiano, 80-350 m dal piano campagna) dove il potenziale piezometrico è in continua crescita da almeno 40 anni. In tal caso gli acquiferi prossimi al piano campagna (ca 0-30 m) potrebbero essere soggetti alla ricarica attraverso questi pozzi abbandonati. Tale effetto di ricarica va ad aggiungersi ad un sistema idrogeologico fortemente condizionato dalle attività antropiche, quali: il drenaggio prodotto dal sistema di bonifiche costituito da numerose idrovore che mantengono su vaste aree il livello freatico e piezometrico al di sotto del piano campagna; la conterminazione dell’intera area di Porto Marghera, sia in corrispondenza della gronda lagunare, sia nelle aree interne (retromargina-mento). Il marginamento si spinge fino a 15-20 m di profondità. Tale conterminazione prevede l’allontanamento delle acque sotterranee in surplus, che - attraversando terreni caratterizzati da un forte livello di contaminazione - devono necessariamente essere allontanate e trattate per un opportuno stoccaggio. La risalita spontanea di flussi di acque sotterranee attraverso pozzi abbandonati a causa di un incremento del potenziale piezometrico negli acquiferi profondi, dal punto di vista scientifico è un argomento poco investigato. I modelli analitici e numerici disponibili nella letteratura scientifica sono rivolti soprattutto alla definizione di un sistema composto da pozzi profondi dismessi, attraverso si possono avere flussi causati dall’iniezione di rifiuti fluidi o anidride carbonica attraverso da pozzi di re-immissione. L’applicazione di tali soluzioni richiede la conoscenza di una serie di parametri idrogeologici. Il più importante di questi è la ricostruzione geometrica degli acquiferi coinvolti. Un modello idrogeologico aggiornato dell’intera area di studio risulta essere necessario. Poiché mancano dati di indagini dirette alle profondità di interesse, è stata effettuata una aggiornata ricostruzione idrostrati-grafica dell’unico carotaggio continuo del quale si hanno numerose informazioni: il Ve-1 realizzato a 951 m nel 1971. La successione idrostratigrafica di riferimento ottenuta ha richiesto l’analisi delle più recenti pubblicazioni scientifiche relative al Ve-1 in ambito sedimentologico, palinologico, magnetostratigrafico. I dati provenienti dalle stratigrafie derivate da alcuni pozzi realizzati a distruzione di nucleo sono stati utilizzati all’interno di un nuovo pacchetto software, sviluppato all’interno del presente studio (modalstrata). Modalstrata consente di ottenere una stratigrafia media da una serie di verticali d’indagine in una determinata area. Nelle aree dove la distribuzione di dati stratigrafici è carente, è stato utilizzato il metodo geofisico della sismica passiva che ha consentito di individuare la conti-nuità laterale di alcuni riflettori principali. Il modello idrostratigrafico così ottenuto è stato validato attraverso il confronto con la successione idrostratigrafica precedentemente definita per il Ve-1. This hydrostratigraphic model is confirmed by the comparison of a first hydrostratigraphic series developed for Ve-1. Il modello idrostratigrafico aggiornato dell’area di studio ha così consentito la definizione delle geometrie da inserire all’interno delle soluzioni analitiche per la definizione delle portate di leakage ad un caso specifico, del quale si dispone di un sufficiente numero di parametri idrogeologici. Un ambiente GIS gestisce un elevato numero di dati ed informazioni. Il ricorso all’uso di applicativi GIS, permette anche lo sviluppo di ulteriori valutazioni geostatistiche e decisionali.

Styles APA, Harvard, Vancouver, ISO, etc.

40

O'Brien, Sean P. « Sedimentology of a Lower Middle Pleistocene Reservoir in Garden Banks Area, Northern Gulf of Mexico : Integration of 3D Seismic, Cores, and Well Logs ». ScholarWorks@UNO, 2010. http://scholarworks.uno.edu/td/1140.

