Fluid-Driven Fault Mechanics and Strain Release: Insights from the 2021 Deformation Episode in the Peloritani-Aeolian Sector

Fluids play a pivotal role in altering rock mechanics by affecting shear strength and influencing strain accommodation. This study integrates GNSS time-series and seismological data to reconstruct the spatiotemporal evolution of deformation during 2021 within the Peloritani Mountains (NE Sicily) and the Aeolian Archipelago. Our analysis identifies significant crustal-scale deformation along the NNW-SSE right-lateral transtensional Aeolian-Tindari-Letojanni Fault System (ATLFS), as well as in WNW-ESE to NW-SE right-lateral transfer zones in the western and central sectors of the Aeolian Archipelago. Specifically, throughout 2021, we observed a distinct acceleration in deformation rates along the eastern block of the ATLFS relative to its western counterpart. This kinematic anomaly was strictly synchronous with a peak in seismic strain release and a significant unrest phase at Vulcano Island, characterized by rapid ground inflation and intense degassing. The temporal correlation between tectonic slip and volcanic activity suggests that enhanced fluid circulation—evidenced by gas emissions in the Peloritani area— may modulate the mechanical response of faults, promoting strain release. These findings provide critical constraints on the interplay between active tectonics, fluid migration, and volcanic processes in the Central Mediterranean.