Identifying the occurrence time of an impending mainshock: a very recent case

The procedure by means of which the occurrence time of an impending mainshock can be identified by analyzing in natural time the seismicity in the candidate area subsequent to the recording of a precursory seismic electric signals (SES) activity is reviewed. Here, we report the application of this procedure to an <i<M</i<<sub<W</sub< 5.4 mainshock that occurred in Greece on 17 November 2014. This mainshock (which is pretty rare since it is the strongest in that area for more than half a century) was preceded by an SES activity recorded on 27 July 2014, and the results of the natural time analysis reveal that the system approached the critical point (mainshock occurrence) early in the morning on 15 November 2014.