Texte intégral

Résumé :

Garden Banks field 236, known as Pimento, is part of a lower middle Pleistocene submarine-fan deposit in the north central Gulf of Mexico. Pimento field represents a classic example of a prograding fan across the continental shelf continuing across the continental slope filling and spilling minibasins. Channel complexes cut through the field as sediment migrated across the shelf and slope to the basin floor. This thesis consists of two papers which utilized donated 3D seismic data on six of the blocks in Pimento field. Public domain data was incorporated with these data to explore the producing reservoir sand in the field. Mapped horizons revealed the overall structural elements of the field including the fill and spill facies of the minibasin that directly influences the deposition of the field. In these papers, channel complexes have been resolved using seismic geomorphological techniques and cross sections. Two potential drilling targets have also been discovered and one has been initially investigated as a drilling target.

Styles APA, Harvard, Vancouver, ISO, etc.

41

Kiuchi, Ryota. « New Ground Motion Prediction Equations for Saudi Arabia and their Application to Probabilistic Seismic Hazard Analysis ». Kyoto University, 2020. http://hdl.handle.net/2433/253095.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

42

Soundararajan, Sujitha. « Seismic Energy Dissipation, Self-Centering, and Settlement of Rocking Foundations : Analysis of Experimental Data with Comparisons to Numerical Modeling ». Thesis, North Dakota State University, 2019. https://hdl.handle.net/10365/31711.

Texte intégral

Résumé :

The major objective of this study is to correlate the rocking foundation performance parameters with their capacity parameters and earthquake demand parameters using the results obtained from 142 centrifuge and shaking table experiments. It is found that seismic energy dissipation and permanent settlement of rocking foundations correlate well with rocking coefficient and Arias intensity of the earthquake, whereas the maximum moment and peak rotation of the foundation correlate well with peak ground acceleration. A numerical model, using the contact interface model available in OpenSees, is developed to simulate the performance of rocking foundations, and it is validated using experimental results. Though the numerical model predicts the moment capacity, seismic energy dissipation, and tipping-over stability of rocking foundations reasonably well, the model appears to overpredict the settlement of foundations. Furthermore, a parametric study showed that settlement reduces as initial vertical stiffness increases and is directly proportional to peak ground displacement.

Styles APA, Harvard, Vancouver, ISO, etc.

43

Dyrnes, Haakon Hannasvik. « Quantative Analyzes of Seismic Inversion in Terms of Acquisition and Interpretation : Example From Southwest Haltenbanken Area in the Norwegian Continental Shelf ». Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for petroleumsteknologi og anvendt geofysikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18492.

Texte intégral

Résumé :

In regular marine acquisition configuration, shallow sources and shallow streamers are used. Because of this configuration the high-frequency content of the seismic is favored, which is needed for sufficient vertical resolution. If the receivers were deployed at a larger depth the low-frequency content would be favored. The low frequencies are needed for inversion, deep penetration and visualization. However, this configuration would attenuate the higher frequencies and would suffer from poor vertical resolution. The attenuation of either high or low frequencies is a result of the receiver ghost, which attenuates higher frequencies for the deep tow, and lower frequencies for the shallow tow. Over/under acquisition method allows the wavefield to be separated into upgoing and downgoing wavefields. The configuration consists of 2 receiver-cables in vertical alignment with each other. By detecting only the upgoing wavefield, we are removing the receiver ghost and hence the frequency bandwidth should be broadened. These cables are towed at 18 and 25 meters, respectively. Regular receiver-cables are normally towed at 7 to 9 meters. Because of the deeper tow, the noise levels should also be lowered and result in a better signal to noise ratio. Post-stack seismic inversion is the process where we analyze the stacked seismic traces and try to reconstruct the velocity structure, or the acoustic impedance, of the sub-surface covered by the seismic. Inversion is sensitive to various parameters and small improvements in the seismic would result in improvements in the inversion volume. In the inversion configuration of this thesis, we are using a background model based on a-priori information from one known well. The a-priori information is used as an initial guess for the inversion to follow. To keep the inversion volumes as data-driven as possible, the inversions were processed with a weight factor on the initial model as low as possible, to enhance the changes made by the differences in the seismic volumes. Quantification of the difference in the inversion volumes based on different acquisition methods for the input seismic resulted in various comparisons of the acoustic impedance volumes. Difference in vertical resolution has been investigated and identified to have a relative difference in favor of the single cable seismic. The differences were due to a change in the wavelet shape and width and also change in dominating frequency of the respective time interval. Comparing the inversion volumes, based on the acquisition method, to their respective average inversion volumes identified changes in the inversion volumes due to feathering of the receiver cables. Further tests illustrated that the feathering had a significant impact on the inversion volumes. Since the feathering causes the receiver cables to deviate from a straight line astern of the vessel, the seismic volume is slightly changed compared to a volume where there is no feathering. Experiments illustrated that the frequency spectra are different. However, the frequency spectrum is not broadened, but shifted and shortened prone to lower frequencies. Dominating frequency was hence lower for cable combination seismic volumes compared to single cable seismic volumes. This resulted also in difference in the seismic wavelet as previously explained. Results indicate a significant change in inversion volumes due to fold, acquisition direction and feathering. Changes caused by the cable combination method were not as first anticipated. Since the method is used with a deeper tow, we were anticipating a significant change in the signal to noise ratio, also considering that receiver ghost is removed when evaluating only the upgoing wave. Results indicate that there was no significant change in signal to noise ratio. However, significant changes in the ratio were found when using the split spread method versus the single direction method (both single cable and cable combination method). This work concludes that the largest impact on the inversion volume is found where we have identified poor alignment of feathering, different acquisition direction and increased fold. The cable combination method doesn’t have significant impact on the inversion volume. Identified changes are quantified in this work and will verify these results.

