VAN earthquake predictions - an attempt at statistical evaluation

Statistical verification of the VAN or SES (seismic electric signals) predictions from 1987-1989 is considered. The test is carried out with the updated ruies proposed by Varotsos et al. [1996]. Although for the Greek (SI-NOA) earthquake catalog the VAN method formally is successful, this high rate of success is due either to the retroactive adjustment of prediction rules or to the non-randomness of seismicity. A simple prediction algorithm accounting for earthquake clustering (foreshock-mainshock-aftershock sequences), yields similar or even better forecast results. If we remove dependent events from the catalog, the 'prediction effect' becomes statistically insignificant. For the PDE (NOAA) catalog the test shows that the VAN predictions' rate of success can be attributed to chance.