Estudo da atividade sísmica em São Caetano-PE em 2007

In this dissertation we studied the seismic activity in the São 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 São 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

Aquisição, processamento e análise de dados de sísmica de alta resolução na plataforma continental norte do Rio Grande do Norte: Vale inciso do rio açu

On the modern Continental Shelf to the north of Rio Grande do Norte state (NE Brazil) is located a paleo-valley, submerged during the last glacial sea-level lowstand, that marks continuation of the most important river of this area (Açu River). Despite the high level of exploration activity of oil industry, there is few information about shallow stratigraphy. Aiming to fill this gap, situated on the Neogene, was worked a marine seismic investigation, the development of a processing flow for high resolution data seismic, and the recognition of the main feature morphology of the study area: the incised valley of the River Açu. The acquisition of shallow seismic data was undertaken in conjunction with the laboratory of Marine Geology/Geophysics and Environmental Monitoring - GGEMMA of Federal University of Rio Grande do Norte UFRN, in SISPLAT project, where the geomorphological structure of the Rio paleovale Açu was the target of the investigation survey. The acquisition of geophysical data has been over the longitudinal and transverse sections, which were subsequently submitted to the processing, hitherto little-used and / or few addressed in the literature, which provided a much higher quality result with the raw data. Once proposed for the flow data was developed and applied to the data of X-Star (acoustic sensor), using available resources of the program ReflexW 4.5 A surface fluvial architecture has been constructed from the bathymetric data and remote sensing image fused and draped over Digital Elevation Models to create three-dimensional (3D) perspective views that are used to analyze the 3D geometry geological features and provide the mapping morphologically defined. The results are expressed in the analysis of seismic sections that extend over the region of the continental shelf and upper slope from mouth of the Açu River to the shelf edge, providing the identification / quantification of geometrical features such as depth, thickness, horizons and units seismic stratigraphyc area, with emphasis has been placed on the palaeoenvironmental interpretation of discordance limit and fill sediment of the incised valley, control by structural elements, and marked by the influence of changes in the sea level. The interpretation of the evolution of this river is worth can bring information to enable more precise descriptions and interpretations, which describes the palaeoenvironmental controls influencing incised valley evolution and preservation to provide a better comprehensive understanding of this reservoir analog system

Interpretação sísmica e análise de atributos - área do levantamento sísmico 3D de siririzinho (Bacia Sergipe-Alagoas, NE do Brasil)

The main objective of the present thesis was the seismic interpretation and seismic attribute analysis of the 3D seismic data from the Siririzinho high, located in the Sergipe Sub-basin (southern portion of Sergipe-Alagoas Basin). This study has enabled a better understanding of the stratigraphy and structure that the Siririzinho high experienced during its development. In a first analysis, we used two types of filters: the dip-steered median filter, was used to remove random noise and increase the lateral continuity of reflections, and fault-enhancement filter was applied to enhance the reflection discontinuities. After this filtering step similarity and curvature attributes were applied in order to identify and enhance the distribution of faults and fractures. The use of attributes and filtering greatly contributed to the identification and enhancement of continuity of faults. Besides the application of typical attributes (similarity and curvature) neural network and fingerprint techniques were also used, which generate meta-attributes, also aiming to highlight the faults; however, the results were not satisfactory. In a subsequent step, well log and seismic data analysis were performed, which allowed the understanding of the distribution and arrangement of sequences that occur in the Siririzinho high, as well as an understanding of how these units are affected by main structures in the region. The Siririzinho high comprises an elongated structure elongated in the NS direction, capped by four seismo-sequences (informally named, from bottom to top, the sequences I to IV, plus the top of the basement). It was possible to recognize the main NS-oriented faults, which especially affect the sequences I and II, and faults oriented NE-SW, that reach the younger sequences, III and IV. Finally, with the interpretation of seismic horizons corresponding to each of these sequences, it was possible to define a better understanding of geometry, deposition and structural relations in the area.

Sismicidade e esforços tectônicos na zona sísmica Acaraú, Nordeste do Brasil

Inside the Borborema Province the Northwestern Ceará (NC) is one of the most seismic active regions. There are reports of an earthquake occurred in 1810 in the Granja town. On January, 2008 the seismic activity in NC has increased and it was deployed a seismographic network with 11 digital stations. In 2009, another earthquake sequence began and it was deployed another seismographic network in the Santana do Acaraú town with 6 stations. This thesis presents the results obtained by analyzing the data recorded in these two networks. The epicentral areas are located near the northeastern part of the Transbrasiliano Lineament, a shear zone with NE-SW-trending that cuts the study area. The hypocenters are located between 1km and 8km. The strike-slip focal mechanisms were found, which is predominant in the Borborema Province. An integration of seismological, geological and geophysical data was performed and it show that the seismogenic faults found are oriented in the same direction to the local brittle structures observed in field and magnetic lineaments. The SHmax (maximum compressional stress) direction in NC was estimated using an inversion of seven focal mechanisms. The horizontal maximum compression stress (σ1 = 300°) with orientation NW-SE and extension (σ3 = 210°) with NE-SW and σ2 vertical. These results are consistent with results of previous studies. The seismic activity recorded in NC is not related to a possible reactivation of the Transbrasiliano Lineament, by now.

