Earthquakes can be stress‐forecast

SUMMARY In 1997, Geller et al. wrote ‘Earthquakes Cannot Be Predicted’ because scale invariance is ubiquitous in self‐organized critical systems, and the Earth is in a state of self‐organized criticality where small earthquakes have some probability of cascading into a large event. Physically however, large earthquakes can only occur if there is sufficient stress‐energy available for release by the specific earthquake magnitude. This stress dependence can be exploited for stress‐forecasting by using shear wave splitting to monitor stress‐accumulation in the rock mass surrounding impending earthquakes. The technique is arguably successful but, because of the assumed unpredictability, requires explicit justification before it can be generally accepted. Avalanches are also phenomena with self‐organized criticality. Recent experimental observations of avalanches in 2‐D piles of spherical beads show that natural physical phenomena with self‐organized criticality, such as avalanches, and earthquakes, can be predicted. The key to predicting both earthquakes and avalanches is monitoring the matrix material, not monitoring impending source zones.