The definition of the released energies is given further below in Sec. We see that the peak energy releases do not temporarly coincidence with the peak numbers of broken beams. The reader familar with magnitude records of earthquakes or of accoustic emission records from laboratory experiments will recognize some ressemblance with our data. In the following we will investigate more closely the temporal clustering of breaking events. We have calculated the lifetime for each burst as the time that elapses between the first and the last breaking event of a burst.
Small bursts occur relatively often while larger bursts are less frequent.
The statistics are made over 729 bursts from 60 samples for and over 862 bursts from 53 crack simulations for . The largest detected burst has a lifetime of approximately . This is also due to the fact that all simulations were stopped after time steps. In order to extract more information from the lifetime distribution we consider in Fig. 9 the less noisy cummulative probability distribution that a given burst has a lifetime shorter or equal to .