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Reply to “Probability of chance correlations of earthquakes with predictions in areas of heterogeneous seismicity rate: The VAN Case,” by M. Wyss and A. Allmann
Author(s) -
Varotsos P.,
Eftaxias K.,
Lazaridou M.,
Dologlou E.,
Hadjicontis V.
Publication year - 1996
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/96gl00908
Subject(s) - magnitude (astronomy) , point (geometry) , order (exchange) , induced seismicity , statistics , mathematics , physics , econometrics , philosophy , geology , seismology , economics , geometry , astrophysics , finance
All conclusions of Wyss and Allmann [1996] (hereafter cited as WA ) are wrong, because their methodology is false. For example, WA's main conclusion 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 procedure exactly, and assuming that all 23 predictions (out of 23 attempts) 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 replies, point by point, in order to show that WA have also made several mistakes and major misinterpretations of the true content of VAN's statements. Characteristic examples of the various misinterpretations (and mistakes) made by WA include: (i) a direct comparison of predicted magnitude 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 statements (and predictions) so that they distort VAN's true meaning, (iii) the use of 22 day prediction time window in the large majority of predictions which, however, correspond to single SES (and hence to an 11 days prediction time window), (iv) an incorrect statement that Varotsos et al. [1993a,b] define the acceptable uncertainty as ΔM ≤ 1.0, while VAN repeatedly published that a prediction is accepted as successful only when ΔM ≤ 0.7, (v) an erroneous claim that when using SI‐NOA “12 out of 22 VAN predictions fail to conform to the error limits,” while the reader can easily check that only 6 (or 7) out of 23 cases deviate from the error limits. Furthermore, WA grossly overestimated the number of the earthquakes (EQs) that should have been predicted, i.e., while VAN clearly stated that predictions are issued only when the expected magnitude is larger than (or equal to) 5.0 units, WA erroneously demand that VAN should predict all EQs with M s ≥ 4.3 or M s ≥ 4.0. Hence they characterize as a “missed earthquake” any event with M s ≥ 4.3 (or M s ≥ 4.0 respectively) for which prediction was not issued. Last but not least, we recall that Wyss and Baer [1981] published long term predictions in Greece (for the same time period discussed in this debate) ‐referring to expected EQs with magnitude 7.75‐ which turned out to be completely unsuccessful.