The analysis of the average force for the time series of (a) the random spatial earthquake model with 〈 k 〉 = 228 and N=128², (b) the OFC model with N=128², and (c) the cycle model with k = 4 and N=128². Different curves correspond to β=0.40 (α=0.10), 0.60 (α=0.15), and 0.80 (α=0.20) from up to bottom. Gray lines represent the average force for the time series and red lines are the fitting of the average force data of the system (see table 1 for fitting details).