Integration of different methodologies to analyze surface deformation: examples from Iceland and Mt. Etna

In structural geology and volcanotectonics, data collection and field observations are essential to understand the role played by magmatic intrusions and tectonics in dictating surface deformation. Unfortunately, this analysis relies on a great amount of field data, to be collected in sites that are often characterized by difficult logistic conditions, thus not easily reachable. As a next step, these data should be interpreted and associated with tectonics and/or magma paths below the surface. Here, we show how the integration of different methodologies can be useful to overcome these difficulties, presenting some examples from active tectonic and volcanic areas around the world, such as in Iceland and Italy. In Iceland, we mapped the whole fracture zones of the Husavik-Flatey Fault (HFF) and the Theistareykir Fissure Swarm (ThFS), in the Northern Volcanic Zone. Here, thanks to the integration of classical field surveys and Structure-from-Motion (SfM) photogrammetry techniques applied to drone-collected images, we placed special emphasis on studying offsets along the easternmost section of the HFF, and the geometry and kinematics of 649 faults and 1208 tension fractures in the ThFS. These data have been integrated with analogue scaled models, aimed at analyzing the possible conditions that could have led to the formation of the observed fracture pattern at the intersection between the two main fracture zones. Thanks to this data synergy, we were able to confirm a prolongation of the HFF through the ThFS. In Italy, we performed a multidisciplinary investigation on faults and fissures associated with the 1928 diking event on the flank of Mt. Etna, based on detailed field surveys and numerical modeling using the Final Element Method (FEM): this resulted in possible, different relations between surface deformation and the geometry and physical characteristics of the underlying dike. Finally, we present here a modern and innovative method aimed at overcoming limitations in data collection, through the use of Immersive Virtual Reality, that allows to navigate within 3D digital outcrop models (DOMs), reconstructed with UAVbased SfM techniques.