Styles APA, Harvard, Vancouver, ISO, etc.

44

Pagano, Francesco. « Smart Systems Based on Electroactive Polymers ». Doctoral thesis, Università di Catania, 2013. http://hdl.handle.net/10761/1307.

Texte intégral

Résumé :

The purpose of this thesis is the development and analysis of smart systems based on electroactive polymers (EAPs). Thanks to their sensing and actuation capabilities, devices based on EAPs, like ionic polymer metal composites (IPMCs), realized by using a noble metal or ionic polymer polymer composites (IP2Cs), where a conducting polymer replaces the metal, pave the road to the development of new integrated devices , being the conditioning circuitry very simple, that could be of high interest in fields such as engineering, biomechanics, aerospace, and robotics. Furthermore, in the near future the entire system, included the conditioning circuitry, could be realized by using plastic based electronics, opening new possibilities for a post-silicon era. Characteristics like the large deformations obtained under the ef-fect of a low level applied voltage signal, the capability to transform a mechanical stimulus into a detectable electrical signal and the vibra-tional characteristics of a cantilever beam, have contributed to selecting the IPMC as candidates for the research carried out. The idea that drove this thesis is to proof the possibility to use EAPs to realize a smart systems that can both perform measurements in harsh environments while being energetically self-sufficient. This has prompted the design, the realization and the test of sen-sors, such as a seismic sensor and a viscometer, and of a device able to harvest energy from ambient vibrations. This work has allowed to assert that, although the technology used is still room for improvement, this idea is feasible.

Styles APA, Harvard, Vancouver, ISO, etc.

45

Marino, Manuela Teresa Monia. « Il ruolo dell'attrito nella vulnerabilità sismica di edifici storici in muratura sollecitati fuori piano ». Doctoral thesis, Università di Catania, 2013. http://hdl.handle.net/10761/1413.

Texte intégral

Résumé :

Il presente lavoro vuole essere un contributo allo studio dei meccanismi di collasso di pannelli murari sollecitati fuori piano. In particolare si è voluto dare un contributo alla definizione di un metodo di analisi da applicare in maniera efficace su larga scala senza perdere di vista la possibilità di controllare direttamente il fenomeno. L'innovazione consiste nel miglioramento di una metodologia di analisi statica equivalente molto utilizzata, l'analisi limite, che applicata alle murature non consente tuttavia la valutazione della dissipazione energetica. Le analisi svolte hanno dimostrato che l'introduzione delle resistenze attritive, nell'equazione dei lavori virtuali, consente invece di valutare, in una certa misura, la dissipazione energetica che avviene durante il cinematismo e di descrivere in maniera più accurata un fenomeno, che nella realtà mostra una riserva di capacità a causa del suo comportamento dinamico (rocking). Il contributo del lavoro vuole essere inoltre quello di dare un metodo applicativo per la valutazione delle resistenze attritive relative ad alcune tipologie murarie tipiche siciliane. Per finire, l'intento è quello di mostrare una corrispondenza fra due approcci fino a poco tempo fa considerati distinti: quello basato sull'analisi qualitativa della tessitura muraria e quello della sperimentazione fisica diretta mediante prove meccaniche per valutare le resistenze ed i parametri meccanici in gioco. Si è mostrato come la correlazione fra il coefficiente di attrito sperimentale ed il giudizio relativo alla qualità della tessitura muraria sia in grado di prevedere con sufficiente precisione i risultati sperimentali su pannelli murari esistenti. Si prevede in futuro di svolgere ulteriori prove sperimentali per confermare i primi risultati ed estenderli ad altre tipologie murarie

