Study area, the UruS province, is located 70 km WNW of city of Ankara. Major settlements in the study area are two counties, UruS and G&uuml / d&uuml / l / and there are a number of villages, such as, from W to E, Macun, Yogunpelit, Kabaca, &Uuml / regil, &Ouml / zk&ouml / y, Tahtaci&ouml / rencik, Kirkkavak, Kavak&ouml / z&uuml / , Kayi and Karaca&ouml / ren. The study area is 189 km2 in size and included in 1/25000-scaled topographic quadrangles of H28a3, a4, d1 and d2. The G&uuml / d&uuml / l- UruS section of the &Ccedil / eltik&ccedil / i morphotectonic depression (&Ccedil / eltik&ccedil / i Basin) drained by the Antecedent Kirmir River and its second-order drainage system was first mapped in detail in the present study, and faults determining northern margin of the &Ccedil / eltik&ccedil / i depression were named as the UruS fault set comprising the SW part of the &Ccedil / eltik&ccedil / i Fault Zone / and the mechanism of the master fault of the UruS fault set was determined as left lateral oblique-slip fault with reverse component by the morphologic markers such as the deformed drainage system and pressure ridges. This was also supported by the fault plane solutions of the 2000.08.22 UruS earthquake. Three fault plane solutions, of which two of them for the 2000.08.22 UruS earthquake, and one of them for the 2003.02.27 &Ccedil / amlidere earthquake, were done to determine nature of the source. Ground material underlying the city of Ankara were divided into three categories: (a) well-lithified basement rocks, (b) Pliocene fluvio-lacustrine v sedimentary sequence, and (c) unconsolidated terrace and alluvial sediments of Quaternary age. Quaternary unconsolidated sediments are densely populated in Ankara. These sediments are fine-grained and have a maximum thickness of 200 m or more. Inside these sediments, static ground water level is very close (as on average: 6 m) to ground surface. These conditions are quite suitable for liquefaction of these unconsolidated alluvial sediments. In addition, basement rocks are full of zone of weakness. Even if, the city of Ankara is characterized by the shallow focus and small earthquakes (M&amp / #8804 / 5), it is open to the risk of large earthquakes to be sourced from the North Anatolian Fault System and the Seyfe Fault Zone located 110 km and 80 km, respectively, owing the ground material conditions beneath the city of Ankara. This point has to be taken out in constructions and site selection solution.

Seafloor hydrothermal systems play a key role in Earth s energy and geochemical budgets. They also support the existence and development of complex chemosynthetic biological ecosystems that use the mineral-laden fluids as a source of energy and nutrients. This dissertation focuses on two inter-related topics: (1) the heat output at mid-ocean ridge (MOR) hydrothermal sites, and (2) the hydrothermal response to earthquakes at mid-ocean ridges. The response of mid-ocean ridge hydrothermal systems to seismic and magmatic activity could provide a means of using seafloor observations to assess processes occurring at crustal depths. Three decades of study of the ocean floor have made clear that tectonic/volcanic perturbations and changes in the hydrothermal activity are correlated. Yet, this relationship is still highly misunderstood. In this dissertation, we developed a mathematical model of hydrothermal circulation affected by magmatic and/or tectonic events occurring at depth. We showed that the perturbations they generate need not propagate through the entire upflow zone, as previously suggested, but need only affect the movement of the boundary layers. In this case, the fluid residence time in the discharge zone is on the order of years. The determination of heat output at MOR hydrothermal sites provides important constraints on the physics of these processes. Yet, such measurements are still very limited, available only for ~30 sites out of the ~10^3 estimated worldwide. This dissertation reports the first measurements of hydrothermal heat output at 9°50' N on the East Pacific Rise (EPR), which has been the most intensively studied site for the past 20 years (~10^2 expeditions). The values we obtained helped constraining the afore-mentioned mathematical model, which was tested based on the March 1995 microearthquake swarm near 9°50' N, EPR. Our results showed that the current interpretation based on a thermal cracking episode at the bottom of the upflow zone, may be incorrect. We argue that a diking scenario better explains the seismic and temperature data, while being consistent with the mechanics of inflation of the axial magma chamber in the 9°50' N, EPR area between two major eruptions, in 1991 and 2006.

