The VAN method – named after P. Varotsos, K. Alexopoulos and K. Nomicos, authors of the 1981 papers describing it[1][2] – measures low frequency electric signals, termed "seismic electric signals" (SES), by which Varotsos and several colleagues claimed to have successfully predicted earthquakes in Greece.
[33] The VAN method has also been used in Japan,[13] but in early attempts success comparable to that achieved in Greece was "difficult" to attain.
[36] The VAN team claim that out of seven mainshocks with magnitude Mw>=6.0 from 2001 through 2010 in the region of latitude N 36° to N 41° and longitude E 19° to E 27°, all but one could be classified with relevant SES activity identified and reported in advance through natural time analysis.
Additionally, they assert that the occurrence time of four of these mainshocks with magnitude Mw>=6.4 were identified to within "a narrow range, a few days to around one week or so.
The VAN team claims that these κ fluctuations exhibit a minimum a few months before a mainshock occurrence and in addition this minimum occurs simultaneously with the initiation of the corresponding SES activity, and that this is the first time in the literature that such a simultaneous appearance of two precursory phenomena in independent datasets of different geophysical observables (electrical measurements, seismicity) has been observed.
No single event correlated at a probability greater than 85%, whereas the level required in statistics for accepting a hypothesis test as positive would more commonly be 95%.
[51] VAN said that the calculations suggested by Wyss would lead to a paradox, i.e., to probability values larger than unity, when applied to an ideal earthquake prediction method.
[55] In 2018, the statistical significance of the method was revisited by the VAN group employing modern techniques, such as event coincidence analysis (ECA)[56] and receiver operating characteristic (ROC),[57] which they interpreted to show that SES exhibit precursory information far beyond chance.
[58] An analysis of the propagation properties of SES in the Earth’s crust showed that it is impossible that signals with the amplitude reported by VAN could have been generated by small earthquakes and transmitted over the several hundred kilometers between the epicenter and the receiving station.
[29] VAN’s publications are further weakened by failure to address the problem of eliminating the many and strong sources of change in the magneto-electric field measured by them, such as telluric currents from weather, and electromagnetic interference (EMI) from man-made signals.
[citation needed] One critical paper (Pham et al 1998) clearly correlates an SES used by the VAN group with digital radio transmissions made from a military base.
[63][64] A work published in 2020[65] examined the statistical significance of the minima of the fluctuations of the order parameter κ1 of seismicity by event coincidence analysis as a possible precursor to strong earthquakes in both regional and global level.
In particular, in the regional studies the time lag was found to be fully compatible with the finding[40] that these mimima are simultaneous with the initiation of SES activities, thus the distinction of the latter precursory signals from those produced by human sources is evident.
With a confidence level of 99.8%, the possibility of this success rate being explained by a random model of earthquake occurrence taking into account the regional factor which includes high seismicity in the prediction area, can be rejected".
[32] Predictions from the early VAN method led to public criticism and the cost associated with false alarms generated ill will.
[67][68] A review of the updated VAN method in 2020 says that it suffers from an abundance of false positives and is therefore not usable as a prediction protocol.