Loss of self-organized criticality in a cascaded sandpile

Abstract

We observe an abrupt loss of SOC behavior in a multi-layer cascade where lower piles are driven by the higher ones. Starting from a simple sandpile with power-law distribution of avalanche sizes S that scales as S1:3, we recover realistic size distributions from the first and second sandpile layers, showing good correspondence with rainfall and landslide magnitude distributions, respectively. Criticality is lost in as early as the third sandpile layer, with average sizes showing linear relationships with the average waiting times. The SOC behavior is lost when driving forces (inter-sandpile cascades) dominate over local stress redistribution mechanisms (intrasandpile cascades), such that avalanche sizes distributions follow the trend of the waiting time up to a scaling factor.