Chapter 18 - Times of Increased Probabilities for Occurrence of Catastrophic Earthquakes: 25 Years of Hypothesis Testing in Real Time

Abstract

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. Regretfully, most of currently known earthquake forecast/prediction methods cannot be adequately tested and evaluated just because of lack of a precise definition and/or shortage of data for a reliable verification. A rare exception is the pattern recognition algorithm M8, which was designed in 1984 for prediction of great, magnitude 8, earthquakes, hence its name. This computer-coded algorithm 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. Since then the M8 algorithm has been used for systematic monitoring of seismic activity in a number of seismic regions worldwide. 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 6months 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. The null hypothesis of random recurrence in earthquake-prone areas has been rejected, at least for magnitude 8.0+ and 7.5+ earthquakes. The results of this global experimental testing are indirect confirmations of: (1) earthquake predictability; (2) the existence of dynamic features that are common in different tectonic environments; and (3) diverse behavior in the course of durable phase transitions in complex hierarchical, nonlinear system of blocks and faults of the naturally fractal lithosphere of our planet Earth.