A 3-D finite-difference algorithm for DC resistivity modelling using conjugate gradient methods

Spitzer, Klaus

doi:10.1111/j.1365-246x.1995.tb06897.x

Cited by 173 publications

(123 citation statements)

References 32 publications

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“…Since the galvanic parameters are determined by the locally uniform induced current and the near surface lateral variation of the electrical conductivity, the near surface electrical conductivity structure can be estimated in some way with the aid of a 3-D DC code (e.g. Spitzer 1995). In this way, Hautot (2005) determines a shallow 3-D electrical conductivity structure, also referring to an electrical conductivity model previously obtained from 2-D and 3-D analyses of the VLF and AMT data .…”

Section: Local Scale Network-mt Observationmentioning

confidence: 99%

EM Monitoring of Crustal Processes Including the Use of the Network-MT Observations

Uyeshima

2007

Surv Geophys

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There are several kinds of coupling mechanisms which can convert mechanical, chemical or thermal energies due to seismic or volcanic activities into electromagnetic energies. As a result of concentrated efforts in laboratory and theoretical research, the basic relationship between the intensity of electromagnetic sources and changes in mechanical, chemical and thermal state is becoming established. Also with the progress of the electromagnetic simulation techniques, it has been possible to evaluate in situ sensitivity. Based on this progress and also due to extensive improvement in measuring techniques, many field experiments have been performed to elucidate subsurface geophysical processes underlying the preparation stage, onset, and subsequent healing stage of earthquakes and volcanic eruptions. In volcanic studies, many studies have reported the measurement of electromagnetic signals which were successfully interpreted in terms of various driving mechanisms. Although there have been numerous reports about the existence of precursory electromagnetic signals in seismic studies, only a few of them could be successfully explained by the proposed mechanisms, whereas coseismic phenomena are often consistent with those mechanisms including the absence of detectable signals. In many cases, one or two orders of higher sensitivity were required, especially for precursory signals. Generally, electromagnetic methods are more sensitive to near-surface phenomena. It will be necessary to discriminate electromagnetic signals due to these near-surface sources, which often possess no relationship with the crustal activities. Further efforts to enhance in situ sensitivity through improvements in observation techniques and in data processing techniques are recommended. At the same time, multi-disciplinary confirmation against the validity of electromagnetic phenomena will inevitably be necessary. A Network-MT observation technique has been developed to determine large-scale deep electrical conductivity structure. In the method, a telephone line network or purpose-built long baseline cables are utilized to measure voltage differences with long electrode separations. Because of the averaging effect of the electric fields, static shift problems due to small-scale, nearsurface lateral heterogeneities can be alleviated. Several field experiments revealed regional scale deep electrical conductivity structures related to slab subduction or its M. Uyeshima (stagnation, which enable us to elucidate underlying physical processes caused by the slab motion. The technique can also be applied to monitor the electric potential field related to crustal activities. The annual variation of the potential field and electrical conductivity in the French Alps were interpreted to be caused by the annual variation of lake water level. The method was also used to monitor the regional scale spatio-temporal variation of the SP field and electrical conductivity before and at the onset of earthquakes and volcanic eruptions.

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Section: Local Scale Network-mt Observationmentioning

confidence: 99%

EM Monitoring of Crustal Processes Including the Use of the Network-MT Observations

Uyeshima

2007

Surv Geophys

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“…The matrix system was iteratively solved by a conjugate gradient method. The implementation details of such an algorithm can be found in Zhang et aL (1995), Spitzer (1995) and Weller et aL (1996).…”

Section: Ij Forward Solutionmentioning

confidence: 99%

Stochastic Inversion of 3D ERT Data

Yang,

LaBrecque

1998

Symposium on the Application of Geophysics to Engineering and Environmental Problems 1998

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This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer.The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction.In the unlikely event that the author dkl not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. I hereby certify that I have read this dissertation prepared under my direction and recommend that it be accepted as fulfilling the dissertation requirement. Dissertati<@ Director Date STATEMENT BY AUTHORThis dissertation has been submitted in partial fiilfiUment of requirements for an advanced degree at The University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library.Brief quotations from this dissertation are aUowable without special permission, provided that accurate acknowledgment of the source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his or her judgment the proposed use of the material is in the interests of scholarship. In all other instances, however, permission must be obtained from the author. SIGNED:4 ACKNOWLEDGMENTS I am very grateful to Dr. Doug LaBrecque, my dissertation supervisor, for his guidance and mvahiable assistance. He walked me step by step from a graduate student to a professional geophysicist. What m^ressed me most is Doug's profound knowledge in all aspects of electrkal and electromagnetic geophysics. It is realty fortunate that I can proceed my career under his guklance for years to come.I am grateful to Dr. \fory Pouhon, my dissertation committee chair, who extended her warm heart and generous hands helping me out of an awkward situatioa I realty appreciate her time and patience in arrangements of try oral conq)rehensive exam and ond defense. It is a great loss that I did not learn enough from her about the unique neural networic technok)gy.Dr. Randall M. Richardson introduced me into the field of geophysical inversion in his Inverse Problems in Geophysics class. The thorough understanding of fundamental mverse problems I gained from 1^ class has proved efifective in solving this con^licated stochastic mverse problem. It is also worth mentioning that the numerical methods taught Dr. Shlomo P. Neuman in Hydrotogy department provided me with inq)lementation details and hands-on experiences m numerical algorithm development. From Dr. Jim Yeh I learned that a large group of hydrotogists have been attacking stochastk: inverse problems u...

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“…To examine the responses of the different orientation arrays in the MTER method, a 3D forward algorithm developed by Spitzer (1995) is used. We consider three arrays of PED, VED, and HED for the feasibility test (Fig.…”

Section: Numerical Forward Modelingmentioning

confidence: 99%

Efficiency of a Marine Towed Electrical Resistivity Method

Chiang¹,

Goto²,

Chen³

et al. 2011

Terr. Atmos. Ocean. Sci.

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In contrast to marine sediments, because of large electrical resistivity anomalies found in sulfide deposits and methane hydrates, resistivity measurements such as marine towed electrical resistivity (MTER) might be a feasible method for discovering those natural minerals. To determine the feasibility of the MTER method we examined arrays consisting of a pole electrical dipole (PED), vertical electrical dipole (VED) and horizontal electrical dipole (HED). The VED array showed a maximum difference in electric fields of 36% and 105% in the resistive and conductive models, respectively, while the PED and HED arrays yielded worse results of around 13% to 19%, respectively. The VED array showed a higher difference in electric fields than both the HED and PED arrays in the two models. Therefore, we suggest that a VED array with a large electrical current would be most conducive leading to the discovery of such minerals during MTER surveys.

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A 3-D finite-difference algorithm for DC resistivity modelling using conjugate gradient methods

Cited by 173 publications

References 32 publications

EM Monitoring of Crustal Processes Including the Use of the Network-MT Observations

EM Monitoring of Crustal Processes Including the Use of the Network-MT Observations

Stochastic Inversion of 3D ERT Data

Efficiency of a Marine Towed Electrical Resistivity Method

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