Styles APA, Harvard, Vancouver, ISO, etc.

46

Stramondo, Paola Roberta. « Formulazione di un metodo di progetto per l'adeguamento sismico di telai in C.A. mediante controventi ad instabilità impedita ». Doctoral thesis, Università di Catania, 2016. http://hdl.handle.net/10761/4061.

Texte intégral

Résumé :

Molti degli edifici in c.a. esistenti sono stati progettati in passato per soli carichi verticali o per modeste azioni sismiche e necessitano di un intervento di adeguamento sismico per rispondere ai requisiti prestazionali previsti dalle normative attuali. Nella presente Tesi di Dottorato è proposto e validato un metodo basato sugli spostamenti per l adeguamento sismico di tali strutture mediante l impiego di controventi a instabilità impedita (BRBs, Buckling-Restrained Braces), la cui idea di base è stata recentemente presentata per il progetto di telai in acciaio con BRBs (Bosco e Marino, 2013; Bosco et al., 2014). I BRBs sono controventi dissipativi in acciaio che manifestano un ciclo isteretico stabile e un comportamento simile in trazione e in compressione, con una buona capacità di dissipazione energetica grazie agli alti valori di duttilità che possono raggiungere. La procedura di progetto proposta permette di definire, a ogni piano, la rigidezza e la resistenza dei BRBs, tramite la scelta di valori appropriati di area della sezione trasversale, lunghezza del segmento duttile e tensione di snervamento dell acciaio. Il metodo di progetto prevede l imposizione di due requisiti: il requisito sugli spostamenti di interpiano riduce la domanda sismica a valori compatibili con la capacità deformativa della struttura e permette di determinare a ciascun piano la rigidezza laterale aggiuntiva da fornire tramite i controventi; il controllo della duttilità massima subita dai BRBs durante il sisma consente di stabilire la tensione di snervamento e, quindi, la resistenza assiale necessaria per i controventi. Il metodo proposto è applicato a tre casi studio rappresentativi di edifici esistenti che necessitano di adeguamento sismico. L efficacia del metodo è evidenziata tramite analisi dinamiche non lineari condotte sulle strutture controventate al variare dei parametri di progetto.

Styles APA, Harvard, Vancouver, ISO, etc.

47

Torrisi, Antonio Maria. « Studi geologici di dettaglio per la definizione di modelli bidimensionali per la valutazione della risposta sismica locale in terreni vulcanici ». Doctoral thesis, Università di Catania, 2016. http://hdl.handle.net/10761/4075.

Texte intégral

Résumé :