Medium change monitoring using ambient seismic noise and coda wave interferometry: examples from intraplate NE Brazil and the Mid-Atlantic Ridge

This thesis presents and discusses the results of ambient seismic noise correlation for two different environments: intraplate and Mid-Atlantic Ridge. The coda wave interferometry method has also been tested for the intraplate data. Ambient noise correlation is a method that allows to retrieve the structural response between two receivers from ambient noise records, as if one of the station was a virtual source. It has been largely used in seismology to image the subsurface and to monitor structural changes associated mostly with volcanic eruptions and large earthquakes. In the intraplate study, we were able to detect localized structural changes related to a small earthquake swarm, which main event is mR 3.7, North-East of Brazil. We also showed that the 1-bit normalization and spectral whitening result on the loss of waveform details and that the phase auto-correlation, which is amplitude unbiased, seems to be more sensitive and robust for our analysis of a small earthquake swarm. The analysis of 6 months of data using cross-correlations detect clear medium changes soon after the main event while the auto-correlations detect changes essentially after 1 month. It could be explained by fluid pressure redistribution which can be initiated by hydromechanical changes and opened path ways to shallower depth levels due to later occurring earthquakes. In the Mid-Atlantic Ridge study, we investigate structural changes associated with a mb 4.9 earthquake in the region of the Saint Paul transform fault. The data have been recorded by a single broadband seismic station located at less than 200 km from the Mid-Atlantic ridge. The results of the phase auto-correlation for a 5-month period, show a strong co-seismic medium change followed by a relatively fast post-seismic recovery. This medium change is likely related to the damages caused by the earthquake’s ground shaking. The healing process (filling of the new cracks) that lasted 60 days can be decomposed in two phases, a fast recovery (70% in ~30 days) in the early post-seismic stage and a relatively slow recovery later (30% in ~30 days). In the coda wave interferometry study, we monitor temporal changes of the subsurface caused by the small intraplate earthquake swarm mentioned previously. The method was first validated with synthetics data. We were able to detect a change of 2.5% in the source position and a 15% decrease of the scatterers’ amount. Then, from the real data, we observed a rapid decorrelation of the seismic coda after the mR 3.7 seismic event. This indicates a rapid change of the subsurface in the fault’s region induced by the earthquake.

Medium change monitoring using ambient seismic noise and coda wave interferometry: examples from intraplate NE Brazil and the Mid-Atlantic Ridge

This thesis presents and discusses the results of ambient seismic noise correlation for two different environments: intraplate and Mid-Atlantic Ridge. The coda wave interferometry method has also been tested for the intraplate data. Ambient noise correlation is a method that allows to retrieve the structural response between two receivers from ambient noise records, as if one of the station was a virtual source. It has been largely used in seismology to image the subsurface and to monitor structural changes associated mostly with volcanic eruptions and large earthquakes. In the intraplate study, we were able to detect localized structural changes related to a small earthquake swarm, which main event is mR 3.7, North-East of Brazil. We also showed that the 1-bit normalization and spectral whitening result on the loss of waveform details and that the phase auto-correlation, which is amplitude unbiased, seems to be more sensitive and robust for our analysis of a small earthquake swarm. The analysis of 6 months of data using cross-correlations detect clear medium changes soon after the main event while the auto-correlations detect changes essentially after 1 month. It could be explained by fluid pressure redistribution which can be initiated by hydromechanical changes and opened path ways to shallower depth levels due to later occurring earthquakes. In the Mid-Atlantic Ridge study, we investigate structural changes associated with a mb 4.9 earthquake in the region of the Saint Paul transform fault. The data have been recorded by a single broadband seismic station located at less than 200 km from the Mid-Atlantic ridge. The results of the phase auto-correlation for a 5-month period, show a strong co-seismic medium change followed by a relatively fast post-seismic recovery. This medium change is likely related to the damages caused by the earthquake’s ground shaking. The healing process (filling of the new cracks) that lasted 60 days can be decomposed in two phases, a fast recovery (70% in ~30 days) in the early post-seismic stage and a relatively slow recovery later (30% in ~30 days). In the coda wave interferometry study, we monitor temporal changes of the subsurface caused by the small intraplate earthquake swarm mentioned previously. The method was first validated with synthetics data. We were able to detect a change of 2.5% in the source position and a 15% decrease of the scatterers’ amount. Then, from the real data, we observed a rapid decorrelation of the seismic coda after the mR 3.7 seismic event. This indicates a rapid change of the subsurface in the fault’s region induced by the earthquake.

O cordel como fonte de informação: a vivacidade dos folhetos de cordeis no Rio Grande do Norte

GAUDENCIO, Sale Mario; BORBA, Maria do Socorro de Azevedo. O cordel como fonte de informaçao: a vivacidade dos folhetos de cordeis no Rio Grande do Norte. Biblioonline, Joao Pessoa, v.6, n. 1, p.82-92, 2010.

