Inversion of the amplitude of the two-dimensional analytic signal of the magnetic anomaly by the particle swarm optimization technique

Abstract

S U M M A R YAmplitude of the 2-D analytic signal of the magnetic anomaly profile is independent of the directions of the Earth's magnetic field vector and remnant magnetization of the causative source. It exhibits peaks corresponding to the locations of the corners of a causative source, modelled by say a polygon. It also exhibits a peak corresponding to different idealized source geometries related to the structural indices. This amplitude is computed from the first-order horizontal and vertical derivatives of the observed magnetic anomaly and is relatively less noisy than second-order derivatives. The amplitude can also be computed directly from the measured derivatives. Particle swarm optimization (PSO)-a global optimization technique is applied to interpret this amplitude in terms of the horizontal location and depth, constant (related to magnetization) and various source geometries through structural indices. Applicability of the proposed technique is evaluated through the analyses of simulated magnetic anomalies (noise-free and corrupted with 20 per cent random noise) over different types of source geometries, namely, a thin dyke and a contact with high accuracy in parameter estimation. Studies on the choices of search parameter space reveal that a relatively wide search space can be assigned. Practical applicability of the proposed technique has been demonstrated through three magnetic anomaly profiles digitized from published literature. The results of PSO, Euler deconvolution, enhanced local wavenumber and drill hole are comparable. PSO results also seem to be more stable than other techniques.

CUDA based Particle Swarm Optimization for geophysical inversion

“…We consider the amplitude of the vertical magnetic anomaly of Boston Township, Ontario, Canada [9]. This anomaly is more than four times the intensity of the Earth's magnetic field.…”

Global nonlinear optimization for the interpretation of source parameters from total gradient of gravity and magnetic anomalies caused by thin dyke

“…The q value for gravity and magnetic anomaly is 0.5 and 1.0 respectively. The detailed derivation of mathematical formulations can be found in Nettleton [1971], Nabighian [1972], Srivastava and Agarwal [2010], Srivastava et al [2014]. For brevity,…”

“…Another field example is taken from the total field aeromagnetic anomaly (Srivastava and Agarwal, 2010) over a magnetic body associated with a mapped bedrock diabase dyke in the Matheson area of northern Ontario, Canada (Figure 15). The amplitude of 2-D analytic signal, from the measured magnetic field anomaly for the same example is taken from Srivastava and Agarwal, 2010.…”

“…The amplitude of 2-D analytic signal, from the measured magnetic field anomaly for the same example is taken from Srivastava and Agarwal, 2010. The aeromagnetic data was taken over a flight height of 12 m (Salem et al 2005).…”

Grey wolf optimizer: a new strategy to invert geophysical data sets

“…PSO has been applied to solve geophysical problems (Shaw and Srivastava ; Sanyi, Shangxu and Nan ; Wilken et al . ; Martinez, Garcia‐Gonzalo and Naudet ; Santos ; Srivastava and Agarwal ). However, the use of ACO in geophysical problems has been quite limited (Sanyi et al .…”