Gravity sparse inversion using the interior-point method and a general model weighting function
- PDF / 871,780 Bytes
- 17 Pages / 475.945 x 680.426 pts Page_size
- 14 Downloads / 194 Views
First Crust Monitoring and Application Center, CEA, Tianjin 300180, China China University of Geosciences, Beijing 100083, China ([email protected]) Shanxi Key Laboratory of Resources, Environment and Disaster Monitoring CN, Shanxi 030006, China
Received: April 17, 2020; Revised: July 2, 2020; Accepted: August 18, 2020
ABSTRACT This study presents an optimized gravity-sparse inversion method. The proposed method minimizes the global objective function using interior-point method for boundary constraints and a general weighting function comprising the depth, compactness, and kernel weighting functions of the density models. For the compactness weighting function, practical experiments demonstrate that the recovered model becomes more compact with an increasing value for the relative exponential factor . However, if no appropriate boundary-constraint method is applied, the inversion results cannot be controlled within the designated constraint bounds when needs to be set to a large value to obtain compact inversion results. The interior-point method allows the use of a larger to obtain more compact inversion results without violating the boundary constraints. Additionally, models in close proximity can more clearly be recognized using this method. To improve the computational efficiency and obtain a more accurate regularization parameter, the preconditioned conjugate gradient and L-curve, or line search methods, were also applied. The proposed method was applied for three synthetic examples: two positive bodies adjacent to each other at different depths inverted using noise-free gravity anomaly data, three bodies (positive or negative) at different depths inverted using noisefree or contaminated gravity anomaly data, and three bodies (positive or negative) characterized by a certain dip angle inverted using contaminated gravity anomaly data. This method was also applied for the inversion of a Woodlawn sulfide body, Missouri iron ore body, and granitoid rock body in the Rio Maria region in the state of Para, Brazil. In all six test cases, larger values were used and the density models were recovered with sharper boundaries within the designated bounds. K e y w o r d s : gravity anomalies, Earth structure, geophysical methods, inverse theory, geodesy
Stud. Geophys. Geod., 64 (2020), DOI: 10.1007/s11200-020-0831-5, in print © 2020 Inst. Geophys. CAS, Prague
i
W. Zhu et al.
1. INTRODUCTION Gravity and magnetic inversions are inexpensive methods that have been extensively applied in the fields of hydrology, geological surveys, oil and gas exploration, mineral exploration, and earthquake prediction (Mendoca and Silva, 1994, 1995; Blakely, 1995; Li and Oldenburg, 1996, 1998; Pilkington, 1997; Portniaguine and Zhdanov, 1999; Chen et al., 2008; Zhdanov, 2015). Discretization of the Earth model into several grids is typically an essential step when using a computer to perform inversion investigations. The design of this model discretization can be divided into two types. The first type uses variable values inside ea
Data Loading...