Κατά την διάρκεια της ύστερης αρχαιότητας στην Β. Πελοπόννησο, ισχυροί σεισμοί έχουν πλήξει κατοικημένες περιοχές, προκαλώντας μεγάλες καταστροφές. Στην παρούσα εργασία εξετάζονται δημοσιευμένες συστηματικές ή/και σωστικές ανασκαφές, που οι ενδείξεις των ευρημάτων τους οδηγούν στο ότι συγκεκριμένες περιοχές έχουν πληγεί από σεισμούς. Πιο συγκεκριμένα, μελετήθηκαν 12 αρχαιολογικές θέσεις στην περιοχή της Β. Πελοποννήσου τη χρονική περίοδο από τον 1ο αιώνα μ.Χ έως και τον 6ο αιώνα μ.Χ. Με την παρούσα εργασία έγινε δυνατός με μεγαλύτερη ακρίβεια ο χρονικός προσδιορισμός της εκδήλωσης των σεισμικών γεγονότων σε σύγκριση με τις υπάρχουσες καταγραφές σε καταλόγους ιστορικών σεισμών ή προστέθηκαν επιπλέον σεισμικά γεγονότα ή αφαιρέθηκαν σεισμοί ανάλογα με το αν έχουν ή δεν έχουν αναγνωρισθεί στις αρχαιολογικές ανασκαφές, Συσχετίσθηκαν ρήγματα με ισχυρούς σεισμούς του παρελθόντος με βάση την γειτνίαση ή την διασπορά των καταστροφών σε αρχαιολογικές ανασκαφικές μαρτυρίες. Τέλος σύμφωνα με τα συμπεράσματα της παρούσας μελέτης, ισχυροί σεισμοί επηρέασαν την περιοχή της Β. Πελοποννήσου σε αρχαιολογικές θέσεις στον δυτικό και ανατολικό Κορινθιακό προσθέτοντας νέα στοιχειά στην χρονολόγηση και στην ένταση τους. Με βάση τα στοιχεία αυτά καταδεικνύεται ότι ο Ανατολικός Κορινθιακός παρουσιάζει συχνότερη σεισμική δραστηριότητα έναντι της δυτικής απόληξής του. / During the late antiquity in northern Peloponnesus, strong earthquakes have hit residential areas, causing considerable damage/major disasters. In the present study published systematic and / or rescue excavations are examined, whose finding evidence lead to the fact that specific regions are affected by earthquakes. More specifically, 12 archaeological sites in Northern Peloponnese have been studied from the period from the 1st century AD to the 6th century AD. In the present research the time of the occurrence of seismic activity was detected with greater precision in comparison with the existing records in the lists of historical earthquakes. Moreover, seismic activities were added or earthquakes were removed, depending on whether or not they have been identified in archeological excavations. Cracks have been associated with strong earthquakes of the past based on the vicinity or outspread of disasters in archaeological excavation evidence. Finally, according to the conclusions of this study, strong earthquakes have affected the area of North Peloponnesus, at archaeological sites in western and eastern Corinthian Gulf, adding new elements to their dating and their intensity. Based on these data it is demonstrated that the East Corinthian Gulf has more frequent seismic activity than its western part.

Les effets de site peuvent augmenter fortement la durée et l’amplitude des sollicitations sismiques imposées aux structures. Les effets de site 2D-3D induisent des amplifications sur une large bande de fréquence qui ne peuvent pas être simulées numériquement jusqu’à haute fréquence (>2-4 Hz) du fait de la limite de résolution des connaissances géologiques, géophysiques et/ou géotechniques du sous-sol. Les évaluations empiriques des effets de site sont donc indispensables pour pouvoir observer ce phénomène complexe de façon fiable jusqu’à haute fréquence. De telles évaluations nécessitent l'enregistrement de bonne qualité de nombreux séismes ce qui rend leur obtention rapide difficile dans les régions faiblement actives.Ce travail présente une analyse comparative de ces évaluations empiriques sur deux sites très différents, l’un en contexte sismique modéré (Provence, France) et l’autre en contexte très actif (Céphalonie, Grèce). Sur le site provençal, 500 séismes ont pu être enregistrés en l’espace de 2½ ans grâce à l’utilisation de vélocimètres. Une mesure du paramètre d’atténuation de site k_0 a ainsi pu être réalisée via l’analyse des spectres en accélération (k_(0_AS)) et en déplacement (k_(0_DS)). La mesure de k_0 n’est relativement fiable que sur les sites au rocher du fait des amplifications de site au sédiment. La méthode des rapports spectraux sismique (SSR) permet l’évaluation des effets de site relatif à partir des nombreux enregistrements de mouvement faible. Les résultats montrent une forte variabilité épistémique attribuable à l’éclairage induit par la position de la source sismique vis-à-vis du bassin. Ainsi, une estimation fiable de la réponse des sites est possible à partir de quelques évènements seulement dans le cas 1D, mais nécessite un nombre beaucoup plus important de séismes répartis de façon homogène autour du site dans les cas 2D-3D. Les résultats SSR moyens sont ensuite comparés à ceux issus des méthodes utilisant le bruit ambiant. Conformément aux attentes, la méthode des rapports spectraux H/V (HVSR) ne permet que de caractériser la fréquence fondamentale pour certains sites. À l’inverse, la méthode SSR appliquée au bruit ambiant (SSRn) montre des résultats très comparables à ceux de la méthode SSR jusqu’à haute fréquence à la condition que le site de référence soit pris dans le bassin sédimentaire. Les approches par corrélation de bruit (cohérence et ANIRF) révèlent qu’une estimation de la fonction de transfert relative à un site de référence