Space-Time Precursory Features within Ground Velocities and Seismicity in North-Central Italy

Earthquakes cannot be predicted with ultimate precision, so that the progressive reduction of the prediction uncertainty in space and time is an evergreen and challenging task, both from the scientific point of view for the intrinsic complexity of seismic phenomenon and for its high societal relevance. To this aim, algorithms (like CN, M8 and M8S) based on objective recognition of seismicity patterns have been already tested for some decades for intermediate-term middle-range prediction of strong earthquakes above a pre-assigned magnitude threshold. Here, moving from some preliminary ideas, we propose an integrated approach to earthquake prediction, based on the synergy of high-density geodetic observations and seismological information, defining a new paradigm for time dependent hazard assessment scenarios. Through a wider and more refined retrospective analysis, duly involving the accuracy analysis of the newly available geodetic results, space–time precursory features are highlighted within ground velocities and seismicity, analyzing the 2016–2017 seismic crisis in Central Italy and the 2012 Emilia sequence. Overall, it is demonstrated that the proper integration of seismological and geodetic information can achieve what here is called intermediate-term narrow-range earthquake prediction. The extent of the alarmed areas, identified for the strong earthquakes by earthquake prediction algorithms based on seismicity patterns, can be significantly reduced from linear dimensions of a few hundred to a few tens of kilometers, leading to an improved more specific implementation of low-key preventive actions, like those recommended by UNESCO as early as in 1991.