...Figure 12. Differences between the continuation results (from Figure  11 ) for the Guspi method and three other methods (Taylor, Xia, and Hansen) for the Kluane study area. ...

... in the space or in the frequency domain, are the basis of several methods. See, among others, the papers by Granser (1987), Chai and Hinze (1988), Reamer and Ferguson (1989), and Rao et al. (1990). Guspi (1990) used polynomial density-depth functions for inverting gravity anomalies into 2-D polygons...

...Fernando Guspí; Iván Novara ABSTRACT The generalized Hilbert transforms of potential fields, particularly magnetic fields, provide a useful resource for improving interpretation. Even though x - and y -Hilbert transforms of a potential field on a plane can be approximately computed from the whole...

...Fernando Guspí; Iván Novara Abstract We have developed an equivalent-source method for performing reduction to the pole and related transforms from magnetic data measured on unevenly spaced stations at different elevations. The equivalent source is composed of points located vertically beneath...

... FFT. Their method actually adapts what was previously presented by them ( Takahashi et al., 2020 ) to process gravity data. All these methods are very efficient in dealing with large amounts of magnetic data. However, they require a planar grid of data. Guspí and Novara (2009) develop...

... level ( Guspí, 1987 ). Collocation methods using vertically continuable covariances ( Lahmeyer, 1988 ) and equivalent source methods ( Cordell, 1992 ) yield the grid values directly on a horizontal plane or at any surface. The second is the necessity to separate from an observed field, gridded...

...Fernando Guspi Abstract To obtain the shape of a homogeneous body from its gravity anomalies, the inverse of Parker's formula is expressed here by means of a power series expansion in the reciprocal of the density contrast. The calculation of the nth coefficient of the series needs the evaluation...

... expansion techniques (based on Taylor expansion and continued fractional expansion) calculate the extended series in either the frequency or space domains ( Evjen, 1936 ; Guspí, 1987 ; Fedi and Florio, 2011 ; Zhang et al., 2013 ; Zhou et al., 2021 ). The extrapolation methods continue the potential...

... and with finite horizontal dimensions composed by a set of point masses, one directly beneath each gravity station. Our method starts from an initial mass distribution that is proportional to the observed gravity data. Iteratively, our approach updates the mass distribution by adding mass corrections...

.... Specialized methods have been proposed to separate fields with overlapping contributions, for instance, by modeling the anomaly spectra with a preincorporated model response using Wiener filtering ( Pawlowski and Hansen, 1990 ), using robust statistics to separate spectral contributions ( Guspí and Introcaso...

... , 1354 – 1360 . Guspi F. Introcaso B. , 2000 , A sparse spectrum technique for gridding and separating potential field anomalies : Geophysics , 65 , 1154 – 1161 . Hanke M. , 1995 , Conjugate gradient type methods for ill-posed problems : Pitman Research Notes...

... inversion, and inverse DFT—are included in designing the reconstruction operator. I refer to this method as a DFT inversion-based seismic reconstruction method. Guspi and Introcaso (2000) also used the sparse spectrum technique for gridding and separating potential field anomalies. Example references...

... attitude (pitch, roll, and heading, as it is usually achieved) but only using the three components recorded by the magnetometer and an approximation of the scalar intensity of the earth’s magnetic field. This method, called scalar calibration, allowed us to eliminate the intrinsic instrumental errors...

... functions and developed the polynomial coefficient inversion (PCI) method, which is an alternative method for mapping subsurface density distributions by inverting the coefficients of density-contrast functions. PCI enables the linear inversion of density variations without vertically subdividing...

...-linear features such as roads. Methods for gridding gravity data are discussed by Eckstein (1989) , Keating (1993) , Rauth and Strohmer (1998) , Li and Gotze (1999) , Guspi and Introcaso (2000) , Billings et al. (2002) , and Li et al. (2002) . A feature of gravity data is that the gravity value...

... that contain reflections. They use the retrieved reflection data to obtain a migrated reflection image of the subsurface. Bastani et al. present a case study for the application of controlled-source and radio-magnetotelluric methods in mineral exploration in northeast Iran. Although the geology is complex...

... to iteratively estimate the two free parameters by a new method: the iterative-ratio (ITRAT) method. This method is based on the linear approximate invariance of the depth and free parameters and the availability of several depth constraints. The free parameters are estimated iteratively to update the interface...

... opportunities for methods uniquely suited for such data sets. The equivalent source technique is one such method. We have applied fast equivalent source construction to two aspects of gravity gradient data processing. First, we denoised multicomponent data and obtained estimates of the incoherent errors...

... a 20-m-spaced grid by using a nearest-neighbor algorithm ( Smith and Wessel, 1990 ). This observed magnetic field grid was then continued upward to a level plane above the bathymetry by using the Guspi (1987) method. The corrected magnetic field was inverted for crustal magnetization by assuming...