au rocher est possible au moins jusqu’à basse fréquence (<4 Hz). L’utilisation du bruit ambiant permet ainsi d’envisager l’évaluation rapide de la réponse des sites et de sa variabilité spatiale (microzonage), même lorsque la sismicité est faible. Partout, les méthodes empiriques d’évaluation des effets de site apportent un complément essentiel aux approches numériques qui reste indispensables.Ces résultats permettent de proposer une méthodologie d’évaluation de l’aléa sismique site-spécifique qui se décompose en trois étapes principales : (i) ajustement des équations de prédictions de mouvement du sol (GMPEs) sur le site de référence au rocher au moyen, entre autres, de k_(0_DS) ; (ii) évaluation empirique fiable de la réponse d’au moins un site dans le bassin relativement au site de référence (pour lequel les GMPEs ont été ajustées) par la méthode SSR; (iii) réalisation de cette évaluation à partir de l’ANIRF dans les régions les moins actives sismiquement et/ou extension à toute la zone d’étude à partir du SSRn. Cette méthodologie permet d’envisager une bien meilleure prise en compte des effets de site (en particulier 2D-3D) et une réduction importante des incertitudes dans les évaluations de l’aléa sismique spécifique à un site. Elle nécessite simplement l’enregistrement simultané de séismes sur au moins deux sites équipé de vélocimètres sensibles, et la réalisation de campagnes de mesure temporaire du bruit ambiant, si nécessaire. / Site effects can greatly increase both the duration and the amplitude of the seismic solicitation imposed on structures. 2D-3D site effects induce broadband amplifications that cannot be simulated up to high frequency (>2-4 Hz) due to the limited resolution of the geological, geophysical and/or geotechnical information. Empirical site effect assessment is therefore essential for reliable observations of this complex phenomenon up to high frequency. However, such assessments often require good quality records from many earthquakes that cannot be rapidly obtained in low seismicity areas.This work presents a comparative analysis of these empirical evaluations on two very different sites, the first in a moderate seismicity context (Provence, France) and the second in a very active context (Kefalonia, Greece). For the Provençal site, nearly 500 earthquakes were recorded in only 2½ years thanks to the use of velocimeters. The site attenuation parameter κ_0 could thus be measured both on the acceleration (κ_(0_AS)) and displacement (κ_(0_DS)) spectra. Our results show that the measurement of κ_0 is relatively reliable on rock sites only, mainly due to the too great disturbance by the amplification for sedimentary sites, even for those that are quite stiff. The standard spectral ratio (SSR) approach provides the relative site effects from the numerous weak motion recordings available at sites located in Provence and Kefalonia. The results show a strong epistemic variability due to the lighting induced by the position of the seismic source with respect to the basin. Thus, while a reliable site response estimation is possible from only a few events for 1D geometries, it requires much more earthquakes evenly distributed around the site when the geometry is 2D-3D. The mean SSR results are then compared with those obtained from methods using the ambient noise. As expected, the H/V spectral ratio approach (HVSR) provides only the fundamental frequency for some sites. Conversely, SSR applied to ambient noise (SSRn) shows very similar results to the SSR method up to high frequency, provided that the reference site is taken in the sedimentary basin. Approaches using the noise correlation (coherence and ANIRF) reveal that the transfer function relative to a rock reference site can be estimated at least up to low frequency (<4 Hz). Methods using ambient noise are promising for a rapid evaluation of the site response and its spatial variability (microzoning), even when seismicity is low. Empirical site effects methods are therefore applicable everywhere. They provide an essential complement to numerical approaches, which remain inevitable when the coverage of available earthquakes is not homogeneous or when soils are likely to present non-linear behaviors.These results led us to propose a methodology for the evaluation of the site-specific seismic hazard, which consists of three main stages: (i) adjustment to the rock reference site of the ground motion prediction equations (GMPEs) using, among others, κ_(0_DS); (ii) Reliable evaluation of the SSR transfer function between at least one site in the basin and the reference site (for which the GMPEs were adjusted); (iii) carrying out this assessment from the ANIRF in the less seismically active regions and/or extension to the entire study area with the SSRn. This methodology allows a much better consideration of the site effects (especially 2D-3D) and a significant reduction of the uncertainties in the evaluations of the site-specific seismic hazard. It only required, simultaneous recording of earthquakes on at least two sites equipped with sensible velocimeters, and to carrying out temporary campaign of ambient noise measurements, if necessary.

