Order parameter fluctuations of seismicity in natural time before and after mainshocks

It is widely accepted that the observed earthquake scaling laws indicate the proximity of the system to a critical point. Using the order parameter (OP) for seismicity suggested on the basis of natural time as well as the detrended fluctuation analysis of the magnitude time-series, we investigate the behavior of seismicity before and after significant earthquakes. The analysis reveals that the fluctuations of the OP before major earthquakes exhibit a characteristic feature which, if quantified properly, may be used as decision variable to predict the occurrence of a large earthquake in the next time step based solely on the magnitudes of previous earthquakes.