Fluid‐Induced Fault Reactivations in Strike‐Slip Regimes: Temporal Constraints From GNSS and Seismological Analysis in the Peloritani Mts and Aeolian Archipelago (Central Mediterranean)

Abstract Fluids can modify the mechanical properties of rocks, including shear strength and strain behavior. We investigate the timing and magnitude of seismic events during fault motion in strike–slip systems across the Peloritani Mountains (northeastern Sicily) and Aeolian Archipelago using GNSS and seismological data analysis. Results reveal a strain partitioning along the already known crustal–scale NNW–SSE trending right–lateral transtensional deformation zone across the Peloritani Mts and its offshore extension up to Vulcano Island (defined as the Aeolian–Tindari–Letojanni Fault System, ATLFS), and WNW–ESE to NW–SE right–lateral transfer zones located in the western and central sectors of the Aeolian Archipelago. During 2021, the eastern block of the ATLFS underwent a significant velocity increase relative to the fixed western block, varying from 1.6 ± 0.28 mm/y (pre–2021 baseline) to 3.3 ± 0.99 mm/y. The acceleration of the eastern block of the ATLFS was accompanied by increased seismic strain release. It temporally correlated with the fastest ground inflation on Vulcano Island (central Aeolian Archipelago), which in turn coincided with the highest CO 2 flux emission on the island. This correlation, along with evidence of gas emissions in the Peloritani Mts, suggests that enhanced fluid pressure lubricated fault surfaces, thereby facilitating slip along the ATLFS. The fluid–induced slip acceleration was sustained for 9 months and was marked by frequent low–magnitude earthquakes.