Three-fifths of the Earth’s crust has been built at oceanic spreading centres in the last 160 million years. To explore crustal extension processes and the architecture of these constructive plate boundaries I have studied the oceanic rift in Iceland. Here the Mid Atlantic Ridge is anomalously elevated above sea level and thus easier to instrument. I have deployed and operated a dense network of seismometers in the remote volcanic highlands in central Iceland, and used the passive seismic data collected from this network to explore crustal structure and volcanic processes in the extensional rift zones. My analysis of persistent seismicity located in an intervening region between individual spreading segments, uniquely records the segmentation of plate spreading on the scale of individual volcanic systems. Precise location and characterisation of micro-earthquakes identifies a series of faults subparallel to the rift fabric, and source mechanisms define left-lateral strike-slip motion on these faults. This extremely high quality microseismic data reveals transform motion being accommodated by bookshelf faulting in a concentrated region between two such volcanic systems, providing evidence for the localisation of spreading in the discrete volcanic systems. While transform motion between spreading centres appears to be accommodated on a continuous basis, the extension of the brittle upper crust within the spreading centres occurs episodically during rifting events. Our local seismic network fortuitously recorded such a rifting episode in August 2014, during which the opening of a 5 metre wide dyke triggered a huge increase in seismicity across large areas of the rift zone. Stress-seismicity-rate modelling of this triggered seismicity, along with geodetic constraints on the deformation, provided a remarkable opportunity with which it was possible to prove the existence of stress-shadowing, a challenge which has eluded earthquake seismologists for decades. Using the excellent coverage of our extended seismic network I have also generated a new high resolution image of the regional crustal seismic structure using surface waves extracted from ambient seismic noise. The structure reveals low seismic velocities which are closely correlated with the volcanic rift zones, and faster wavespeeds in the older and non-volcanically active Tertiary crust. The strongest anomalies are seen in the north-west of the Vatnajökull icecap, at the location of thickest crust and inferred centre of the underlying mantle plume. Inversion for shear wave velocity structure shows high velocity-gradients in the top 10 km, defining a thickened extrusive upper crust in Iceland compared to standard oceanic crust, where it is normally 2–3 km thick. Below this, the shear wave velocity structure reveals a distinct low-velocity zone in the mid crust between 14–20 km depth, which is widespread across Iceland and shallows into the active volcanic rifts. This extensive feature suggests high mid-crustal temperatures and a high temperature-gradient between the extrusives of the upper crust and the intrusive mid-to-lower crust in Iceland.

Made available in DSpace on 2015-02-24T19:48:44Z (GMT). No. of bitstreams: 1 HelenoCLN_TESE.pdf: 5085114 bytes, checksum: 8f73b093043e3323a8310182a887e244 (MD5) Previous issue date: 2013-08-16 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This thesis presents and discusses the results of the various seismic areas in the State of Pernambuco, with the aim of having a vision of regional seismicity and its causes. To the papers published in journals were added two new original works submitted to international journals, dealing with seismic areas located in the counties of S?o Caetano, Cupira, and Agrestina. All seismic areas mentioned in this thesis are located on the Pernambuco Lineament and its surroundings (both in branches or single faults within 40 km of it). The Pernambuco Lineament is a Neoproterozoic shear zone of continental-scale that deformed the Borborema Province, and presents as branches, shear zones with NE-SW direction. The new submitted papers are from the analysis of data collected by three local networks of stations that operated in the following areas: network SO07 (seismicity in the district of Santa Luzia - S?o Caetano, 2007), network BM10 (data from seismic areas of Serra Verde ( Cupira) and Barra do Chata (Agrestina), in 2010), network SO10 (seismicity near the urban center of S?o Caetano in 2010). These data were used for determining the hypocenters and focal mechanisms in order to discuss the relationship between the seismicity and geological features of the area. The new mechanisms obtained, as well as the previously published allowed the determination of the direction of the average stress in the region. The direction of stress in the region involving the various seismic