Times of Increased Probabilities for Occurrence of Catastrophic Earthquakes: 25 Years of Hypothesis Testing in Real Time

Earthquake prediction is an uncertain profession. Many methods for earthquake forecast/prediction have been proposed and some of these methods may be reliable. Some of those might be even useful in mitigating seismic risks and reducing losses due to catastrophic earthquakes and associated phenomena. The pattern recognition algorithm M8, designed in 1984 for prediction of great, magnitude 8, earthquakes, was originally conceived for application targeting other magnitude ranges, so that by 1986 it was already tested in retrospective applications aimed at earthquakes, down to magnitude 5. After successful early forecasts of the 1988 Spitak (Armenia) and the 1989 Loma Prieta (California) earthquakes, a rigid test to evaluate the efficiency of the reproducible intermediate-term middle-range earthquake prediction technique has been designed. Since 1991 every 6 months the algorithm M8, along and in combination with its refinement MSc, has been applied in a real-time prediction mode to seismicity of the entire Earth to outline the areas where magnitude 8.0+ and 7.5+ earthquakes are most likely to occur before the next update. Each of the four statistics achieved to date in the Global Test proves with confidence above 99 percent rather high efficiency of the M8 and M8-MSc predictions limited to intermediate-term middle- and narrow-range accuracy. After 50 semiannual updates in the real-time prediction mode, we (1) confirm statistically approved high confidence of the M8–MSc predictions and (2) conclude a possibility of expanding the territory of the Global Test of the algorithms M8 and MSc.