A FEW CONSIDERATIONS FOR ASCRIBING STATISTICAL SIGNIFICANCE TO EARTHQUAKE PREDICTIONS - REPLY

Several remarks made by Stark [1996] are in basic agreement with those of Varotsos et al. [1996a] (e.g., ''If we choose to issue a predictio n only when the expected magnitude exceeds 5.0, then, if our predictio n algorithm works, we would expect to fail to predict some events with magnitude 5.0 and smaller (and even some larger events)'', '' It is g enerally accepted that ''raw'' seismicity series are not Poisson distr ibuted...'', etc.). However, in this Reply we clarify a few misunderst andings that led Stark [1996] to state that Varotsos et al. [1996a] ma de some erroneous suggestions. We emphasize that the tolerance limits in the big majority of the VAN predictions were not calibrated a poste riori, because these limits were published one year before the period 1987-1989 under discussion. Only in two, out of 25, successful correla tions the Delta t-value was extended, a posteriori; we emphasize, howe ver, that these two predictions were recognized well in advance as bel onging to a new case which was then labelled as SES electrical activit y (sequence of SESs) that differs from the case of single (isolated) S ES. We do agree with the Stark's [1996] suggestions according to which one ''avoids the necessity of specifying a probability distribution f or earthquake variables, a task that is both controversial and problem atic.''