GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 1.2 GNGTS 2023 Volcanic and Seismic source Modelling (VSM) - An open tool for geodetic data modelling E. Trasatti Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Nazionale Terremoti, Roma Introduction Natural processes and anthropogenic activities often generate changes in the stress state of the crust, and, consequently, measurable surface deformation. Volcanic activity produces surface displacements as a result of phenomena including magma recharge/deployment and migration, and fluid flow. The accurate measurement of surface deformation is one of the most relevant parameters to measure tectonic stress accumulation and for studying the seismic cycle. Improved monitoring capabilities also capture surface deformations related to coastal erosion and its connection to climate change, landslides and deep-seated gravitational slopes, and other hydrogeological hazards. Earth ground deformations are measured by means of remote sensing and terrestrial techniques. Monitoring to quantify spatial and temporal evolution of the deformation is therefore essential and powerful for, at least, volcano and seismic hazard estimates and for many other natural and anthropogenic hazards. Synthetic Aperture Radar (SAR) satellites have been quickly developing in the last decades, in terms of cost lowering, improvement of processing algorithms and (near) real-time data availability. Currently, ESA’s (European Space Agency) satellites Sentinel 1A-B of the European program Copernicus provide open access data for the whole solid Earth surface every 6 or 12 days. Interferometric SAR (InSAR) analysis produces high-quality, coherent data covering wide areas. The combination of multiple InSAR datasets with different imaging geometries (the satellite's Line of Sight - LOS) helps to overcome the limitation of the radar single look. GNSS data allows to map nearly 3D deformation patterns, but often the network consists of few benchmarks. The joint use of SAR and GPS data compensate the intrinsic limitations of each technique. Levelling is a branch of surveying that measures the geodetic height of a benchmark using a levelling instrument. The difference of quote between two or more campaigns is the vertical displacement. The technique is capable of high accuracy. Electro-optical Distance Measuring (EDM) is a terrestrial technique to measure the change in the distance between two benchmarks. Borehole dilatometers provide derivative measurements of the surface displacements. Tiltmeters measure the horizontal change of the vertical component of the displacement, or, conversely, the horizontal change along the vertical direction. Strainmeters measure the volumetric strain.