Multiridge Method for Studying Ground-Deformation Sources: Application to Volcanic Environments

Volcanic phenomena are currently monitored by the detection of physical and chemical observations. Generally, the ground deformation field is the most relevant shallow expression of the geometric and physical parameters variations in the magmatic reservoir. In this study, we propose a novel method for the direct estimation of the geometric parameters of sources responsible for volcanic ground deformation detected via the DInSAR technique. Starting with the biharmonic properties of the deformation field, we define an approach based on the Multiridge and ScalFun methods to achieve relevant information about both the positions and shapes of active sources, such as the Mogi source. Our methodology is definitely different from the methods currently used for modeling ground-deformation sources, mainly based on forward or inverse techniques. In fact, (i) it does not require any assumptions about the source type, and (ii) it is not influenced by the distribution of medium elastic parameters or (iii) the presence of high-frequency noise in the dataset. For synthetic cases, we accurately estimate the depth to the source within a 3% error. Finally, we study the real case of the Okmok volcano ground-deformation field and achieve results compatible with those in previous works.