PROBABILITY OF CHANCE CORRELATIONS OF EARTHQUAKES WITH PREDICTIONS INAREAS OF HETEROGENEOUS SEISMICITY RATE - THE VAN CASE - REPLY

All conclusions of Wyss and Allmann [1996] (hereafter cited as WA) are wrong, because their methodology is false. For example, WA's main con clusion reads: ''the probability [P] that the observed correlations of [VAN] predictions with earthquakes (...11 out of 23 attempts) was due to chance is estimated as... 96%...'' However, when following WA's pr ocedure exactly, and assuming that all 23 predictions (out of 23 attem pts) are correct, we find a paradox, i.e., values of the probability P larger than unity. In view of this example, any further discussion on WA's claims becomes unnecessary. However, we proceed to detailed repl ies, point by point, in order to show that WA have also made several m istakes and major misinterpretations of the true content of VAN's stat ements. Characteristic examples of the various misinterpretations (and mistakes) made by WA include: (i) a direct comparison of predicted ma gnitude values with M(s);(PDE), while VAN had clearly stated that the magnitude values mentioned in the predictions correspond to M(s)(ATH), i.e., to M(L)+0.5. Such a comparison is not allowed because M(L)+0.5 significantly differs (i.e., on the average by 1.0 unit) from M(s)(PDE ), (ii) an addition (or deletion) of critical wording to the VAN state ments (and predictions) so that they distort VAN's true meaning, (iii) the use of 22 day prediction time window in the large majority of pre dictions which, however, correspond to single SES (and hence to an 11 days prediction time window), (iv) an incorrect statement that Varotso s et al. [1993a,b] define the acceptable uncertainty as Delta M less t han or equal to 1.0, while VAN repeatedly published that a prediction is accepted as successful only when Delta M less than or equal to 0.7, (v) an erroneous claim that when using SI-NOA ''12 out of 22 VAN pred ictions fail to conform to the error limits,'' while the reader can ea sily check that only 6 (or 7) out of 23 cases deviate from the error l imits. Furthermore, WA grossly overestimated the number of the earthqu akes (EQs) that should have been predicted, i.e., while VAN clearly st ated that predictions are issued only when the expected magnitude is l arger than (or equal to) 5.0 units, WA erroneously demand that VAN sho uld predict all EQs with M(s) greater than or equal to 4.3 or M(s) gre ater than or equal to 4.0. Hence they characterize as a ''missed earth quake'' any event with M(s) greater than or equal to 4.3 (or M(s) grea ter than or equal to 4.0 respectively)for which prediction was not iss ued. Last but not least, we recall that Wyss and Baer [1981] published long term predictions in Greece (for the same time period discussed i n this debate) -referring to expected EQs with magnitude 7.75- which t urned out to be completely unsuccessful.