areas, now or previously studied, is quite stable and approximate EW direction (SHmax). The correlation between seismicity and geological features is observed on the lineament and north of it. In the south (Cupira and Agrestina), in seismic areas nearby shear zones NE-SW, there is no correlation and seismogenic EW normal faults are active and its motion is compatible with regional stresses. It is probable that these active faults are more recent than the Neoproterozoic, probably of the Cretaceous period, when the last great movement of the Pernambuco Lineament occurred / Nesta tese s?o apresentados e discutidos os resultados do estudo de diversas ?reas s?smicas no Estado de Pernambuco com o objetivo de se ter uma vis?o regional da sismicidade e suas causas. Aos trabalhos j? publicados em revistas foram acrescentados dois novos trabalhos originais, submetidos a peri?dicos internacionais, abordando as ?reas s?smicas localizadas nos munic?pios de S?o Caetano, Cupira e Agrestina. Todas as ?reas s?smicas abordadas nesta tese est?o situadas sobre o Lineamento Pernambuco ou seu entorno (seja em ramifica??es ou falhas isoladas a menos de 40 km do mesmo). O Lineamento Pernambuco ? uma zona de cisalhamento Neoproteroz?ica de escala continental que deformou a Prov?ncia Borborema e que apresenta, como ramifica??es, zonas de cisalhamento com dire??o NE-SW. Os novos trabalhos submetidos s?o decorrentes da an?lise de dados coletados por tr?s redes de esta??es que operaram nas seguintes ?reas: rede SO07 (sismicidade no distrito de Santa Luzia - S?o Caetano, em 2007); rede BM10 (dados das ?reas s?smicas de Serra Verde (Cupira) e Barra do Chata (Agrestina), em 2010); rede SO10 (sismicidade pr?xima ao centro urbano de S?o Caetano, em 2010). Esses dados foram utilizados na determina??o dos hipocentros e mecanismos focais visando discutir a correla??o entre a sismicidade e as principais fei??es geol?gicas da regi?o. Os novos mecanismos obtidos, bem como os anteriormente publicados permitiram a determina??o da dire??o do esfor?o m?dio na regi?o. A dire??o dos esfor?os na regi?o envolvendo as diversas ?reas s?smicas, agora ou anteriormente estudadas, ? bastante est?vel e de dire??o aproximada EW (SHmax). A correla??o entre a sismicidade e fei??es geol?gicas ? observada sobre o lineamento e ao norte do mesmo. Ao sul (Cupira e Agrestina), em ?reas s?smicas pr?ximas a zonas de cisalhamento NE-SW, n?o h? correla??o e falhas sismog?nicas normais de dire??o EW est?o ativas e seu movimento ? compat?vel com os esfor?os regionais. ? prov?vel que essas falhas ativas sejam mais recentes que o Neoproteroz?ico, provavelmente do per?odo Cret?ceo, ?poca do ?ltimo grande movimento do Lineamento Pernambuco

Made available in DSpace on 2015-03-13T17:08:18Z (GMT). No. of bitstreams: 1 HelenoCLN.pdf: 2214181 bytes, checksum: 4b9d5dbc7db9006737b75bcf1a77385e (MD5) Previous issue date: 2009-03-06 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / In this dissertation we studied the seismic activity in the S?o Caetano county, Pernambuco State, Northeastern Brazil, located near the Pernambuco Lineament. The Pernambuco Lineament is a one of Neoproterozoic continental-scale shear zones that deforms the Borborema province. The seismicity estudied occurred in a NE trending branch of Pernambuco Lineament. The seismic activity in S?o Caetano started in 2006 and in May 20th, 2006 a 4,0 mb earthquake hit there. This was the largest earthquake ever reported in Pernambuco State. This dissertation is the result of a campaign done in the period from Februay 1th 2007 to July 31 th 2007. In this campaign up to nine three-component digital seismographic stations were deployed and the collected data was used to determine hypocenters and focal mechanism. A total of 214 earthquakes, recorded at least by three stations, were analyzed. To determine hypocenters and time origin the HYPO71 program was used assuming a half-space model with parameters : VP (P-wave velocity) equal to 5.90 km/s and the ratio VP/VS 1.70, where VS is the S-wave velocity. The earthquakes hypocentral distribution was approximately 4 km long and agrees with the NE-SW direction of the Pernambuco Lineamento branch. Hypocentres depth range from 2 to 8 km. The composed focal mechanism was made from a group of 14 selected earthquakes. We try firstly to find the fault plane solution matching the polarity distribution at stations, using the FPFIT program. The result was 43 deg ? 15 deg for strike, 59 deg ? 9 deg for dip and -142 deg ? 