Abstract：
The current local wavenumber methods for the interpretation of magnetic anomalies compute the locations of geological bodies by solving complex matrices. Presently, such methods require to know the structural index, which is a parameter that represents the source type. The structural index is hard to know in real data; consequently, the precision of current methods is low. We present the fast local wavenumber (FLW) method, and define the squared sum of the horizontal and vertical local wavenumbers as the cumulative local wavenumber. The FLW method is the linear combination of the umulative local wavenumberand other wavenumbers, and is used to compute the locations and structural index of the source without a priori information and matrix solution. We apply the FLW method to synthetic magnetic anomalies, and the results suggest that the FLW method is insensitive to background and oblique magnetization. Next, we apply the FLW method to real magnetic data to obtain the location and structural index of the source.
. Fast local wavenumber (FLW) method for the inversion of magnetic source parameters[J]. APPLIED GEOPHYSICS, 2018, 15(2): 353-360.
[1]
Abbas, M. A., Fedi, M., and Florio, G., 2014, Improving the local wavenumber method by automatic DEXP transformation: Journal of Applied Geophysics, 111, 250-255.
[2]
Blakely, R. J., 1995, Potential theory in gravity and magnetic application: Cambridge University Press, Britain.
[3]
Bracewell, R. N., 1965, The Fourier transform and its application: McGraw Hill Book Co., American.
[4]
Cooper, G. R. J., 2016, The amplitude and phase of the derivatives of the magnetic anomalies of thin dykes and contacts: Exploration Geophysics, 47, 290-295.
[5]
Fedi, M., Florio, G., and Cascone L., 2012, Multiscale analysis of potential fields by a ridge consistency criterion: the reconstruction of the Bishop basement: Geophysical Journal International, 188, 103-114.
[6]
Keating, P., 2009, Improved use of the local wavenumber in potential-field interpretation: Geophysics, 74(6), L75-L85.
[7]
Li, L. L., Du, X. J., Meng, L. S., et al., 2012, Improved Local Wavenumber Methods in the Interpretation of Magnetic Fields, Journal of Jilin University(Earth Science Edition) (In Chinese), 42(4), 1179-1185.
[8]
Li, X., 2006, Understanding 3D analytic signal amplitude: Geophysics, 71(1), L13-L16.
[9]
Ma, G. Q., Huang, D. N., Li, L. L., et al., 2014, A normalized local wavenumber method for interpretation of gravity and magnetic anomalies: Chinese J. Geophys. (In Chinese), 57(4), 1300-1309.
[10]
Ma, G. Q., Liu, C., Xu, J., et al., 2017, Correlation imaging method based on local wavenumber for interpreting magnetic data: Journal of Applied Geophysics, 138, 17-22.
[11]
Ma, G. Q., 2013, Improved local wavenumber methods in the interpretation of potential field data: Pure and Applied Geophysics, 170(4), 633-643.
[12]
Nabighian, M.N., Grauch, V. J. S., Hansen, R. O., et al., 2005, The historical development of the magnetic method in exploration: Geophysics, 70(6), 33-61.
[13]
Pilkington, M., and Keating, P., 2006, The relationship between local wavenumber and analytic signal in magnetic interpretation: Geophysics, 71(1), L1-L3.
[14]
Reid, A. B., Allsop, J. M., Granser, H., et al., 1990, Magnetic interpretation in three dimensions using Euler deconvolution: Geophysics, 55, 80-91.
[15]
Salem, A., 2005, Interpretation of magnetic data using analytic signal derivatives: Geophysical Prospecting, 53, 75-82.
[16]
Salem, A., Elsirafi, A., and Ushijima, K., 1999, Design and application of high-resolution aeromagnetic survey over Gebel Duwi area and its offshore extension, Egypt: Memoirs of the Faculty of Engineering, Kyushu University, 59(3), 201-213.
[17]
Salem, A., and Smith, R. S., 2005, Depth and structural index from the normalized local wavenumber of 2Dmagnetic anomalies: Geophysical Prospecting, 51, 83-89.
[18]
Salem, A., Ravat, D., Smith, R., et al., 2005, Interpretation of magnetic data using an enhanced local wavenumber (ELW) method: Geophysics, 70(2), L7-L12.
[19]
Salem, A., Williams, S., Fairhead, D., et al., 2008, Interpretation of magnetic data using tilt-angle derivatives: Geophysics, 73, L1-L10.
[20]
Smith, R. S., Thurston, J. B., Dai, T., et al., 1998, iSPI—The improved source parameter imaging method: Geophysical Prospecting, 46, 141-151.
[21]
Stavrev, P., and Reid, A. B., 2007, Degrees of homogeneity of potential fields and structural indices of Euler deconvolution: Geophysics, 72(1), L1-L12.
[22]
Thompson, D, T., 1982, 'EULDPH'-a new technique for making computer-assisted Depth Estimates from Magnetic Data: Geophysics, 47, 31-37.
[23]
Thurston, J. B., and Smith, R. S., 1997, Automatic conversion of magnetic data to depth dip and susceptibility contrast using the SPI method: Geophysics, 62, 807-813.
2018, Vol. 15 