Il progetto di ricerca, i cui contenuti riguardano il versante orientale dell'area vulcanica del Monte Etna, consiste principalmente in studi geologici di dettaglio per la definizione di modelli bidimensionali ai fini della valutazione della Risposta Sismica Locale (RSL). Inizialmente l attività di ricerca è stata incentrata sulla ricostruzione del modello geologico di questi territori, prestando particolare attenzione alla distinzione tra i terreni di copertura e quelli del bedrock. La Carta geologica del versante orientale dell Etna (scala 1:25.000) rappresenta il più importante risultato ottenuto al termine di questa fase della ricerca. Durante la realizzazione della carta, oltre le unità laviche, sono stati cartografati i depositi marini e continentali che caratterizzano la successione vulcanostratigrafica. I dati raccolti, unitamente alle indagini di sottosuolo e alle datazioni disponibili in letteratura, hanno portato all individuazione di diversi orizzonti epiclastici. Tali depositi sono caratterizzati da una buona continuità laterale che ne consente l uso come livelli guida nella correlazione di successioni stratigrafiche affioranti in settori diversi del vulcano. Applicando questa metodologia, le diverse unità laviche sono state definite in base alla loro posizione rispetto agli orizzonti epiclastici di riferimento. La Carta geologica, corredata di dettagliate sezioni geologiche, mette in evidenza la complessità della geometria del sottosuolo etneo, dominato da una notevole variabilità sia laterale che verticale delle diverse litologie, anche a brevissima distanza. Nella seconda fase della ricerca, dopo aver individuato alcuni siti campione da utilizzare come modelli per la comprensione dei fattori che influenzano la RSL nell'area vulcanica etnea, si è proceduto all analisi numerica della risposta in superficie attraverso il codice di calcolo STRATA. I risultati delle simulazioni consentono di affermare che l'amplificazione sismica in questi terreni, indipendentemente dalla profondità cui viene posto il bedrock, è principalmente governata dal contrasto d'impedenza dovuto agli strati di copertura più superficiali, con velocità delle onde di taglio Vs più basse. Le misure di noise confermano tale ipotesi considerato che non sono stati rilevati picchi di amplificazione a bassa frequenza attribuibili a contrasti d'impedenza profondi.

Styles APA, Harvard, Vancouver, ISO, etc.

48

Karadeniz, Deniz. « Pilot program to assess seismic hazards of the Granite City, Monks Mound, and Columbia Bottom quadrangles, St. Louis Metropolitan area, Missouri and Illinois ». Diss., Rolla, Mo. : University of Missouri-Rolla, 2007. http://scholarsmine.mst.edu/thesis/pdf/Karadeniz_09007dcc8042c729.pdf.

Texte intégral

Résumé :

Thesis (Ph. D.)--University of Missouri--Rolla, 2007.
Vita. The entire thesis text is included in file. Accompanying "this dissertation is a CD-ROM, which contains site amplification and seismic hazard results for each grid point (1974 points) considered in the study. The results have prepared as .txt files. The CD-ROM also contains the maps generated from these estimated results. The maps are prepared as .png files." Title from title screen of thesis/dissertation PDF file (viewed January 28, 2008) Includes bibliographical references (p. 249-269).

Styles APA, Harvard, Vancouver, ISO, etc.

49

Rigano, Laura. « Analisi prestazionale del comportamento sismico di opere di sostegno in terra rinforzata ». Doctoral thesis, Università di Catania, 2012. http://hdl.handle.net/10761/1161.

Texte intégral

Résumé :

Lo scopo della ricerca condotta è stato quello di estendere al caso delle opere di sostegno in terra rinforzata, il metodo pseudo-statico equivalente. L analisi individua un coefficiente sismico equivalente keq che, se utilizzato nell analisi pseudo-statica, conduce ad un valore del fattore di sicurezza congruente con quello che si otterrebbe dall analisi agli spostamenti. In particolare si può determinare un valore di keq per cui i margini di sicurezza in termini di forze Fpsd e di spostamenti Fk sono coincidenti e l analisi pseudo-statica risulta congruente con quella prestazionale. Fra i meccanismi di collasso dei muri in terra rinforzata ne sono stati individuati alcuni analizzati, poi, con il metodo dell equilibrio limite o con l analisi limite. Per ciascuno di questi meccanismi è stata trovata l espressione del coefficiente critico kh,crit e del coefficiente sismico equivalente keq. Si è inoltre valutato il coefficiente di forma Cw, che entra in gioco nella stima degli spostamenti permanenti con il metodo di integrazione proposto da Newmark (1965). Per determinare gli spostamenti infatti, dopo aver valutato il coefficiente sismico critico kh,cr si procede alla doppia integrazione dell equazione del moto. Questa differisce in base al meccanismo di collasso esaminato, rispetto alla classica equazione del blocco che scorre su un piano orizzontale, differisce per un coefficiente di forma. Nel caso dei pendii tale coefficiente oscilla intorno all unità mentre per i muri di sostegno rigidi è spesso superiore all unità. Una delle applicazioni principali del metodo pseudo-statico equivalente è la valutazione del coefficiente di riduzione bm, che moltiplicato per il coefficiente sismico orizzontale kh fornisce il valore del coefficiente sismico da utilizzare nelle analisi pseudo-statiche. L importanza di questa valutazione nasce dalla considerazione che le Norme Tecniche per le Costruzioni (2008) forniscono dei valori di bm valutati per i muri di sostegno rigidi, per cui è possibile comprendere se tali valori sono effettivamente validi anche per i muri in terra rinforzata.

