PREDICTABILITY OF LARGE AVALANCHES ON A SANDPILE

When grains are added to a large sandpile, quasiperiodic large avalanc hes maintain the steady state mass. The buildup periods between the la rge 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 sandpil e avalanches is identical to the behavior of earthquakes on a model fa ult proposed by Carlson and Langer. As that model suggests, the runnin g total number of small avalanches can in principle predict the occurr ence of the large avalanches.