Inversion of airborne-ground-borehole vertical gravity gradient data based on fuzzy C-means clustering
Three-dimensional inversion of gravity gradient data can obtain a subsurface density structure model,which can be used for geological resource exploration and other fields.Gravity gradient data from airborne,ground,and borehole observations contain information at different frequencies.Joint inversion of these data can reduce the non-uniqueness of inversion and improve imaging resolution.However,for underground anomalous bodies with complex morphology,the vertical resolution of current joint inversion of multi-scale data,especially the imaging resolution of the anomalous body bottom still needs improvement.To address this issue,the joint in-version of airborne-ground-borehole vertical gravity gradient data was studied in this paper.Firstly,a fuzzy C-means clustering algorithm was introduced into the regularization inversion,and the clustering constraint was added during the iteration process to reduce non-uniqueness.Secondly,a joint inversion method was proposed by combining airborne,ground,and borehole vertical gravity gradient data,and GPU acceleration was utilized for computation.Thirdly,the inversion was applied to theoretical model data and gravity gradient data from the Vinton Dome,USA,so as to verify the effectiveness of the method and discuss the influence of borehole loca-tions on the results.Finally,the performance of GPU acceleration-based parallel inversion was analyzed.The data test demonstrates that the fuzzy C-means clustering can reduce the non-uniqueness of inversion,and the joint inversion can obtain accurate density distributions with certain anti-noise ability.Using the data from anomaly-side and anomaly-through boreholes can improve imaging resolution.The computed density distribu-tion of the Vinton Dome area is close to the conclusions of other researchers,demonstrating the effective-ness and feasibility of the proposed method.The test results also show that the GPU parallel method has a high acceleration ratio,and the proposed method can provide technical support for geological explorations and other studies.