GEOMAGNETISM AND MAGNETIC PROSPECTING

Author: HEISE WIEBKE.
Year: 2003.
University: BARCELONA [www.ub.es].
Place of defense: GEOLOGIA.
Place of preparation: UNIVERSITAT DE BARCELONA.

Summary: The thesis "Contributions to the interpretation of data magnetotelúricos: anisotropy and modeling 3D" helps to solve some problems concerning the interpretation of data magnetolúricos related to the anisotropy and modelitzación of 3D effects. The thesis develops two aspects metodológicos.En First, a new method which can detect and recover the electrical anisotropy using programs for investment 2D models isótropos. This procedure detects anisotropy in the absence of evidence apparent in functions transfer and considerably simplifies its interpretation through a macroscopic anisotropy. Secondly there has been modeling phases anomalous in excess 90Â º model 2D from two structures anisótropas two different directions of anisotropía.Este aspect opens up new possibilities for modeling data magnetotelúricos as it allows modelitzar this type of anomaly until it was now excluded from the modelización.Este procedure has been applied to the interpretation of a profile magnetotelúrica made to the SW of the Iberian Peninsula where polls appear to exceed 90Â fourth stages in an area where there are blocks surface with macroanisotropía. As applied aspects, in addition to the study described in SW to the Iberian Peninsula, including an investigation of audio-magnetotelúrica and magnetotelúrica done in the Caldera de Las Cañadas, Tenerife, which offers a coherent structures drivers inside the boiler . This study has identified berreras hidrologícas matching structural elements of the caldera.Se have adjusted phases with a large overhang, which had to overcome 90Â sixth in the long term, with a 3D model which incorporates a channel driver around the island and a conducting layer deep.

Author: GABÁS GASA ANNA.
Year: 2003.
University: BARCELONA [www.ub.es].
Place of defense: GEOLOGÍA.
Place of preparation: FACULTAD DE GEOLOGÍA.

Summary: The electrical and electromagnetic methods recorded certain components of the electromagnetic field and subsurface structures characterized by electrical conductivity. Within the broad range of methods of exploring this thesis focuses on the study of the methods magnetrotelúrico and electric power contunua.La integration of these two techniques can significantly improve the models that describe the distribution of electrical conductivity of the subsurface. In this work and develop different methodological aspects on methods magnetotelúricos and electrical DC, with the object of improving eltratamineto of experimental data and optimize the process of investment for better models. Thus, the memory is divided into two main parts, according to the two previous methods, each with specific targets. In the magnetotelluric method are two aspects differentiated and innovative. The goal of the first esoptimizar the informaación that enters lainversión to prevent, for example, specific answers control the resultado.Paraa It explores the influence of each type of response magnetotelúrica in this process and presents a new theoretical relationship between errors two different answers. This section is completed with the use of an alternative method for estimating relationships between quantities when it is not possible to deduce analytically. The second aspect aims to develop a new method for identifying and correcting the effect of galvanic distortion on the data experimentales.Estel effect provoke a mistaken interpretation of the subsurface structures, and that is why its correction should be applied as a step prior to interpretation. The methodology follows two phases, the first analytical expressions are obtained from the fundamental equations of magnetotelluric method (Maxwell Equations), and in the second phase, these expressions are evaluated with synthetic data and experimental data. Work on the method of prospecting electric DC objectives optimize the solution to the modeling program and develop an investment program for two-dimensional models. To control and optimize stages of the process have been implemented methods that improve the performance of programas.En modeling has designed a strategy overlap between two mesh that allows the discretization thin model, has developed a procedure that improves the calculation of potential electrical and joined the effects of topografía.En investment, in addition to implementing the program, has deepened the main problem of investment, the calculation of the sensitivity matrix. The programs were applied on vertical profiles of electric polls and profiles electrical tomography, in particular devices Dipolo-Dipolo and Wenner-Schlumberger. Thus, this theory offers as a result, the necessary tools for data integration geoléctricos, corresponding to one of the lines of inquiry Current Prospecting Geophysics, and opens up new prospects for the future in this field.

Author: GAYA PIQUÉ LUÍS R..
Year: 2003.
University: RAMÓN LLULL [www.url.edu].
Place of defense: INSTITUTO UNIVERSITARIO OBSERVATORIO DEL EBRO.
Place of preparation: INSTITUTO UNIVERSITARIO DEL EBRO.

