What Seismic Phase is L'Aquila in Fifteen Years After the Mw6.1 Earthquake of April 6, 2009?

On April 6, 2009, central Italy was hit by a Mw 6.1 earthquake that caused 308 victims in the city and province of L’Aquila; subsequently, in 2016, two Mw 6+ shocks were recorded in an area located a few dozen kilometers further north, respectively in Amatrice and Norcia. Since, like many of the physical phenomena we observe on the Earth, seismic generation processes are characterized by long-term dependence and governed by power laws, the magnitudes of the two seismic sequences associated with these strong events were analyzed separately in the framework of nonextensive statistical mechanics to examine the connection between the variations of the magnitude probability distribution and the phases of a seismic crisis. In this work, instead, we consider all the events recorded in the same area as a whole, starting from the beginning of the most complete part of the Italian catalog ISIDe, i.e. from 2005, up to 2024. The aim is to verify whether the variations observed in the Tsallis entropy and in its parameters before both L’Aquila and Amatrice-Norcia earthquakes are sufficient, as well as necessary, conditions for the occurrence of strong shocks, so that they can be considered as reliable seismic precursors. The same analysis is repeated for the corresponding data set drawn from the most recent HOmogenized instRUmental Seismic catalog (HORUS) released sinced July 2020. It turns out that the predictive capacity of such precursors increases when joint variations of more parameters are taken into account.