Resolving Three-Dimensional Displacements Caused by Subsurface Fluid Activities From InSAR and Volumetric Strain Model: Adaptive Estimation of Model Parameters

Monitoring the actual surface deformation caused by subsurface fluid activities is crucial for comprehending the subsurface fluid mutation process. Incorporation of InSAR observations in a prior volume strain model can facilitate the estimation of subsurface fluid volumetric changes and three-dimensional (3-D) surface deformation. However, the model parameters, i.e., the thickness and depth of the subsurface fluid reservoir, are assumed to be known a priori. Therefore, it is impossible to acquire the precise model parameters in practice. Therefore, we proposed a novel approach for adaptive estimation of the model parameters by utilizing the black hole strategy method integrated with the particle swarm optimization algorithm. First, the performance of this method was tested through simulation experiments. The results suggest that the proposed method can precisely determine the model parameters and 3-D deformations of the subsurface fluids. Finally, the proposed model was tested using actual data from the Shale gas area in Texas and the Kilauea Caldera volcano in Hawaii, USA. For long-term, slow small deformations or sudden large deformations caused by the subsurface fluids, the proposed algorithm can obtain corresponding 3-D deformations, especially in the presence of incoherent regions, which can still obtain a complete 3-D deformation field.