Comparison of the semi-major axis evolution (solid black) in the FARGO simulations vs. the azimuthally averaged surface density at the 2:1 (solid blue) and 3:2 (solid orange) mean motion resonance location in the corresponding disc. Only the runs in which the planet was parked due to planet-disc interactions are shown. The horizontal dotted lines are drawn at Σ_2:1 = 10⁻¹ g cm^‒2 and Σ_3:2 = 10⁻² g cm^‒2 and cross the corresponding vertical line where the planet is considered to be parked fully.