From Fault Ruptures to Atmospheric Perturbations: Examining the 2016 Norcia Seismic Sequence

This study examines the seismic sequence, which stroke the Central Italy in 2016, focusing on the relationship between static displacement fields and induced atmospheric perturbations in terms of Acoustic Gravity Waves (AGWs). Specifically, we investigated the three events of the sequence occurred on August 24th, October 26th and October 30th. Displacement fields for the main earthquakes were modeled using the Okada approach and validated with Global Navigation Satellite System (GNSS) data, providing strong geodetic constraints. AGW activity was assessed through potential energy derived from ERA-5 temperature profiles. For the August 24th earthquake (Mw 6.1, EQ1), the observed AGW was well reproduced by the Magnetosphere Ionosphere Lithosphere Coupling (MILC) model confirming the direct connection between seismic event and atmospheric temperature perturbations. The October 26th earthquake (Mw 5.9, EQ2) showed no AGW injection, consistent with model predictions. During the October 30th event (Mw 6.5, EQ3), the presence of adverse meteorological events inhibited any detection of potential seismic-induced AGW signals. These findings highlight that also moderate-to-strong earthquakes might generate propagating AGWs which are crucial for reliable earthquake precursor identification.