Complex systems are open dynamical systems consisting of units with simple and predictable features. However, the unique characteristic of the kind of systems is the unpredictable behavior of an assembly of such units. This behavior has no direct relation with the individual properties of each component of the system. The sandpile model is a simple demonstration of this kind of complex system with the sand grains as the basic units. In this model, just one condition is established, for the occurrence of an avalanche which may have a variable size depending on the topplings. The topplings appear always when the condition for avalanche is reached. The relation between the avalanche size and its frequency follows a power law.
self organized criticality; sandpile; power law
