Comparison of the maximum eccentricity e_max reached by particles at the second-order 1/3 SOR (blue) compared with the first-order 2/3 (red) and 1/2 (green) SORs. Three values µ = 0.1, 0.01, 0.001 are compared. For µ = 0.1, the theoretical e_max associated with the 2/3 and 1/2 resonances at the location of 1/3 resonance are 30% and 8% of that due to 1/3 resonance, respectively. For other µ values the ratios at the 1/3 SOR location scale proportionally to µ^1/2.