Abstract

ESHAGHZADEH, Ata  and  HAJIAN, Alireza. Modelling of Residual Gravity Data due to a Near Surface Dyke Structure Using Damped SVD and Marquardt Inverse Methods. Geofís. Intl [online]. 2022, vol.61, n.4, pp.325-350.  Epub Nov 18, 2022. ISSN 2954-436X.  https://doi.org/10.22201/igeof.00167169p.2022.61.4.2203.

In this paper, two inverse modeling methods based on the damped singular value decomposition (DSVD) as a linear inverter and Marquardt optimization algorithm as a nonlinear inverter are described. The damped SVD solve the ill-posed problems and specify the subsurface density contribution directly. The Marquardt inversion estimate the model parameters. The efficiency of the both methods is investigated using the synthetic gravity data, with and without random noise, as the acceptable results attained. The introduced approaches are employed for the interpretation of a real gravity data set from Iran. The gravity causative mass in the study area are almost the magmatic deposit with a high percent of the Manganese dioxide where there have penetrated inside of the fractures and have approximately formed the tabular structures. The inverted structures from the both methods are almost corresponding. The evaluated width, extension and depth to the top and bottom for the buried structure via the damped SVD technique are 15 m, 22 m, 7.5 m and 25 m, respectively and by the Marquardt's algorithm are 15.8 m, 20.3 m, 9.4 m and 21.9 m, respectively. The simulated source has a trend NW-SE with a dip of 38.04 degree.

Keywords : damped singular value decomposition (DSVD); gravity and Marquardt.

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