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Modified Bott-Parker method for gravimetric Moho modeling
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DOI：10.1190/GEO2024-0382.1.png)
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Abstract
En 中文
Determining the detailed Moho topography is crucial for understanding geodynamic processes. Inversion of the Moho depth in the frequency domain from gravity observations is an effective tool for this purpose. However, existing inversion methods such as the Parker-Oldenburg (P-O) and Bott-Parker (B-P) methods face challenges including nonconvergence and noise amplification. We develop a modified B-P (mB-P) method to estimate the Moho depth with variable density contrast from gravity data. Our method casts exponential density-based Parker's formula into the iterative continuation theoretical framework, allowing the use of an adaptive filter that has been proven effective in iterative continuation studies. This modification retains the efficiency of the B-P method while offering improved control over solution stability. Gauss-fast Fourier transform is adopted to improve the precision of the forward and inverse Fourier transforms in the inversion process. Furthermore, the mathematical connection between the P-O and B-P methods is established. Specifically, the B-P method acts as a low-pass filter to reduce the downward continuation effect in the P-O method and recovers the nonlinear topography through the non- linearity of the fitting function. Synthetic inversion tests demonstrate that our method achieves superior inversion accuracy compared with the P-O and B-P methods under 3% gravity observation noise and significantly outperforms the P-O method in terms of computational efficiency. We apply the mB-P method to estimate the Moho depth beneath the Tibetan Plateau using satellite gravity data and seismic data, achieving reasonable agreement between the gravimetric model and seismic data.
Keywords:
GRAVITY INVERSION
POTENTIAL-FIELD
DOWNWARD CONTINUATION
BASEMENT RELIEF
SEDIMENTARY BASINS
CRUSTAL THICKNESS
ITERATION METHOD
DEPTH
INTERFACE
PROGRAM