15 deg for rake. We also fitted a plane using the hypocentral distribution to obtain the dip and azimuth of the hypocentral distribution. The results obtained by this fit were 58 deg for the azimuth, 55 deg for the dip and -155 deg for rake. This result shows a mechanism of a strike-slip dextral fault with a normal component. This dissertation shows, once more, that there is a good correlation between the seismic activity and geological features in the region near the Pernambuco Lineament and its NE branches / Nesta disserta??o foi estudada a atividade s?smica no munic?pio de S?o Caetano, estado de Pernambuco, Nordeste brasileiro, localizado pr?ximo ao Lineamento Pernambuco. O Lineamento Pernambuco ? uma zona de cisalhamento Neoproteroz?ica de escala continental que deforma a prov?ncia Borborema. A sismicidade estudada ocorreu numa ramifica??o para nordeste do Lineamento Pernambuco. A atividade s?smica em S?o Caetano iniciou em 2006 e no dia 20/05/2007 ocorreu, neste munic?pio, um sismo de magnitude 4,0 mb. Este ? o sismo de maior magnitude que ocorreu no estado de Pernambuco. Este trabalho ? decorrente da an?lise de dados coletados durante o per?odo de monitoramento na regi?o que foi de 01/02/2007 at? 21/07/2007. Nesse monitoramento foi utilizado de seis at? nove esta??es sismogr?ficas digitais. Os dados coletados por essas esta??es foram analisados, objetivando a determina??o dos hipocentros e do mecanismo focal composto. Foram utilizados 214 sismos, registrados em pelo menos tr?s esta??es. Na determina??o hipocentral, foi utilizado o programa HYPO71, assumindo-se um modelo de semi-espa?o, com os par?metros: velocidade da onda P (VP) e raz?o VP/VS, respectivamente, 5,90 km/s e 1,70. Os hipocentros dos sismos ocorridos na regi?o deste estudo acompanham uma ramifica??o para nordeste do Lineamento Pernambuco e possui aproximadamente 4km de extens?o e profundidade variando entre 2 at? 8 km. O mecanismo focal composto foi feito para um conjunto de 14 sismos selecionados. N?s primeiramente tentamos encontrar a solu??o do plano de falha considerando apenas a distribui??o de polaridades utilizando o programa FPFIT. Os resultados foram: 43? ? 15? para o azimute, 59? ? 9? para o mergulho e -142? ? 15? para o rake. N?s tamb?m ajustamos o plano usando a distribui??o hipocentral. Os resultados obtidos foram: 58? para o azimute, 55? para o mergulho, O valor do rake foi fixado em -155?. Este resultado mostra um mecanismo de uma falha transcorrente dextral com uma componente normal. Esta disserta??o mostra, mais uma vez, que existe uma boa correla??o entre a sismicidade e falhas mapeadas na regi?o pr?xima ao Lineamento Pernambuco e suas ramifica??es para nordeste

Made available in DSpace on 2015-03-13T17:08:21Z (GMT). No. of bitstreams: 1 GeorgeSLAF.pdf: 2410781 bytes, checksum: 6ab634dc538d6826e3c66393e3ca3803 (MD5) Previous issue date: 1999-07-12 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The Tucunduba Dam, is west of Fortaleza, Cear? State. The seismic monitoring of the area, with an analogical station and seven digital stations, had beginning on June 11, 1997. The digital stations, operated from June to November 1997. The data collected in the period of digital monitoring was analyzed for determination of hypocenters, focal mechanisms, and shear-wave anisotropy analysis. For determination of hypocenters, it was possible to find an active zone of nearly 1 km in length, with depth between 4.5 and 5.2 km. A 60&#61616;AZ/88&#61616;SE fault plane was determined using the least-squares method and hypocenters of a selected set of 16 earthquakes recorded. Focal mechanisms were determined, in the composite fault plane solution, a strike-slip fault, trending nearly E-W, was found. Single fault plane solutions were obteined to some earthquakes presented mean values of 65&#61616; (azimuth), and 80&#61616; (dip). Shear-wave anisotropy was found in the data. Polarization directions and travel time delays, between S spliting waves, were determined. It was not possible to obtain any conclusion on the cause of the observed anisotropy. It is not clear if there is correlation between seismicity and mapped faults in the area, although the directions obtained starting from the hipocentros and focal mechanism are they are consistent with directions, observed in the area, photo, topographic and fractures directions observed in the area / o A?ude Tucunduba est? localizado no munic?pio de Senador S?, a aproximadamente 290 km a oeste de Fortaleza - CE. O monitorarnento s?smico da regi?o, por meio de urna rede sismogr?fica local, teve in?cio em 11 de junho de 1997, logo ap?s a ocorr?ncia de um evento com magnitude 3,2 mb, no dia 09 de junho de 1997. O monitorarnento foi realizado com uma esta??o anal?gica (utilizada na determina??o da magnitude com a dura??o e na contagem do n?mero de eventos por dia), e sete esta??es digitais. As esta??es digitais, com tr?s componentes cada, operaram no per?odo de junho a novembro de 1997. Neste trabalho foram analisados os dados coletados pelas esta??es digitais objetivando a determina??o de hipocentros, mecanismos focais e an?lise de anisotropia s?smica. Na determina??o hipocentral utilizou-se o programa HYPO71, com o modelo de semiespa?o, de