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9th International Congress of the Brazilian Geophysical Society
- Conference date: 11 Sep 2005 - 14 Sep 2005
- Location: Salvador, Bahia, Brazil
- Published: 11 September 2005
41 - 60 of 462 results
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Prospecção para águas subterrâneas através de dois métodos geofísicos em Pureza- RJ
More LessThis paper presents a hidrogeology study carried out with two geophysical methods: the VLF– and the Resistivity Method. This study was made at State of Rio de Janeiro in Municipal of Pureza. The site was investigated by photograph aerial, map topography, map geology and the two methods were evaluated for the capacity to detect the interfaces between different layers structural, in particular the structural of area for ground water.
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Pseudo-seções de dados eletromagnéticos multi-freqüência
Authors J. da Conceição Batista and H.K. SatoThe interpretation scheme developed by Sato (1979), to construct pseudo-sections of resistivity versus depth, is analyzed using theoretical EM response due to layered earth. Some pseudo-sections of apparent resistivity were constructed for models using two and three horizontal layers, with alternating sequences of high and low resistivity values.
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MT modeling of a 2-D structure perpendicular to the Equatorial Electrojet
Authors M.W.C. Silva and L. RijoThe magnetotelluric method (MT) for the determination of subsurface electrical conductivity is based on the assumption that the incident field is laterally uniform and it is considered as plane waves. In the mid latitudes this hypothesis is valid and MT response depends only on the electrical structure of the earth. In equatorial latitudes, the geomagnetic fields shows an strong enhancement associated with electrical currents located in the ionosphere above the magnetic equator, termed Equatorial Electrojet (EEJ), which can make the primary fields nonuniform.
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Utilização de Caminhamento Elétrico para localização de canal aterrado
Authors J.E. da Silva, L.M.L. Yokoyama, L. Moutinho, V.R. Elis and F.Y. HiodoThe purpose of the geophysical work was to delineate a-buried channel of one streamlet, to landscape recovery.The studied area is located in São Carlos city -SP.To reach this objective was used electroresistivity profiling in dipole-dipole array with five meters dipole spacing. Resistivity data processing by an inversion software RES2Dinv provided true electrical resistivity values in five levels of investigation depth.The geophysical methodology of the electroresistivity allowed the localization of the overburden channel, associated with low values of resistivity.
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Mapas de isorresistividades elétricas aparentes do solo superficial de Manaus
Vertical electric surveys (VES) were performed in the city of Manaus in order to allow the elaboration of maps of apparent electric resistivity of the superficial soil. Several interpolation methods of electric resistivity were studied, however, only two methods will be approached here.
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Procedimentos informatizados na modelagem, representação e interpretação no método da eletrorresistividade
Authors E.N.A. Urasaki and H.K. SatoThe graphic implementation of the computer program SCHL, of the model of layers homogeneous, plane parallel, regarding the method of the electro-resistivity, through the technique of the vertical electrical sounding (VES) with Schlumberger and Wenner array, was accomplished from way to turn it more interactive, contributing so that the modeling, representation and interpretation of the observed data are more efficient, including automatic inversion using Gauss-Newton linearized inversion.
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Estudos dos Efeitos do Manto de Intemperismo Sobre Anomalias ( VLF ) Geradas por Corpos Inclinados Artavés de Modelagem Numérica
Authors G.E.R. Vogado and O.P. VermaWe have studied the effects of a partially conductive overburden on VLF anomaliesof an inclined prism placed in a highly resistive half space. This study is carried out
through numerical modelling using Finite Element techniques.
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Method of electrical resistivity (DC) applied in studies of contamination of soils and underground waters by gasoline
Authors M.T. Cardinali, A.C. de Oliveira Braga and T.M. CulhariUsing the geophysical method of the electrical resistivity (DC), through the techniques of the vertical electrical soundings and profiling (Schlumberger and dipole – dipole configurations), were analyzed, the temporary variations of the resistivity of sandy and clay materials, contaminated with gasoline, in reduced field scale.
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Aplicação de tomografia elétrica na detecção de tambores plásticos na área do Sítio Controlado de Geofísica Rasa do IAG/USP
Authors E.M.A. da Silva, V.R. Elis, W. Rodrigues Borges, J.L. Porsani and F.Y. HiodoO resumo mostra resultados de tomografia elétrica 2D realizada sobre tambores plásticos enterrados na área do Sítio Controlado de Geofísica Rasa do IAG/USP. A metodologia aplicada teve como objetivo identificar o padrão das anomalias elétricas dos tambores plásticos utilizando o arranjo dipolo-dipolo com espaçamento entre os dipolos de 1 metro. Os resultados mostraram que os parâmetros de campo utilizados permitiram somente identificar a posição horizontal dos tambores. Os alvos apresentaram anomalias de alta resistividade e baixo valor de cargabilidade.
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Estudo audiomagnetotelúrico (AMT) na porção onshore da Bacia de Almada, Bahia
Authors P.G. Freire, E.F. La Terra, S.L. Fontes and V.C.F. BarbosaFifty audiomagnetotelluric (AMT) measurements covering 10 KHz – 10 Hz frequency range have been carried out on the onshore portion of Almada basin, Bahia state. AMT data were recorded in two roughly orthogonal profiles and our approach interprets the AMT soundings using the first–order Tikhonov regularization 2D inversion method to estimate the resistivity distribution in the subsurface that explained the field observations to within a preset error.
