Anatomy of seismicity clustering from parametric space-time analysis

A multi-parametric study of the space-time evolution of the seismicity from 2015 to the beginning of 2020 is performed within a well-focused area, located between the Alps and the Prealps, in the central part of the Friuli Venezia Giulia region (Northeastern Italy). The study area is characterized by a complex tectonic pattern resulting from the interference of differently oriented fault systems and involving mechanically heterogeneous rocks. From 2018 to 2019, the area experienced a significant increase and clustering of radiated seismic energy. The estimated damage pattern emphasizes the tectonic complexity. Notably, the most energetic events are located in correspondence with the sharp transitions from zones of low damage to zones of intermediate damage. The evolution of seismicity is analyzed through the temporal variation of the Shannon entropy, b-value, fractal dimension, nearest neighbour distance, and changing orientation of the planes inferred from Principal Component Analysis...