PREDICTABILITY OF LARGE AVALANCHES ON A SANDPILE

When grains are added to a large sandpile, quasiperiodic large avalanches maintain the steady state mass. The buildup periods between the large avalanches contain many small avalanches. The size distribution of the small events does not vary during a buildup period but their mean rate of occurrence does. The qualitative behavior of the real sandpile avalanches is identical to the behavior of earthquakes on a model fault proposed by Carlson and Langer. As that model suggests, the running total number of small avalanches can in principle predict the occurrence of the large avalanches.