Bayesian Reassessment of Seismic Moment Tensors and Their Uncertainties in the Adriatic Sea Region

The determination of seismic moment tensor (MT) parameters is subject to uncertainties from data noise and structural error due to the imperfect Earth model, which is rarely considered in regional earthquake catalogs. In this study, we apply a hierarchical Bayesian MT inversion with uncertainty quantification to seven moderate-earthquakes Mw 4.5–5.5 in the Adriatic Sea region. The event collection includes three in mainland Croatia: the 2020 Mw 5.4 Zagreb earthquake and its Mw 4.9 aftershock, and the Mw 5.0 foreshock of the 2020 Petrinja earthquake, two events in the offshore Adriatic Sea: the 2021 Mw 5.2 central Adriatic earthquake, the 2024 Mw 4.6 southern Adriatic earthquake, and two in Italy: the 2022 Mw 5.5 Costa Marchigiana-Pesarese earthquake, and the 2023 Mw 4.9 earthquake in Marradi (Tuscany). The inversion output features the source depth and the posterior distributions of the MT parameters, enabling the uncertainty quantification. Comparing our results with regional routine catalogs highlights the improvement in source determination, particularly in confidence of non-double-couple components when incorporating the data and structural uncertainties. The refined source mechanisms could be useful for understanding the complex geological settings, assessing the hazard potential, and further improving the regional earthquake catalogs in the Adriatic Sea region.