par?metros iguais a 5,95, para a velocidade da onda P, e 1,69, para a raz?o Entre as velocidades das ondas P e S. Dessa forma, foi poss?vel detectar urna zona ativa, de aproximadamente 1 km de extens?o e profundidade variando de 4,5 a 5,2 km. Com um conjunto de 16 sismos, registrados na mesmas seis esta??es, foi determinado um plano de falha a partir dos hipocentros, pelo m?todo dos m?nimos quadrados, obtendo-se os valores de 60? para o azimute e 88? para o mergulho. A determina??o de mecanismos focais foi feita de duas formas distintas, utilizando-se os programas FPFIT e FOCMEC. Na solu??o do mecanismo composto (FPFIT), encontrou-se uma falha de dire??o aproximadamente E-W (265? para o azimute, 88? para o mergulho), transcorrente, sinistral, com componente normal.Foram determinados v?rios mecanismos individuais (FOCMEC), tendo-se obtido um valor m?dio de 65? para o azimute e 80? para o mergulho. Estimativas preliminares do esfor?o horizontal m?ximo, a partir da dire??o do eixo P, n?o s?o concordantes com valores anteriormente obtidos para sismos ao sul do A?ude Tucunduba. Na regi?o tamb?m foi feito um estudo de anisotropia, onde se verificou a presen?a de anisotropia na propaga??o da onda S, possibilitando a obten??o das dire??es de polariza??es e dos tempos de atraso entre as ondas S divididas, para duas esta??es. A dificuldade de se ter uma boa estimativa para o esfor?o horizontal m?ximo, na regi?o, impossibilitou qualquer conclus?o sobre a causa da anisotropia observada. N?o se pode concluir, de forma clara, que a atividade s?smica possa estar associada diretamente a falhas mapeadas na regi?o. As dire??es do plano de falha pelo ajuste por m?nimos quadrados, FPFIT e FOCMEC (valor m?dio) est?o no intervalo de NE e EW. Estes valores s?o consistentes com as dire??es de fotolineamentos, lineamentos topogr?ficos, positivos e negativos, e de fraturas secas, observadas na regi?o.

Made available in DSpace on 2015-03-13T17:08:23Z (GMT). No. of bitstreams: 1 LucianoFCJ.pdf: 1898824 bytes, checksum: ceb5971b03c32817c3191b8feacf5ac8 (MD5) Previous issue date: 2001-02-21 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This study describes brittle deformation and seismicity in the Castanh?o Dam region, Cear? State, Brazil. This reservoir will include a hidroeletric power plant and will store about 6,7 billions m3 of water. Five main litostratigraphic unit were identified in the region: gneissic-migmatitic basement, metavolcanosedimentary sequence, granitoid plutons of Brasiliano age, Mesozoic basaltic dike swarm, and Cenozoic fluvial terraces of the Jaguaribe river. The region has experienced several faulting events that occurred at different crustal levels. Faults formed at depths less than about 12 km present left-lateral movement and are associated with epidote and quartz infillings. Faults formed at depths less than 7 km are mainly strike-slip present cataclastic rocks, fault breccia and gouge. Both fault groups form mainly NE-trendind lineaments and represent reactivation of ductile shear zones or new formed faults that cut across existing structures. Seismically-induced liquefaction fractures take place in Cenozoic terraces and indicate paleoearthquakes that may have reached at leat 6,8 MS. In short, this work indicate that the level of paleoseismicity is much greater than one observed in the instrumental record. Several faults are favourably oriented for reactivation and induced seismicity should be expected after the Castanh?o Dam impoudment / O presente estudo descreve os aspectos deformacionais fr?geis e a sismicidade na regi?o que ser? inundada pelo reservat?rio do A?ude do Castanh?o, por??o leste do estado do Cear?. O lago artificial ter? a capacidade para armazenar em torno de 6,7 bilh?es de m3 de ?gua. Tamb?m ? planejada a instala??o de uma usina hidroel?trica de pequeno porte. Cinco principais unidades litoestratigr?ficas foram identificadas na regi?o: complexo gn?issico-migmat?tico, seq??ncia metavulcanosedimentar, granit?ides brasilianos, enxame de diques bas?lticos mesoz?icos e terra?os fluviais do Rio Jaguaribe. As falhas indicam a presen?a de sucessivos eventos de reativa??o em n?veis crustais diferentes. As falhas de n?vel crustal profundo (at? 12 km), apresentam uma cinem?tica transcorrente e s?o associadas com preenchimento de ep?doto ou quartzo. As falhas de n?vel crustal intermedi?rio a raso (at? 7 km), s?o principalmente transcorrentes, estando associadas ? cataclasito, brecha e gouge de falha. Ambos os grupos de falhas apresentam um trend principal NE, que pode representar a reativa??o de zonas de cisalhamento d?cteis ou a exist?ncia de eventos fr?geis cenoz?icos. Na ?rea existem v?rias evid?ncias de sismitos, estruturas geol?gicas geradas por paleossismos, em n?veis conglomer?ticos nos Terra?os Fluviais do Rio Jaguaribe, que indicam a ocorr?ncia de sismos com magnitude 6,8 MS, no m?nimo, na regi?o. Assim sendo, a regi?o que ser? inundada do A?ude do Castanh?o, e sua circunvizinhan?a, no decorrer do tempo j? foi atingida por in?meros abalos s?smicos. T?m-se registros hist?ricos, instrumentais e geol?gicos claros destas atividades. Com base nestas informa??es, pode-se afirmar que a regi?o ? predisposta a ser afetada por tremores de terra. Mas isto n?o significa que a obra do A?ude do Castanh?o futuramente poder? ser atingida ou danificada por algum abalo que venha a ocorrer, pois a constru??o est? preparada para resistir, no m?nimo, aos maiores abalos s?smicos j? registrados at? o presente momento na regi?o

