Solar fares activity is investigated by looking at the statistics of the wa
iting times between hard X-ray bursts. It is found that the distribution ha
s a power-law tail which indicates the existence of nontrivial dynamics wit
h long-range correlations. A shell model for MHD turbulence is capable to r
eproduce the power-law distribution through an identification of the interm
ittent bursts of dissipation with solar flares. This result suggests that t
he nonlinear dynamics could play a role more relevant than the particular t
opology associated with the field configuration. Comparisons with results f
rom models based on self-organized criticality are made. (C) 2000 Elsevier
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