Styles APA, Harvard, Vancouver, ISO, etc.

50

Distefano, Salvatore. « Stratigraphic, structural and geomorphological features of the Sicilian continental shelf : study cases from Southern Tyrrhenian and Sicily Channel ». Doctoral thesis, Università di Catania, 2017. http://hdl.handle.net/10761/3854.

Texte intégral

Résumé :

The Pelagian Archipelago is located in a complex and wide geodynamic system characterized by the occurrence of two independent tectonic processes acting simultaneously: convergence along the Apennine-Maghrebian accretionary wedge and late Miocene-early Pliocene rifting in the Sicily Channel. Through high resolution seismic profiles acquired around the Lampedusa Island offshore, the reconstruction of an updated structural setting of this area and its regional correlation has been performed. The late Miocene-early Pliocene rifting affects directly the structural evolution of the Lampedusa plateau, with the development of a graben and half-graben setting in most of the offshore area, widely filled with the syn-rift deposits. In the northern sector, the activity of the normal faults associated with the rifting is active up to the early Pliocene, whereas it is quiescent since late Miocene in southern sector. This current fabric of the Lampedusa plateau derives by its involvement in regional extensional regime, lying in a dextral-transtensive zone and marked by pull-apart basins. In particular, two systems of the normal faults in the Lampedusa offshore have been recognized. The Master Extensional Faults oriented WNW-ESE represent the main structural alignment of the Lampedusa offshore and reflect the extensional trending of the Sicily Channel. The Second order of Extensional Faults, oriented NNW-SSE, bounds smaller pull-apart basins and are probably associated with the main dextral-transtensive regional regime. From the comparison with some preexisting models, an update stratigraphic-structural model is proposed also to the southeastern continental shelf between the Gela-Catania foredeep and the Hyblean foreland offshore, along the Marina di Ragusa offshore. The seismo-stratigraphic interpretation shows a NE-SW extensional faults system that involves only the late Miocene formations, probably connected to history of the Scicli Line. Furthermore, the late Miocene extensional tectonic activity involves widely affects the offshore portions of the Hyblean foreland and its ramp, but it does not show evidences that this activity has involved the Plio-Pleistocene succession. The deposition of the Gessoso-Solfifera Formation has been widely recognized in the Hyblean foreland ramp, demonstrating that the evaporitic deposition does not is a peculiarity only of the deposits within the semi-isolated and marginal sub-basins or of the thrust top mini-basins of the Appennine-Maghrebides belt, but extends also in areas where the extensional tectonic have been dominant. Through Multibeam bathymetric data, an update characterization of the geomorphological setting of the north-east Sicily continental shelf, between Milazzo Promontory and the area offshore from the Saponara River, is provided. Furthermore, through high-resolution CHIRP seismic profiles interpretation, a reconstruction of the evolution of the last eustatic sea level cycle is performed. The lowstand succession, corresponding with the foreset of the prograding clinoforms of the continental margin deposits, determines the accommodation space for the depositional processes that occur during the rise of the sea level. In fact, the evolution of the transgressive and highstand wedges is strongly influenced by the geometry of the underlying lowstand succession. The transgressive wedge is developed in the 80-100 m bathymetric range and consists of the relict geomorphic elements that represent past landscape. These elements tracked the variations in coastline position during the last sea-level rise, formed during an interval of relatively reduced rate of sealevel rise. Furthermore, a reconstruction of the geomorphological evolution of the past coastal systems during the last transgressive stage is provided. The highstand wedge consists of the Corriolo, Muto, Niceto, Cocuzzaro and Rometta delta deposits that widely develop on the offshore portions of the inner continental shelf.

Styles APA, Harvard, Vancouver, ISO, etc.

Thèses sur le sujet « Seismic area »

Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres