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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 the seismic phenomenon and for its high societal relevance. To this aim, algorithms exist (like CN, M8, and M8S) based on objective recognition of seismicity patterns that have been already tested for some decades for intermediate-term middle-range prediction of strong earthquakes above a preassigned magnitude threshold. Here, we review the fundamental ideas of an integrated approach to earthquake prediction, based on the synergy of high-density geodetic observations (GNSS and SAR) and seismological information, and the results obtained so far through a completely new retrospective analysis of the 2016–17 seismic crisis in Central Italy and the 2012 Emilia sequence, where space-time precursory features are highlighted within intermediate-term ground velocities and seismicity. This integrated approach defines a new paradigm for time-dependent hazard assessment scenarios, and 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.

An operational procedure for time-dependent seismic hazard assessment has been developed during the last 2 decades, which integrates fully formalized earthquake forecasting information from pattern recognition analysis (by CN and M8S algorithms), with the scenario-based neo-deterministic approach to seismic hazard assessment. The algorithms CN and M8S permit to deal with multiple sets of seismic precursors, and use a detectable inverse cascade of the seismic process to allow for a diagnosis of the intervals of time when a strong event is likely to occur inside a specified region. CN and M8S intermediate-term middle-range forecasts for the Italian territory and its surroundings, as well as the related time-dependent ground motion scenarios associated with the alarmed areas, are regularly updated since 2006. We review the results obtained so far by rigorous prospective testing of the developed procedure, including analysis of the statistical significance of issued forecasts, which supports validation of the applied methodologies.

Lessons learnt from the destructive earthquakes occurred during the new millennium provide new opportunities to take action, revise, and improve the procedure for seismic hazard assessment (SHA). A single hazard map cannot meet the requirements from different end-users; the mapping of the expected earthquake ground motion that accounts for events' recurrence may be suitable for insurances. When dealing with cultural heritage and critical structures (e.g., nuclear power plants), where it is necessary to consider extremely long time intervals, the standard hazard estimates are by far unsuitable, due to their basic heuristic limitations. While time-dependent SHA may be suitable to increase earthquake preparedness, by planning adequate mitigation actions, for critical structures (i.e., those for which the consequences of failure are intolerable) the maximum possible seismic input is relevant. Therefore the need for an appropriate estimate of the seismic hazard, aimed not only at the seismic classification of the national territory, but also at the capability of properly accounting for the local amplifications of ground shaking, as well as for the fault properties, is a pressing concern for seismic engineers. A viable alternative to traditional SHA is represented by the use of the scenario earthquakes, characterized at least in terms of magnitude, distance, and faulting style, and by the treatment of complex source processes. The relevance of the realistic modeling, which permits the generalization of empirical observations by means of physically sound theoretical considerations, is evident, as it allows the optimization of the structural design with respect to the site of interest. The time information associated with the scenarios of ground motion, given by the intermediate-term middle-range earthquake predictions, can be useful to public authorities in assigning priorities for timely mitigation actions. Therefore, the approach we have developed naturally supplies realistic time series of ground motion useful to preserve urban settings, historical monuments, and relevant man-made structures.