Inserção de fornecedores locais como fonte de desempenhos em custos de transação e legitimidade: estudo de caso na cadeia produtiva do petróleo e gás do Rio Grande do Norte

The inclusion of local suppliers in production chains has considerable impact on its performance, but most notably in its main actors. The results of this process may be of different kinds and can be analyzed from economic or institutional approaches. This study aimed to verify the existence of different performances of Petrobras due to the inclusion of local suppliers in the oil and gas production chain in the state of Rio Grande do Norte, from the viewpoints of transaction costs and the Institutional Theory. In order to this, were made the characterization of the PROMINP, the description of its actions and results, the mapping of its institutional context of reference, and identification of results obtained by Petrobras in terms of transaction costs and legitimacy. The theoretical framework is based on authors dealing with industrial concentration, as like Marshall, Krugman, Porter and Schmitz, from the sociological perspective of neoinstitucional theory, as like DiMaggio and Powell and Scott and Meyer, and transaction costs, as like Williamson. This is a qualitative research, with data collection done by consulting secondary fonts and semi-structured interviews with nineteen actors of three groups, namely: actors involved in actions of the program, representatives of enterprises and representative of Petrobras. To analyze the content was used the Suchman s model (1995) for categories associated with strategies of legitimation and fourteen variables associated with the three variables assets specificity, bounded rationality and opportunism (Williamson, 1995, 1989) in the case of transaction costs. The results indicate that PROMINP has achieved its objectives by encouraging the increased participation of local companies in the oil and gas production chain, reflecting in the economic development of the state. The Redepetro/RN, fostered and built upon the interaction of the participants, is presented as a solution of continuity to the participation of enterprises in the chain, after the closure of the actions of the program. PROMINP demands responses to coercive, legislative and regulatory pressures of the organizational field, whose institutional context of reference is wide. From the point of view of legitimacy, through strategies to gain cognitive legitimacy and maintaining pragmatic legitimacy, Petrobras can manipulate the environment, ensuring the compliance of the constituents to their technical and institutional demands. Enterprises, in turn, respond to the demands through compliance with technical demands, mainly through the certification of processes, and cultural changes. There aren t clear gains related to the transaction costs, however, gains in legitimacy can be seen as a cumulative capital that can serve as a competitive differential that generates economic gains. In terms of theoretical findings, it was found that, due to its explanatory power for actions that are difficult to explain only in economic terms, Institutional Theory may be used as theoretical support concurrent with other theories. TCE model has limitations in explaining the program actions. In the case, it s emphasized that Petrobras doesn t seek only economic efficiency, but has in its mission the commitment to social development.

Desenvolvimento de um sistema de nitretação por plasma em fonte pulsada e sua influencia sobre a nitretação do titânio

The pulsed plasma nitriding is a solution currently used in the metallurgical industry to resolve problems earlier in the processing of parts by using plasma DC voltage. These problems consisted mainly of edge effect and opening arches caused due to non-uniformity of electric fields on uneven surfaces. By varying the pulse width can reduce these effects. However, variations in pulse width can drastically affect the population of the plasma species and hence the final microstructure of the nitrided layer. In literature, little is known about the effect of process parameters on the properties of the plasma species and, consequently, the surface properties. We have developed a system of nitriding with pulsed source with fixed period of 800  pulse width is variable. Examined the variation of these parameters on the properties of nitrided surface when keeping constant temperature, gas composition, flow, pressure and power. It was found that the values of width and pulse repetition time of considerable influence in the intensities of the species present in plasma. Moreover, we observed the existence of the edge effect for some values of pulse widths, as well as changes in surface roughness and hardness

Síntese de zeólita A a partir de diatomita como fonte de aluminossilicato

The synthesis of zeolites from natural sources of silicon and aluminum are promising alternative routes to obtain porous or zeolite MCM family. Such materials are typically used in catalytic processes and / or adsorption is to obtain new products or for separation and purification processes thereof. Environmental legislation is becoming stricter and requires the use of materials more efficient, aiming to achieve pollution prevention, by gas or liquid contaminants in the environment. In order to obtain a material with environmentally friendly features, this study aimed at the synthesis of zeolite A, from an amorphous sediment, diatomite, which is found in abundance in the northeast region of Brazil, may be substituted for conventional products the production of zeolite, involving higher costs. The methodology for obtaining the "Zeolite A" using as a source of silica and alumina diatomite is simple, since this is a source of silicon, not requiring therefore a structural driver, but also by heat treatment, only drying conventional to remove water. The "zeolite A" was obtained from diatomite, but as an intermediate step we obtained the sodalite. The characterization was made by the following techniques: EDX, XRD, FT-IR, SEM and determining a specific area by the BET method and the BJH method for checking the diameter of pores. By characterization of the obtained material was first demonstrated the achievement of sodalite and after modification of the same, there was obtained zeolite A