Summary: Through this thesis I tested the geomagnetic field in Antarctica during the past more than four decades with all the information that I have prepared, for the purpose of obtaining a tool to reduce, in the most accurate way possible, the many campaigns magnetic conducted in the region during the period of validity of the model. Regardless of this major utility, the end result has service to obtain an analytical representation of the main field and its secular variation (as well as the wavelengths of higher cortical area) on this region of the Earth's surface. To meet these objectives, has been dedicated on the one hand special attention to technical analysis, and the other, and have carefully analyzed available data sets. The magnetic field reference in Antarctica ARM, I know the first full-field (main field and secular variation) for Antarctica, has proven to be a useful tool in the development of magnetic studies below the -60Â degrees south from 1960 to 2005. The model has been developed based on the annual measures of the components of the magnetic field measures 25 observatories Antarctic stratospheric a campaign for the first time analyzed in this work, and six satellite missions covering different periods of more than 40 years validity of the model. These data have been selected according to various criteria for access to data minimally contaminated by external magnetic fields. The modeling technique has been used on harmonic analysis spherical cup. There has been a broad overview of the art, developments since its appearance in 1985, and the advantages and disadvantages that the technique presents. We have conducted numerous tests to verify the best possible model parameterization. The final model has been compared with two models of global magnetic field. The adjustment to the data used to develop the model as well as data sets independent and representation of the temporal variation of the field, allow us to affirm the validity of ARM as a reference model. As applications of the model are presented the possibility to create maps for the magnetic components in Antarctica, studying the position of the magnetic pole and the phenomenon known as the jerk magnetic, etc.. Finally demonstrates the usefulness of magnetic campaigns ARM reducing marine and air, obtaining results that show that ARM can be used to develop guarantees for studies of magnetic anomalies in Antarctica. The developments and progress can be found on the project's website http://www.ingv.it/arm.

Author: GAYA PIQUÉ LUÍS R..
Year: 2003.
University: RAMÓN LLULL [www.url.edu].
Place of defense: INSTITUTO UNIVERSITARIO OBSERVATORIO DEL EBRO.
Place of preparation: INSTITUTO UNIVERSITARIO OBSERVATORIO DEL EBRO.

Summary: Through this thesis I tested the geomagnetic field in Antarctica during the past more than four decades with all the information that I have prepared, for the purpose of obtaining a tool to reduce, in the most accurate way possible, the many campaigns magnetic conducted in the region during the period of validity of the model. Regardless of this major utility, the end result has been used to obtain an analytic's main camp and its secular variation (as well as the wavelengths of higher cortical area) on this region of the Earth's surface. To meet these objectives, has been dedicated on the one hand special attention to the technique of anáiisis, and the other has been carefully analyzed available data sets. The magnetic field reference in Antarctica ARM, I know the first full-field (field printipal and secular variation) for Antarctica, has proven to be a useful tool in the development of magnetic studies below the -600 latitude south 1960 to 2005. The model has been developed based on the annual average of the components of the magnetic field measures 25 observatories Antarctic stratospheric a campaign for the first time analyzed in this work, and six satellite missions covering different periods of more than 40 years validity of the model. These data have been selected according to various criteria for access to data minimally contaminated by external magnetic fields. The technique has been used for modeling analysis armónicq on spherical cup. There has been a broad overview of the art, developments since its appearance in 1985, and the advantages and disadvantages that the technique presents. We have conducted numerous tests to verify the best possible model parameterization. The final model has been compared with two models for magnetic field commonly accepted as benchmarks for all kinds of magnetic studies. The adjustment to the data used to develop the model as well as to independent data sets and the representation of temporal variation of the field, allow us to affirm the validity of ARM as a reference model. As applications of the model are presented the possibility to create maps for the magnetic components in Antarctica, studying the position of the magnetic pole and the phenomenon known as the jerk magnetic, etc.. Finally demonstrates the usefulness of magnetic campaigns ARM reducing marine and air, obtaining results that show that MRA can be used with guarantees to develop studies of magnetic anomalies in Antarctica. The developments and progress can be found on the website of proyecto.http: / / www.ingv.it / arm.