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Estudos Magnetotelúricos na Bacia do Iguatu (CE): Primeiros Resultados
Authors A.J.A. Marçal, S.L. Fontes, J.M. Flexor and C.R. GermanoA multidisciplinary geophysical and geochemical project has been proposed to study the set of Iguatu basins, Ceará state, aiming at contributing to the evaluation of the groundwater resources in this semiarid region of Brazil.
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eGs 3.0 (electrical GEOPHYSICS suite) – Pacote de programas para modelagem e interpretação de dados geofísicos elétricos e eletromagnéticos
Authors L. Rijo, G.L. Pereira and R.E. Conceição SilvaThis is the third version of the suite of computer programs denominated electrical GEOPHYSICS suite (eGs 3.0) for modeling and interpretation of electric and electromagnetic geophysical data. The eGs 3.0 is software of free distribution, built to run in the MSWindows operating system.
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Potencialização de magnetômetros de precessão nuclear de prótons com o recurso de microcontroladores
Authors F.Y. Hiodo, K. Blane, N. Silva, R. Francesconi and J.E. SilvaA digital interface was developed to replace all output module with seven segments LED displays of a nuclear precession magnetometer (UNIMAG- GEOMETRICS). System based in microcontroller has low cost and one very friendly programming compiler. A two way communication in alphanumeric mode is used to link with operator through a liquid crystal display LCD with 2 lines and 16 characters by line and a 3 microswitchs keyboard.
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Sistema de prospecção geofísica pelo método Eletromagnético Indutivo (EM) com aplicações no Sítio Controlado do IAG/USP
Authors H.F. Saar, F.Y. Hiodo, N. Silva, K. Blaine, E. Bronizeski, A. Rugenski, J.L. Porsani and W.R. BorgesAn electromagnetic equipment operating in frequency domain was developed to prospect shallow conductive targets, as found in hydrogeological and archaeological surveys. Using low magnetic induction number concepts and lock-in circuits, it became possible to characterize conductors and ferromagnetics materials buried in subsurface, using the dipole electromagnetic profiling method.
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Geoelectric directionality analysis of a magnetotelluric (MT) survey in Parecis Basin (States of Mato Grosso and Rondônia), Brazil
Authors J.M. Flexor, C.M. Martins and S.L. FontesEighty eight broadband (.001 – 1000 sec) magnetotelluric (MT) soundings have been made along a profile crossing the Parecis Basin (Mato Grosso and Rondônia) in a di-rection almost perpendicular to the main geological lineaments.
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Modelagens magnetotelúricas e sísmicas da Bacia do Espírito Santo
Authors S. de A. José, L.B. Teixeira and A.A.G. CarrasquillaConstructing a consistent and reliable model of a complex geophysical/geological system is one of the main question in Geophysics. In order to solve this matter, many studies have been published about data integration of different surveys. In this work, the goal consists in making magnetotelluric and seismic modelings in areas where seismic method has shown limitations. The results have suggested that magnetotelluric method (MT) can be used as an alternative complementary geophysical tool.
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Ensaios Geoelétricos no Estudo de Dutovias em Subsuperfície
Authors M.A.M. Jeronymo and S.W.M. dos SantosO presente trabalho visa apresentar os resultados de ensaios não destrutivos utilizados na detecção de dutos diversos em subsuperfície utilizando para isso métodos geofísicos-geoelétricos tais como GPR (Ground Penetration Radar) e PCM (Pipe Current Mapper). Essas metodologias sobressaem-se de outras principalmente por não possuírem caráter invasivo e impactante no meio ambiente.
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Interfaces Instrumental e de Programação para Aquisição Automática de Dados Geoelétricos Usando Múltiplos Eletrodos
Authors L.R.P. Lisboa and O.A.L. de LimaIn this paper we describe a hardware and software
developed to perform the automatic acquisition of
geoelectrical data using multiple electrodes. The
hardware consists of an electronic switching unit
controlled by a personal computer trough a RS-232 line,
which contains a digital microcontroller that performs the
switching from the resistivity-IP measuring equipment
inputs and outputs to one of 64 electrodes of an electrode
set. Software part consists of a PC-based application
designed to control the electrode switching and to record
incoming data from equipment.
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The preconditioned biconjugate gradient algorithm applied to geophysical electromagnetic modeling
Authors V.C.T. de Souza, L. Rijo and M.W.C. SilvaSolution of the large system of equations that results from a finite-element approximation in electromagnetic modelling over a mesh strongly refined is most commonly done iteratively, because direct solution requires excessive amounts of memory and computation. The conjugate gradient – type methods used in combination with preconditioning – are among the most effective iterative procedures for solving large sparse nonsingular systems of linear equations Ax = b.
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Estatística aplicada à resistividade elétrica dos solos
By A.F. LimaThis paper ilustrates an statistical approach for geophysical data analysis. Concepts of mode and standard deviation are applied to underground electrical resistivity data. In the end a comparison between the subjective and the statistical processing data is made. The graphical and processing software applied was completely developed by the Brain Tecnologia processing and development group.
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