Made available in DSpace on 2015-03-13T17:08:27Z (GMT). No. of bitstreams: 1 AlineGS_DISSERT.pdf: 3853241 bytes, checksum: 58a2024c558cc1fe962ac52b1b91989a (MD5) Previous issue date: 2010-04-05 / Hydraulic fracturing is an operation in which pressurised fluid is injected in the geological formation surrounding the producing well to create new permeable paths for hydrocarbons. The injection of such fluids in the reservoir induces seismic events. The measurement of this reservoir stimulation can be made by location these induced microseismic events. However, microseismic monitoring is an expensive operation because the acquisition and data interpretation system using in this monitoring rely on high signal-to-noise ratios (SNR). In general, the sensors are deployed in a monitoring well near the treated well and can make a microseismic monitoring quite an expensive operation. In this dissertation we propose the application of a new method for recording and location of microseismic events called nanoseismic monitoring (Joswig, 2006). In this new method, a continuous recording is performed and the interpreter can separate events from noise using sonograms. This new method also allows the location of seismic sources even when P and S phases onsets are not clear like in situations of 0 dB SNR. The clear technical advantage of this new method is also economically advantageous since the sensors can potentially be installed on the surface rather than in observation well. In this dissertation field tests with controlled sources were made. In the first test small explosives using fire works at 28 m (slant distances) were detected yealding magnitudes between -2.4 &#8804; ML &#8804; -1.6.. In a second test, we monitored perforation shots in a producing oil field. In this second test, one perforation shot was located with slant distances of 861 m and magnitude 2.4 ML. Data from the tests allow us to say that the method has potential to be used in the oil industry to monitor hydrofracture / O fraturamento hidr?ulico consiste em injetar um fluido pressurizado na forma??o em volta do po?o produtor a fim de criar novos caminhos para o hidrocarboneto fluir. A inje??o de fluido em reservat?rio de hidrocarboneto durante o processo de fraturamento hidr?ulico induz eventos micross?smicos. Medir a efici?ncia dessa estimula??o do reservat?rio pode ser feita, de forma indireta, identificando os locais afetados atrav?s da localiza??o dos microssismos induzidos. Mas hoje, isso tem um custo elevado por que o sistema de aquisi??o e interpreta??o de dados no monitoramento s?smico s? funciona bem em ambientes onde a raz?o sinal-ru?do ? consideravelmente alta, implicando na necessidade de acoplar sensores em po?os de observa??o a uma mesma profundidade do fraturamento. Nesse trabalho, propomos a aplica??o de um novo m?todo de registro e localiza??o de microssismos, o m?todo nanoss?smico (Joswig, 2006). O m?todo consiste em um monitoramento cont?nuo no tempo, deixando o usu?rio distinguir ru?dos e eventos s?smicos atrav?s da an?lise do conte?do espectral do sinal. O programa de an?lise do m?todo, HypoLine, permite a localiza??o de eventos sem fases clara de onda P e S. Dessa forma, pode-se identificar e localizar eventos de raz?o sinal - ru?do de at? 0 dB. Essa ? a principal vantagem do m?todo. Sua aplica??o para detectar microssismos induzidos por inje??o de fluido pode trazer grande retorno financeiro, caso n?o se tenha mais a necessidade de acoplar sensores a uma mesma profundidade do fraturamento hidr?ulico. Neste trabalho, testes foram realizados, onde o tempo de origem do sinal e a localiza??o da fonte eram conhecidos, a fim de conhecer a potencialidade do m?todo para aplica??o futura em monitoramento de fraturamentos hidr?ulico. Em um primeiro teste, fontes s?smicas (simuladas com fogos de artif?cios) foram localizadas a 28 m do sensor e magnitude -2.4 &#8804; ML &#8804; -1.6. Em um segundo teste, um monitoramento de canhoneios em um po?o de petr?leo, fonte foi detectada e localizada a uma dist?ncia do sensor de 861m com magnitude de 2.4 ML. Dados obtidos nestes testes permite dizer que o m?todo tem potencial para ser usado em monitoramento de hidrofraturas pela ind?stria do petr?leo