  Energy dissipation is highly intermittent in turbulent plasmas, being
localized in coherent structures such as current sheets. The statistical
analysis of spatial dissipative structures is an effective approach to studying
turbulence. In this paper, we generalize this methodology to investigate
four-dimensional spatiotemporal structures, i.e., dissipative processes
representing sets of interacting coherent structures, which correspond to
flares in astrophysical systems. We develop methods for identifying and
characterizing these processes, and then perform a statistical analysis of
dissipative processes in numerical simulations of driven magnetohydrodynamic
turbulence. We find that processes are often highly complex, long-lived, and
weakly asymmetric in time. They exhibit robust power-law probability
distributions and scaling relations, including a distribution of dissipated
energy with power-law index near -1.75, indicating that intense dissipative
events dominate the overall energy dissipation. We compare our results with the
previously observed statistical properties of solar flares.
